warn when a handler didn't complete its job

issue #16
for some reason I couldn't get it to work
it looked like the options weren't properly parsed

.editorconfig

@@ -1,8 +0,0 @@
-root = true
-
-[*]
-end_of_line = lf
-insert_final_newline = true
-charset = utf-8
-ident_style = tab
-max_line_length = 100

.gitignore

@@ -1 +1,3 @@
 /build
+tests/catch.h
+src/version.h

CHANGELOG.md

@@ -1,108 +0,0 @@
-opustags changelog
-==================
-
-1.10.1 - 2024-05-19
--------------------
-
-Fix a build error on recent systems.
-
-1.10.0 - 2024-05-03
--------------------
-
-- Introduce -z to delimit tags with null bytes.
-
-This option makes it possible to leverage GNU sed or GNU grep for automated tag edition with
-`opustags -z … | sed -z … | opustags -z -S …`, while also supporting multi-line tags.
-
-1.9.0 - 2023-06-07
-------------------
-
-- Introduce --vendor and --set-vendor.
-- Close the input file before finalizing the output, in order to fix --in-place on SMB drives.
-
-1.8.0 - 2023-03-07
-------------------
-
-- Introduce --set-cover and --output-cover.
-
-opustags is now able to extract and edit the cover art of Opus files. The underlying
-METADATA_BLOCK_PICTURE tag will still appear as a regular tag, but you won’t have to handle it
-manually anymore.
-
-1.7.0 - 2023-02-13
-------------------
-
-- Support arbitrary large OpusTags headers.
-- Handle multiline tags by prefixing their continuation lines with tabs.
-
-1.6.0 - 2021-01-01
-------------------
-
-- UTF-8 conversion errors are now fatal.
-- Introduce --raw for disabling encoding conversions.
-- Improve platform compatibility.
-
-This also happens to be opustags’s 8-year anniversary!
-
-1.5.1 - 2020-11-21
-------------------
-
-- Improve BSD support.
-
-1.5.0 - 2020-11-08
-------------------
-
-- Introduce --edit for interactive edition.
-
-1.4.0 - 2020-10-04
-------------------
-
-- Preserve permissions when overwriting files.
-- Support multiple files with --in-place.
-- Fix BSD support.
-
-Thanks to Reuben Thomas for contributing the pièce de résistance of this
-release!
-
-1.3.0 - 2019-02-02
-------------------
-
-- Support for non-Unicode systems. Tags are automatically converted to and from the system locale.
-- It is now possible to delete specific NAME=VALUE pairs.
-- Option `--set-all` is now stricter and aborts with an error if the input is not valid.
-- Printing tags will display a warning if the tags contain control characters.
-
-opustags is now more aware of its limitations, and will print more helpful error messages when
-trying to edit an unsupported file. It is also more cautious against corrupted streams.
-
-1.2.0 - 2018-11-25
-------------------
-
-- Preserve extra data in OpusTags past the comments.
-- Improve error reporting.
-- Fix various bugs.
-
-This is the biggest release for opustags. The whole code base was reviewed for robustness and
-clarity. The program is now built as C++14, and the code refactored without sacrificing the
-original simplicity. It is shipped with a new test suite.
-
-1.1.1 - 2018-10-24
-------------------
-
-- Mac OS X support.
-- Tolerate but truncate the data in the OpusTags packet past the comments.
-
-1.1 - 2013-01-02
-----------------
-
-- Add the --in-place option.
-- Fix a bug is --set-all where the last unterminated line was ignored.
-- Remove broken output files on failure.
-
-1.0 - 2013-01-01
-----------------
-
-This is the first release of opustags. It supports all the main feature for basic tag editing.
-
-It was written in a day, and the code is quick and dirty, though the program is simple and
-efficient.

CMakeLists.txt

@@ -1,56 +1,78 @@
-cmake_minimum_required(VERSION 3.11)
+cmake_minimum_required (VERSION 2.8.8)
+project (opustags)
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD_REQUIRED on)
+set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/modules/")
+set(CMAKE_SOURCE_DIR "${CMAKE_BINARY_DIR}/../")
 
-project(
-	opustags
-	VERSION 1.10.1
-	LANGUAGES CXX
-)
+# ------------
+# Dependencies
+# ------------
+find_package(Ogg REQUIRED)
+include_directories(${Ogg_INCLUDE_DIR})
+link_directories(${Ogg_LIBRARY_DIRS})
 
-set(CMAKE_CXX_STANDARD 20)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
+# --------------------
+# Global build options
+# --------------------
+if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wextra")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pedantic")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wold-style-cast")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unused-parameter")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14") # for MinGW-w64
+endif()
 
-# opustags is mainly developed with glibc, which introduces a few
-# incompatibilites with BSDs, like getline not being defined by default.
-# _GNU_SOURCE should trigger BSD’s libc GNU compatibility mode to fix that.
-add_definitions(-D_GNU_SOURCE)
+# -------
+# Version
+# -------
+execute_process(COMMAND git describe --tags --abbrev=0 OUTPUT_VARIABLE VERSION_SHORT OUTPUT_STRIP_TRAILING_WHITESPACE)
+execute_process(COMMAND git describe --always --dirty --long --tags OUTPUT_VARIABLE VERSION_LONG OUTPUT_STRIP_TRAILING_WHITESPACE)
+if("${VERSION_SHORT}" STREQUAL "")
+    set(VERSION_SHORT "0.0")
+    set(VERSION_LONG "?")
+endif()
+configure_file("${CMAKE_SOURCE_DIR}/src/version.h.in" "${CMAKE_SOURCE_DIR}/src/version.h" @ONLY)
 
-find_package(PkgConfig REQUIRED)
-pkg_check_modules(OGG REQUIRED ogg)
-add_compile_options(${OGG_CFLAGS})
-link_directories(${OGG_LIBRARY_DIRS})
+# ------------
+# Source files
+# ------------
+file(GLOB_RECURSE common_sources "${CMAKE_SOURCE_DIR}/src/*.cc")
+file(GLOB_RECURSE common_headers "${CMAKE_SOURCE_DIR}/src/*.h")
+file(GLOB_RECURSE test_sources "${CMAKE_SOURCE_DIR}/tests/*.cc")
+file(GLOB_RECURSE test_headers "${CMAKE_SOURCE_DIR}/tests/*.h")
+list(REMOVE_ITEM common_sources "${CMAKE_SOURCE_DIR}/src/main.cc")
+list(REMOVE_ITEM test_sources "${CMAKE_SOURCE_DIR}/tests/main.cc")
 
-include(FindIconv)
+# -------------------
+# 3rd party libraries
+# -------------------
+# Catch
+set(CATCH_PATH "${CMAKE_SOURCE_DIR}/tests/catch.h")
+if (NOT EXISTS "${CATCH_PATH}")
+    message("Downloading Catch...")
+    file(DOWNLOAD "http://raw.githubusercontent.com/philsquared/Catch/master/single_include/catch.hpp" "${CATCH_PATH}")
+endif()
 
-# We need endian.h on Linux, and sys/endian.h on BSD.
-include(CheckIncludeFileCXX)
-check_include_file_cxx(endian.h HAVE_ENDIAN_H)
-check_include_file_cxx(sys/endian.h HAVE_SYS_ENDIAN_H)
+# ------------
+# Installation
+# ------------
+install(FILES ${CMAKE_SOURCE_DIR}/doc/opustags.1 DESTINATION ${CMAKE_INSTALL_PREFIX}/man/man1)
+install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/opustags DESTINATION ${CMAKE_INSTALL_PREFIX}/bin)
+add_custom_target(uninstall COMMAND
+    rm -f "${CMAKE_INSTALL_PREFIX}/man/man1/opustags.1" &&
+    rm -f "${CMAKE_INSTALL_PREFIX}/bin/opustags" )
 
-include(CheckStructHasMember)
-check_struct_has_member("struct stat" st_mtim sys/stat.h HAVE_STAT_ST_MTIM LANGUAGE CXX)
-check_struct_has_member("struct stat" st_mtimespec sys/stat.h HAVE_STAT_ST_MTIMESPEC LANGUAGE CXX)
-
-configure_file(src/config.h.in config.h @ONLY)
-include_directories(BEFORE src "${CMAKE_BINARY_DIR}" ${OGG_INCLUDE_DIRS} ${Iconv_INCLUDE_DIRS})
-
-add_library(
-	ot
-	STATIC
-	src/base64.cc
-	src/cli.cc
-	src/ogg.cc
-	src/opus.cc
-	src/system.cc
-)
-target_link_libraries(ot PUBLIC ${OGG_LIBRARIES} ${Iconv_LIBRARIES})
-
-add_executable(opustags src/opustags.cc)
-target_link_libraries(opustags ot)
-
-include(GNUInstallDirs)
-install(TARGETS opustags DESTINATION "${CMAKE_INSTALL_BINDIR}")
-configure_file(opustags.1 . @ONLY)
-install(FILES "${CMAKE_BINARY_DIR}/opustags.1" DESTINATION "${CMAKE_INSTALL_MANDIR}/man1")
-install(FILES CHANGELOG.md CONTRIBUTING.md LICENSE README.md DESTINATION ${CMAKE_INSTALL_DOCDIR})
-
-add_subdirectory(t)
+# -------------------
+# Linking definitions
+# -------------------
+add_library(common OBJECT ${common_sources} ${common_headers})
+add_executable(opustags "${CMAKE_SOURCE_DIR}/src/main.cc" $<TARGET_OBJECTS:common>)
+add_executable(run_tests "${CMAKE_SOURCE_DIR}/tests/main.cc" $<TARGET_OBJECTS:common> ${test_sources} ${test_headers})
+target_link_libraries(opustags ${OGG_LIBRARY})
+target_link_libraries(run_tests ${OGG_LIBRARY})
+target_include_directories(common BEFORE PUBLIC "${CMAKE_SOURCE_DIR}/src")
+target_include_directories(opustags BEFORE PUBLIC "${CMAKE_SOURCE_DIR}/src")
+target_include_directories(run_tests BEFORE PUBLIC "${CMAKE_SOURCE_DIR}/src")
+target_include_directories(run_tests BEFORE PUBLIC "${CMAKE_SOURCE_DIR}/tests")

CONTRIBUTING.md

@@ -1,70 +0,0 @@
-# Contributing to opustags
-
-opustags should now be mature enough, and contributions for new features are
-welcome.
-
-Before you open a pull request, you might want to talk about the change you'd
-like to make to make sure it's relevant. In that case, feel free to open an
-issue. You can expect a response within a week.
-
-## Submitting pull requests
-
-opustags has nothing really special, so basic git etiquette is just enough.
-
-Please make focused pull requests, one feature at a time. Don't make huge
-commits. Give clear names to your commits and pull requests. Extended
-descriptions are welcome.
-
-Stay objective in your changes. Adding a feature or fixing a bug is a clear
-improvement, but stylistic changes like renaming a function or moving a few
-braces around won't help the project move forward.
-
-You should check that your changes don't break the test suite by running
-`make check`
-
-Following these practices is important to keep the history clean, and to allow
-for better code reviews.
-
-You can submit pull requests on GitHub at <https://github.com/fmang/opustags>,
-or email me your patches at <fmang+opustags@mg0.fr>.
-
-## History of opustags
-
-opustags is originally a small project made to fill a need to edit tags in Opus
-audio files when most taggers didn't support Opus at all. It was written in C
-with libogg, and should be very light and fast compared to most alternatives.
-However, because it was written on a whim, the code is hardly structured and
-might even be fragile, who knows.
-
-An ambitious desire to rewrite it in C++ with bells and whistles gave birth to
-the `next` branch, but sadly it wasn't finalized and is currently not usable,
-though it contains good pieces of code.
-
-With the growing support of Opus in tag editors, the usefulness of opustags was
-questioned, and it was thus abandoned for a few years. Judging by the
-inquiries and contributions, albeit few, on GitHub, it looks like it remains
-relevant, so let's dust it off a bit.
-
-Today, opustags is written in C++ and features a unit test suite in C++, and
-an integration test suite in Perl. The code was refactored, organized into
-modules, and reviewed for safety.
-
-1.3.0 was focused on correctness, and detects edge cases as early as possible,
-instead of hoping something will eventually fail if something is weird.
-
-Subsequent releases have been adding new features.
-
-## Candidate features
-
-The code contains a few `\todo` markers where something could be improved in the
-code.
-
-More generally, here are a few features that could be added in the future:
-
-- Discouraging non-ASCII field names.
-- Logicial stream listing and selection for multiplexed files.
-- Escaping control characters with --escape.
-- Edition of the arbitrary binary block past the comments.
-- Colored output.
-
-Don't hesitate to contact me before you do anything, I'll give you directions.

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2013-2024, Frédéric Mangano
+Copyright (c) 2013, Frédéric Mangano
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without modification,

README.md

@@ -1,74 +1,45 @@
 opustags
 ========
 
-View and edit Ogg Opus comments.
-
-opustags supports the following features:
-
-- interactive editing using your preferred text editor,
-- batch editing with command-line flags,
-- tags exporting and importing through text files.
-
-opustags is designed to be fast and as conservative as possible, to the point that if you edit tags
-then edit them again to their previous values, you should get a bit-perfect copy of the original
-file. No under-the-cover operation like writing "edited with opustags" or timestamp tagging will
-ever be performed.
-
-opustags is tag-agnostic: you can write arbitrary key-value tags, and none of them will be treated
-specially. After all, common tags like TITLE or ARTIST are nothing more than conventions.
-
-The project’s homepage is located at <https://github.com/fmang/opustags>.
+View and edit Opus comments.
 
 Requirements
 ------------
 
-* a POSIX-compliant system,
-* a C++20 compiler,
-* CMake ≥ 3.11,
-* libogg 1.3.3.
-
-The version numbers are indicative, and it's very likely opustags will build and work fine with
-other versions too, as CMake and libogg are quite mature.
+* A POSIX-compliant system,
+* `libogg`.
 
 Installing
 ----------
 
-opustags is a commonplace CMake project.
-
-Here's how to install it in your `.local`, under your home:
-
-    mkdir build
-    cd build
-    cmake -DCMAKE_INSTALL_PREFIX=~/.local ..
+    mkdir build && cd build
+    cmake ..
     make
     make install
 
-Note that you don't need to install opustags in order to run it, as the executable is standalone.
-
 Documentation
 -------------
 
     Usage: opustags --help
-           opustags [OPTIONS] FILE
-           opustags OPTIONS -i FILE...
-           opustags OPTIONS FILE -o FILE
+           opustags [OPTIONS] INPUT
+           opustags [OPTIONS] -o OUTPUT INPUT
 
     Options:
-      -h, --help                    print this help
-      -o, --output FILE             specify the output file
-      -i, --in-place                overwrite the input files
-      -y, --overwrite               overwrite the output file if it already exists
-      -a, --add FIELD=VALUE         add a comment
-      -d, --delete FIELD[=VALUE]    delete previously existing comments
-      -D, --delete-all              delete all the previously existing comments
-      -s, --set FIELD=VALUE         replace a comment
-      -S, --set-all                 import comments from standard input
-      -e, --edit                    edit tags interactively in VISUAL/EDITOR
-      --output-cover FILE           extract and save the cover art, if any
-      --set-cover FILE              sets the cover art
-      --vendor                      print the vendor string
-      --set-vendor VALUE            set the vendor string
-      --raw                         disable encoding conversion
-      -z                            delimit tags with NUL
+      -h, --help              print this help
+      -V, --version           print version
+      -o, --output FILE       write the modified tags to this file
+      -i, --in-place [SUFFIX] use a temporary file then replace the original file
+      -y, --overwrite         overwrite the output file if it already exists
+          --stream ID         select stream for the next operations
+      -l, --list              display a pretty listing of all tags
+          --no-color          disable colors in --list output
+      -d, --delete FIELD      delete all the fields of a specified type
+      -a, --add FIELD=VALUE   add a field
+      -s, --set FIELD=VALUE   delete then add a field
+      -D, --delete-all        delete all the fields!
+          --full              enable full file scan
+          --export            dump the tags to standard output for --import
+          --import            set the tags from scratch basing on stanard input
+      -e, --edit              spawn the $EDITOR and apply --import on the result
 
 See the man page, `opustags.1`, for extensive documentation.

doc/opustags.1

@@ -0,0 +1,209 @@
+.TH opustags 1 "2016"
+.SH NAME
+opustags \- Opus comment editor
+.SH SYNOPSIS
+.B opustags \-\-help
+.br
+.B opustags
+.RI [ OPTIONS ]
+.I INPUT
+.br
+.B opustags
+.RI [ OPTIONS ]
+.B \-o
+.I OUTPUT INPUT
+.SH DESCRIPTION
+.PP
+\fBopustags\fP can read and edit the comment header of an Opus file.
+It has two modes of operation: read\-only for tag listing, and read\-write for
+tag edition.
+.PP
+Edition mode is triggered by the \fB\-\-ouput\fP and \fB\-\-in\-place\fP
+options. Otherwise, the default mode is listing.
+.PP
+Edition options are incompatible in listing mode, the same way as listing
+options are incompatible in edition mode.
+.PP
+\fIINPUT\fP can either be the name of a file or \fB\-\fP to read from standard input.
+.SS Listing
+.PP
+In listing mode, the tags are printed on standard output. Two listing formats
+are available: pretty and raw. By default, pretty listing is implied if the
+output is a terminal, and raw listing if it isn't.
+.PP
+Pretty listing is enabled with the option \fB\-\-list\fP. Colors are enabled
+unless you use the \fB\-\-no\-color\fP option.
+.PP
+Dumping with \fB\-\-export\fP outputs the raw tags in UTF-8, for automatic
+processing. You can restore exported tags with the \fB\-\-import\fP option.
+.SS Editing
+.PP
+As for the edition mode, you need to specify an output file (or \fB\-\fP for
+standard output). It must be different from the input file. You may want to
+use \fB\-\-overwrite\fP if you know what you're doing. To overwrite the input
+file, use \fB\-\-in\-place\fP.
+.PP
+Tag edition is done with the \fB\-\-add\fP, \fB\-\-delete\fP and \fB\-\-set\fP
+options. You can use these options as many times as you wish.
+.PP
+You can delete all the tags with \fB\-\-delete\-all\fP. This operation can be
+combined with \fB\-\-add\fP to set new tags without being bothered by the old
+ones.
+.PP
+If you want to process tags yourself, you can use the \fB\-\-import\fP option
+which will cause \fBopustags\fP to read tags from standard input. The format
+is the same as the one used for output with \fB\-\-export\fP.
+Note that this option implies \fB\-\-delete\-all\fP.
+Also, input is read as UTF-8.
+.PP
+You can use \fB\-\-edit\fP to spawn your \fBEDITOR\fP and edit the tags
+interactively. In read\-write mode, if no other option is specified, this one
+is implied.
+.SS Stream Selection
+.PP
+In case an Ogg file contains multiple streams, the \fB\-\-stream\fP option lets
+you specify the particular streams to modify. You can modify several streams in
+different ways by using this option more than once. Only operations specified
+after this option and relevant, and until another \fB\-\-stream\fP option is
+found.
+.PP
+	opustags \-\-stream 1 \-\-stream 2 \-\-list # BAD
+.PP
+The above command would only show the second stream. To display both streams,
+use instead:
+.PP
+	opustags \-\-stream 1,2 \-\-list
+.PP
+See also the examples at the end of this page, and the documentation of the
+\fB\-\-stream\fP option.
+.PP
+You can easily find the id's of the available streams by calling opustags with
+no options to list the tags. Usually, you'll only have one stream, id 1.
+.SH OPTIONS
+.SS General
+.TP
+.B \-h, \-\-help
+Display a brief description of the options.
+.TP
+.B \-V, \-\-version
+Display the version of opustags.
+.TP
+.B \-\-stream \fIID\fP
+Specify the stream that will be affected by the options following it. The
+special id \fBall\fP selects all the Opus streams found, and is the default
+value.
+.sp
+The identifer of a stream is determined from its position in the file. The
+first stream found will have id 1, the second 2, and so on.
+.sp
+You can select more than one stream with this option by separated id's with commas. For example: \-\-stream 1,3. Ranges are not supported.
+.sp
+In edition mode, this option should be set if the input file contains more than
+one Opus stream, otherwise a warning is generated. If in\-place modification is
+selected, this warning becomes a fatal error.
+.SS Listing
+.TP
+.B \-l, \-\-list
+Display a pretty listing of all the tags found. This is the default option in
+read\-only mode if the standard output is a terminal.
+.TP
+.B \-\-no\-color
+By default, when listing tags with \fB\-\-list\fP, colors are used. Use this
+option to disable it.
+.TP
+.B \-\-export
+Dump the tags on standard output in a format compatible with \fB\-\-import\fP.
+If only one stream is specified, the output format is compatible with other
+tools such as vorbiscomment.
+.sp
+When exporting, output is encoded in UTF\-8 in
+order not to lose information.
+.TP
+.B \-\-full
+For performance reasons, only the beginning of the input is read, because
+that's where tags are expected. If, however, you think you have an
+unconventional file and you suspect that opustags is missing some streams, you
+can use this option to force it to read the whole file.
+.sp
+This option shouldn't be needed, but if you do find files that require this
+option, please submit a bug report (see the bottom of the page).
+.SS Edition
+.TP
+.B \-o, \-\-output \fIFILE\fI
+Edition mode. The input file will be read, its tags edited, then written to the
+specified output file. If \fIFILE\fP is \fB\-\fP then the resulting Opus file
+will be written to standard output. The output file can't be the same as the
+input file, use \fB\-\-in\-place\fP instead. This option may be specified at
+most once.
+.TP
+.B \-i, \-\-in\-place \fR[\fP\fISUFFIX\fP\fR]\fP
+Use this when you want to modify the input file in\-place. This creates a
+temporary file with the specified suffix (\fI.otmp\fP by default). This implies
+\fB\-\-overwrite\fP in that if a file with the same temporary name already
+exists, it will be overwritten without warning. Of course, this overwrites the
+input file too. You cannot use this option when the input file is the standard
+input.
+.TP
+.B \-y, \-\-overwrite
+By default, opustags refuses to overwrite an already existent file. Use
+this option to allow that.
+.TP
+.B \-d, \-\-delete \fIFIELD\fP
+Delete all the tags whose field name is \fIFIELD\fP. Note that one tag key,
+like \fIARTIST\fP, may appear more than once, in which case all of those are
+deleted.
+.TP
+.B \-a, \-\-add \fIFIELD=VALUE\fP
+Add a tag. It doesn't matter if a tag of the same type already exist (think
+about the case where there are several artists).
+.TP
+.B \-s, \-\-set \fIFIELD=VALUE\fP
+This option is provided for convenience. It deletes all the fields of the same
+type that may already exist, then adds it with the wanted value. This is
+strictly equivalent to \fB\-\-delete\fP \fIFIELD\fP \fB\-\-add\fP
+\fIFIELD=VALUE\fP.
+You can combine it with \fB\-\-add\fP to add more tags with that same \fIFIELD\fP.
+.TP
+.B \-D, \-\-delete\-all
+Delete all the tags before adding any.
+.TP
+.B \-\-import
+Set the tags from scratch. All the original tags are deleted and new ones are
+read from standard input.
+.sp
+Each line must specify a \fIFIELD=VALUE\fP pair and be LF\-terminated (except
+for the last line). Invalid lines are skipped and issue a warning. Blank lines
+are ignored. Lines whose first non-blank character is \fB#\fP are ignored.
+Blank characters at the beginning of a line are also skipped.
+.sp
+Input is read as UTF\-8, disregarding the current locale of your system.
+.TP
+.B \-e, \-\-edit
+Spawn the program specified in the environment variable \fBEDITOR\fP to edit
+tags interactively. If this variable can't be read or is empty, an error
+message is displayed.
+.sp
+The expected format is the same as the one \fB\-\-import\fP expects.
+.SH EXAMPLES
+Here's how you would list all tags in a stream:
+.PP
+	opustags in.ogg
+.PP
+Here's how you would edit two streams at once, setting the title and artist of
+the first, and only the title of the second:
+.PP
+	opustags \-\-stream 1 \-\-set TITLE=X \-\-set ARTIST=Y \-\-stream 2 \-\-set TITLE=Y in.ogg \-o out.ogg
+.PP
+Here's how you would set two artists:
+.PP
+	opustags \-\-delete ARTIST \-\-add ARTIST=A \-\-add ARTIST=B in.ogg \-o out.ogg
+.PP
+Hoping that helped!
+.SH SEE ALSO
+.BR vorbiscomment (1),
+.BR sed (1)
+.SH AUTHORS
+Frédéric Mangano <fmang+opustags@mg0.fr>,
+rr\- <https://github.com/rr\->.
+.PP
+Please report issues on GitHub at <https://github.com/fmang/opustags/issues>.

modules/FindOgg.cmake

@@ -0,0 +1,23 @@
+# Base Io build system
+# Written by Jeremy Tregunna <jeremy.tregunna@me.com>
+#
+# Find libogg.
+
+FIND_PATH(OGG_INCLUDE_DIR ogg/ogg.h)
+
+SET(OGG_NAMES ${OGG_NAMES} ogg libogg)
+FIND_LIBRARY(OGG_LIBRARY NAMES ${OGG_NAMES} PATH)
+
+IF(OGG_INCLUDE_DIR AND OGG_LIBRARY)
+	SET(OGG_FOUND TRUE)
+ENDIF(OGG_INCLUDE_DIR AND OGG_LIBRARY)
+
+IF(OGG_FOUND)
+	IF(NOT Ogg_FIND_QUIETLY)
+		MESSAGE(STATUS "Found Ogg: ${OGG_LIBRARY}")
+	ENDIF (NOT Ogg_FIND_QUIETLY)
+ELSE(OGG_FOUND)
+	IF(Ogg_FIND_REQUIRED)
+		MESSAGE(FATAL_ERROR "Could not find ogg")
+	ENDIF(Ogg_FIND_REQUIRED)
+ENDIF (OGG_FOUND)

opustags.1

@@ -1,189 +0,0 @@
-.TH opustags 1 "April 2024" "@PROJECT_NAME@ @PROJECT_VERSION@"
-.SH NAME
-opustags \- Ogg Opus tag editor
-.SH SYNOPSIS
-.B opustags --help
-.br
-.B opustags
-.RI [ OPTIONS ]
-.I INPUT
-.br
-.B opustags
-.I OPTIONS
-.B -i
-\fIFILE\fP...
-.br
-.B opustags
-.I OPTIONS
-.B -o
-.I OUTPUT INPUT
-.SH DESCRIPTION
-.PP
-\fBopustags\fP can read and edit the comment header of an Ogg Opus file.
-It has two modes: read-only, and read-write for tag editing.
-.PP
-In read-only mode, only the beginning of \fIINPUT\fP is read, and the tags are
-printed on standard output. Lines prefixed by tabs are continuation of the previous tag.
-\fIINPUT\fP can either be the name of a file or \fB-\fP to read from standard input.
-You can use the options below to edit the tags before printing them.
-This could be useful to preview some changes before writing them.
-.PP
-In editing mode, you need to specify an output file with \fB--output\fP, or use \fB--in-place\fP to
-overwrite the input files. If the output is a regular file, the result is first written to a
-temporary file and then moved to its final location on success. On error, the temporary output file
-is deleted.
-.PP
-Tag editing can be performed with the \fB--add\fP, \fB--delete\fP and \fB--set\fP
-options. Options can be specified in any order and don’t conflict with each other.
-First the specified tags are deleted, then the new tags are added.
-.PP
-You can delete all the tags with \fB--delete-all\fP. This operation can be combined with \fB--add\fP
-to set new tags without being bothered by the old ones.
-.PP
-If you want to replace all the tags, you can use the \fB--set-all\fP option which will cause
-\fBopustags\fP to read tags from standard input.
-The format is the same as the one used for output: newline-separated \fIFIELD=Value\fP assignment.
-All the previously existing tags as deleted.
-.PP
-The Opus format specifications requires that tags are encoded in UTF-8, so that's the only encoding
-opustags supports. If your system encoding is different, the tags are automatically converted to and
-from your system locale. When you edit an Opus file whose tags contains characters unsupported by
-your system encoding, the original UTF-8 values will be preserved for the tags you don't explicitly
-modify.
-.SH OPTIONS
-.TP
-.B \-h, \-\-help
-Display a brief description of the options.
-.TP
-.B \-o, \-\-output \fIFILE\fI
-Specify the output file.
-The input file will be read, its tags edited, then written to the specified output file. If
-\fIFILE\fP is \fB-\fP then the resulting Opus file will be written to standard output.
-The output file can’t be the same as the input file.
-.TP
-.B \-i, \-\-in-place
-Overwrite the input file instead of creating a separate output file. It has the same effect as
-setting \fB--output\fP to the same path as the input file and enabling \fB--overwrite\fP.
-This option conflicts with \fB--output\fP.
-.TP
-.B \-y, \-\-overwrite
-By default, \fBopustags\fP refuses to overwrite an already-existent file.
-Use \fB-y\fP to allow overwriting.
-Note that this option is not needed when the output is a special file like \fI/dev/null\fP.
-.TP
-.B \-d, \-\-delete \fIFIELD[=VALUE]\fP
-If value is not specified, delete all the tags whose field name is \fIFIELD\fP.
-Otherwise, delete all the comments whose field name is \fIFIELD\fP and value is \fIVALUE\fP.
-In both cases, the field names are case-insensitive, and expected to be ASCII.
-.TP
-.B \-a, \-\-add \fIFIELD=VALUE\fP
-Add a tag. Note that multiple tags with the same field name are perfectly acceptable, so you can add
-multiple fields with the same name, and previously existing tags will also be preserved.
-When the \fB--delete\fP is used with the same \fIFIELD\fP, only the older tags are deleted.
-.TP
-.B \-s, \-\-set \fIFIELD=VALUE\fP
-This option is provided for convenience. It delete all the fields of the same
-type that may already exist, then adds it with the wanted value.
-This is strictly equivalent to \fB--delete\fP \fIFIELD\fP \fB--add\fP
-\fIFIELD=VALUE\fP. You can combine it with \fB--add\fP to add tags of the same
-type. As deletion occurs before adding, \fB--set\fP won’t erase the tags
-added with \fB--add\fP.
-.TP
-.B \-D, \-\-delete-all
-Delete all the previously existing tags.
-.TP
-.B \-S, \-\-set-all
-Sets the tags from scratch.
-All the original tags are deleted and new ones are read from standard input.
-Each line must specify a \fIFIELD=VALUE\fP pair and be separated with line feeds.
-Empty lines and lines starting with \fI#\fP are ignored.
-Multiline tags must have their continuation lines prefixed by a single tab (in other words, every
-\fI\\n\fP must be replaced by \fI\\n\\t\fP).
-.TP
-.B \-e, \-\-edit
-Edit tags interactively by spawning the program specified by the EDITOR
-environment variable. The allowed format is the same as \fB--set-all\fP.
-If TERM and VISUAL are set, VISUAL takes precedence over EDITOR.
-.TP
-.B \-\-output-cover \fIFILE\fP
-Save the cover art of the input Opus file to the specified location.
-If the input file does not contain any cover art, this option has no effect.
-To allow overwriting the target location, specify \fB--overwrite\fP.
-In the case of multiple pictures embedded in the Opus tags, only the first one is saved.
-Note that the since the image format is not fixed, you should consider an extension-less file name
-and rely on the magic number to deduce the type. opustags does not add or check the target file’s
-extension.
-You can specify \fB-\fP for standard output, in which case the regular output will be suppressed.
-.TP
-.B \-\-set-cover \fIFILE\fP
-Replace or set the cover art to the specified picture.
-Specify \fB-\fP to read the picture from standard input.
-In theory, an Opus file may contain multiple pictures with different roles, though in practice only
-the front cover really matters. opustags can currently only handle one front cover and nothing else.
-.TP
-.B \-\-vendor
-Print the vendor string from the OpusTags packet and do nothing else. Standard tags operations are
-not supported when specifying this flag.
-.TP
-.B \-\-set-vendor \fIVALUE\fP
-Replace the vendor string by the specified value. This action can be performed alongside tag
-edition.
-.TP
-.B \-\-raw
-OpusTags metadata should always be encoded in UTF-8, as per RFC 7845. However, some files may be
-corrupted or possibly even contain intentional binary data. In that case, --raw lets you edit that
-kind of binary data without ensuring the validity of the tags encoding. This option may also be
-useful when your system encoding is different from UTF-8 and you wish to preserve the full UTF-8
-character set even though your system cannot display it.
-.TP
-.B \-z
-When editing tags programmatically with line-based tools like grep or sed, tags containing newlines
-are likely to corrupt the result because these tools won’t interpret multi-line tags as a whole. To
-make automatic processing easier, \fB-z\fP delimits tags by a null byte (ASCII NUL) instead of line
-feeds. That same \fB-z\fP flag is also supported by GNU grep or GNU sed and, combined with opustags
--z, would make them process the input tag-by-tag instead of line-by-line, thus supporting multi-line
-tags as well. This option also disables the TAB prefix for continuation lines after a line feed.
-.SH EXAMPLES
-.PP
-List all the tags in file foo.opus:
-.PP
-	opustags foo.opus
-.PP
-Copy in.opus to out.opus, with the TITLE tag added:
-.PP
-	opustags in.opus --output out.opus --add "TITLE=Hello world!"
-.PP
-Remove the previously existing ARTIST tags and add the two X and Y ARTIST tags, then display the new
-tags without writing them to the Opus file:
-.PP
-	opustags in.opus --add ARTIST=X --add ARTIST=Y --delete ARTIST
-.PP
-Edit tags interactively in Vim:
-.PP
-	EDITOR=vim opustags --in-place --edit file.opus
-.PP
-Replace all the tags in dest.opus with the ones from src.opus:
-.PP
-	opustags src.opus | opustags --in-place dest.opus --set-all
-.PP
-Use GNU grep to remove all the CHAPTER* tags, with -z to support multi-line tags:
-.PP
-	opustags -z file.opus | grep -z -v ^CHAPTER | opustags -z --in-place file.opus --set-all
-.SH CAVEATS
-.PP
-\fBopustags\fP currently has the following limitations:
-.IP \[bu]
-Multiplexed streams are not supported.
-.IP \[bu]
-Control characters inside tags are printed raw rather than being escaped.
-.PP
-Internally, the OpusTags packet in an Ogg Opus file may contain extra arbitrary binary data after
-the comments.  This block of data is currently not editable, but is always preserved. The same
-applies for the vendor string.
-.PP
-If you need a feature not currently supported, feel free to open an issue or send an email with your
-use case.
-.SH AUTHOR
-Frédéric Mangano <fmang+opustags@mg0.fr>
-.PP
-Report bugs at <https://github.com/fmang/opustags/issues>

src/actions.cc

@@ -0,0 +1,83 @@
+#include "actions.h"
+
+using namespace opustags;
+
+void opustags::list_tags(ogg::Decoder &dec, ITagsHandler &handler, bool full)
+{
+    std::map<long, int> sequence_numbers;
+    int stream_count = 0;
+    int remaining_streams = 0;
+    std::shared_ptr<ogg::Stream> s;
+    while (!handler.done()) {
+        s = dec.read_page();
+        if (s == nullptr)
+            break; // end of stream
+        switch (s->state) {
+            case ogg::HEADER_READY:
+                stream_count++;
+                sequence_numbers[s->stream.serialno] = stream_count;
+                handler.start_of_stream(stream_count, s->type);
+                if (!handler.relevant(stream_count))
+                    s->downgrade();
+                remaining_streams++;
+                break;
+            case ogg::TAGS_READY:
+                handler.list(sequence_numbers[s->stream.serialno], s->tags);
+                s->downgrade(); // no more use for it
+            default:
+                remaining_streams--;
+        }
+        if (!full && remaining_streams <= 0) {
+            break;
+            // premature exit, but calls end_of_stream anyway
+            // we want our optimization to be transparent to the TagsHandler
+        }
+    }
+    handler.end_of_file();
+}
+
+void opustags::edit_tags(
+    ogg::Decoder &in, ogg::Encoder &out, ITagsHandler &handler)
+{
+    std::map<long, int> sequence_numbers;
+    int stream_count = 0;
+    std::shared_ptr<ogg::Stream> s;
+    for (;;) {
+        s = in.read_page();
+        if (s == nullptr)
+            break; // end of stream
+        switch (s->state) {
+
+            case ogg::HEADER_READY:
+                stream_count++;
+                sequence_numbers[s->stream.serialno] = stream_count;
+                handler.start_of_stream(stream_count, s->type);
+                if (!handler.relevant(stream_count))
+                    s->downgrade(); // makes it UNKNOWN
+                if (s->type == ogg::UNKNOWN_STREAM) {
+                    out.write_raw_page(in.current_page);
+                } else {
+                    out.forward(*s);
+                }
+                break;
+
+            case ogg::TAGS_READY:
+                handler.edit(sequence_numbers[s->stream.serialno], s->tags);
+                handler.list(sequence_numbers[s->stream.serialno], s->tags);
+                out.write_tags(s->stream.serialno, s->tags);
+                break;
+
+            case ogg::DATA_READY:
+                out.forward(*s);
+                break;
+
+            case ogg::RAW_READY:
+                out.write_raw_page(in.current_page);
+                break;
+
+            default:
+                ;
+        }
+    }
+    handler.end_of_file();
+}

src/actions.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "ogg.h"
+#include "tags_handler.h"
+
+namespace opustags {
+
+    // Decode a file and call the handler's list method every time a tags
+    // header is read. Set full to true if you want to make sure every single
+    // page of the stream is read.
+    //
+    // Use:
+    //   std::ifstream in("in.ogg");
+    //   ogg::Decoder dec(in);
+    //   TagsLister lister(options);
+    //   list_tags(dec, lister);
+    //
+    void list_tags(ogg::Decoder&, ITagsHandler &, bool full = false);
+
+    // Forward the input data to the output stream, transforming tags on-the-go
+    // with the handler's edit method.
+    //
+    // Use:
+    //   std::ifstream in("in.ogg");
+    //   ogg::Decoder dec(in);
+    //   std::ofstream out("out.ogg");
+    //   std::Encoder enc(out);
+    //   TagsEditor editor(options);
+    //   edit_tags(dec, enc, editor);
+    //
+    void edit_tags(ogg::Decoder &in, ogg::Encoder &out, ITagsHandler &);
+
+}

src/base64.cc

@@ -1,97 +0,0 @@
-/**
- * \file src/base64.cc
- * \brief Base64 encoding/decoding (RFC 4648).
- *
- * Inspired by Jouni Malinen’s BSD implementation at
- * <http://web.mit.edu/freebsd/head/contrib/wpa/src/utils/base64.c>.
- *
- * This implementation is used to decode the cover arts embedded in the tags. According to
- * <https://wiki.xiph.org/VorbisComment>, line feeds are not allowed and padding is required.
- */
-
-#include <opustags.h>
-
-#include <string.h>
-
-static const char8_t base64_table[65] =
-	u8"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-
-std::u8string ot::encode_base64(ot::byte_string_view src)
-{
-	size_t len = src.size();
-	size_t num_blocks = (len + 2) / 3; // Count of 3-byte blocks, rounded up.
-	size_t olen = num_blocks * 4; // Each 3-byte block becomes 4 base64 bytes.
-	if (olen < len)
-		throw std::overflow_error("failed to encode excessively long base64 block");
-
-	std::u8string out;
-	out.resize(olen);
-
-	const uint8_t* in = src.data();
-	const uint8_t* end = in + len;
-	char8_t* pos = out.data();
-	while (end - in >= 3) {
-		*pos++ = base64_table[in[0] >> 2];
-		*pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
-		*pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
-		*pos++ = base64_table[in[2] & 0x3f];
-		in += 3;
-	}
-
-	if (end - in) {
-		*pos++ = base64_table[in[0] >> 2];
-		if (end - in == 1) {
-			*pos++ = base64_table[(in[0] & 0x03) << 4];
-			*pos++ = '=';
-		} else { // end - in == 2
-			*pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
-			*pos++ = base64_table[(in[1] & 0x0f) << 2];
-		}
-		*pos++ = '=';
-	}
-
-	return out;
-}
-
-ot::byte_string ot::decode_base64(std::u8string_view src)
-{
-	// Remove the padding and rely on the string length instead.
-	while (src.back() == u8'=')
-		src.remove_suffix(1);
-
-	size_t olen = src.size() / 4 * 3; // Whole blocks;
-	switch (src.size() % 4) {
-		case 1: throw status {st::error, "invalid base64 block size"};
-		case 2: olen += 1; break;
-		case 3: olen += 2; break;
-	}
-
-	ot::byte_string out;
-	out.resize(olen);
-	uint8_t* pos = out.data();
-
-	unsigned char dtable[256];
-	memset(dtable, 0x80, 256);
-	for (size_t i = 0; i < sizeof(base64_table) - 1; ++i)
-		dtable[(size_t) base64_table[i]] = (unsigned char) i;
-
-	unsigned char block[4];
-	size_t count = 0;
-	for (unsigned char c : src) {
-		unsigned char tmp = dtable[c];
-		if (tmp == 0x80)
-			throw status {st::error, "invalid base64 character"};
-
-		block[count++] = tmp;
-		if (count == 2) {
-			*pos++ = (block[0] << 2) | (block[1] >> 4);
-		} else if (count == 3) {
-			*pos++ = (block[1] << 4) | (block[2] >> 2);
-		} else if (count == 4) {
-			*pos++ = (block[2] << 6) | block[3];
-			count = 0;
-		}
-	}
-
-	return out;
-}

src/cli.cc

@@ -1,647 +0,0 @@
-/**
- * \file src/cli.cc
- * \ingroup cli
- *
- * Provide all the features of the opustags executable from a C++ API. The main point of separating
- * this module from the main one is to allow easy testing.
- */
-
-#include <opustags.h>
-
-#include <errno.h>
-#include <getopt.h>
-#include <limits.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/stat.h>
-#include <unistd.h>
-#include <algorithm>
-
-static const char help_message[] =
-PROJECT_NAME " version " PROJECT_VERSION
-R"raw(
-
-Usage: opustags --help
-       opustags [OPTIONS] FILE
-       opustags OPTIONS -i FILE...
-       opustags OPTIONS FILE -o FILE
-
-Options:
-  -h, --help                    print this help
-  -o, --output FILE             specify the output file
-  -i, --in-place                overwrite the input files
-  -y, --overwrite               overwrite the output file if it already exists
-  -a, --add FIELD=VALUE         add a comment
-  -d, --delete FIELD[=VALUE]    delete previously existing comments
-  -D, --delete-all              delete all the previously existing comments
-  -s, --set FIELD=VALUE         replace a comment
-  -S, --set-all                 import comments from standard input
-  -e, --edit                    edit tags interactively in VISUAL/EDITOR
-  --output-cover FILE           extract and save the cover art, if any
-  --set-cover FILE              sets the cover art
-  --vendor                      print the vendor string
-  --set-vendor VALUE            set the vendor string
-  --raw                         disable encoding conversion
-  -z                            delimit tags with NUL
-
-See the man page for extensive documentation.
-)raw";
-
-static struct option getopt_options[] = {
-	{"help", no_argument, 0, 'h'},
-	{"output", required_argument, 0, 'o'},
-	{"in-place", optional_argument, 0, 'i'},
-	{"overwrite", no_argument, 0, 'y'},
-	{"delete", required_argument, 0, 'd'},
-	{"add", required_argument, 0, 'a'},
-	{"set", required_argument, 0, 's'},
-	{"delete-all", no_argument, 0, 'D'},
-	{"set-all", no_argument, 0, 'S'},
-	{"edit", no_argument, 0, 'e'},
-	{"output-cover", required_argument, 0, 'c'},
-	{"set-cover", required_argument, 0, 'C'},
-	{"vendor", no_argument, 0, 'v'},
-	{"set-vendor", required_argument, 0, 'V'},
-	{"raw", no_argument, 0, 'r'},
-	{NULL, 0, 0, 0}
-};
-
-ot::options ot::parse_options(int argc, char** argv, FILE* comments_input)
-{
-	options opt;
-	const char* equal;
-	ot::status rc;
-	std::list<std::string> local_to_add; // opt.to_add before UTF-8 conversion.
-	std::list<std::string> local_to_delete; // opt.to_delete before UTF-8 conversion.
-	bool set_all = false;
-	std::optional<std::string> set_cover;
-	std::optional<std::string> set_vendor;
-	opt = {};
-	if (argc == 1)
-		throw status {st::bad_arguments, "No arguments specified. Use -h for help."};
-	int c;
-	optind = 0;
-	while ((c = getopt_long(argc, argv, ":ho:iyd:a:s:DSez", getopt_options, NULL)) != -1) {
-		switch (c) {
-		case 'h':
-			opt.print_help = true;
-			break;
-		case 'o':
-			if (opt.path_out)
-				throw status {st::bad_arguments, "Cannot specify --output more than once."};
-			opt.path_out = optarg;
-			break;
-		case 'i':
-			opt.in_place = true;
-			opt.overwrite = true;
-			break;
-		case 'y':
-			opt.overwrite = true;
-			break;
-		case 'd':
-			local_to_delete.emplace_back(optarg);
-			break;
-		case 'a':
-		case 's':
-			equal = strchr(optarg, '=');
-			if (equal == nullptr)
-				throw status {st::bad_arguments, "Comment does not contain an equal sign: "s + optarg + "."};
-			if (c == 's')
-				local_to_delete.emplace_back(optarg, equal - optarg);
-			local_to_add.emplace_back(optarg);
-			break;
-		case 'S':
-			opt.delete_all = true;
-			set_all = true;
-			break;
-		case 'D':
-			opt.delete_all = true;
-			break;
-		case 'e':
-			opt.edit_interactively = true;
-			break;
-		case 'c':
-			if (opt.cover_out)
-				throw status {st::bad_arguments, "Cannot specify --output-cover more than once."};
-			opt.cover_out = optarg;
-			break;
-		case 'C':
-			if (set_cover)
-				throw status {st::bad_arguments, "Cannot specify --set-cover more than once."};
-			set_cover = optarg;
-			break;
-		case 'v':
-			opt.print_vendor = true;
-			break;
-		case 'V':
-			if (set_vendor)
-				throw status {st::bad_arguments, "Cannot specify --set-vendor more than once."};
-			set_vendor = optarg;
-			break;
-		case 'r':
-			opt.raw = true;
-			break;
-		case 'z':
-			opt.tag_delimiter = '\0';
-			break;
-		case ':':
-			throw status {st::bad_arguments, "Missing value for option '"s + argv[optind - 1] + "'."};
-		default:
-			throw status {st::bad_arguments, "Unrecognized option '" +
-			              (optopt ? "-"s + static_cast<char>(optopt) : argv[optind - 1]) + "'."};
-		}
-	}
-	if (opt.print_help)
-		return opt;
-
-	// All non-option arguments are input files.
-	size_t stdin_uses = 0;
-	for (int i = optind; i < argc; i++) {
-		if (strcmp(argv[i], "-") == 0)
-			++stdin_uses;
-		opt.paths_in.emplace_back(argv[i]);
-	}
-	bool stdin_as_input = stdin_uses > 0;
-
-	if (set_cover == "-")
-		++stdin_uses;
-	if (set_all)
-		++stdin_uses;
-	if (stdin_uses > 1)
-		throw status { st::bad_arguments, "Cannot use standard input more than once." };
-
-	// Convert arguments to UTF-8.
-	if (opt.raw) {
-		// Cast the user data without any encoding conversion.
-		auto cast_to_utf8 = [](std::string_view in)
-			{ return std::u8string(reinterpret_cast<const char8_t*>(in.data()), in.size()); };
-		std::transform(local_to_add.begin(), local_to_add.end(),
-			       std::back_inserter(opt.to_add), cast_to_utf8);
-		std::transform(local_to_delete.begin(), local_to_delete.end(),
-			       std::back_inserter(opt.to_delete), cast_to_utf8);
-		if (set_vendor)
-			opt.set_vendor = cast_to_utf8(*set_vendor);
-	} else {
-		try {
-			std::transform(local_to_add.begin(), local_to_add.end(),
-			               std::back_inserter(opt.to_add), encode_utf8);
-			std::transform(local_to_delete.begin(), local_to_delete.end(),
-			               std::back_inserter(opt.to_delete), encode_utf8);
-			if (set_vendor)
-				opt.set_vendor = encode_utf8(*set_vendor);
-		} catch (const ot::status& rc) {
-			throw status {st::bad_arguments, "Could not encode argument into UTF-8: " + rc.message};
-		}
-	}
-
-	bool read_only = !opt.in_place && !opt.path_out.has_value();
-
-	if (opt.in_place && opt.path_out)
-		throw status {st::bad_arguments, "Cannot combine --in-place and --output."};
-
-	if (opt.in_place && stdin_as_input)
-		throw status {st::bad_arguments, "Cannot modify standard input in place."};
-
-	if ((!opt.in_place || opt.edit_interactively) && opt.paths_in.size() != 1)
-		throw status {st::bad_arguments, "Exactly one input file must be specified."};
-
-	if (opt.edit_interactively && (stdin_as_input || opt.path_out == "-" || opt.cover_out == "-"))
-		throw status {st::bad_arguments, "Cannot edit interactively when standard input or standard output are already used."};
-
-	if (opt.edit_interactively && read_only)
-		throw status {st::bad_arguments, "Cannot edit interactively when no output is specified."};
-
-	if (opt.edit_interactively && (opt.delete_all || !opt.to_add.empty() || !opt.to_delete.empty()))
-		throw status {st::bad_arguments, "Cannot mix --edit with -adDsS."};
-
-	if (opt.cover_out == "-" && opt.path_out == "-")
-		throw status {st::bad_arguments, "Cannot specify standard output for both --output and --output-cover."};
-
-	if (opt.cover_out && opt.paths_in.size() > 1)
-		throw status {st::bad_arguments, "Cannot use --output-cover with multiple input files."};
-
-	if (opt.print_vendor && !read_only)
-		throw status {st::bad_arguments, "--vendor is only supported in read-only mode."};
-
-	if (set_cover) {
-		byte_string picture_data = ot::slurp_binary_file(set_cover->c_str());
-		opt.to_delete.push_back(u8"METADATA_BLOCK_PICTURE"s);
-		opt.to_add.push_back(ot::make_cover(picture_data));
-	}
-
-	if (set_all) {
-		// Read comments from stdin and prepend them to opt.to_add.
-		std::list<std::u8string> comments = read_comments(comments_input, opt);
-		opt.to_add.splice(opt.to_add.begin(), std::move(comments));
-	}
-	return opt;
-}
-
-/** Format a UTF-8 string by adding tabulations (\t) after line feeds (\n) to mark continuation for
- *  multiline values. With -z, this behavior applies for embedded NUL characters instead of LF. */
-static std::u8string format_value(const std::u8string& source, const ot::options& opt)
-{
-	auto newline_count = std::count(source.begin(), source.end(), opt.tag_delimiter);
-
-	// General case: the value fits on a single line. Use std::string’s copy constructor for the
-	// most efficient copy we could hope for.
-	if (newline_count == 0)
-		return source;
-
-	std::u8string formatted;
-	formatted.reserve(source.size() + newline_count);
-	for (auto c : source) {
-		formatted.push_back(c);
-		if (c == opt.tag_delimiter)
-			formatted.push_back(u8'\t');
-	}
-	return formatted;
-}
-
-/**
- * Convert the comment from UTF-8 to the system encoding if relevant, and print it with a trailing
- * line feed.
- */
-static void puts_utf8(std::u8string_view str, FILE* output, const ot::options& opt)
-{
-	if (opt.raw) {
-		fwrite(str.data(), 1, str.size(), output);
-	} else {
-		try {
-			std::string local = ot::decode_utf8(str);
-			fwrite(local.data(), 1, local.size(), output);
-		} catch (ot::status& rc) {
-			rc.message += " See --raw.";
-			throw;
-		}
-	}
-	putc(opt.tag_delimiter, output);
-}
-
-/**
- * Print comments in a human readable format that can also be read back in by #read_comment.
- *
- * To disambiguate between a newline embedded in a comment and a newline representing the start of
- * the next tag, continuation lines always have a single TAB (^I) character added to the beginning.
- */
-void ot::print_comments(const std::list<std::u8string>& comments, FILE* output, const ot::options& opt)
-{
-	bool has_control = false;
-	for (const std::u8string& source_comment : comments) {
-		if (!has_control) { // Don’t bother analyzing comments if the flag is already up.
-			for (unsigned char c : source_comment) {
-				if (c < 0x20 && c != '\n') {
-					has_control = true;
-					break;
-				}
-			}
-		}
-		std::u8string utf8_comment = format_value(source_comment, opt);
-		puts_utf8(utf8_comment, output, opt);
-	}
-	if (has_control)
-		fputs("warning: Some tags contain control characters.\n", stderr);
-}
-
-std::list<std::u8string> ot::read_comments(FILE* input, const ot::options& opt)
-{
-	std::list<std::u8string> comments;
-	comments.clear();
-	char* source_line = nullptr;
-	size_t buflen = 0;
-	ssize_t nread;
-	std::u8string* previous_comment = nullptr;
-	while ((nread = getdelim(&source_line, &buflen, opt.tag_delimiter, input)) != -1) {
-		if (nread > 0 && source_line[nread - 1] == opt.tag_delimiter)
-			--nread; // Chomp.
-
-		std::u8string line;
-		if (opt.raw) {
-			line = std::u8string(reinterpret_cast<char8_t*>(source_line), nread);
-		} else {
-			try {
-				line = encode_utf8(std::string_view(source_line, nread));
-			} catch (const ot::status& rc) {
-				free(source_line);
-				throw ot::status {ot::st::badly_encoded, "UTF-8 conversion error: " + rc.message};
-			}
-		}
-
-		if (line.empty()) {
-			// Ignore empty lines.
-			previous_comment = nullptr;
-		} else if (line[0] == u8'#') {
-			// Ignore comments.
-			previous_comment = nullptr;
-		} else if (line[0] == u8'\t') {
-			// Continuation line: append the current line to the previous tag.
-			if (previous_comment == nullptr) {
-				ot::status rc = {ot::st::error, "Unexpected continuation line: " + std::string(source_line, nread)};
-				free(source_line);
-				throw rc;
-			} else {
-				line[0] = opt.tag_delimiter;
-				previous_comment->append(line);
-			}
-		} else if (line.find(u8'=') == decltype(line)::npos) {
-			ot::status rc = {ot::st::error, "Malformed tag: " + std::string(source_line, nread)};
-			free(source_line);
-			throw rc;
-		} else {
-			previous_comment = &comments.emplace_back(std::move(line));
-		}
-	}
-	free(source_line);
-	return comments;
-}
-
-void ot::delete_comments(std::list<std::u8string>& comments, const std::u8string& selector)
-{
-	auto name = selector.data();
-	auto equal = selector.find(u8'=');
-	auto value = (equal == std::u8string::npos ? nullptr : name + equal + 1);
-	auto name_len = value ? equal : selector.size();
-	auto value_len = value ? selector.size() - equal - 1 : 0;
-	auto it = comments.begin(), end = comments.end();
-	while (it != end) {
-		auto current = it++;
-		/** \todo Avoid using strncasecmp because it assumes the system locale is UTF-8. */
-		bool name_match = current->size() > name_len + 1 &&
-		                  (*current)[name_len] == '=' &&
-		                  strncasecmp((const char*) current->data(), (const char*) name, name_len) == 0;
-		if (!name_match)
-			continue;
-		bool value_match = value == nullptr ||
-		                   (current->size() == selector.size() &&
-		                    memcmp(current->data() + equal + 1, value, value_len) == 0);
-		if (value_match)
-			comments.erase(current);
-	}
-}
-
-/** Apply the modifications requested by the user to the opustags packet. */
-static void edit_tags(ot::opus_tags& tags, const ot::options& opt)
-{
-	if (opt.set_vendor)
-		tags.vendor = *opt.set_vendor;
-
-	if (opt.delete_all) {
-		tags.comments.clear();
-	} else for (const std::u8string& name : opt.to_delete) {
-		ot::delete_comments(tags.comments, name);
-	}
-
-	for (const std::u8string& comment : opt.to_add)
-		tags.comments.emplace_back(comment);
-}
-
-/** Spawn VISUAL or EDITOR to edit the given tags. */
-static void edit_tags_interactively(ot::opus_tags& tags, const std::optional<std::string>& base_path, const ot::options& opt)
-{
-	const char* editor = nullptr;
-	if (getenv("TERM") != nullptr)
-		editor = getenv("VISUAL");
-	if (editor == nullptr) // without a terminal, or if VISUAL is unset
-		editor = getenv("EDITOR");
-	if (editor == nullptr)
-		throw ot::status {ot::st::error,
-		                 "No editor specified in environment variable VISUAL or EDITOR."};
-
-	// Building the temporary tags file.
-	ot::status rc;
-	std::string tags_path = base_path.value_or("tags") + ".XXXXXX.opustags";
-	int fd = mkstemps(const_cast<char*>(tags_path.data()), 9);
-	ot::file tags_file;
-	if (fd == -1 || (tags_file = fdopen(fd, "w")) == nullptr)
-		throw ot::status {ot::st::standard_error,
-		                  "Could not open '" + tags_path + "': " + strerror(errno)};
-	ot::print_comments(tags.comments, tags_file.get(), opt);
-	tags_file.reset();
-
-	// Spawn the editor, and watch the modification timestamps.
-	timespec before = ot::get_file_timestamp(tags_path.c_str());
-	ot::status editor_rc;
-	try {
-		ot::run_editor(editor, tags_path);
-		editor_rc = ot::st::ok;
-	} catch (const ot::status& rc) {
-		editor_rc = rc;
-	}
-	timespec after = ot::get_file_timestamp(tags_path.c_str());
-	bool modified = (before.tv_sec != after.tv_sec || before.tv_nsec != after.tv_nsec);
-	if (editor_rc != ot::st::ok) {
-		if (modified)
-			fprintf(stderr, "warning: Leaving %s on the disk.\n", tags_path.c_str());
-		else
-			remove(tags_path.c_str());
-		throw editor_rc;
-	} else if (!modified) {
-		remove(tags_path.c_str());
-		fputs("Cancelling edition because the tags file was not modified.\n", stderr);
-		throw ot::status {ot::st::cancel};
-	}
-
-	// Applying the new tags.
-	tags_file = fopen(tags_path.c_str(), "re");
-	if (tags_file == nullptr)
-		throw ot::status {ot::st::standard_error, "Error opening " + tags_path + ": " + strerror(errno)};
-	try {
-		tags.comments = ot::read_comments(tags_file.get(), opt);
-	} catch (const ot::status& rc) {
-		fprintf(stderr, "warning: Leaving %s on the disk.\n", tags_path.c_str());
-		throw;
-	}
-	tags_file.reset();
-
-	// Remove the temporary tags file only on success, because unlike the
-	// partial Ogg file that is irrecoverable, the edited tags file
-	// contains user data, so let’s leave users a chance to recover it.
-	remove(tags_path.c_str());
-}
-
-static void output_cover(const ot::opus_tags& tags, const ot::options &opt)
-{
-	std::optional<ot::picture> cover = extract_cover(tags);
-	if (!cover) {
-		fputs("warning: No cover found.\n", stderr);
-		return;
-	}
-
-	ot::file output;
-	if (opt.cover_out == "-") {
-		output = stdout;
-	} else {
-		struct stat output_info;
-		if (stat(opt.cover_out->c_str(), &output_info) == 0) {
-			if (S_ISREG(output_info.st_mode) && !opt.overwrite)
-				throw ot::status {ot::st::error, "'" + opt.cover_out.value() + "' already exists. Use -y to overwrite."};
-		} else if (errno != ENOENT) {
-			throw ot::status {ot::st::error, "Could not identify '" + opt.cover_out.value() + "': " + strerror(errno)};
-		}
-
-		output = fopen(opt.cover_out->c_str(), "w");
-		if (output == nullptr)
-			throw ot::status {ot::st::standard_error, "Could not open '" + opt.cover_out.value() + "' for writing: " + strerror(errno)};
-	}
-
-	if (fwrite(cover->picture_data.data(), 1, cover->picture_data.size(), output.get()) < cover->picture_data.size())
-		throw ot::status {ot::st::standard_error, "fwrite error: "s + strerror(errno)};
-}
-
-/**
- * Main loop of opustags. Read the packets from the reader, and forwards them to the writer.
- * Transform the OpusTags packet on the fly.
- *
- * The writer is optional. When writer is nullptr, opustags runs in read-only mode.
- */
-static void process(ot::ogg_reader& reader, ot::ogg_writer* writer, const ot::options &opt)
-{
-	bool focused = false; /*< the stream on which we operate is defined */
-	int focused_serialno; /*< when focused, the serialno of the focused stream */
-
-	/** When the number of pages the OpusTags packet takes differs from the input stream to the
-	 *  output stream, we need to renumber all the succeeding pages. If the input stream
-	 *  contains gaps, the offset will naively reproduce the gaps: page numbers 0 (1) 2 4 will
-	 *  become 0 (1 2) 3 5, where (…) is the OpusTags packet, and not 0 (1 2) 3 4. */
-	int pageno_offset = 0;
-
-	while (reader.next_page()) {
-		auto serialno = ogg_page_serialno(&reader.page);
-		auto pageno = ogg_page_pageno(&reader.page);
-		if (!focused) {
-			focused = true;
-			focused_serialno = serialno;
-		} else if (serialno != focused_serialno) {
-			/** \todo Support mixed streams. */
-			throw ot::status {ot::st::error, "Muxed streams are not supported yet."};
-		}
-		if (reader.absolute_page_no == 0) { // Identification header
-			if (!ot::is_opus_stream(reader.page))
-				throw ot::status {ot::st::error, "Not an Opus stream."};
-			if (writer)
-				writer->write_page(reader.page);
-		} else if (reader.absolute_page_no == 1) { // Comment header
-			ot::opus_tags tags;
-			reader.process_header_packet([&tags](ogg_packet& p) { tags = ot::parse_tags(p); });
-			if (opt.cover_out)
-				output_cover(tags, opt);
-			edit_tags(tags, opt);
-			if (writer) {
-				if (opt.edit_interactively) {
-					fflush(writer->file); // flush before calling the subprocess
-					edit_tags_interactively(tags, writer->path, opt);
-				}
-				auto packet = ot::render_tags(tags);
-				writer->write_header_packet(serialno, pageno, packet);
-				pageno_offset = writer->next_page_no - 1 - reader.absolute_page_no;
-			} else {
-				if (opt.cover_out != "-") {
-					if (opt.print_vendor)
-						puts_utf8(tags.vendor, stdout, opt);
-					else
-						ot::print_comments(tags.comments, stdout, opt);
-				}
-				break;
-			}
-		} else if (writer) {
-			ot::renumber_page(reader.page, pageno + pageno_offset);
-			writer->write_page(reader.page);
-		}
-	}
-	if (reader.absolute_page_no < 1)
-		throw ot::status {ot::st::error, "Expected at least 2 Ogg pages."};
-}
-
-static void run_single(const ot::options& opt, const std::string& path_in, const std::optional<std::string>& path_out)
-{
-	ot::file input;
-	if (path_in == "-")
-		input = stdin;
-	else if ((input = fopen(path_in.c_str(), "re")) == nullptr)
-		throw ot::status {ot::st::standard_error,
-		                  "Could not open '" + path_in + "' for reading: " + strerror(errno)};
-	ot::ogg_reader reader(input.get());
-
-	/* Read-only mode. */
-	if (!path_out) {
-		process(reader, nullptr, opt);
-		return;
-	}
-
-	/* Read-write mode.
-	 *
-	 * The output pointer is set to one of:
-	 *  - stdout for "-",
-	 *  - final_output.get() for special files like /dev/null,
-	 *  - temporary_output.get() for regular files.
-	 *
-	 * We use a temporary output file for the following reasons:
-	 *  1. A partial .opus output would be seen by softwares like media players, but a .part
-	 *     (for partial) won’t.
-	 *  2. If the process crashes badly, or the power cuts off, we don't want to leave a partial
-	 *     file at the final location. The temporary file is going to remain though.
-	 *  3. If we're overwriting a regular file, we'd rather avoid wiping its content before we
-	 *     even started reading the input file. That way, the original file is always preserved
-	 *     on error or crash.
-	 *  4. It is necessary for in-place editing. We can't reliably open the same file as both
-	 *     input and output.
-	 */
-
-	FILE* output = nullptr;
-	ot::partial_file temporary_output;
-	ot::file final_output;
-
-	struct stat output_info;
-	if (path_out == "-") {
-		output = stdout;
-	} else if (stat(path_out->c_str(), &output_info) == 0) {
-		/* The output file exists. */
-		if (!S_ISREG(output_info.st_mode)) {
-			/* Special files are opened for writing directly. */
-			if ((final_output = fopen(path_out->c_str(), "we")) == nullptr)
-				throw ot::status {ot::st::standard_error,
-				                  "Could not open '" + path_out.value() + "' for writing: " + strerror(errno)};
-			output = final_output.get();
-		} else if (opt.overwrite) {
-			temporary_output.open(path_out->c_str());
-			output = temporary_output.get();
-		} else {
-			throw ot::status {ot::st::error, "'" + path_out.value() + "' already exists. Use -y to overwrite."};
-		}
-	} else if (errno == ENOENT) {
-		temporary_output.open(path_out->c_str());
-		output = temporary_output.get();
-	} else {
-		throw ot::status {ot::st::error, "Could not identify '" + path_out.value() + "': " + strerror(errno)};
-	}
-
-	ot::ogg_writer writer(output);
-	writer.path = path_out;
-	process(reader, &writer, opt);
-
-	// Close the input file and finalize the output. When --in-place is specified, some file
-	// systems like SMB require that the input is closed first.
-	input.reset();
-	temporary_output.commit();
-}
-
-void ot::run(const ot::options& opt)
-{
-	if (opt.print_help) {
-		fputs(help_message, stdout);
-		return;
-	}
-
-	ot::status global_rc = st::ok;
-	for (const auto& path_in : opt.paths_in) {
-		try {
-			run_single(opt, path_in, opt.in_place ? path_in : opt.path_out);
-		} catch (const ot::status& rc) {
-			global_rc = st::error;
-			if (!rc.message.empty())
-				fprintf(stderr, "%s: error: %s\n", path_in.c_str(), rc.message.c_str());
-		}
-	}
-	if (global_rc != st::ok)
-		throw global_rc;
-}

src/config.h.in

@@ -1,7 +0,0 @@
-#cmakedefine PROJECT_NAME "@PROJECT_NAME@"
-#cmakedefine PROJECT_VERSION "@PROJECT_VERSION@"
-
-#cmakedefine HAVE_ENDIAN_H @HAVE_ENDIAN_H@
-#cmakedefine HAVE_SYS_ENDIAN_H @HAVE_SYS_ENDIAN_H@
-#cmakedefine HAVE_STAT_ST_MTIM @HAVE_STAT_ST_MTIM@
-#cmakedefine HAVE_STAT_ST_MTIMESPEC @HAVE_STAT_ST_MTIMESPEC@

src/log.h

@@ -0,0 +1,29 @@
+#pragma once
+
+namespace opustags {
+
+    enum class LogLevel {
+        LOG_NORMAL = 0,
+        LOG_VERBOSE = 1,
+        LOG_DEBUG = 2,
+        LOG_DEBUG_EXTRA = 3,
+    };
+
+    class Log
+    {
+    public:
+        Log(std::ostream &out);
+
+        LogLevel level;
+
+        Log& operator<<(LogLevel lvl);
+        template<class T> Log& operator<<(const T&);
+
+    private:
+        std::ostream &out;
+    };
+
+
+    extern Log log;
+
+}

src/main.cc

@@ -0,0 +1,88 @@
+#include "actions.h"
+#include "options.h"
+#include "version.h"
+
+#include <iostream>
+#include <fstream>
+#include <cstring>
+
+static void show_usage(const bool include_help)
+{
+    static const auto usage =
+        "Usage: opustags --help\n"
+        "       opustags [OPTIONS] INPUT\n"
+        "       opustags [OPTIONS] -o OUTPUT INPUT\n";
+
+    static const auto help =
+        "Options:\n"
+        "  -h, --help              print this help\n"
+        "  -V, --version           print version\n"
+        "  -o, --output FILE       write the modified tags to this file\n"
+        "  -i, --in-place [SUFFIX] use a temporary file then replace the original file\n"
+        "  -y, --overwrite         overwrite the output file if it already exists\n"
+        "      --stream ID         select stream for the next operations\n"
+        "  -l, --list              display a pretty listing of all tags\n"
+        "      --no-color          disable colors in --list output\n"
+        "  -d, --delete FIELD      delete all the fields of a specified type\n"
+        "  -a, --add FIELD=VALUE   add a field\n"
+        "  -s, --set FIELD=VALUE   delete then add a field\n"
+        "  -D, --delete-all        delete all the fields!\n"
+        "      --full              enable full file scan\n"
+        "      --export            dump the tags to standard output for --import\n"
+        "      --import            set the tags from scratch basing on stanard input\n"
+        "  -e, --edit              spawn the $EDITOR and apply --import on the result\n";
+
+    std::cout << "opustags v" << opustags::version_short << "\n";
+    std::cout << usage;
+    if (include_help) {
+        std::cout << "\n";
+        std::cout << help;
+    }
+}
+
+static void show_version()
+{
+    std::cout << "opustags v" << opustags::version_long << "\n";
+}
+
+int main(int argc, char **argv)
+{
+    if (argc == 1) {
+        show_usage(false);
+        return EXIT_SUCCESS;
+    }
+
+    try {
+        auto options = opustags::parse_args(argc, argv);
+        if (options.show_help) {
+            show_usage(true);
+            return EXIT_SUCCESS;
+        }
+        if (options.show_version) {
+            show_version();
+            return EXIT_SUCCESS;
+        }
+
+        if (options.path_out.empty()) {
+            std::ifstream in(options.path_in);
+            opustags::ogg::Decoder dec(in);
+            list_tags(dec, options.tags_handler, options.full);
+            // TODO: report errors if user tries to edit the stream
+        } else {
+            std::ifstream in(options.path_in);
+            std::ofstream out(options.path_out);
+            opustags::ogg::Decoder dec(in);
+            opustags::ogg::Encoder enc(out);
+            edit_tags(dec, enc, options.tags_handler);
+        }
+
+    } catch (const std::exception &e) {
+        if (errno)
+            std::cerr << "fatal error: " << e.what() << " (" << strerror(errno) << ")" << std::endl;
+        else
+            std::cerr << "fatal error: " << e.what() << std::endl;
+        return EXIT_FAILURE;
+    }
+
+    return EXIT_SUCCESS;
+}

src/ogg.cc

@@ -1,137 +1,308 @@
-/**
- * \file src/ogg.c
- * \ingroup ogg
- *
- * High-level interface for libogg.
- *
- * This module is not meant to be a complete libogg wrapper, but rather a convenient and highly
- * specialized layer above libogg and stdio.
- */
+#include "ogg.h"
 
-#include <opustags.h>
+#include <stdexcept>
+#include <fstream>
+#include <sstream>
+#include <cstring>
+#include <endian.h>
 
-#include <errno.h>
-#include <string.h>
+using namespace opustags;
 
-bool ot::is_opus_stream(const ogg_page& identification_header)
+////////////////////////////////////////////////////////////////////////////////
+// ogg::Stream
+
+ogg::Stream::Stream(int streamno)
 {
-	if (ogg_page_bos(&identification_header) == 0)
-		return false;
-	if (identification_header.body_len < 8)
-		return false;
-	return (memcmp(identification_header.body, "OpusHead", 8) == 0);
+    state = ogg::BEGIN_OF_STREAM;
+    type = ogg::UNKNOWN_STREAM;
+    if (ogg_stream_init(&stream, streamno) != 0)
+        throw std::runtime_error("ogg_stream_init failed");
 }
 
-bool ot::ogg_reader::next_page()
+ogg::Stream::~Stream()
 {
-	int rc;
-	while ((rc = ogg_sync_pageout(&sync, &page)) != 1) {
-		if (rc == -1) {
-			throw status {st::bad_stream,
-			              absolute_page_no == (size_t) -1 ? "Input is not a valid Ogg file."
-			                                              : "Unsynced data in stream."};
-		}
-		if (ogg_sync_check(&sync) != 0)
-			throw status {st::libogg_error, "ogg_sync_check signalled an error."};
-		if (feof(file)) {
-			if (sync.fill != sync.returned)
-				throw status {st::bad_stream, "Unsynced data at end of stream."};
-			return false; // end of sream
-		}
-		char* buf = ogg_sync_buffer(&sync, 65536);
-		if (buf == nullptr)
-			throw status {st::libogg_error, "ogg_sync_buffer failed."};
-		size_t len = fread(buf, 1, 65536, file);
-		if (ferror(file))
-			throw status {st::standard_error, "fread error: "s + strerror(errno)};
-		if (ogg_sync_wrote(&sync, len) != 0)
-			throw status {st::libogg_error, "ogg_sync_wrote failed."};
-	}
-	++absolute_page_no;
-	return true;
+    ogg_stream_clear(&stream);
 }
 
-void ot::ogg_reader::process_header_packet(const std::function<void(ogg_packet&)>& f)
+void ogg::Stream::flush_packets()
 {
-	if (ogg_page_continued(&page))
-		throw status {ot::st::error, "Unexpected continued header page."};
-
-	ogg_packet packet;
-	ogg_logical_stream stream(ogg_page_serialno(&page));
-	stream.pageno = ogg_page_pageno(&page);
-
-	for (;;) {
-		if (ogg_stream_pagein(&stream, &page) != 0)
-			throw status {st::libogg_error, "ogg_stream_pagein failed."};
-
-		int rc = ogg_stream_packetout(&stream, &packet);
-		if (ogg_stream_check(&stream) != 0 || rc == -1) {
-			throw status {ot::st::libogg_error, "ogg_stream_packetout failed."};
-		} else if (rc == 0) {
-			// Not enough data: read the next page.
-			if (!next_page())
-				throw status {ot::st::error, "Unterminated header packet."};
-			continue;
-		} else {
-			// The packet was successfully read.
-			break;
-		}
-	}
-
-	f(packet);
-
-	/* Ensure that there are no other segments left in the packet using the lacing state of the
-	 * stream. These are the relevant variables, as far as I understood them:
-	 *  - lacing_vals: extensible array containing the lacing values of the segments,
-	 *  - lacing_fill: number of elements in lacing_vals (not the capacity),
-	 *  - lacing_returned: index of the next segment to be processed. */
-	if (stream.lacing_returned != stream.lacing_fill)
-		throw status {ot::st::error, "Header page contains more than a single packet."};
+    ogg_packet op;
+    while (ogg_stream_packetout(&stream, &op) > 0);
 }
 
-void ot::ogg_writer::write_page(const ogg_page& page)
+bool ogg::Stream::page_in(ogg_page &og)
 {
-	if (page.header_len < 0 || page.body_len < 0)
-		throw status {st::int_overflow, "Overflowing page length"};
+    if (state != ogg::BEGIN_OF_STREAM && type == ogg::UNKNOWN_STREAM) {
+        state = ogg::RAW_READY;
+        return true;
+    }
+    flush_packets(); // otherwise packet_out keeps returning the same packet
+    if (ogg_stream_pagein(&stream, &og) != 0)
+        throw std::runtime_error("ogg_stream_pagein failed");
 
-	long pageno = ogg_page_pageno(&page);
-	if (pageno != next_page_no)
-		fprintf(stderr, "Output page number mismatch: expected %ld, got %ld.\n", next_page_no, pageno);
-	next_page_no = pageno + 1;
-
-	auto header_len = static_cast<size_t>(page.header_len);
-	auto body_len = static_cast<size_t>(page.body_len);
-	if (fwrite(page.header, 1, header_len, file) < header_len)
-		throw status {st::standard_error, "fwrite error: "s + strerror(errno)};
-	if (fwrite(page.body, 1, body_len, file) < body_len)
-		throw status {st::standard_error, "fwrite error: "s + strerror(errno)};
+    if (state == ogg::BEGIN_OF_STREAM || state == ogg::HEADER_READY) {
+        // We're expecting a header, so we parse it.
+        return handle_page();
+    } else {
+        // We're past the first two headers.
+        state = ogg::DATA_READY;
+        return true;
+    }
 }
 
-void ot::ogg_writer::write_header_packet(int serialno, int pageno, ogg_packet& packet)
+// Read the first packet of the page and parses it.
+bool ogg::Stream::handle_page()
 {
-	ogg_logical_stream stream(serialno);
-	stream.b_o_s = (pageno != 0);
-	stream.pageno = pageno;
-	if (ogg_stream_packetin(&stream, &packet) != 0)
-		throw status {ot::st::libogg_error, "ogg_stream_packetin failed"};
-
-	ogg_page page;
-	while (ogg_stream_flush(&stream, &page) != 0)
-		write_page(page);
-
-	if (ogg_stream_check(&stream) != 0)
-		throw status {st::libogg_error, "ogg_stream_check failed"};
+    ogg_packet op;
+    int rc = ogg_stream_packetpeek(&stream, &op);
+    if (rc < 0)
+        throw std::runtime_error("ogg_stream_packetout failed");
+    else if (rc == 0) // insufficient data
+        return false; // asking for a new page
+    // We've read the first packet successfully.
+    // The headers are supposed to contain only one packet, so this is enough
+    // for us. Still, we could ensure there are no other packets.
+    handle_packet(op);
+    return true;
 }
 
-void ot::renumber_page(ogg_page& page, long new_pageno)
+void ogg::Stream::handle_packet(const ogg_packet &op)
 {
-	// Quick optimization: don’t bother recomputing the CRC if the pageno did not change.
-	long old_pageno = ogg_page_pageno(&page);
-	if (old_pageno == new_pageno)
-		return;
-
-	/** The pageno field is located at bytes 18 to 21 (0-indexed, little-endian). */
-	uint32_t le_pageno = htole32(new_pageno);
-	memcpy(&page.header[18], &le_pageno, 4);
-	ogg_page_checksum_set(&page);
+    if (state == ogg::BEGIN_OF_STREAM)
+        parse_header(op);
+    else if (state == ogg::HEADER_READY)
+        parse_opustags(op);
+    // else shrug
+}
+
+void ogg::Stream::parse_header(const ogg_packet &op)
+{
+    if (op.bytes >= 8 && memcmp(op.packet, "OpusHead", 8) == 0)
+        type = OPUS_STREAM;
+    else
+        type = UNKNOWN_STREAM;
+    state = HEADER_READY;
+}
+
+// For reference:
+// https://tools.ietf.org/html/draft-ietf-codec-oggopus-14#section-5.2
+void ogg::Stream::parse_opustags(const ogg_packet &op)
+{
+    // This part is gonna be C-ish because I don't see how I'd do this in C++
+    // without being inefficient, both in volume of code and performance.
+    char *data = reinterpret_cast<char*>(op.packet);
+    long remaining = op.bytes;
+    if (remaining < 8 || memcmp(data, "OpusTags", 8) != 0)
+        throw std::runtime_error("expected OpusTags header");
+    data += 8;
+    remaining -= 8;
+
+    // Vendor string
+    if (remaining < 4)
+        throw std::runtime_error("no space for vendor string length");
+    uint32_t vendor_length = le32toh(*reinterpret_cast<uint32_t*>(data));
+    if (remaining - 4 < vendor_length)
+        throw std::runtime_error("invalid vendor string length");
+    tags.vendor = std::string(data + 4, vendor_length);
+    data += 4 + vendor_length;
+    remaining -= 4 + vendor_length;
+
+    // User comments count
+    if (remaining < 4)
+        throw std::runtime_error("no space for user comment list length");
+    long comment_count = le32toh(*reinterpret_cast<uint32_t*>(data));
+    data += 4;
+    remaining -= 4;
+
+    // Actual comments
+    // We iterate on a long type to prevent infinite looping when comment_count == UINT32_MAX.
+    for (long i = 0; i < comment_count; i++) {
+        if (remaining < 4)
+            throw std::runtime_error("no space for user comment length");
+        uint32_t comment_length = le32toh(*reinterpret_cast<uint32_t*>(data));
+        if (remaining - 4 < comment_length)
+            throw std::runtime_error("no space for comment contents");
+        tags.add(parse_tag(std::string(data + 4, comment_length)));
+        data += 4 + comment_length;
+        remaining -= 4 + comment_length;
+    }
+
+    // Extra data to keep if the least significant bit of the first byte is 1
+    if (remaining > 0 && (*data & 1) == 1 )
+        tags.extra = std::string(data, remaining);
+
+    state = TAGS_READY;
+}
+
+void ogg::Stream::downgrade()
+{
+    type = ogg::UNKNOWN_STREAM;
+    if (state != ogg::BEGIN_OF_STREAM && state != ogg::END_OF_STREAM)
+        state = RAW_READY;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// ogg::Decoder
+
+ogg::Decoder::Decoder(std::istream &in)
+    : input(in)
+{
+    if (!in)
+        throw std::runtime_error("invalid stream to decode");
+    input.exceptions(std::ifstream::badbit);
+    ogg_sync_init(&sync);
+}
+
+ogg::Decoder::~Decoder()
+{
+    ogg_sync_clear(&sync);
+}
+
+std::shared_ptr<ogg::Stream> ogg::Decoder::read_page()
+{
+    while (page_out()) {
+        int streamno = ogg_page_serialno(&current_page);
+        auto i = streams.find(streamno);
+        if (i == streams.end()) {
+            // we could check the page number to detect new streams (pageno = 0)
+            auto s = std::make_shared<Stream>(streamno);
+            i = streams.emplace(streamno, s).first;
+        }
+        if (i->second->page_in(current_page))
+            return i->second;
+    }
+    return nullptr; // end of stream
+}
+
+// Read the next page and return true on success, false on end of stream.
+bool ogg::Decoder::page_out()
+{
+    int rc;
+    for (;;) {
+        rc = ogg_sync_pageout(&sync, &current_page);
+        if (rc < 0) {
+            throw std::runtime_error("ogg_sync_pageout failed");
+        } else if (rc == 1) {
+            break; // page complete
+        } else if (!buff()) {
+            // more data required but end of file reached
+            // TODO check sync.unsynced flag in case we've got an incomplete page
+            return false;
+        }
+    }
+    return true;
+}
+
+// Read data from the stream into the sync's buffer.
+bool ogg::Decoder::buff()
+{
+    if (input.eof())
+        return false;
+    char *buf = ogg_sync_buffer(&sync, 65536);
+    if (buf == nullptr)
+        throw std::runtime_error("ogg_sync_buffer failed");
+    input.read(buf, 65536);
+    ogg_sync_wrote(&sync, input.gcount());
+    return true;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// ogg::Encoder
+
+ogg::Encoder::Encoder(std::ostream &out)
+    : output(out)
+{
+    if (!output)
+        throw std::runtime_error("invalid stream to decode");
+    output.exceptions(std::ifstream::badbit);
+}
+
+ogg::Stream& ogg::Encoder::get_stream(int streamno)
+{
+    auto i = streams.find(streamno);
+    if (i == streams.end()) {
+        auto s = std::make_shared<Stream>(streamno);
+        i = streams.emplace(streamno, s).first;
+    }
+    return *(i->second);
+}
+
+void ogg::Encoder::forward(ogg::Stream &in)
+{
+    ogg::Stream *out = &get_stream(in.stream.serialno);
+    forward_stream(in, *out);
+    flush_stream(*out);
+}
+
+void ogg::Encoder::forward_stream(ogg::Stream &in, ogg::Stream &out)
+{
+    int rc;
+    ogg_packet op;
+    for (;;) {
+        rc = ogg_stream_packetout(&in.stream, &op);
+        if (rc < 0) {
+            throw std::runtime_error("ogg_stream_packetout failed");
+        } else if (rc == 0) {
+            break;
+        } else {
+            if (ogg_stream_packetin(&out.stream, &op) != 0)
+                throw std::runtime_error("ogg_stream_packetin failed");
+        }
+    }
+}
+
+void ogg::Encoder::flush_stream(ogg::Stream &out)
+{
+    ogg_page og;
+    if (ogg_stream_flush(&out.stream, &og))
+            write_raw_page(og);
+}
+
+void ogg::Encoder::write_raw_page(const ogg_page &og)
+{
+    output.write(reinterpret_cast<const char*>(og.header), og.header_len);
+    output.write(reinterpret_cast<const char*>(og.body), og.body_len);
+}
+
+void ogg::Encoder::write_tags(int streamno, const Tags &tags)
+{
+    ogg_packet op;
+    op.b_o_s = 0;
+    op.e_o_s = 0;
+    op.granulepos = 0;
+    op.packetno = 1; // checked on a file from ffmpeg
+
+    std::string data = render_opustags(tags);
+    op.bytes = data.size();
+    op.packet = reinterpret_cast<unsigned char*>(const_cast<char*>(data.data()));
+
+    std::shared_ptr<ogg::Stream> s = streams.at(streamno); // assume it exists
+    if (ogg_stream_packetin(&s->stream, &op) != 0)
+        throw std::runtime_error("ogg_stream_packetin failed");
+    flush_stream(*s);
+}
+
+std::string ogg::Encoder::render_opustags(const Tags &tags)
+{
+    std::stringbuf s;
+    uint32_t length;
+    s.sputn("OpusTags", 8);
+    length = htole32(tags.vendor.size());
+    s.sputn(reinterpret_cast<char*>(&length), 4);
+    s.sputn(tags.vendor.data(), tags.vendor.size());
+
+    auto assocs = tags.get_all();
+    length = htole32(assocs.size());
+    s.sputn(reinterpret_cast<char*>(&length), 4);
+
+    for (const auto assoc : assocs) {
+        length = htole32(assoc.key.size() + 1 + assoc.value.size());
+        s.sputn(reinterpret_cast<char*>(&length), 4);
+        s.sputn(assoc.key.data(), assoc.key.size());
+        s.sputc('=');
+        s.sputn(assoc.value.data(), assoc.value.size());
+    }
+
+    s.sputn(tags.extra.data(), tags.extra.size());
+    return s.str();
 }

src/ogg.h

@@ -0,0 +1,129 @@
+#pragma once
+
+#include "tags.h"
+
+#include <iostream>
+#include <map>
+#include <memory>
+#include <ogg/ogg.h>
+
+namespace opustags {
+namespace ogg
+{
+    enum StreamState {
+        BEGIN_OF_STREAM,
+        HEADER_READY,
+        TAGS_READY,
+        DATA_READY,
+        RAW_READY,
+        END_OF_STREAM,
+        // Meaning of these states below, in Stream.
+    };
+
+    enum StreamType {
+        UNKNOWN_STREAM = 0,
+        OPUS_STREAM,
+    };
+
+    // An Ogg file may contain many logical bitstreams, and among them, many
+    // Opus streams. This class represents one stream, whether it is Opus or
+    // not.
+    struct Stream
+    {
+        Stream(int streamno);
+        Stream(const Stream&) = delete;
+        ~Stream();
+
+        // Called by Decoder once a page was read.
+        // Returns true if it's ready, false if it expects more data.
+        // In the latter case, Decoder::read_page will keep reading.
+        bool page_in(ogg_page&);
+
+        // Make the stream behave as if it were unknown.
+        // As a consequence, no more effort would be made in extracting data.
+        void downgrade();
+
+        StreamState state;
+        StreamType type;
+        Tags tags;
+
+        // Here are the meanings of the state variable:
+        //   BEGIN_OF_STREAM: the stream was just initialized,
+        //   HEADER_READY: the header (first packet) was found,
+        //   TAGS_READY: the tags are parsed and complete,
+        //   DATA_READY: we've read a data page whose meaning is no concern to us,
+        //   RAW_READY: we don't even know what kind of stream that is, so don't alter it,
+        //   END_OF_STREAM: no more thing to read, not even the current page.
+
+        // From the state, we decide what to do with the Decoder's current_page.
+        // The difference between DATA_READY and RAW_DATA is that the former
+        // might require a reencoding of the current page. For example, if the
+        // tags grow and span over two pages, all the following pages are gonna
+        // need a new sequence number.
+
+        // For an Opus stream, the sequence will be:
+        //   BEGIN_OF_STREAM → HEADER_READY → TAGS_READY → DATA_READY* → END_OF_STREAM
+        // For an unknown stream:
+        //   BEGIN_OF_STREAM → HEADER_READY → RAW_READY* → END_OF_STREAM
+
+        ogg_stream_state stream;
+
+    private:
+        void flush_packets();
+        bool handle_page();
+        void handle_packet(const ogg_packet&);
+        void parse_header(const ogg_packet&);
+        void parse_opustags(const ogg_packet&);
+    };
+
+    struct Decoder
+    {
+        Decoder(std::istream&);
+        Decoder(const Decoder&) = delete;
+        ~Decoder();
+
+        // Read a page, dispatch it, and return the stream it belongs to.
+        // The read page is given to Stream::page_in before this function
+        // returns.
+        // After the end of the file is reached, it returns NULL.
+        std::shared_ptr<Stream> read_page();
+
+        std::istream &input;
+
+        ogg_sync_state sync;
+        ogg_page current_page;
+        std::map<int, std::shared_ptr<Stream>> streams;
+
+    private:
+        bool page_out();
+        bool buff();
+    };
+
+    struct Encoder
+    {
+        Encoder(std::ostream&);
+
+        // Copy the input stream's current page.
+        void forward(Stream &in);
+
+        // Write the page without even ensuring its page number is correct.
+        // It would be an efficient way to copy a stream identically, and also
+        // needed for write_page.
+        void write_raw_page(const ogg_page&);
+
+        void write_tags(int streamno, const Tags&);
+
+        std::ostream &output;
+
+        // We're gonna need some ogg_stream_state for adjusting the page
+        // numbers and splitting large packets as it's gotta be done.
+        std::map<int, std::shared_ptr<Stream>> streams;
+
+    private:
+        Stream& get_stream(int streamno);
+        void forward_stream(Stream &in, Stream &out);
+        void flush_stream(Stream &out);
+        std::string render_opustags(const Tags &tags);
+    };
+}
+}

src/options.cc

@@ -0,0 +1,199 @@
+#include "options.h"
+
+#include "tags_handlers/insertion_tags_handler.h"
+#include "tags_handlers/modification_tags_handler.h"
+#include "tags_handlers/external_edit_tags_handler.h"
+#include "tags_handlers/export_tags_handler.h"
+#include "tags_handlers/import_tags_handler.h"
+#include "tags_handlers/listing_tags_handler.h"
+#include "tags_handlers/removal_tags_handler.h"
+
+#include <getopt.h>
+#include <regex>
+#include <sstream>
+
+using namespace opustags;
+
+ArgumentError::ArgumentError(const std::string &message)
+    : std::runtime_error(message.c_str())
+{
+}
+
+Options::Options() :
+    show_help(false),
+    show_version(false),
+    overwrite(false),
+    full(false),
+    in_place(false)
+{
+}
+
+Options opustags::parse_args(const int argc, char **argv)
+{
+    static const auto short_def = "hVeo:i::yd:a:s:Dl";
+
+    static const option long_def[] = {
+        {"help",        no_argument,        0, 'h'},
+        {"version",     no_argument,        0, 'V'},
+        {"full",        no_argument,        0, 0},
+        {"output",      required_argument,  0, 'o'},
+        {"in-place",    optional_argument,  0, 'i'},
+        {"overwrite",   no_argument,        0, 'y'},
+        {"delete",      required_argument,  0, 'd'},
+        {"add",         required_argument,  0, 'a'},
+        {"stream",      required_argument,  0, 0},
+        {"set",         required_argument,  0, 's'},
+        {"list",        no_argument,        0, 'l'},
+        {"delete-all",  no_argument,        0, 'D'},
+        {"edit",        no_argument,        0, 'e'},
+        {"import",      no_argument,        0, 0},
+        {"export",      no_argument,        0, 0},
+
+        // TODO: parse no-colors
+
+        {nullptr, 0, 0, 0}
+    };
+
+    // TODO: use --list as default switch
+
+    Options options;
+
+    std::vector<int> current_streamnos {StreamTagsHandler::ALL_STREAMS};
+    int option_index;
+    char c;
+    optind = 0;
+
+    while ((c = getopt_long(
+        argc, argv, short_def, long_def, &option_index)) != -1) {
+
+        const std::string arg(optarg == nullptr ? "" : optarg);
+
+        switch (c) {
+            case 'h':
+                options.show_help = true;
+                break;
+
+            case 'V':
+                options.show_version = true;
+                break;
+
+            case 'o':
+                if (arg.empty())
+                    throw ArgumentError("Output path cannot be empty");
+                options.path_out = arg;
+                break;
+
+            case 'i':
+                // TODO: shouldn't we generate random file name here to which
+                // we apply the arg, rather than use the arg as a whole?
+                options.path_out = arg.empty() ? ".otmp" : arg;
+                options.in_place = true;
+                break;
+
+            case 'y':
+                options.overwrite = true;
+                break;
+
+            case 'd':
+                if (arg.find('=') != std::string::npos)
+                    throw ArgumentError("Invalid field: '" + arg + "'");
+                for (const auto streamno : current_streamnos) {
+                    options.tags_handler.add_handler(
+                        std::make_shared<RemovalTagsHandler>(streamno, arg));
+                }
+                break;
+
+            case 'a':
+            case 's':
+            {
+                std::smatch match;
+                std::regex regex("^(\\w+)=(.*)$");
+                if (!std::regex_match(arg, match, regex))
+                    throw ArgumentError("Invalid field: '" + arg + "'");
+                for (const auto streamno : current_streamnos) {
+                    if (c == 's') {
+                        options.tags_handler.add_handler(
+                            std::make_shared<ModificationTagsHandler>(
+                                streamno, match[1], match[2]));
+                    } else {
+                        options.tags_handler.add_handler(
+                            std::make_shared<InsertionTagsHandler>(
+                                streamno, match[1], match[2]));
+                    }
+                }
+                break;
+            }
+
+            case 'l':
+                for (const auto streamno : current_streamnos) {
+                    options.tags_handler.add_handler(
+                        std::make_shared<ListingTagsHandler>(
+                            streamno, std::cout));
+                }
+                break;
+
+            case 'e':
+                options.tags_handler.add_handler(
+                    std::make_shared<ExternalEditTagsHandler>());
+                break;
+
+            case 'D':
+                for (const auto streamno : current_streamnos) {
+                    options.tags_handler.add_handler(
+                        std::make_shared<RemovalTagsHandler>(streamno));
+                }
+                break;
+
+            case 0:
+            {
+                std::string long_arg = long_def[option_index].name;
+                if (long_arg == "stream") {
+                    int i;
+                    current_streamnos.clear();
+                    std::stringstream ss(optarg);
+                    while (ss >> i) {
+                        current_streamnos.push_back(i);
+                        if (ss.peek() == ',')
+                            ss.ignore();
+                    }
+                }
+                else if (long_arg == "full")
+                    options.full = true;
+                else if (long_arg == "export")
+                    options.tags_handler.add_handler(
+                        std::make_shared<ExportTagsHandler>(std::cout));
+                else if (long_arg == "import")
+                    options.tags_handler.add_handler(
+                        std::make_shared<ImportTagsHandler>(std::cin));
+                break;
+            }
+
+            default:
+                throw ArgumentError("Invalid flag");
+        }
+    }
+
+    std::vector<std::string> stray;
+    while (optind < argc)
+        stray.push_back(argv[optind++]);
+
+    if (!options.show_help && !options.show_version) {
+        if (stray.empty())
+            throw ArgumentError("Missing input path");
+
+        options.path_in = stray.at(0);
+        if (options.path_in.empty())
+            throw ArgumentError("Input path cannot be empty");
+
+        if (stray.size() > 1)
+            throw ArgumentError("Extra argument: " + stray.at(1));
+
+        if (options.path_out.empty()) {
+            options.tags_handler.add_handler(
+                std::make_shared<ListingTagsHandler>(
+                    StreamTagsHandler::ALL_STREAMS, std::cout));
+        }
+    }
+
+    return options;
+}

src/options.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "tags_handlers/composite_tags_handler.h"
+
+#include <stdexcept>
+#include <map>
+#include <vector>
+
+namespace opustags
+{
+    struct Options final
+    {
+        Options();
+
+        bool show_help;
+        bool show_version;
+        bool overwrite;
+        bool full;
+
+        bool in_place;
+        std::string path_in;
+        std::string path_out;
+
+        CompositeTagsHandler tags_handler;
+    };
+
+    struct ArgumentError : std::runtime_error
+    {
+        ArgumentError(const std::string &message);
+    };
+
+    Options parse_args(const int argc, char **argv);
+}

src/opus.cc

@@ -1,212 +0,0 @@
-/**
- * \file src/opus.cc
- * \ingroup opus
- *
- * The way Opus is encapsulated into an Ogg stream, and the content of the packets we're dealing
- * with here is defined by [RFC 7845](https://tools.ietf.org/html/rfc7845.html).
- *
- * Section 3 "Packet Organization" is critical for us:
- *
- * - The first page contains exactly 1 packet, the OpusHead, and it contains it entirely.
- * - The second page begins the OpusTags packet, which may span several pages.
- * - The OpusTags packet must finish the page on which it completes.
- *
- * The structure of the OpusTags packet is defined in section 5.2 "Comment Header" of the RFC.
- *
- * OpusTags is similar to [Vorbis Comment](https://www.xiph.org/vorbis/doc/v-comment.html), which
- * gives us some context, but let's stick to the RFC for the technical details.
- *
- * \todo Validate that the vendor string and comments are valid UTF-8.
- * \todo Validate that field names are ASCII: 0x20 through 0x7D, 0x3D ('=') excluded.
- *
- */
-
-#include <opustags.h>
-
-#include <string.h>
-#include <algorithm>
-
-ot::opus_tags ot::parse_tags(const ogg_packet& packet)
-{
-	if (packet.bytes < 0)
-		throw status {st::int_overflow, "Overflowing comment header length"};
-	size_t size = static_cast<size_t>(packet.bytes);
-	const uint8_t* data = reinterpret_cast<uint8_t*>(packet.packet);
-	size_t pos = 0;
-	opus_tags my_tags;
-
-	// Magic number
-	if (8 > size)
-		throw status {st::cut_magic_number, "Comment header too short for the magic number"};
-	if (memcmp(data, u8"OpusTags", 8) != 0)
-		throw status {st::bad_magic_number, "Comment header did not start with OpusTags"};
-
-	// Vendor
-	pos = 8;
-	if (pos + 4 > size)
-		throw status {st::cut_vendor_length,
-		        "Vendor string length did not fit the comment header"};
-	size_t vendor_length = le32toh(*((uint32_t*) (data + pos)));
-	if (pos + 4 + vendor_length > size)
-		throw status {st::cut_vendor_data, "Vendor string did not fit the comment header"};
-	my_tags.vendor = std::u8string(reinterpret_cast<const char8_t*>(&data[pos + 4]), vendor_length);
-	pos += 4 + my_tags.vendor.size();
-
-	// Comment count
-	if (pos + 4 > size)
-		throw status {st::cut_comment_count, "Comment count did not fit the comment header"};
-	uint32_t count = le32toh(*((uint32_t*) (data + pos)));
-	pos += 4;
-
-	// Comments' data
-	for (uint32_t i = 0; i < count; ++i) {
-		if (pos + 4 > size)
-			throw status {st::cut_comment_length,
-			              "Comment length did not fit the comment header"};
-		uint32_t comment_length = le32toh(*((uint32_t*) (data + pos)));
-		if (pos + 4 + comment_length > size)
-			throw status {st::cut_comment_data,
-			              "Comment string did not fit the comment header"};
-		auto comment_value = reinterpret_cast<const char8_t*>(&data[pos + 4]);
-		my_tags.comments.emplace_back(comment_value, comment_length);
-		pos += 4 + comment_length;
-	}
-
-	// Extra data
-	my_tags.extra_data = byte_string(data + pos, size - pos);
-
-	return my_tags;
-}
-
-ot::dynamic_ogg_packet ot::render_tags(const opus_tags& tags)
-{
-	size_t size = 8 + 4 + tags.vendor.size() + 4;
-	for (const std::u8string& comment : tags.comments)
-		size += 4 + comment.size();
-	size += tags.extra_data.size();
-
-	dynamic_ogg_packet op(size);
-	op.b_o_s = 0;
-	op.e_o_s = 0;
-	op.granulepos = 0;
-	op.packetno = 1;
-
-	unsigned char* data = op.packet;
-	uint32_t n;
-	memcpy(data, "OpusTags", 8);
-	n = htole32(tags.vendor.size());
-	memcpy(data+8, &n, 4);
-	memcpy(data+12, tags.vendor.data(), tags.vendor.size());
-	data += 12 + tags.vendor.size();
-	n = htole32(tags.comments.size());
-	memcpy(data, &n, 4);
-	data += 4;
-	for (const std::u8string& comment : tags.comments) {
-		n = htole32(comment.size());
-		memcpy(data, &n, 4);
-		memcpy(data+4, comment.data(), comment.size());
-		data += 4 + comment.size();
-	}
-	memcpy(data, tags.extra_data.data(), tags.extra_data.size());
-
-	return op;
-}
-
-/**
- * The METADATA_BLOCK_PICTURE binary data, after base64 decoding, is organized like this:
- *
- *  - 4 bytes for the picture type,
- *  - 4 + n bytes for the MIME type,
- *  - 4 + n bytes for the description string,
- *  - 16 bytes of picture attributes,
- *  - 4 + n bytes for the picture data.
- *
- * Integers are all big endian.
- */
-ot::picture::picture(ot::byte_string block)
-	: storage(std::move(block))
-{
-	size_t mime_offset = 4;
-	if (storage.size() < mime_offset + 4)
-		throw status { st::invalid_size, "missing MIME type in picture block" };
-	uint32_t mime_size = be32toh(*reinterpret_cast<const uint32_t*>(&storage[mime_offset]));
-
-	size_t desc_offset = mime_offset + 4 + mime_size;
-	if (storage.size() < desc_offset + 4)
-		throw status { st::invalid_size, "missing description in picture block" };
-	uint32_t desc_size = be32toh(*reinterpret_cast<const uint32_t*>(&storage[desc_offset]));
-
-	size_t pic_offset = desc_offset + 4 + desc_size + 16;
-	if (storage.size() < pic_offset + 4)
-		throw status { st::invalid_size, "missing picture data in picture block" };
-	uint32_t pic_size = be32toh(*reinterpret_cast<const uint32_t*>(&storage[pic_offset]));
-
-	if (storage.size() != pic_offset + 4 + pic_size)
-		throw status { st::invalid_size, "invalid picture block size" };
-
-	mime_type = byte_string_view(&storage[mime_offset + 4], mime_size);
-	picture_data = byte_string_view(&storage[pic_offset + 4], pic_size);
-}
-
-ot::byte_string ot::picture::serialize() const
-{
-	ot::byte_string bytes;
-	size_t mime_offset = 4;
-	size_t pic_offset = mime_offset + 4 + mime_type.size() + 4 + 0 + 16;
-	bytes.resize(pic_offset + 4 + picture_data.size());
-	*reinterpret_cast<uint32_t*>(&bytes[0]) = htobe32(3); // Picture type: front cover.
-	*reinterpret_cast<uint32_t*>(&bytes[mime_offset]) = htobe32(mime_type.size());
-	std::copy(mime_type.begin(), mime_type.end(), std::next(bytes.begin(), mime_offset + 4));
-	*reinterpret_cast<uint32_t*>(&bytes[pic_offset]) = htobe32(picture_data.size());
-	std::copy(picture_data.begin(), picture_data.end(), std::next(bytes.begin(), pic_offset + 4));
-	return bytes;
-}
-
-/**
- * \todo Take into account the picture types (first 4 bytes of the tag value).
- */
-std::optional<ot::picture> ot::extract_cover(const ot::opus_tags& tags)
-{
-	static const std::u8string_view prefix = u8"METADATA_BLOCK_PICTURE="sv;
-	auto is_cover = [](const std::u8string& tag) { return tag.starts_with(prefix); };
-	auto cover_tag = std::find_if(tags.comments.begin(), tags.comments.end(), is_cover);
-	if (cover_tag == tags.comments.end())
-		return {}; // No cover art.
-
-	auto extra_cover_tag = std::find_if(std::next(cover_tag), tags.comments.end(), is_cover);
-	if (extra_cover_tag != tags.comments.end())
-		fputs("warning: Found multiple covers; only the first will be extracted."
-		              " Please report your use case if you need a finer selection.\n", stderr);
-
-	std::u8string_view cover_value = *cover_tag;
-	cover_value.remove_prefix(prefix.size());
-	return picture(decode_base64(cover_value));
-}
-
-/**
- * Detect the MIME type of the given data block by checking the first bytes. Only the most common
- * image formats are currently supported. Using magic(5) would give better results but that level of
- * exhaustiveness is probably not necessary.
- */
-static ot::byte_string_view detect_mime_type(ot::byte_string_view data)
-{
-	static std::initializer_list<std::pair<ot::byte_string_view, ot::byte_string_view>> magic_numbers = {
-		{ "\xff\xd8\xff"_bsv, "image/jpeg"_bsv },
-		{ "\x89PNG"_bsv, "image/png"_bsv },
-		{ "GIF8"_bsv, "image/gif"_bsv },
-	};
-	for (auto [magic, mime] : magic_numbers) {
-		if (data.starts_with(magic))
-			return mime;
-	}
-	fputs("warning: Could not identify the MIME type of the picture; defaulting to application/octet-stream.\n", stderr);
-	return "application/octet-stream"_bsv;
-}
-
-std::u8string ot::make_cover(ot::byte_string_view picture_data)
-{
-	picture pic;
-	pic.mime_type = detect_mime_type(picture_data);
-	pic.picture_data = picture_data;
-	return u8"METADATA_BLOCK_PICTURE=" + encode_base64(pic.serialize());
-}

src/opustags.cc

@@ -1,28 +0,0 @@
-/**
- * \file src/opustags.cc
- * \brief Main function for opustags.
- *
- * See opustags.h for the program's documentation.
- */
-
-#include <opustags.h>
-
-#include <locale.h>
-
-/**
- * Main function of the opustags binary.
- *
- * Does practically nothing but call the cli module.
- */
-int main(int argc, char** argv) {
-	try {
-		setlocale(LC_ALL, "");
-		ot::options opt = ot::parse_options(argc, argv, stdin);
-		ot::run(opt);
-		return 0;
-	} catch (const ot::status& rc) {
-		if (!rc.message.empty())
-			fprintf(stderr, "error: %s\n", rc.message.c_str());
-		return rc == ot::st::bad_arguments ? 2 : 1;
-	}
-}

src/opustags.h

@@ -1,587 +0,0 @@
-/**
- * \file src/opustags.h
- *
- * Welcome to opustags!
- *
- * Let's have a quick tour around. The project is split into the following modules:
- *
- * - The system module provides a few generic tools for interating with the system.
- * - The ogg module reads and writes Ogg files, letting you manipulate Ogg pages and packets.
- * - The opus module parses the contents of Ogg packets according to the Opus specifications.
- * - The cli module implements the main logic of the program.
- * - The opustags module contains the main function, which is a simple wrapper around cli.
- *
- * Each module is implemented in its eponymous .cc file. Their interfaces are all defined and
- * documented together in this header file. Look into the .cc files for implementation-specific
- * details.
- *
- * To understand how this program works, you need to know what an Ogg files is made of, in
- * particular the streams, pages, and packets. You hardly need any knowledge of the actual Opus
- * audio codec, but need the RFC 7845 "Ogg Encapsulation for the Opus Audio Codec" that defines the
- * format of the header packets that are essential to opustags.
- *
- */
-
-#pragma once
-
-#include <config.h>
-
-#include <iconv.h>
-#include <ogg/ogg.h>
-#include <stdio.h>
-#include <time.h>
-
-#include <functional>
-#include <list>
-#include <memory>
-#include <optional>
-#include <string>
-#include <string_view>
-#include <vector>
-
-#ifdef HAVE_ENDIAN_H
-#  include <endian.h>
-#endif
-
-#ifdef HAVE_SYS_ENDIAN_H
-#  include <sys/endian.h>
-#endif
-
-#ifdef __APPLE__
-#include <libkern/OSByteOrder.h>
-#define htole32(x) OSSwapHostToLittleInt32(x)
-#define le32toh(x) OSSwapLittleToHostInt32(x)
-#define htobe32(x) OSSwapHostToBigInt32(x)
-#define be32toh(x) OSSwapBigToHostInt32(x)
-#endif
-
-using namespace std::literals;
-
-namespace ot {
-
-/**
- * Possible return status code, ranging from errors to special statuses. They are usually
- * accompanied with a message with the #status structure.
- *
- * Error codes do not need to be ultra specific, and are mainly used to report special conditions to
- * the caller function. Ultimately, only the error message in the #status is shown to the user.
- *
- * The cut error family means that the end of packet was reached when attempting to read the
- * overflowing value. For example, cut_comment_count means that after reading the vendor string,
- * less than 4 bytes were left in the packet.
- */
-enum class st {
-	/* Generic */
-	ok,
-	error,
-	standard_error, /**< Error raised by the C standard library. */
-	int_overflow,
-	cancel,
-	/* System */
-	badly_encoded,
-	child_process_failed,
-	/* Ogg */
-	bad_stream,
-	libogg_error,
-	/* Opus */
-	bad_magic_number,
-	cut_magic_number,
-	cut_vendor_length,
-	cut_vendor_data,
-	cut_comment_count,
-	cut_comment_length,
-	cut_comment_data,
-	invalid_size,
-	/* CLI */
-	bad_arguments,
-};
-
-/**
- * Wraps a status code with an optional message. It is implictly converted to and from a
- * #status_code. It may be thrown on error by any of the ot:: functions.
- *
- * All the statuses except #st::ok should be accompanied with a relevant error message, in case it
- * propagates back to the main function and is shown to the user.
- */
-struct status {
-	status(st code = st::ok) : code(code) {}
-	template<class T> status(st code, T&& message) : code(code), message(message) {}
-	operator st() const { return code; }
-	st code;
-	std::string message;
-};
-
-using byte_string = std::basic_string<uint8_t>;
-using byte_string_view = std::basic_string_view<uint8_t>;
-
-/***********************************************************************************************//**
- * \defgroup system System
- * \{
- */
-
-/**
- * Smart auto-closing FILE* handle.
- *
- * It implictly converts from an already opened FILE*.
- */
-struct file : std::unique_ptr<FILE, decltype(&fclose)> {
-	file(FILE* f = nullptr) : std::unique_ptr<FILE, decltype(&fclose)>(f, &fclose) {}
-};
-
-/**
- * A partial file is a temporary file created to store the result of something. When it is complete,
- * it is moved to a final destination. Open it with #open and then you can either #commit it to save
- * it to its destination, or you can #abort to delete the temporary file. When the #partial_file
- * object is destroyed, it deletes the currently opened temporary file, if any.
- */
-class partial_file {
-public:
-	~partial_file() { abort(); }
-	/**
-	 * Open a temporary file meant to be moved to the specified destination file path. The
-	 * temporary file is created in the same directory as its destination in order to make the
-	 * final move operation instant.
-	 */
-	void open(const char* destination);
-	/** Close then move the partial file to its final location. */
-	void commit();
-	/** Delete the temporary file. */
-	void abort();
-	/** Get the underlying FILE* handle. */
-	FILE* get() { return file.get(); }
-	/** Get the name of the temporary file. */
-	const char* name() const { return file == nullptr ? nullptr : temporary_name.c_str(); }
-private:
-	std::string temporary_name;
-	std::string final_name;
-	ot::file file;
-};
-
-/** Read a whole file into memory and return the read content. */
-byte_string slurp_binary_file(const char* filename);
-
-/** Convert a string from the system locale’s encoding to UTF-8. */
-std::u8string encode_utf8(std::string_view);
-
-/** Convert a string from UTF-8 to the system locale’s encoding. */
-std::string decode_utf8(std::u8string_view);
-
-/** Escape a string so that a POSIX shell interprets it as a single argument. */
-std::string shell_escape(std::string_view word);
-
-/**
- * Execute the editor process specified in editor. Wait for the process to exit and
- * return st::ok on success, or st::child_process_failed if it did not exit with 0.
- *
- * editor is passed unescaped to the shell, and may contain CLI options.
- * path is the name of the file to edit, which will be passed as the last argument to editor.
- */
-void run_editor(std::string_view editor, std::string_view path);
-
-/**
- * Return the specified path’s mtime, i.e. the last data modification
- * timestamp.
- */
-timespec get_file_timestamp(const char* path);
-
-std::u8string encode_base64(byte_string_view src);
-byte_string decode_base64(std::u8string_view src);
-
-/** \} */
-
-/***********************************************************************************************//**
- * \defgroup ogg Ogg
- * \{
- */
-
-/**
- * RAII-aware wrapper around libogg's ogg_stream_state. Though it handles automatic destruction, it
- * does not prevent copying or implement move semantics correctly, so it's your responsibility to
- * ensure these operations don't happen.
- */
-struct ogg_logical_stream : ogg_stream_state {
-	ogg_logical_stream(int serialno) {
-		if (ogg_stream_init(this, serialno) != 0)
-			throw std::bad_alloc();
-	}
-	~ogg_logical_stream() {
-		ogg_stream_clear(this);
-	}
-};
-
-/**
- * Identify the codec of a logical stream based on the first bytes of the first packet of the first
- * page. For Opus, the first 8 bytes must be OpusHead. Any other signature is assumed to be another
- * codec.
- */
-bool is_opus_stream(const ogg_page& identification_header);
-
-/**
- * Ogg reader, combining a FILE input, an ogg_sync_state reading the pages.
- *
- * Call #read_page repeatedly until it returns false to consume the stream, and use #page to check
- * its content.
- */
-struct ogg_reader {
-	/**
-	 * Initialize the reader with the given input file handle. The caller is responsible for
-	 * keeping the file handle alive, and to close it.
-	 */
-	ogg_reader(FILE* input) : file(input) { ogg_sync_init(&sync); }
-	/**
-	 * Clear all the internal memory allocated by libogg for the sync and stream state. The
-	 * page and the packet are owned by these states, so nothing to do with them.
-	 *
-	 * The input file is not closed.
-	 */
-	~ogg_reader() { ogg_sync_clear(&sync); }
-	/**
-	 * Read the next page from the input file. The result is made available in the #page field,
-	 * is owned by the Ogg reader, and is valid until the next call to #read_page.
-	 *
-	 * Return true if a page was read, false on end of stream.
-	 */
-	bool next_page();
-	/**
-	 * Read the single packet contained in the last page read, assuming it's a header page, and
-	 * call the function f on it. This function has no side effect, and calling it twice on the
-	 * same page will read the same packet again.
-	 *
-	 * It is currently limited to packets that fit on a single page, and should be later
-	 * extended to support packets spanning multiple pages.
-	 */
-	void process_header_packet(const std::function<void(ogg_packet&)>& f);
-	/**
-	 * Current page from the sync state.
-	 *
-	 * Its memory is managed by libogg, inside the sync state, and is valid until the next call
-	 * to ogg_sync_pageout, wrapped by #read_page.
-	 */
-	ogg_page page;
-	/**
-	 * Page number in the physical stream of the last read page, disregarding multiplexed
-	 * streams. The first page number is 0. When no page has been read, its value is
-	 * (size_t) -1.
-	 */
-	size_t absolute_page_no = -1;
-	/**
-	 * The file is our source of binary data. It is not integrated to libogg, so we need to
-	 * handle it ourselves.
-	 *
-	 * The file is not owned by the ogg_reader instance.
-	 */
-	FILE* file;
-	/**
-	 * The sync layer gets binary data and yields a sequence of pages.
-	 *
-	 * A page contains packets that we can extract using the #stream state, but we only do that
-	 * for the headers. Once we got the OpusHead and OpusTags packets, all the following pages
-	 * are simply forwarded to the Ogg writer.
-	 */
-	ogg_sync_state sync;
-};
-
-/**
- * An Ogg writer lets you write ogg_page objets to an output file, and assemble packets into pages.
- *
- * Its packet writing facility is limited to writing single-page header packets, because that's all
- * we need for opustags.
- */
-struct ogg_writer {
-	/**
-	 * Initialize the writer with the given output file handle. The caller is responsible for
-	 * keeping the file handle alive, and to close it.
-	 */
-	explicit ogg_writer(FILE* output) : file(output) {}
-	/**
-	 * Write a whole Ogg page into the output stream.
-	 *
-	 * This is a basic I/O operation and does not even require libogg, or the stream.
-	 */
-	void write_page(const ogg_page& page);
-	/**
-	 * Write a header packet and flush the page. Header packets are always placed alone on their
-	 * pages.
-	 */
-	void write_header_packet(int serialno, int pageno, ogg_packet& packet);
-	/**
-	 * Output file. It should be opened in binary mode. We use it to write whole pages,
-	 * represented as a block of data and a length.
-	 */
-	FILE* file;
-	/**
-	 * Path to the output file.
-	 */
-	std::optional<std::string> path;
-	/**
-	 * Custom counter for the sequential page number to be written. It allows us to detect
-	 * ogg_page_pageno mismatches and renumber the pages if needed.
-	 */
-	long next_page_no = 0;
-};
-
-/**
- * Ogg packet with dynamically allocated data.
- *
- * Provides a wrapper around libogg's ogg_packet with RAII.
- */
-struct dynamic_ogg_packet : ogg_packet {
-	/** Construct an ogg_packet of the given size. */
-	explicit dynamic_ogg_packet(size_t size) {
-		bytes = size;
-		data = std::make_unique<unsigned char[]>(size);
-		packet = data.get();
-	}
-private:
-	/** Owning reference to the data. Use the packet field from ogg_packet instead. */
-	std::unique_ptr<unsigned char[]> data;
-};
-
-/** Update the Ogg pageno field in the given page. The CRC is recomputed if needed. */
-void renumber_page(ogg_page& page, long new_pageno);
-
-/** \} */
-
-/***********************************************************************************************//**
- * \defgroup opus Opus
- * \{
- */
-
-/**
- * Faithfully represent *all* the data in an OpusTags packet, exactly as they will be written in the
- * final stream, disregarding the current system locale or anything else.
- *
- * The vendor and comment strings are expected to contain valid UTF-8, but we should keep their
- * values intact even if the string is not UTF-8 clean, or encoded in any other way.
- */
-struct opus_tags {
-	/**
-	 * OpusTags packets begin with a vendor string, meant to identify the implementation of the
-	 * encoder. It is expected to be an arbitrary UTF-8 string.
-	 */
-	std::u8string vendor;
-	/**
-	 * Comments are strings in the NAME=Value format. A comment may also be called a field, or a
-	 * tag.
-	 *
-	 * The field name in vorbis comments is usually case-insensitive and ASCII, while the value
-	 * can be any valid UTF-8 string. The specification is not too clear for Opus, but let's
-	 * assume it's the same.
-	 */
-	std::list<std::u8string> comments;
-	/**
-	 * According to RFC 7845:
-	 * > Immediately following the user comment list, the comment header MAY contain
-	 * > zero-padding or other binary data that is not specified here.
-	 *
-	 * The first byte is supposed to indicate whether this data should be kept or not, but let's
-	 * assume it's here for a reason and always keep it. Better safe than sorry.
-	 *
-	 * In the future, we could add options to manipulate this data: view it, edit it, truncate
-	 * it if it's marked as padding, truncate it unconditionally.
-	 */
-	byte_string extra_data;
-};
-
-/**
- * Read the given OpusTags packet and extract its content into an opus_tags object.
- */
-opus_tags parse_tags(const ogg_packet& packet);
-
-/**
- * Serialize an #opus_tags object into an OpusTags Ogg packet.
- */
-dynamic_ogg_packet render_tags(const opus_tags& tags);
-
-/**
- * Extracted data from the METADATA_BLOCK_PICTURE tag. See
- * <https://xiph.org/flac/format.html#metadata_block_picture> for the full specifications.
- *
- * It may contain all kinds of metadata but most are not used at all. For now, let’s assume all
- * pictures have picture type 3 (front cover), and empty metadata.
- */
-struct picture {
-	picture() = default;
-
-	/** Extract the picture information from serialized binary data.*/
-	picture(byte_string block);
-	byte_string_view mime_type;
-	byte_string_view picture_data;
-
-	/**
-	 * Encode the picture attributes (mime_type, picture_data) into a binary block to be stored
-	 * into METADATA_BLOCK_PICTURE.
-	 */
-	byte_string serialize() const;
-
-	/** To avoid needless copies of the picture data, move the original data block there. The
-	 *  string_view attributes will refer to it. */
-	byte_string storage;
-};
-
-/** Extract the first picture embedded in the tags, regardless of its type. */
-std::optional<picture> extract_cover(const opus_tags& tags);
-
-/**
- * Return a METADATA_BLOCK_PICTURE tag defining the front cover art to the given picture data (JPEG,
- * PNG). The MIME type is deduced from the magic number.
- */
-std::u8string make_cover(byte_string_view picture_data);
-
-/** \} */
-
-/***********************************************************************************************//**
- * \defgroup cli Command-Line Interface
- * \{
- */
-
-/**
- * Structured representation of the command-line arguments to opustags.
- */
-struct options {
-	/**
-	 * When true, opustags prints a detailed help and exits. All the other options are ignored.
-	 *
-	 * Option: --help
-	 */
-	bool print_help = false;
-	/**
-	 * Paths to the input files. The special string "-" means stdin.
-	 *
-	 * At least one input file must be given. If `--in-place` is used,
-	 * more than one may be given.
-	 */
-	std::vector<std::string> paths_in;
-	/**
-	 * Optional path to output file. The special string "-" means stdout. For in-place
-	 * editing, the input file name is used. If no output file name is supplied, and
-	 * --in-place is not used, opustags runs in read-only mode.
-	 *
-	 * Options: --output, --in-place
-	 */
-	std::optional<std::string> path_out;
-	/**
-	 * By default, opustags won't overwrite the output file if it already exists. This can be
-	 * forced with --overwrite. It is also enabled by --in-place.
-	 *
-	 * Options: --overwrite, --in-place
-	 */
-	bool overwrite = false;
-	/**
-	 * Process files in-place.
-	 *
-	 * Options: --in-place
-	 */
-	bool in_place = false;
-	/**
-	 * Spawn EDITOR to edit tags interactively.
-	 *
-	 * stdin and stdout must be left free for the editor, so paths_in and
-	 * path_out can’t take `-`, and --set-all is not supported.
-	 *
-	 * Option: --edit
-	 */
-	bool edit_interactively = false;
-	/**
-	 * List of comments to delete. Each string is a selector according to the definition of
-	 * #delete_comments.
-	 *
-	 * When #delete_all is true, this option is meaningless.
-	 *
-	 * #to_add takes precedence over #to_delete, so if the same comment appears in both lists,
-	 * the one in #to_delete applies only to the previously existing tags.
-	 *
-	 * Option: --delete, --set
-	 */
-	std::list<std::u8string> to_delete;
-	/**
-	 * Delete all the existing comments.
-	 *
-	 * Option: --delete-all, --set-all
-	 */
-	bool delete_all = false;
-	/**
-	 * List of comments to add, in the current system encoding. For exemple `TITLE=a b c`. They
-	 * must be valid.
-	 *
-	 * Options: --add, --set, --set-all
-	 */
-	std::list<std::u8string> to_add;
-	/**
-	 * If set, the input file’s cover art is exported to the specified file. - for stdout. Does
-	 * not overwrite the file if it already exists unless -y is specified. Does nothing if the
-	 * input file does not contain a cover art.
-	 *
-	 * Option: --output-cover
-	 */
-	std::optional<std::string> cover_out;
-	/**
-	 * Print the vendor string at the beginning of the OpusTags packet instead of printing the
-	 * tags. Only applicable in read-only mode.
-	 *
-	 * Option: --vendor
-	 */
-	bool print_vendor = false;
-	/**
-	 * Replace the vendor string by the one specified by the user.
-	 *
-	 * Option: --set-vendor
-	 */
-	std::optional<std::u8string> set_vendor;
-	/**
-	 * Disable encoding conversions. OpusTags are specified to always be encoded as UTF-8, but
-	 * if for some reason a specific file contains binary tags that someone would like to
-	 * extract and set as-is, encoding conversion would get in the way.
-	 */
-	bool raw = false;
-	/**
-	 * In text mode (default), tags are separated by a line feed. However, when combining
-	 * opustags with grep or other line-based tools, this proves to be a bad separator because
-	 * tag values may contain newlines. Changing the delimiter to '\0' with -z eases the
-	 * processing of multi-line tags with other tools that support null-terminated lines.
-	 */
-	char tag_delimiter = '\n';
-};
-
-/**
- * Parse the command-line arguments. Does not perform I/O related validations, but checks the
- * consistency of its arguments. Comments are read if necessary from the given stream.
- */
-options parse_options(int argc, char** argv, FILE* comments);
-
-/**
- * Print all the comments, separated by line breaks. Since a comment may contain line breaks, this
- * output is not completely reliable, but it fits most cases.
- *
- * The comments must be encoded in UTF-8, and are converted to the system locale when printed,
- * unless raw is true.
- *
- * The output generated is meant to be parseable by #ot::read_comments.
- */
-void print_comments(const std::list<std::u8string>& comments, FILE* output, const options& opt);
-
-/**
- * Parse the comments outputted by #ot::print_comments. Unless raw is true, the comments are
- * converted from the system encoding to UTF-8, and returned as UTF-8.
- */
-std::list<std::u8string> read_comments(FILE* input, const options& opt);
-
-/**
- * Remove all comments matching the specified selector, which may either be a field name or a
- * NAME=VALUE pair. The field name is case-insensitive.
- */
-void delete_comments(std::list<std::u8string>& comments, const std::u8string& selector);
-
-/**
- * Main entry point to the opustags program, and pretty much the same as calling opustags from the
- * command-line.
- */
-void run(const options& opt);
-
-/** \} */
-
-}
-
-/** Handy literal suffix for building byte strings. */
-ot::byte_string operator""_bs(const char* data, size_t size);
-ot::byte_string_view operator""_bsv(const char* data, size_t size);

src/system.cc

@@ -1,275 +0,0 @@
-/**
- * \file src/system.cc
- * \ingroup system
- *
- * Provide a high-level interface to system-related features, like filesystem manipulations.
- *
- * Ideally, all OS-specific features should be grouped here.
- *
- * This modules shoumd not depend on any other opustags module.
- */
-
-#include <opustags.h>
-
-#include <errno.h>
-#include <fstream>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/stat.h>
-#include <sys/wait.h>
-#include <unistd.h>
-
-ot::byte_string operator""_bs(const char* data, size_t size)
-{
-	return ot::byte_string(reinterpret_cast<const uint8_t*>(data), size);
-}
-
-ot::byte_string_view operator""_bsv(const char* data, size_t size)
-{
-	return ot::byte_string_view(reinterpret_cast<const uint8_t*>(data), size);
-}
-
-void ot::partial_file::open(const char* destination)
-{
-	final_name = destination;
-	temporary_name = final_name + ".XXXXXX.part";
-	int fd = mkstemps(const_cast<char*>(temporary_name.data()), 5);
-	if (fd == -1)
-		throw status {st::standard_error,
-		              "Could not create a partial file for '" + final_name + "': " +
-		              strerror(errno)};
-	file = fdopen(fd, "w");
-	if (file == nullptr)
-		throw status {st::standard_error,
-		              "Could not get the partial file handle to '" + temporary_name + "': " +
-		              strerror(errno)};
-}
-
-static mode_t get_umask()
-{
-	// libc doesn’t seem to provide a way to get umask without changing it, so we need this workaround.
-	// https://www.gnu.org/software/libc/manual/html_node/Setting-Permissions.html
-	mode_t mask = umask(0);
-	umask(mask);
-	return mask;
-}
-
-/**
- * Try reproducing the file permissions of file `source` onto file `dest`. If
- * this fails for whatever reason, print a warning and leave the current
- * permissions. When the source doesn’t exist, use the default file creation
- * permissions according to umask.
- */
-static void copy_permissions(const char* source, const char* dest)
-{
-	mode_t target_mode;
-	struct stat source_stat;
-	if (stat(source, &source_stat) == 0) {
-		// We could technically preserve a bit more than that but who
-		// would ever need S_ISUID and friends on an Opus file?
-		target_mode = source_stat.st_mode & 0777;
-	} else if (errno == ENOENT) {
-		target_mode = 0666 & ~get_umask();
-	} else {
-		fprintf(stderr, "warning: Could not read mode of %s: %s\n", source, strerror(errno));
-		return;
-	}
-	if (chmod(dest, target_mode) == -1)
-		fprintf(stderr, "warning: Could not set mode of %s: %s\n", dest, strerror(errno));
-}
-
-void ot::partial_file::commit()
-{
-	if (file == nullptr)
-		return;
-	file.reset();
-	copy_permissions(final_name.c_str(), temporary_name.c_str());
-	if (rename(temporary_name.c_str(), final_name.c_str()) == -1)
-		throw status {st::standard_error,
-		              "Could not move the result file '" + temporary_name + "' to '" +
-		              final_name + "': " + strerror(errno) + "."};
-}
-
-void ot::partial_file::abort()
-{
-	if (file == nullptr)
-		return;
-	file.reset();
-	remove(temporary_name.c_str());
-}
-
-/**
- * Determine the file size, in bytes, of the given file. Return -1 on for streams.
- */
-static long get_file_size(FILE* f)
-{
-	if (fseek(f, 0L, SEEK_END) != 0) {
-		clearerr(f); // Recover.
-		return -1;
-	}
-	long file_size = ftell(f);
-	rewind(f);
-	return file_size;
-}
-
-ot::byte_string ot::slurp_binary_file(const char* filename)
-{
-	file f = strcmp(filename, "-") == 0 ? freopen(nullptr, "rb", stdin)
-	                                    : fopen(filename, "rb");
-	if (f == nullptr)
-		throw status { st::standard_error,
-		               "Could not open '"s + filename + "': " + strerror(errno) + "." };
-
-	byte_string content;
-	long file_size = get_file_size(f.get());
-	if (file_size == -1) {
-		// Read the input stream block by block and resize the output byte string as needed.
-		uint8_t buffer[4096];
-		while (!feof(f.get())) {
-			size_t read_len = fread(buffer, 1, sizeof(buffer), f.get());
-			content.append(buffer, read_len);
-			if (ferror(f.get()))
-				throw status { st::standard_error,
-					       "Could not read '"s + filename + "': " + strerror(errno) + "." };
-		}
-	} else {
-		// Lucky! We know the file size, so let’s slurp it at once.
-		content.resize(file_size);
-		if (fread(content.data(), 1, file_size, f.get()) < file_size)
-			throw status { st::standard_error,
-				       "Could not read '"s + filename + "': " + strerror(errno) + "." };
-	}
-
-	return content;
-}
-
-/** C++ wrapper for iconv. */
-class encoding_converter {
-public:
-	/**
-	 * Allocate the iconv conversion state, initializing the given source and destination
-	 * character encodings. If it's okay to have some information lost, make sure `to` ends with
-	 * "//TRANSLIT", otherwise the conversion will fail when a character cannot be represented
-	 * in the target encoding. See the documentation of iconv_open for details.
-	 */
-	encoding_converter(const char* from, const char* to);
-	~encoding_converter();
-	/**
-	 * Convert text using iconv. If the input sequence is invalid, return #st::badly_encoded and
-	 * abort the processing, leaving out in an undefined state.
-	 */
-	template<class InChar, class OutChar>
-	std::basic_string<OutChar> convert(std::basic_string_view<InChar>);
-private:
-	iconv_t cd; /**< conversion descriptor */
-};
-
-encoding_converter::encoding_converter(const char* from, const char* to)
-{
-	cd = iconv_open(to, from);
-	if (cd == (iconv_t) -1)
-		throw std::bad_alloc();
-}
-
-encoding_converter::~encoding_converter()
-{
-	iconv_close(cd);
-}
-
-template<class InChar, class OutChar>
-std::basic_string<OutChar> encoding_converter::convert(std::basic_string_view<InChar> in)
-{
-	iconv(cd, nullptr, nullptr, nullptr, nullptr);
-	std::basic_string<OutChar> out;
-	out.reserve(in.size());
-	const char* in_data = reinterpret_cast<const char*>(in.data());
-	char* in_cursor = const_cast<char*>(in_data);
-	size_t in_left = in.size();
-	constexpr size_t chunk_size = 1024;
-	char chunk[chunk_size];
-	for (;;) {
-		char *out_cursor = chunk;
-		size_t out_left = chunk_size;
-		size_t rc = iconv(cd, &in_cursor, &in_left, &out_cursor, &out_left);
-
-		if (rc == (size_t) -1 && errno == E2BIG) {
-			// Loop normally.
-		} else if (rc == (size_t) -1) {
-			throw ot::status {ot::st::badly_encoded, strerror(errno) + "."s};
-		} else if (rc != 0) {
-			throw ot::status {ot::st::badly_encoded,
-			                 "Some characters could not be converted into the target encoding."};
-		}
-
-		out.append(reinterpret_cast<OutChar*>(chunk), out_cursor - chunk);
-		if (in_cursor == nullptr)
-			break;
-		else if (in_left == 0)
-			in_cursor = nullptr;
-	}
-	return out;
-}
-
-std::u8string ot::encode_utf8(std::string_view in)
-{
-	static encoding_converter to_utf8_cvt("", "UTF-8");
-	return to_utf8_cvt.convert<char, char8_t>(in);
-}
-
-std::string ot::decode_utf8(std::u8string_view in)
-{
-	static encoding_converter from_utf8_cvt("UTF-8", "");
-	return from_utf8_cvt.convert<char8_t, char>(in);
-}
-
-std::string ot::shell_escape(std::string_view word)
-{
-	std::string escaped_word;
-	// Pre-allocate the result, assuming most of the time enclosing it in single quotes is enough.
-	escaped_word.reserve(2 + word.size());
-
-	escaped_word += '\'';
-	for (char c : word) {
-		if (c == '\'')
-			escaped_word += "'\\''";
-		else if (c == '!')
-			escaped_word += "'\\!'";
-		else
-			escaped_word += c;
-	}
-	escaped_word += '\'';
-
-	return escaped_word;
-}
-
-void ot::run_editor(std::string_view editor, std::string_view path)
-{
-	std::string command = std::string(editor) + " " + shell_escape(path);
-	int status = system(command.c_str());
-
-	if (status == -1)
-		throw ot::status {st::standard_error, "waitpid error: "s + strerror(errno)};
-	else if (!WIFEXITED(status))
-		throw ot::status {st::child_process_failed,
-		                 "Child process did not terminate normally: "s + strerror(errno)};
-	else if (WEXITSTATUS(status) != 0)
-		throw ot::status {st::child_process_failed,
-		                  "Child process exited with " + std::to_string(WEXITSTATUS(status))};
-}
-
-timespec ot::get_file_timestamp(const char* path)
-{
-	timespec mtime;
-	struct stat st;
-	if (stat(path, &st) == -1)
-		throw status {st::standard_error, path + ": stat error: "s + strerror(errno)};
-#if defined(HAVE_STAT_ST_MTIM)
-	mtime = st.st_mtim;
-#elif defined(HAVE_STAT_ST_MTIMESPEC)
-	mtime = st.st_mtimespec;
-#else
-	mtime.tv_sec = st.st_mtime;
-	mtime.tv_nsec = st.st_mtimensec;
-#endif
-	return mtime;
-}

src/tags.cc

@@ -0,0 +1,103 @@
+#include "tags.h"
+#include <algorithm>
+
+using namespace opustags;
+
+// ASCII only, but for tag keys it's good enough
+static bool iequals(const std::string &a, const std::string &b)
+{
+    if (a.size() != b.size())
+        return false;
+    for (size_t i = 0; i < a.size(); i++)
+        if (std::tolower(a[i]) != std::tolower(b[i]))
+            return false;
+    return true;
+}
+
+bool Tag::operator !=(const Tag &other_tag) const
+{
+    return !operator ==(other_tag);
+}
+
+bool Tag::operator ==(const Tag &other_tag) const
+{
+    return key == other_tag.key
+        && value == other_tag.value;
+}
+
+Tags::Tags()
+{
+}
+
+Tags::Tags(const std::vector<Tag> &tags) : tags(tags)
+{
+}
+
+const std::vector<Tag> Tags::get_all() const
+{
+    return tags;
+}
+
+std::string Tags::get(const std::string &key) const
+{
+    for (auto &tag : tags)
+        if (iequals(tag.key, key))
+            return tag.value;
+    throw std::runtime_error("Tag '" + key + "' not found.");
+}
+
+void Tags::add(const Tag &tag)
+{
+    tags.push_back(tag);
+}
+
+void Tags::add(const std::string &key, const std::string &value)
+{
+    tags.push_back({key, value});
+}
+
+void Tags::clear()
+{
+    tags.clear();
+}
+
+void Tags::remove(const std::string &key)
+{
+    std::vector<Tag> new_tags;
+    std::copy_if(
+        tags.begin(),
+        tags.end(),
+        std::back_inserter(new_tags),
+        [&](const Tag &tag) { return !iequals(tag.key, key); });
+    tags = new_tags;
+}
+
+bool Tags::contains(const std::string &key) const
+{
+    return std::count_if(
+        tags.begin(),
+        tags.end(),
+        [&](const Tag &tag) { return iequals(tag.key, key); }) > 0;
+}
+
+Tag opustags::parse_tag(const std::string &assoc)
+{
+    size_t eq = assoc.find_first_of('=');
+    if (eq == std::string::npos)
+        throw std::runtime_error("misconstructed tag");
+    std::string name = assoc.substr(0, eq);
+    std::string value = assoc.substr(eq + 1);
+    return { name, value };
+}
+
+bool Tags::operator !=(const Tags &other_tags) const
+{
+    return !operator ==(other_tags);
+}
+
+bool Tags::operator ==(const Tags &other_tags) const
+{
+    return vendor == other_tags.vendor
+        && extra == other_tags.extra
+        && get_all() == other_tags.get_all();
+}

src/tags.h

@@ -0,0 +1,49 @@
+#pragma once
+
+#include <map>
+#include <vector>
+#include <utility>
+
+namespace opustags {
+
+    struct Tag final
+    {
+        bool operator !=(const Tag &other_tag) const;
+        bool operator ==(const Tag &other_tag) const;
+
+        std::string key;
+        std::string value;
+    };
+
+    // A std::map adapter that keeps the order of insertion.
+    class Tags final
+    {
+    public:
+        Tags();
+        Tags(const std::vector<Tag> &tags);
+
+        const std::vector<Tag> get_all() const;
+
+        std::string get(const std::string &key) const;
+        void add(const Tag &tag);
+        void add(const std::string &key, const std::string &value);
+        void remove(const std::string &key);
+        bool contains(const std::string &key) const;
+        void clear();
+
+        bool operator !=(const Tags &other_tags) const;
+        bool operator ==(const Tags &other_tags) const;
+
+        // Additional fields are required to match the specs:
+        // https://tools.ietf.org/html/draft-ietf-codec-oggopus-14#section-5.2
+
+        std::string vendor;
+        std::string extra;
+
+    private:
+        std::vector<Tag> tags;
+    };
+
+    Tag parse_tag(const std::string &assoc); // KEY=value
+
+}

src/tags_handler.h

@@ -0,0 +1,50 @@
+#pragma once
+
+#include "tags.h"
+
+namespace opustags {
+
+    // TagsHandler define various operations related to tags and stream in
+    // order to control the main loop.
+    // In its implementation, it is expected to receive an option structure.
+    class ITagsHandler
+    {
+    public:
+        // Irrelevant streams don't even need to be parsed, so we can save some
+        // effort with this method.
+        // Returns true if the stream should be parsed, false if it should be
+        // ignored (list) or copied identically (edit).
+        virtual bool relevant(const int streamno) = 0;
+
+        // The list method is called by list_tags every time it has
+        // successfully parsed an OpusTags header.
+        virtual void list(const int streamno, const Tags &) = 0;
+
+        // Transform the tags at will.
+        // Returns true if the tags were indeed modified, false if they weren't.
+        // The latter case may be used for optimization.
+        virtual bool edit(const int streamno, Tags &) = 0;
+
+        // The work is done.
+        // When listing tags, once we've caught the streams we wanted, it's no
+        // use keeping reading the file for new streams. In that case, a true
+        // return value would abort any further processing.
+        virtual bool done() = 0;
+
+        // Signals a new stream was found.
+        // The meaning of type is in ogg::StreamType, but all you should assume
+        // is that when type is null (UNKNOWN_STREAM), list or edit won't be
+        // called.
+        virtual void start_of_stream(const int streamno, const int type) {}
+
+        // Signals the end of the file (and all the streams).
+        // If after this function is called, done() returns false, it's an
+        // error. However, it would be better to raise the error inside
+        // end_of_stream().
+        // For example, if you expect to find the stream #1 and reach the
+        // end-of-stream before finding it, better tell the user that you
+        // didn't do what he expected.
+        virtual void end_of_file() {}
+    };
+
+}

src/tags_handlers/composite_tags_handler.cc

@@ -0,0 +1,44 @@
+#include "tags_handlers/composite_tags_handler.h"
+
+using namespace opustags;
+
+void CompositeTagsHandler::add_handler(std::shared_ptr<ITagsHandler> handler)
+{
+    handlers.push_back(std::move(handler));
+}
+
+bool CompositeTagsHandler::relevant(const int streamno)
+{
+    for (const auto &handler : handlers)
+        if (handler->relevant(streamno))
+            return true;
+    return false;
+}
+
+void CompositeTagsHandler::list(const int streamno, const Tags &tags)
+{
+    for (const auto &handler : handlers)
+        handler->list(streamno, tags);
+}
+
+bool CompositeTagsHandler::edit(const int streamno, Tags &tags)
+{
+    bool modified = false;
+    for (const auto &handler : handlers)
+        modified |= handler->edit(streamno, tags);
+    return modified;
+}
+
+bool CompositeTagsHandler::done()
+{
+    for (const auto &handler : handlers)
+        if (!handler->done())
+            return false;
+    return true;
+}
+
+const std::vector<std::shared_ptr<ITagsHandler>>
+    CompositeTagsHandler::get_handlers() const
+{
+    return handlers;
+}

src/tags_handlers/composite_tags_handler.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+#include "tags_handler.h"
+
+namespace opustags {
+
+    class CompositeTagsHandler final : public ITagsHandler
+    {
+    public:
+        void add_handler(std::shared_ptr<ITagsHandler> handler);
+
+        bool relevant(const int streamno) override;
+        void list(const int streamno, const Tags &) override;
+        bool edit(const int streamno, Tags &) override;
+        bool done() override;
+
+        const std::vector<std::shared_ptr<ITagsHandler>> get_handlers() const;
+
+    private:
+        std::vector<std::shared_ptr<ITagsHandler>> handlers;
+    };
+
+}

src/tags_handlers/export_tags_handler.cc

@@ -0,0 +1,31 @@
+#include "tags_handlers/export_tags_handler.h"
+
+using namespace opustags;
+
+ExportTagsHandler::ExportTagsHandler(std::ostream &output_stream)
+    : output_stream(output_stream)
+{
+}
+
+bool ExportTagsHandler::relevant(const int)
+{
+    return true;
+}
+
+void ExportTagsHandler::list(const int streamno, const Tags &tags)
+{
+    output_stream << "[Stream " << streamno << "]\n";
+    for (const auto tag : tags.get_all())
+        output_stream << tag.key << "=" << tag.value << "\n";
+    output_stream << "\n";
+}
+
+bool ExportTagsHandler::edit(const int, Tags &)
+{
+    return false;
+}
+
+bool ExportTagsHandler::done()
+{
+    return false;
+}

src/tags_handlers/export_tags_handler.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <iostream>
+#include "tags_handler.h"
+
+namespace opustags {
+
+    class ExportTagsHandler : public ITagsHandler
+    {
+    public:
+        ExportTagsHandler(std::ostream &output_stream);
+
+        bool relevant(const int streamno) override;
+        void list(const int streamno, const Tags &) override;
+        bool edit(const int streamno, Tags &) override;
+        bool done() override;
+
+    private:
+        std::ostream &output_stream;
+    };
+
+}

src/tags_handlers/external_edit_tags_handler.cc

@@ -0,0 +1,22 @@
+#include "tags_handlers/external_edit_tags_handler.h"
+
+using namespace opustags;
+
+bool ExternalEditTagsHandler::relevant(const int streamno)
+{
+    return false;
+}
+
+void ExternalEditTagsHandler::list(const int streamno, const Tags &)
+{
+}
+
+bool ExternalEditTagsHandler::edit(const int streamno, Tags &)
+{
+    return false;
+}
+
+bool ExternalEditTagsHandler::done()
+{
+    return true;
+}

src/tags_handlers/external_edit_tags_handler.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <iostream>
+#include "tags_handler.h"
+
+namespace opustags {
+
+    class ExternalEditTagsHandler : public ITagsHandler
+    {
+    public:
+        bool relevant(const int streamno) override;
+        void list(const int streamno, const Tags &) override;
+        bool edit(const int streamno, Tags &) override;
+        bool done() override;
+    };
+
+}

src/tags_handlers/import_tags_handler.cc

@@ -0,0 +1,67 @@
+#include <regex>
+#include "tags_handlers/import_tags_handler.h"
+
+using namespace opustags;
+
+ImportTagsHandler::ImportTagsHandler(std::istream &input_stream)
+    : parsed(false), input_stream(input_stream)
+{
+}
+
+bool ImportTagsHandler::relevant(const int)
+{
+    return true;
+}
+
+void ImportTagsHandler::list(const int, const Tags &)
+{
+}
+
+bool ImportTagsHandler::edit(const int streamno, Tags &tags)
+{
+    // the reason why we do it this way is because the tests indirectly create
+    // this handler with std::cin, and we do not want the constructor to block!
+    parse_input_stream_if_needed();
+
+    const auto old_tags = tags;
+    tags.clear();
+
+    if (tag_map.find(streamno) != tag_map.end()) {
+        const auto &source_tags = tag_map.at(streamno);
+        for (const auto &source_tag : source_tags.get_all())
+            tags.add(source_tag.key, source_tag.value);
+    }
+
+    return old_tags != tags;
+}
+
+bool ImportTagsHandler::done()
+{
+    return false;
+}
+
+void ImportTagsHandler::parse_input_stream_if_needed()
+{
+    if (parsed)
+        return;
+    parsed = true;
+
+    const std::regex whitespace_regex("^\\s*$");
+    const std::regex stream_header_regex(
+        "^\\s*\\[stream\\s+(\\d+)\\]\\s*$", std::regex_constants::icase);
+    const std::regex tag_regex(
+        "^\\s*([a-z0-9]+)\\s*=\\s*(.*?)\\s*$", std::regex_constants::icase);
+
+    int current_stream_number = 1;
+    std::string line;
+    while (std::getline(input_stream, line)) {
+        std::smatch match;
+        if (std::regex_match(line, match, stream_header_regex)) {
+            current_stream_number = std::atoi(match[1].str().c_str());
+        } else if (std::regex_match(line, match, tag_regex)) {
+            tag_map[current_stream_number].add(match[1], match[2]);
+        } else if (!std::regex_match(line, match, whitespace_regex)) {
+            throw std::runtime_error("Malformed input data near line " + line);
+        }
+    }
+}

src/tags_handlers/import_tags_handler.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <iostream>
+#include <map>
+#include "tags_handler.h"
+
+namespace opustags {
+
+    class ImportTagsHandler : public ITagsHandler
+    {
+    public:
+        ImportTagsHandler(std::istream &input_stream);
+
+        bool relevant(const int streamno) override;
+        void list(const int streamno, const Tags &) override;
+        bool edit(const int streamno, Tags &) override;
+        bool done() override;
+
+    private:
+        void parse_input_stream_if_needed();
+
+        bool parsed;
+        std::istream &input_stream;
+        std::map<int, Tags> tag_map;
+    };
+
+}

src/tags_handlers/insertion_tags_handler.cc

@@ -0,0 +1,28 @@
+#include "tags_handlers/insertion_tags_handler.h"
+#include "tags_handlers_errors.h"
+
+using namespace opustags;
+
+InsertionTagsHandler::InsertionTagsHandler(
+    const int streamno,
+    const std::string &tag_key,
+    const std::string &tag_value)
+    : StreamTagsHandler(streamno), tag_key(tag_key), tag_value(tag_value)
+{
+}
+
+std::string InsertionTagsHandler::get_tag_key() const
+{
+    return tag_key;
+}
+
+std::string InsertionTagsHandler::get_tag_value() const
+{
+    return tag_value;
+}
+
+bool InsertionTagsHandler::edit_impl(Tags &tags)
+{
+    tags.add(tag_key, tag_value);
+    return true;
+}

src/tags_handlers/insertion_tags_handler.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "tags_handlers/stream_tags_handler.h"
+
+namespace opustags {
+
+    class InsertionTagsHandler : public StreamTagsHandler
+    {
+    public:
+        InsertionTagsHandler(
+            const int streamno,
+            const std::string &tag_key,
+            const std::string &tag_value);
+
+        std::string get_tag_key() const;
+        std::string get_tag_value() const;
+
+    protected:
+        bool edit_impl(Tags &) override;
+
+    private:
+        const std::string tag_key;
+        const std::string tag_value;
+    };
+
+}

src/tags_handlers/listing_tags_handler.cc

@@ -0,0 +1,16 @@
+#include "tags_handlers/listing_tags_handler.h"
+
+using namespace opustags;
+
+ListingTagsHandler::ListingTagsHandler(
+    const int streamno,
+    std::ostream &output_stream)
+    : StreamTagsHandler(streamno), output_stream(output_stream)
+{
+}
+
+void ListingTagsHandler::list_impl(const Tags &tags)
+{
+    for (const auto &tag : tags.get_all())
+        output_stream << tag.key << "=" << tag.value << "\n";
+}

src/tags_handlers/listing_tags_handler.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <iostream>
+#include "tags_handlers/stream_tags_handler.h"
+
+namespace opustags {
+
+    class ListingTagsHandler : public StreamTagsHandler
+    {
+    public:
+        ListingTagsHandler(const int streamno, std::ostream &output_stream);
+
+    protected:
+        void list_impl(const Tags &) override;
+
+    private:
+        std::ostream &output_stream;
+    };
+
+}

src/tags_handlers/modification_tags_handler.cc

@@ -0,0 +1,33 @@
+#include "tags_handlers/modification_tags_handler.h"
+
+using namespace opustags;
+
+ModificationTagsHandler::ModificationTagsHandler(
+    const int streamno,
+    const std::string &tag_key,
+    const std::string &tag_value)
+    : StreamTagsHandler(streamno), tag_key(tag_key), tag_value(tag_value)
+{
+}
+
+std::string ModificationTagsHandler::get_tag_key() const
+{
+    return tag_key;
+}
+
+std::string ModificationTagsHandler::get_tag_value() const
+{
+    return tag_value;
+}
+
+bool ModificationTagsHandler::edit_impl(Tags &tags)
+{
+    if (tags.contains(tag_key)) {
+        if (tags.get(tag_key) == tag_value)
+            return false;
+        tags.remove(tag_key);
+    }
+
+    tags.add(tag_key, tag_value);
+    return true;
+}

src/tags_handlers/modification_tags_handler.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "tags_handlers/stream_tags_handler.h"
+
+namespace opustags {
+
+    class ModificationTagsHandler : public StreamTagsHandler
+    {
+    public:
+        ModificationTagsHandler(
+            const int streamno,
+            const std::string &tag_key,
+            const std::string &tag_value);
+
+        std::string get_tag_key() const;
+        std::string get_tag_value() const;
+
+    protected:
+        bool edit_impl(Tags &) override;
+
+    private:
+        const std::string tag_key;
+        const std::string tag_value;
+    };
+
+}

src/tags_handlers/removal_tags_handler.cc

@@ -0,0 +1,35 @@
+#include "tags_handlers/removal_tags_handler.h"
+#include "tags_handlers_errors.h"
+
+using namespace opustags;
+
+RemovalTagsHandler::RemovalTagsHandler(const int streamno)
+    : StreamTagsHandler(streamno)
+{
+}
+
+RemovalTagsHandler::RemovalTagsHandler(
+    const int streamno, const std::string &tag_key)
+    : StreamTagsHandler(streamno), tag_key(tag_key)
+{
+}
+
+std::string RemovalTagsHandler::get_tag_key() const
+{
+    return tag_key;
+}
+
+bool RemovalTagsHandler::edit_impl(Tags &tags)
+{
+    if (tag_key.empty()) {
+        const auto anything_removed = tags.get_all().size() > 0;
+        tags.clear();
+        return anything_removed;
+    } else {
+        if (!tags.contains(tag_key))
+            return false;
+
+        tags.remove(tag_key);
+        return true;
+    }
+}

src/tags_handlers/removal_tags_handler.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "tags_handlers/stream_tags_handler.h"
+
+namespace opustags {
+
+    class RemovalTagsHandler : public StreamTagsHandler
+    {
+    public:
+        RemovalTagsHandler(const int streamno);
+        RemovalTagsHandler(const int streamno, const std::string &tag_key);
+
+        std::string get_tag_key() const;
+
+    protected:
+        bool edit_impl(Tags &) override;
+
+    private:
+        const std::string tag_key;
+    };
+
+}

src/tags_handlers/stream_tags_handler.cc

@@ -0,0 +1,59 @@
+#include "tags_handlers/stream_tags_handler.h"
+
+#include <iostream>
+
+using namespace opustags;
+
+const int StreamTagsHandler::ALL_STREAMS = -1;
+
+StreamTagsHandler::StreamTagsHandler(const int streamno)
+    : streamno(streamno), work_finished(false)
+{
+}
+
+int StreamTagsHandler::get_streamno() const
+{
+    return streamno;
+}
+
+bool StreamTagsHandler::relevant(const int streamno)
+{
+    return streamno == this->streamno || this->streamno == ALL_STREAMS;
+}
+
+void StreamTagsHandler::list(const int streamno, const Tags &tags)
+{
+    if (!relevant(streamno))
+        return;
+    list_impl(tags);
+    work_finished = this->streamno != ALL_STREAMS;
+}
+
+bool StreamTagsHandler::edit(const int streamno, Tags &tags)
+{
+    if (!relevant(streamno))
+        return false;
+    const auto ret = edit_impl(tags);
+    work_finished = this->streamno != ALL_STREAMS;
+    return ret;
+}
+
+bool StreamTagsHandler::done()
+{
+    return work_finished;
+}
+
+void StreamTagsHandler::end_of_file()
+{
+    if (!work_finished && streamno != ALL_STREAMS)
+        std::cerr << "warning: stream " << streamno << " wasn't found" << std::endl;
+}
+
+void StreamTagsHandler::list_impl(const Tags &)
+{
+}
+
+bool StreamTagsHandler::edit_impl(Tags &)
+{
+    return false;
+}

src/tags_handlers/stream_tags_handler.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "tags_handler.h"
+
+namespace opustags {
+
+    // Base handler that holds the stream number it's supposed to work with
+    // and performs the usual boilerplate.
+    class StreamTagsHandler : public ITagsHandler
+    {
+    public:
+        static const int ALL_STREAMS;
+
+        StreamTagsHandler(const int streamno);
+
+        int get_streamno() const;
+
+        bool relevant(const int streamno) override;
+        void list(const int streamno, const Tags &) override;
+        bool edit(const int streamno, Tags &) override;
+        bool done() override;
+        void end_of_file() override;
+
+    protected:
+        virtual void list_impl(const Tags &);
+        virtual bool edit_impl(Tags &);
+
+    private:
+        const int streamno;
+        bool work_finished;
+    };
+
+}

src/tags_handlers_errors.cc

@@ -0,0 +1,13 @@
+#include "tags_handlers_errors.h"
+
+using namespace opustags;
+
+TagAlreadyExistsError::TagAlreadyExistsError(const std::string &tag_key)
+    : std::runtime_error("Tag already exists: " + tag_key)
+{
+}
+
+TagDoesNotExistError::TagDoesNotExistError(const std::string &tag_key)
+    : std::runtime_error("Tag does not exist: " + tag_key)
+{
+}

src/tags_handlers_errors.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <stdexcept>
+
+namespace opustags {
+
+    struct TagAlreadyExistsError : std::runtime_error
+    {
+        TagAlreadyExistsError(const std::string &tag_key);
+    };
+
+    struct TagDoesNotExistError : std::runtime_error
+    {
+        TagDoesNotExistError(const std::string &tag_key);
+    };
+
+}

src/version.h.in

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <string>
+
+namespace opustags {
+
+    static const std::string version_short = "@VERSION_SHORT@";
+    static const std::string version_long = "@VERSION_LONG@";
+
+}

t/CMakeLists.txt

@@ -1,26 +0,0 @@
-add_executable(system.t EXCLUDE_FROM_ALL system.cc)
-target_link_libraries(system.t ot)
-
-add_executable(opus.t EXCLUDE_FROM_ALL opus.cc)
-target_link_libraries(opus.t ot)
-
-add_executable(ogg.t EXCLUDE_FROM_ALL ogg.cc)
-target_link_libraries(ogg.t ot)
-
-add_executable(cli.t EXCLUDE_FROM_ALL cli.cc)
-target_link_libraries(cli.t ot)
-
-add_executable(base64.t EXCLUDE_FROM_ALL base64.cc)
-target_link_libraries(base64.t ot)
-
-add_executable(oggdump EXCLUDE_FROM_ALL oggdump.cc)
-target_link_libraries(oggdump ot)
-
-configure_file(gobble.opus . COPYONLY)
-configure_file(pixel.png . COPYONLY)
-
-add_custom_target(
-	check
-	COMMAND prove "${CMAKE_CURRENT_BINARY_DIR}" "${CMAKE_CURRENT_SOURCE_DIR}"
-	DEPENDS opustags gobble.opus system.t opus.t ogg.t cli.t base64.t
-)

t/base64.cc

@@ -1,46 +0,0 @@
-#include <opustags.h>
-#include "tap.h"
-
-static void check_encode_base64()
-{
-	opaque_is(ot::encode_base64(""_bsv), u8"", "empty");
-	opaque_is(ot::encode_base64("a"_bsv), u8"YQ==", "1 character");
-	opaque_is(ot::encode_base64("aa"_bsv), u8"YWE=", "2 characters");
-	opaque_is(ot::encode_base64("aaa"_bsv), u8"YWFh", "3 characters");
-	opaque_is(ot::encode_base64("aaaa"_bsv), u8"YWFhYQ==", "4 characters");
-	opaque_is(ot::encode_base64("\xFF\xFF\xFE"_bsv), u8"///+", "RFC alphabet");
-	opaque_is(ot::encode_base64("\0x"_bsv), u8"AHg=", "embedded null bytes");
-}
-
-static void check_decode_base64()
-{
-	opaque_is(ot::decode_base64(u8""), ""_bsv, "empty");
-	opaque_is(ot::decode_base64(u8"YQ=="), "a"_bsv, "1 character");
-	opaque_is(ot::decode_base64(u8"YWE="), "aa"_bsv, "2 characters");
-	opaque_is(ot::decode_base64(u8"YQ"), "a"_bsv, "padless 1 character");
-	opaque_is(ot::decode_base64(u8"YWE"), "aa"_bsv, "padless 2 characters");
-	opaque_is(ot::decode_base64(u8"YWFh"), "aaa"_bsv, "3 characters");
-	opaque_is(ot::decode_base64(u8"YWFhYQ=="), "aaaa"_bsv, "4 characters");
-	opaque_is(ot::decode_base64(u8"///+"), "\xFF\xFF\xFE"_bsv, "RFC alphabet");
-	opaque_is(ot::decode_base64(u8"AHg="), "\0x"_bsv, "embedded null bytes");
-
-	try {
-		ot::decode_base64(u8"Y===");
-		throw failure("accepted a bad block size");
-	} catch (const ot::status& e) {
-	}
-
-	try {
-		ot::decode_base64(u8"\xFF bad message!");
-		throw failure("accepted an invalid character");
-	} catch (const ot::status& e) {
-	}
-}
-
-int main(int argc, char **argv)
-{
-	std::cout << "1..2\n";
-	run(check_encode_base64, "base64 encoding");
-	run(check_decode_base64, "base64 decoding");
-	return 0;
-}

t/cli.cc

@@ -1,234 +0,0 @@
-#include <opustags.h>
-#include "tap.h"
-
-#include <string.h>
-
-static ot::status read_comments(FILE* input, std::list<std::u8string>& comments, bool raw)
-{
-	ot::options opt;
-	opt.raw = raw;
-	try {
-		comments = ot::read_comments(input, opt);
-	} catch (const ot::status& rc) {
-		return rc;
-	}
-	return ot::st::ok;
-}
-
-void check_read_comments()
-{
-	std::list<std::u8string> comments;
-	ot::status rc;
-	{
-		std::string txt = "TITLE=a b c\n\nARTIST=X\nArtist=Y\n"s;
-		ot::file input = fmemopen((char*) txt.data(), txt.size(), "r");
-		rc = read_comments(input.get(), comments, false);
-		if (rc != ot::st::ok)
-			throw failure("could not read comments");
-		auto&& expected = {u8"TITLE=a b c", u8"ARTIST=X", u8"Artist=Y"};
-		if (!std::equal(comments.begin(), comments.end(), expected.begin(), expected.end()))
-			throw failure("parsed user comments did not match expectations");
-	}
-	{
-		std::string txt = "CORRUPTED=\xFF\xFF\n"s;
-		ot::file input = fmemopen((char*) txt.data(), txt.size(), "r");
-		rc = read_comments(input.get(), comments, false);
-		if (rc != ot::st::badly_encoded)
-			throw failure("did not get the expected error reading corrupted data");
-	}
-	{
-		std::string txt = "RAW=\xFF\xFF\n"s;
-		ot::file input = fmemopen((char*) txt.data(), txt.size(), "r");
-		rc = read_comments(input.get(), comments, true);
-		if (rc != ot::st::ok)
-			throw failure("could not read comments");
-		if (comments.front() != (char8_t*) "RAW=\xFF\xFF")
-			throw failure("parsed user comments did not match expectations");
-	}
-	{
-		std::string txt = "MULTILINE=First\n\tSecond\n"s;
-		ot::file input = fmemopen((char*) txt.data(), txt.size(), "r");
-		rc = read_comments(input.get(), comments, true);
-		if (rc != ot::st::ok)
-			throw failure("could not read comments");
-		if (comments.front() != u8"MULTILINE=First\nSecond")
-			throw failure("parsed user comments did not match expectations");
-	}
-	{
-		std::string txt = "MALFORMED\n"s;
-		ot::file input = fmemopen((char*) txt.data(), txt.size(), "r");
-		rc = read_comments(input.get(), comments, false);
-		if (rc != ot::st::error)
-			throw failure("did not get the expected error reading malformed comments");
-	}
-	{
-		std::string txt = "\tBad"s;
-		ot::file input = fmemopen((char*) txt.data(), txt.size(), "r");
-		rc = read_comments(input.get(), comments, true);
-		if (rc != ot::st::error)
-			throw failure("did not get the expected error reading bad continuation line");
-	}
-}
-
-/**
- * Wrap #ot::parse_options with a higher-level interface much more convenient for testing.
- * In practice, the argc/argv combo are enough though for the current state of opustags.
- */
-static ot::status parse_options(const std::vector<const char*>& args, ot::options& opt, FILE *comments)
-{
-	int argc = args.size();
-	char* argv[argc];
-	for (int i = 0; i < argc; ++i)
-		argv[i] = strdup(args[i]);
-	ot::status rc = ot::st::ok;
-	try {
-		opt = ot::parse_options(argc, argv, comments);
-	} catch (const ot::status& e) {
-		rc = e;
-	}
-	for (int i = 0; i < argc; ++i)
-		free(argv[i]);
-	return rc;
-}
-
-void check_good_arguments()
-{
-	auto parse = [](std::vector<const char*> args) {
-		ot::options opt;
-		std::string txt = "N=1\n"s;
-		ot::file input = fmemopen((char*) txt.data(), txt.size(), "r");
-		ot::status rc = parse_options(args, opt, input.get());
-		if (rc.code != ot::st::ok)
-			throw failure("unexpected option parsing error");
-		return opt;
-	};
-
-	ot::options opt;
-	opt = parse({"opustags", "--help", "x", "-o", "y"});
-	if (!opt.print_help)
-		throw failure("did not catch --help");
-
-	opt = parse({"opustags", "x", "--output", "y", "-D", "-s", "X=Y Z", "-d", "a=b"});
-	if (opt.paths_in.size() != 1 || opt.paths_in.front() != "x" || !opt.path_out ||
-	    opt.path_out != "y" || !opt.delete_all || opt.overwrite || opt.to_delete.size() != 2 ||
-	    opt.to_delete.front() != u8"X" || *std::next(opt.to_delete.begin()) != u8"a=b" ||
-	    opt.to_add != std::list<std::u8string>{ u8"X=Y Z" })
-		throw failure("unexpected option parsing result for case #1");
-
-	opt = parse({"opustags", "-S", "x", "-S", "-a", "x=y z", "-i"});
-	if (opt.paths_in.size() != 1 || opt.paths_in.front() != "x" || opt.path_out ||
-	    !opt.overwrite || opt.to_delete.size() != 0 ||
-	    opt.to_add != std::list<std::u8string>{ u8"N=1", u8"x=y z" })
-		throw failure("unexpected option parsing result for case #2");
-
-	opt = parse({"opustags", "-i", "x", "y", "z"});
-	if (opt.paths_in.size() != 3 || opt.paths_in[0] != "x" || opt.paths_in[1] != "y" ||
-	    opt.paths_in[2] != "z" || !opt.overwrite || !opt.in_place)
-		throw failure("unexpected option parsing result for case #3");
-
-	opt = parse({"opustags", "-ie", "x"});
-	if (opt.paths_in.size() != 1 || opt.paths_in[0] != "x" ||
-	    !opt.edit_interactively || !opt.overwrite || !opt.in_place)
-		throw failure("unexpected option parsing result for case #4");
-
-	opt = parse({"opustags", "-a", "X=\xFF", "--raw", "x"});
-	if (!opt.raw || opt.to_add.front() != u8"X=\xFF")
-		throw failure("--raw did not disable transcoding");
-}
-
-void check_bad_arguments()
-{
-	auto error_code_case = [](std::vector<const char*> args, const char* message, ot::st error_code, const std::string& name) {
-		ot::options opt;
-		std::string txt = "N=1\nINVALID"s;
-		ot::file input = fmemopen((char*) txt.data(), txt.size(), "r");
-		ot::status rc = parse_options(args, opt, input.get());
-		if (rc.code != error_code)
-			throw failure("bad error code for case " + name);
-		if (!rc.message.starts_with(message))
-			throw failure("bad error message for case " + name + ", got: " + rc.message);
-	};
-	auto error_case = [&error_code_case](std::vector<const char*> args, const char* message, const std::string& name) {
-		 error_code_case(args, message, ot::st::bad_arguments, name);
-	};
-	error_case({"opustags"}, "No arguments specified. Use -h for help.", "no arguments");
-	error_case({"opustags", "-a", "X"}, "Comment does not contain an equal sign: X.", "bad comment for -a");
-	error_case({"opustags", "--set", "X"}, "Comment does not contain an equal sign: X.", "bad comment for --set");
-	error_case({"opustags", "-a"}, "Missing value for option '-a'.", "short option with missing value");
-	error_case({"opustags", "-x"}, "Unrecognized option '-x'.", "unrecognized short option");
-	error_case({"opustags", "--derp"}, "Unrecognized option '--derp'.", "unrecognized long option");
-	error_case({"opustags", "-x=y"}, "Unrecognized option '-x'.", "unrecognized short option with value");
-	error_case({"opustags", "--derp=y"}, "Unrecognized option '--derp=y'.", "unrecognized long option with value");
-	error_case({"opustags", "-aX=Y"}, "Exactly one input file must be specified.", "no input file");
-	error_case({"opustags", "-i", "-o", "/dev/null", "-"}, "Cannot combine --in-place and --output.", "in-place + output");
-	error_case({"opustags", "-S", "-"}, "Cannot use standard input more than once.", "set all and read opus from stdin");
-	error_case({"opustags", "-i", "-"}, "Cannot modify standard input in place.", "write stdin in-place");
-	error_case({"opustags", "-o", "x", "--output", "y", "z"},
-	           "Cannot specify --output more than once.", "double output");
-	error_code_case({"opustags", "-S", "x"}, "Malformed tag: INVALID", ot::st::error, "attempt to read invalid argument with -S");
-	error_case({"opustags", "-o", "", "--output", "y", "z"},
-	           "Cannot specify --output more than once.", "double output with first filename empty");
-	error_case({"opustags", "-e", "-i", "x", "y"},
-	           "Exactly one input file must be specified.", "editing interactively two files at once");
-	error_case({"opustags", "--edit", "-", "-o", "x"},
-	           "Cannot edit interactively when standard input or standard output are already used.",
-	           "editing interactively from stdandard intput");
-	error_case({"opustags", "--edit", "x", "-o", "-"},
-	           "Cannot edit interactively when standard input or standard output are already used.",
-	           "editing interactively to stdandard output");
-	error_case({"opustags", "--edit", "x"}, "Cannot edit interactively when no output is specified.", "editing without output");
-	error_case({"opustags", "--edit", "x", "-i", "-a", "X=Y"}, "Cannot mix --edit with -adDsS.", "mixing -e and -a");
-	error_case({"opustags", "--edit", "x", "-i", "-d", "X"}, "Cannot mix --edit with -adDsS.", "mixing -e and -d");
-	error_case({"opustags", "--edit", "x", "-i", "-D"}, "Cannot mix --edit with -adDsS.", "mixing -e and -D");
-	error_case({"opustags", "--edit", "x", "-i", "-S"}, "Cannot mix --edit with -adDsS.", "mixing -e and -S");
-	error_case({"opustags", "--output-cover", "x", "--output-cover", "y"},
-	           "Cannot specify --output-cover more than once.", "multiple --output-cover");
-	error_case({"opustags", "x", "-o", "-", "--output-cover", "-"},
-	            "Cannot specify standard output for both --output and --output-cover.", "-o and --output-cover conflict");
-	error_case({"opustags", "-i", "x", "y", "--output-cover", "z"},
-	            "Cannot use --output-cover with multiple input files.", "--output-cover with multiple input");
-	error_case({"opustags", "-i", "--vendor", "x"},
-	            "--vendor is only supported in read-only mode.", "--vendor when editing");
-	error_case({"opustags", "-d", "\xFF", "x"},
-	           "Could not encode argument into UTF-8:",
-	           "-d with binary data");
-	error_case({"opustags", "-a", "X=\xFF", "x"},
-	           "Could not encode argument into UTF-8:",
-	           "-a with binary data");
-	error_case({"opustags", "-s", "X=\xFF", "x"},
-	           "Could not encode argument into UTF-8:",
-	           "-s with binary data");
-}
-
-static void check_delete_comments()
-{
-	using C = std::list<std::u8string>;
-	C original = {u8"TITLE=X", u8"Title=Y", u8"Title=Z", u8"ARTIST=A", u8"artIst=B"};
-
-	C edited = original;
-	ot::delete_comments(edited, u8"derp");
-	if (!std::equal(edited.begin(), edited.end(), original.begin(), original.end()))
-		throw failure("should not have deleted anything");
-
-	ot::delete_comments(edited, u8"Title");
-	C expected = {u8"ARTIST=A", u8"artIst=B"};
-	if (!std::equal(edited.begin(), edited.end(), expected.begin(), expected.end()))
-		throw failure("did not delete all titles correctly");
-
-	edited = original;
-	ot::delete_comments(edited, u8"titlE=Y");
-	ot::delete_comments(edited, u8"Title=z");
-	expected = {u8"TITLE=X", u8"Title=Z", u8"ARTIST=A", u8"artIst=B"};
-	if (!std::equal(edited.begin(), edited.end(), expected.begin(), expected.end()))
-		throw failure("did not delete a specific title correctly");
-}
-
-int main(int argc, char **argv)
-{
-	std::cout << "1..4\n";
-	run(check_read_comments, "check tags parsing");
-	run(check_good_arguments, "check options parsing");
-	run(check_bad_arguments, "check options parsing errors");
-	run(check_delete_comments, "delete comments");
-	return 0;
-}

t/ogg.cc

@@ -1,167 +0,0 @@
-#include <opustags.h>
-#include "tap.h"
-
-#include <string.h>
-
-static void check_ref_ogg()
-{
-	ot::file input = fopen("gobble.opus", "r");
-	if (input == nullptr)
-		throw failure("could not open gobble.opus");
-
-	ot::ogg_reader reader(input.get());
-
-	if (reader.next_page() != true)
-		throw failure("could not read the first page");
-	if (!ot::is_opus_stream(reader.page))
-		throw failure("failed to identify the stream as opus");
-	reader.process_header_packet([](ogg_packet& p) {
-		if (p.bytes != 19)
-			throw failure("unexpected length for the first packet");
-	});
-
-	if (reader.next_page() != true)
-		throw failure("could not read the second page");
-	reader.process_header_packet([](ogg_packet& p) {
-		if (p.bytes != 62)
-			throw failure("unexpected length for the second packet");
-	});
-
-	while (!ogg_page_eos(&reader.page)) {
-		if (reader.next_page() != true)
-			throw failure("failure reading a page");
-	}
-	if (reader.next_page() != false)
-		throw failure("did not correctly detect the end of stream");
-}
-
-static ogg_packet make_packet(const char* contents)
-{
-	ogg_packet op {};
-	op.bytes = strlen(contents);
-	op.packet = (unsigned char*) contents;
-	return op;
-}
-
-static bool same_packet(const ogg_packet& lhs, const ogg_packet& rhs)
-{
-	return lhs.bytes == rhs.bytes && memcmp(lhs.packet, rhs.packet, lhs.bytes) == 0;
-}
-
-/**
- * Build an in-memory Ogg stream using ogg_writer, and then read it with ogg_reader.
- */
-static void check_memory_ogg()
-{
-	ogg_packet first_packet  = make_packet("First");
-	ogg_packet second_packet = make_packet("Second");
-	std::vector<unsigned char> my_ogg(128);
-	size_t my_ogg_size;
-
-	{
-		ot::file output = fmemopen(my_ogg.data(), my_ogg.size(), "w");
-		if (output == nullptr)
-			throw failure("could not open the output stream");
-		ot::ogg_writer writer(output.get());
-		writer.write_header_packet(1234, 0, first_packet);
-		writer.write_header_packet(1234, 1, second_packet);
-		my_ogg_size = ftell(output.get());
-		if (my_ogg_size != 67)
-			throw failure("unexpected output size");
-	}
-
-	{
-		ot::file input = fmemopen(my_ogg.data(), my_ogg_size, "r");
-		if (input == nullptr)
-			throw failure("could not open the input stream");
-		ot::ogg_reader reader(input.get());
-		if (reader.next_page() != true)
-			throw failure("could not read the first page");
-		reader.process_header_packet([&first_packet](ogg_packet &p) {
-			if (!same_packet(p, first_packet))
-				throw failure("unexpected content in the first packet");
-		});
-		if (reader.next_page() != true)
-			throw failure("could not read the second page");
-		reader.process_header_packet([&second_packet](ogg_packet &p) {
-			if (!same_packet(p, second_packet))
-				throw failure("unexpected content in the second packet");
-		});
-		if (reader.next_page() != false)
-			throw failure("unexpected third page");
-	}
-}
-
-void check_bad_stream()
-{
-	auto err_msg = "did not detect the stream is not an ogg stream";
-	ot::file input = fmemopen((void*) err_msg, 20, "r");
-	ot::ogg_reader reader(input.get());
-	try {
-		reader.next_page();
-		throw failure("did not raise an error");
-	} catch (const ot::status& rc) {
-		if (rc != ot::st::bad_stream)
-			throw failure(err_msg);
-	}
-}
-
-void check_identification()
-{
-	auto good_header = (unsigned char*)
-		"\x4f\x67\x67\x53\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x42\xf2"
-		"\xe6\xc7\x00\x00\x00\x00\x7e\xc3\x57\x2b\x01\x13";
-	auto good_body = (unsigned char*) "OpusHeadABCD";
-
-	ogg_page id;
-	id.header = good_header;
-	id.header_len = 28;
-	id.body = good_body;
-	id.body_len = 12;
-	if (!ot::is_opus_stream(id))
-		throw failure("could not identify opus header");
-
-	// Bad body
-	id.body_len = 7;
-	if (ot::is_opus_stream(id))
-		throw failure("opus header was too short to be valid");
-	id.body_len = 12;
-	id.body = (unsigned char*) "Not_OpusHead";
-	if (ot::is_opus_stream(id))
-		throw failure("was not an opus header");
-	id.body = good_body;
-
-	// Remove the BoS bit from the header.
-	id.header = (unsigned char*)
-		"\x4f\x67\x67\x53\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x42\xf2"
-		"\xe6\xc7\x00\x00\x00\x00\x7e\xc3\x57\x2b\x01\x13";
-	if (ot::is_opus_stream(id))
-		throw failure("was not the beginning of a stream");
-}
-
-void check_renumber_page()
-{
-	ot::file input = fopen("gobble.opus", "r");
-	if (input == nullptr)
-		throw failure("could not open gobble.opus");
-
-	ot::ogg_reader reader(input.get());
-	if (reader.next_page() != true)
-		throw failure("could not read the first page");
-
-	long new_pageno = 1234;
-	ot::renumber_page(reader.page, new_pageno);
-	if (ogg_page_pageno(&reader.page) != new_pageno)
-		throw failure("renumbering failed");
-}
-
-int main(int argc, char **argv)
-{
-	std::cout << "1..5\n";
-	run(check_ref_ogg, "check a reference ogg stream");
-	run(check_memory_ogg, "build and check a fresh stream");
-	run(check_bad_stream, "read a non-ogg stream");
-	run(check_identification, "stream identification");
-	run(check_renumber_page, "page renumbering");
-	return 0;
-}

t/oggdump.cc

@@ -1,42 +0,0 @@
-/**
- * \file t/oggdump.cc
- *
- * Dump brief information about the pages containted in an Ogg file.
- *
- * This tool is not build by default or installed, and is mainly meant to help understand how Ogg
- * files are built, and to debug.
- */
-
-#include <opustags.h>
-
-#include <iostream>
-#include <string.h>
-
-int main(int argc, char** argv)
-{
-	if (argc != 2) {
-		std::cerr << "Usage: oggdump FILE\n";
-		return 1;
-	}
-	ot::file input = fopen(argv[1], "r");
-	if (input == nullptr) {
-		std::cerr << "Error opening '" << argv[1] << "': " << strerror(errno) << "\n";
-		return 1;
-	}
-	ot::ogg_reader reader(input.get());
-	ot::status rc;
-	while ((rc = reader.read_page()) == ot::st::ok) {
-		std::cout << "Stream " << ogg_page_serialno(&reader.page) << ", "
-		             "page #" << ogg_page_pageno(&reader.page) << ", "
-		          << ogg_page_packets(&reader.page) << " packet(s)";
-		if (ogg_page_bos(&reader.page)) std::cout << ", BoS";
-		if (ogg_page_eos(&reader.page)) std::cout << ", EoS";
-		if (ogg_page_continued(&reader.page)) std::cout << ", continued";
-		std::cout << "\n";
-	}
-	if (rc != ot::st::ok && rc != ot::st::end_of_stream) {
-		std::cerr << "error: " << rc.message << "\n";
-		return 1;
-	}
-	return 0;
-}

t/opus.cc

@@ -1,194 +0,0 @@
-#include <opustags.h>
-#include "tap.h"
-
-#include <string.h>
-
-static const char standard_OpusTags[] =
-	"OpusTags"
-	"\x14\x00\x00\x00" "opustags test packet"
-	"\x02\x00\x00\x00"
-	"\x09\x00\x00\x00" "TITLE=Foo"
-	"\x0a\x00\x00\x00" "ARTIST=Bar";
-
-static void parse_standard()
-{
-	ogg_packet op;
-	op.bytes = sizeof(standard_OpusTags) - 1;
-	op.packet = (unsigned char*) standard_OpusTags;
-	ot::opus_tags tags = ot::parse_tags(op);
-	if (tags.vendor != u8"opustags test packet")
-		throw failure("bad vendor string");
-	if (tags.comments.size() != 2)
-		throw failure("bad number of comments");
-	auto it = tags.comments.begin();
-	if (*it != u8"TITLE=Foo")
-		throw failure("bad title");
-	++it;
-	if (*it != u8"ARTIST=Bar")
-		throw failure("bad artist");
-	if (tags.extra_data.size() != 0)
-		throw failure("found mysterious padding data");
-}
-
-static ot::status try_parse_tags(const ogg_packet& packet)
-{
-	try {
-		ot::parse_tags(packet);
-		return ot::st::ok;
-	} catch (const ot::status& rc) {
-		return rc;
-	}
-}
-
-/**
- * Try parse_tags with packets that should not valid, or that might even
- * corrupt the memory. Run this one with valgrind to ensure we're not
- * overflowing.
- */
-static void parse_corrupted()
-{
-	size_t size = sizeof(standard_OpusTags);
-	char packet[size];
-	memcpy(packet, standard_OpusTags, size);
-	ot::opus_tags tags;
-	ogg_packet op;
-	op.packet = (unsigned char*) packet;
-	op.bytes = size;
-
-	char* header_data = packet;
-	char* vendor_length = header_data + 8;
-	char* vendor_string = vendor_length + 4;
-	char* comment_count = vendor_string + *vendor_length;
-	char* first_comment_length = comment_count + 4;
-	char* first_comment_data = first_comment_length + 4;
-	char* end = packet + size;
-
-	op.bytes = 7;
-	if (try_parse_tags(op) != ot::st::cut_magic_number)
-		throw failure("did not detect the overflowing magic number");
-	op.bytes = 11;
-	if (try_parse_tags(op) != ot::st::cut_vendor_length)
-		throw failure("did not detect the overflowing vendor string length");
-	op.bytes = size;
-
-	header_data[0] = 'o';
-	if (try_parse_tags(op) != ot::st::bad_magic_number)
-		throw failure("did not detect the bad magic number");
-	header_data[0] = 'O';
-
-	*vendor_length = end - vendor_string + 1;
-	if (try_parse_tags(op) != ot::st::cut_vendor_data)
-		throw failure("did not detect the overflowing vendor string");
-	*vendor_length = end - vendor_string - 3;
-	if (try_parse_tags(op) != ot::st::cut_comment_count)
-		throw failure("did not detect the overflowing comment count");
-	*vendor_length = comment_count - vendor_string;
-
-	++*comment_count;
-	if (try_parse_tags(op) != ot::st::cut_comment_length)
-		throw failure("did not detect the overflowing comment length");
-	*first_comment_length = end - first_comment_data + 1;
-	if (try_parse_tags(op) != ot::st::cut_comment_data)
-		throw failure("did not detect the overflowing comment data");
-}
-
-static void recode_standard()
-{
-	ogg_packet op;
-	op.bytes = sizeof(standard_OpusTags) - 1;
-	op.packet = (unsigned char*) standard_OpusTags;
-	ot::opus_tags tags = ot::parse_tags(op);
-	auto packet = ot::render_tags(tags);
-	if (packet.b_o_s != 0)
-		throw failure("b_o_s should not be set");
-	if (packet.e_o_s != 0)
-		throw failure("e_o_s should not be set");
-	if (packet.granulepos != 0)
-		throw failure("granule_post should be 0");
-	if (packet.packetno != 1)
-		throw failure("packetno should be 1");
-	if (packet.bytes != sizeof(standard_OpusTags) - 1)
-		throw failure("the packet is not the right size");
-	if (memcmp(packet.packet, standard_OpusTags, packet.bytes) != 0)
-		throw failure("the rendered packet is not what we expected");
-}
-
-static void recode_padding()
-{
-	std::string padded_OpusTags(standard_OpusTags, sizeof(standard_OpusTags));
-	// ^ note: padded_OpusTags ends with a null byte here
-	padded_OpusTags += "hello";
-	ogg_packet op;
-	op.bytes = padded_OpusTags.size();
-	op.packet = (unsigned char*) padded_OpusTags.data();
-
-	ot::opus_tags tags = ot::parse_tags(op);
-	if (tags.extra_data != "\0hello"_bsv)
-		throw failure("corrupted extra data");
-	// recode the packet and ensure it's exactly the same
-	auto packet = ot::render_tags(tags);
-	if (static_cast<size_t>(packet.bytes) < padded_OpusTags.size())
-		throw failure("the packet was truncated");
-	if (static_cast<size_t>(packet.bytes) > padded_OpusTags.size())
-		throw failure("the packet got too big");
-	if (memcmp(packet.packet, padded_OpusTags.data(), packet.bytes) != 0)
-		throw failure("the rendered packet is not what we expected");
-}
-
-static void extract_cover()
-{
-	ot::byte_string_view picture_data = ""_bsv
-		"\x00\x00\x00\x03" // Picture type 3.
-		"\x00\x00\x00\x09" "image/foo" // MIME type.
-		"\x00\x00\x00\x00" "" // Description.
-		"\x00\x00\x00\x00" // Width.
-		"\x00\x00\x00\x00" // Height.
-		"\x00\x00\x00\x00" // Color depth.
-		"\x00\x00\x00\x00" // Palette size.
-		"\x00\x00\x00\x0C" "Picture data";
-
-	ot::opus_tags tags;
-	tags.comments = { u8"METADATA_BLOCK_PICTURE=" + ot::encode_base64(picture_data) };
-	std::optional<ot::picture> cover = ot::extract_cover(tags);
-	if (!cover)
-		throw failure("could not extract the cover");
-	if (cover->mime_type != "image/foo"_bsv)
-		throw failure("bad extracted MIME type");
-	if (cover->picture_data != "Picture data"_bsv)
-		throw failure("bad extracted picture data");
-
-	ot::byte_string_view truncated_data = picture_data.substr(0, picture_data.size() - 1);
-	tags.comments = { u8"METADATA_BLOCK_PICTURE=" + ot::encode_base64(truncated_data) };
-	try {
-		ot::extract_cover(tags);
-		throw failure("accepted a bad picture block");
-	} catch (const ot::status& rc) {}
-}
-
-static void make_cover()
-{
-	ot::byte_string_view picture_block = ""_bsv
-		"\x00\x00\x00\x03" // Picture type 3.
-		"\x00\x00\x00\x09" "image/png" // MIME type.
-		"\x00\x00\x00\x00" "" // Description.
-		"\x00\x00\x00\x00" // Width.
-		"\x00\x00\x00\x00" // Height.
-		"\x00\x00\x00\x00" // Color depth.
-		"\x00\x00\x00\x00" // Palette size.
-		"\x00\x00\x00\x11" "\x89PNG Picture data";
-
-	std::u8string expected = u8"METADATA_BLOCK_PICTURE=" + ot::encode_base64(picture_block);
-	opaque_is(ot::make_cover("\x89PNG Picture data"_bsv), expected, "build the picture tag");
-}
-
-int main()
-{
-	std::cout << "1..6\n";
-	run(parse_standard, "parse a standard OpusTags packet");
-	run(parse_corrupted, "correctly reject invalid packets");
-	run(recode_standard, "recode a standard OpusTags packet");
-	run(recode_padding, "recode a OpusTags packet with padding");
-	run(extract_cover, "extract the cover art");
-	run(make_cover, "encode the cover art");
-	return 0;
-}

t/opustags.t

@@ -1,344 +0,0 @@
-#!/usr/bin/env perl
-
-use strict;
-use warnings;
-use utf8;
-
-use Test::More tests => 66;
-use Test::Deep qw(cmp_deeply re);
-
-use Digest::MD5;
-use File::Basename;
-use File::Copy;
-use IPC::Open3;
-use List::MoreUtils qw(any);
-use Symbol 'gensym';
-
-my $opustags = '../opustags';
-BAIL_OUT("$opustags does not exist or is not executable") if (! -x $opustags);
-
-my $is_utf8;
-open(my $ctype, 'locale -k LC_CTYPE |');
-while (<$ctype>) { $is_utf8 = 1 if (/^charmap="UTF-?8"$/i) }
-close($ctype);
-BAIL_OUT("this test must be run from an UTF-8 environment") unless $is_utf8;
-
-sub opustags {
-	my %opt;
-	%opt = %{pop @_} if ref $_[-1];
-	my ($pid, $pin, $pout, $perr);
-	$perr = gensym;
-	$pid = open3($pin, $pout, $perr, $opustags, @_);
-	binmode($pin, $opt{mode} // ':utf8');
-	binmode($pout, $opt{mode} // ':utf8');
-	binmode($perr, ':utf8');
-	local $/;
-	print $pin $opt{in} if defined $opt{in};
-	close $pin;
-	my $out = <$pout>;
-	my $err = <$perr>;
-	waitpid($pid, 0);
-	[$out, $err, $?]
-}
-
-####################################################################################################
-# Tests related to the overall opustags executable, like the help message.
-# No Opus file is manipulated here.
-
-is_deeply(opustags(), ['', <<EOF, 512], 'no options is a failure');
-error: No arguments specified. Use -h for help.
-EOF
-
-my $help = opustags('--help');
-$help->[0] =~ /^([^\n]*+)/;
-my $version = $1;
-like($version, qr/^opustags version (\d+\.\d+\.\d+)/, 'get the version string');
-
-my $expected_help = qr{opustags version .*\n\nUsage: opustags --help\n};
-cmp_deeply(opustags('--help'), [re($expected_help), '', 0], '--help displays the help message');
-cmp_deeply(opustags('-h'), [re($expected_help), '', 0], '-h displays the help message too');
-
-is_deeply(opustags('--derp'), ['', <<"EOF", 512], 'unrecognized option shows an error');
-error: Unrecognized option '--derp'.
-EOF
-
-is_deeply(opustags('../opustags'), ['', <<"EOF", 256], 'not an Ogg stream');
-../opustags: error: Input is not a valid Ogg file.
-EOF
-
-####################################################################################################
-# Test the main features of opustags on an Ogg Opus sample file.
-
-sub md5 {
-	my ($file) = @_;
-	open(my $fh, '<', $file) or return;
-	my $ctx = Digest::MD5->new;
-	$ctx->addfile($fh);
-	$ctx->hexdigest
-}
-
-is(md5('gobble.opus'), '111a483596ac32352fbce4d14d16abd2', 'the sample is the one we expect');
-is_deeply(opustags('gobble.opus'), [<<'EOF', '', 0], 'read the initial tags');
-encoder=Lavc58.18.100 libopus
-EOF
-
-unlink('out.opus');
-my $previous_umask = umask(0022);
-is_deeply(opustags(qw(gobble.opus -o out.opus)), ['', '', 0], 'copy the file without changes');
-is(md5('out.opus'), '111a483596ac32352fbce4d14d16abd2', 'the copy is faithful');
-is((stat 'out.opus')[2] & 0777, 0644, 'apply umask on new files');
-umask($previous_umask);
-
-# empty out.opus
-{ my $fh; open($fh, '>', 'out.opus') and close($fh) or die }
-is_deeply(opustags(qw(gobble.opus -o out.opus)), ['', <<'EOF', 256], 'refuse to override');
-gobble.opus: error: 'out.opus' already exists. Use -y to overwrite.
-EOF
-is(md5('out.opus'), 'd41d8cd98f00b204e9800998ecf8427e', 'the output wasn\'t written');
-
-is_deeply(opustags(qw(gobble.opus -o /dev/null)), ['', '', 0], 'write to /dev/null');
-
-chmod(0604, 'out.opus');
-is_deeply(opustags(qw(gobble.opus -o out.opus --overwrite)), ['', '', 0], 'overwrite');
-is(md5('out.opus'), '111a483596ac32352fbce4d14d16abd2', 'successfully overwritten');
-is((stat 'out.opus')[2] & 0777, 0604, 'overwriting preserves output file\'s mode');
-
-chmod(0700, 'out.opus');
-is_deeply(opustags(qw(--in-place out.opus -a A=B --add=A=C --add), "TITLE=Foo Bar",
-                   qw(--delete A --add TITLE=七面鳥 --set encoder=whatever -s 1=2 -s X=1 -a X=2 -s X=3)),
-          ['', '', 0], 'complex tag editing');
-is(md5('out.opus'), '66780307a6081523dc9040f3c47b0448', 'check the footprint');
-is((stat 'out.opus')[2] & 0777, 0700, 'in-place editing preserves file mode');
-
-is_deeply(opustags('out.opus'), [<<'EOF', '', 0], 'check the tags written');
-A=B
-A=C
-TITLE=Foo Bar
-TITLE=七面鳥
-encoder=whatever
-1=2
-X=1
-X=2
-X=3
-EOF
-
-is_deeply(opustags(qw(out.opus -d A -d foo -s X=4 -a TITLE=gobble -d title=七面鳥)), [<<'EOF', '', 0], 'dry editing');
-TITLE=Foo Bar
-encoder=whatever
-1=2
-X=4
-TITLE=gobble
-EOF
-is(md5('out.opus'), '66780307a6081523dc9040f3c47b0448', 'the file did not change');
-
-is_deeply(opustags(qw(-i out.opus -a fatal=yes -a FOO -a BAR)), ['', <<'EOF', 512], 'bad tag with --add');
-error: Comment does not contain an equal sign: FOO.
-EOF
-is(md5('out.opus'), '66780307a6081523dc9040f3c47b0448', 'the file did not change');
-
-is_deeply(opustags('out.opus', '-D', '-a', "X=foobar\tquux"), [<<'END_OUT', <<'END_ERR', 0], 'control characters');
-X=foobar	quux
-END_OUT
-warning: Some tags contain control characters.
-END_ERR
-
-is_deeply(opustags('out.opus', '-D', '-a', "X=foo\n\nbar"), [<<'END_OUT', '', 0], 'newline characters');
-X=foo
-	
-	bar
-END_OUT
-
-is_deeply(opustags(qw(-i out.opus -s fatal=yes -s FOO -s BAR)), ['', <<'EOF', 512], 'bad tag with --set');
-error: Comment does not contain an equal sign: FOO.
-EOF
-is(md5('out.opus'), '66780307a6081523dc9040f3c47b0448', 'the file did not change');
-
-is_deeply(opustags(qw(out.opus --delete-all -a OK=yes)), [<<'EOF', '', 0], 'delete all');
-OK=yes
-EOF
-
-is_deeply(opustags(qw(out.opus --set-all -a A=B -s X=Z -d OK), {in => <<'END_IN'}), [<<'END_OUT', '', 0], 'set all');
-OK=yes again
-ARTIST=七面鳥
-
-A=A
-X=Y
-#IGNORE=COMMENTS
-END_IN
-OK=yes again
-ARTIST=七面鳥
-A=A
-X=Y
-A=B
-X=Z
-END_OUT
-
-is_deeply(opustags(qw(out.opus -S), {in => <<'END_IN'}), [<<'END_OUT', <<'END_ERR', 256], 'set all with bad tags');
-whatever
-wrong=yes
-END_IN
-END_OUT
-error: Malformed tag: whatever
-END_ERR
-
-sub slurp {
-	my ($filename) = @_;
-	local $/;
-	open(my $fh, '<', $filename);
-	binmode($fh);
-	my $data = <$fh>;
-	$data
-}
-
-my $data = slurp 'out.opus';
-is_deeply(opustags('-', '-o', '-', {in => $data, mode => ':raw'}), [$data, '', 0], 'read opus from stdin and write to stdout');
-
-unlink('out.opus');
-
-# Test --in-place
-unlink('out2.opus');
-copy('gobble.opus', 'out.opus');
-is_deeply(opustags(qw(out.opus --add BAR=baz -o out2.opus)), ['', '', 0], 'process multiple files with --in-place');
-is_deeply(opustags(qw(--in-place --add FOO=bar out.opus out2.opus)), ['', '', 0], 'process multiple files with --in-place');
-is(md5('out.opus'), '30ba30c4f236c09429473f36f8f861d2', 'the tags were added correctly (out.opus)');
-is(md5('out2.opus'), '0a4d20c287b2e46b26cb0eee353c2069', 'the tags were added correctly (out2.opus)');
-
-unlink('out.opus');
-unlink('out2.opus');
-
-####################################################################################################
-# Interactive edition
-
-$ENV{EDITOR} = 'sed -i -e y/aeiou/AEIOU/ `sleep 0.1`';
-is_deeply(opustags('gobble.opus', '-eo', "'screaming !'.opus"), ['', '', 0], 'edit a file with EDITOR');
-is(md5("'screaming !'.opus"), '56e85ccaa83a13c15576d75bbd6d835f', 'the tags were modified');
-
-$ENV{EDITOR} = 'true';
-is_deeply(opustags('-ie', "'screaming !'.opus"), ['', "Cancelling edition because the tags file was not modified.\n", 256], 'close -e without saving');
-is(md5("'screaming !'.opus"), '56e85ccaa83a13c15576d75bbd6d835f', 'the tags were not modified');
-
-$ENV{EDITOR} = 'false';
-is_deeply(opustags('-ie', "'screaming !'.opus"), ['', "'screaming !'.opus: error: Child process exited with 1\n", 256], 'editor exiting with an error');
-is(md5("'screaming !'.opus"), '56e85ccaa83a13c15576d75bbd6d835f', 'the tags were not modified');
-
-unlink("'screaming !'.opus");
-
-####################################################################################################
-# Test muxed streams
-
-system('ffmpeg -loglevel error -y -i gobble.opus -c copy -map 0:0 -map 0:0 -shortest muxed.ogg') == 0
-	or BAIL_OUT('could not create a muxed stream');
-
-is_deeply(opustags('muxed.ogg'), ['', <<'END_ERR', 256], 'muxed streams detection');
-muxed.ogg: error: Muxed streams are not supported yet.
-END_ERR
-
-unlink('muxed.ogg');
-
-####################################################################################################
-# Locale
-
-my $locale = 'en_US.iso88591';
-my @all_locales = split(' ', `locale -a`);
-
-SKIP: {
-skip "locale $locale is not present", 5 unless (any { $_ eq $locale } @all_locales);
-
-opustags(qw(gobble.opus -a TITLE=七面鳥 -a ARTIST=éàç -o out.opus -y));
-
-local $ENV{LC_ALL} = $locale;
-local $ENV{LANGUAGE} = '';
-
-is_deeply(opustags(qw(-S out.opus), {in => <<"END_IN", mode => ':raw'}), [<<"END_OUT", '', 0], 'set all in ISO-8859-1');
-T=\xef\xef\xf6
-END_IN
-T=\xef\xef\xf6
-END_OUT
-
-is_deeply(opustags('-i', 'out.opus', "--add=I=\xf9\xce", {mode => ':raw'}), ['', '', 0], 'write tags in ISO-8859-1');
-
-is_deeply(opustags('out.opus', {mode => ':raw'}), [<<"END_OUT", <<"END_ERR", 256], 'read tags in ISO-8859-1 with incompatible characters');
-encoder=Lavc58.18.100 libopus
-END_OUT
-out.opus: error: Invalid or incomplete multibyte or wide character. See --raw.
-END_ERR
-
-is_deeply(opustags(qw(out.opus -d TITLE -d ARTIST), {mode => ':raw'}), [<<"END_OUT", '', 0], 'read tags in ISO-8859-1');
-encoder=Lavc58.18.100 libopus
-I=\xf9\xce
-END_OUT
-
-$ENV{LC_ALL} = '';
-
-is_deeply(opustags('out.opus'), [<<"END_OUT", '', 0], 'read tags in UTF-8');
-encoder=Lavc58.18.100 libopus
-TITLE=七面鳥
-ARTIST=éàç
-I=ùÎ
-END_OUT
-
-unlink('out.opus');
-}
-
-####################################################################################################
-# Raw edition
-
-is_deeply(opustags(qw(-S gobble.opus -o out.opus --raw -a), "U=\xFE", {in => <<"END_IN", mode => ':raw'}), ['', '', 0], 'raw set-all with binary data');
-T=\xFF
-END_IN
-
-is_deeply(opustags(qw(out.opus --raw), { mode => ':raw' }), [<<"END_OUT", '', 0], 'raw read');
-T=\xFF
-U=\xFE
-END_OUT
-
-unlink('out.opus');
-
-####################################################################################################
-# Multiple-page tags
-
-my $big_tags = "DATA=x\n" x 15000; # > 90K, which is over the max page size of 64KiB.
-is_deeply(opustags(qw(-S gobble.opus -o out.opus), {in => $big_tags}), ['', '', 0], 'write multi-page header');
-is_deeply(opustags('out.opus'), [$big_tags, '', 0], 'read multi-page header');
-is_deeply(opustags(qw(out.opus -i -D -a), 'encoder=Lavc58.18.100 libopus'), ['', '', 0], 'shrink the header');
-is(md5('out.opus'), '111a483596ac32352fbce4d14d16abd2', 'the result is identical to the original file');
-unlink('out.opus');
-
-####################################################################################################
-# Cover arts
-
-is_deeply(opustags(qw(-D --set-cover pixel.png gobble.opus -o out.opus)), ['', '', 0], 'set the cover');
-is_deeply(opustags(qw(--output-cover out.png out.opus)), [<<'END_OUT', '', 0], 'extract the cover');
-METADATA_BLOCK_PICTURE=AAAAAwAAAAlpbWFnZS9wbmcAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEWJUE5HDQoaCgAAAA1JSERSAAAAAQAAAAEIAgAAAJB3U94AAAAMSURBVAjXY/j//z8ABf4C/tzMWecAAAAASUVORK5CYII=
-END_OUT
-is(md5('out.png'), md5('pixel.png'), 'the extracted cover is identical to the one set');
-unlink('out.opus');
-unlink('out.png');
-
-is_deeply(opustags(qw(-D --set-cover - gobble.opus), { in => "GIF8 x" }), [<<'END_OUT', '', 0], 'read the cover from stdin');
-METADATA_BLOCK_PICTURE=AAAAAwAAAAlpbWFnZS9naWYAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAZHSUY4IHg=
-END_OUT
-
-####################################################################################################
-# Vendor string
-
-is_deeply(opustags(qw(--vendor gobble.opus)), ["Lavf58.12.100\n", '', 0], 'print the vendor string');
-
-is_deeply(opustags(qw(--set-vendor opustags gobble.opus -o out.opus)), ['', '', 0], 'set the vendor string');
-is_deeply(opustags(qw(--vendor out.opus)), ["opustags\n", '', 0], 'the vendor string was updated');
-unlink('out.opus');
-
-####################################################################################################
-# Multi-line tags
-
-is_deeply(opustags(qw(--set-all gobble.opus -o out.opus), { in => "MULTILINE=one\n\ttwo\nSIMPLE=three\n" }), ['', '', 0], 'parses continuation lines');
-is_deeply(opustags(qw(out.opus -z)), ["MULTILINE=one\ntwo\0SIMPLE=three\0", '', 0], 'delimits output with NUL on -z');
-unlink('out.opus');
-
-is_deeply(opustags(qw(--set-all gobble.opus -o out.opus -z), { in => "MULTILINE=one\ntwo\0SIMPLE=three\0" }), ['', '', 0], 'delimits input with NUL on -z');
-is_deeply(opustags(qw(out.opus)), [<<'END', '', 0], 'indents continuation lines');
-MULTILINE=one
-	two
-SIMPLE=three
-END
-unlink('out.opus');

t/system.cc

@@ -1,78 +0,0 @@
-#include <opustags.h>
-#include "tap.h"
-
-#include <string.h>
-#include <unistd.h>
-
-void check_partial_files()
-{
-	static const char* result = "partial_file.test";
-	std::string name;
-	{
-		ot::partial_file bad_tmp;
-		try {
-			bad_tmp.open("/dev/null");
-			throw failure("opening a device as a partial file should fail");
-		} catch (const ot::status& rc) {
-			is(rc, ot::st::standard_error, "opening a device as a partial file fails");
-		}
-
-		bad_tmp.open(result);
-		name = bad_tmp.name();
-		if (name.size() != strlen(result) + 12 ||
-		    name.compare(0, strlen(result), result) != 0)
-			throw failure("the temporary name is surprising: " + name);
-	}
-	is(access(name.c_str(), F_OK), -1, "expect the temporary file is deleted");
-
-	ot::partial_file good_tmp;
-	good_tmp.open(result);
-	name = good_tmp.name();
-	good_tmp.commit();
-	is(access(name.c_str(), F_OK), -1, "expect the temporary file is deleted");
-	is(access(result, F_OK), 0, "expect the final result file");
-	is(remove(result), 0, "remove the result file");
-}
-
-void check_slurp()
-{
-	static const ot::byte_string_view pixel = ""_bsv
-		"\x89\x50\x4e\x47\x0d\x0a\x1a\x0a\x00\x00\x00\x0d"
-		"\x49\x48\x44\x52\x00\x00\x00\x01\x00\x00\x00\x01"
-		"\x08\x02\x00\x00\x00\x90\x77\x53\xde\x00\x00\x00"
-		"\x0c\x49\x44\x41\x54\x08\xd7\x63\xf8\xff\xff\x3f"
-		"\x00\x05\xfe\x02\xfe\xdc\xcc\x59\xe7\x00\x00\x00"
-		"\x00\x49\x45\x4e\x44\xae\x42\x60\x82";
-	opaque_is(ot::slurp_binary_file("pixel.png"), pixel, "loads a whole file");
-}
-
-void check_converter()
-{
-	setlocale(LC_ALL, "");
-	is(ot::decode_utf8(ot::encode_utf8("Éphémère")), "Éphémère", "decode_utf8 reverts encode_utf8");
-	opaque_is(ot::encode_utf8(ot::decode_utf8(u8"Éphémère")), u8"Éphémère",
-	          "encode_utf8 reverts decode_utf8");
-
-	try {
-		ot::decode_utf8((char8_t*) "\xFF\xFF");
-		throw failure("conversion from bad UTF-8 did not fail");
-	} catch (const ot::status&) {}
-}
-
-void check_shell_esape()
-{
-	is(ot::shell_escape("foo"), "'foo'", "simple string");
-	is(ot::shell_escape("a'b"), "'a'\\''b'", "string with a simple quote");
-	is(ot::shell_escape("a!b"), "'a'\\!'b'", "string with a bang");
-	is(ot::shell_escape("a!b'c!d'e"), "'a'\\!'b'\\''c'\\!'d'\\''e'", "string with a bang");
-}
-
-int main(int argc, char **argv)
-{
-	plan(4);
-	run(check_partial_files, "test partial files");
-	run(check_slurp, "file slurping");
-	run(check_converter, "test encoding converter");
-	run(check_shell_esape, "test shell escaping");
-	return 0;
-}

t/tap.h

@@ -1,73 +0,0 @@
-/**
- * \file t/tap.h
- *
- * \brief
- * Helpers for following the Test Anything Protocol.
- *
- * Its interface mimics Test::More from Perl:
- * https://perldoc.perl.org/Test/More.html
- *
- * Unlike Test::More, a test failure raises an exception and aborts the whole subtest.
- */
-
-#pragma once
-
-#include <exception>
-#include <iostream>
-
-inline namespace tap {
-
-struct failure : std::runtime_error {
-	failure(const std::string& what) : std::runtime_error(what) {}
-};
-
-template <typename F>
-static void run(F test, const char *name)
-{
-	bool ok = false;
-	try {
-		test();
-		ok = true;
-	} catch (failure& e) {
-		std::cerr << "# fail: " << e.what() << "\n";
-	} catch (const ot::status &rc) {
-		std::cerr << "# unexpected error: " << rc.message << "\n";
-	}
-	std::cout << (ok ? "ok" : "not ok") << " - " << name << "\n";
-}
-
-void plan(int tests)
-{
-	std::cout << "1.." << tests << "\n";
-}
-
-template <typename T, typename U>
-void is(const T& got, const U& expected, const char* name)
-{
-	if (got != expected) {
-		std::cerr << "# got: " << got << "\n"
-		             "# expected: " << expected << "\n";
-		throw failure(name);
-	}
-}
-
-template <typename T, typename U>
-void opaque_is(const T& got, const U& expected, const char* name)
-{
-	if (got != expected)
-		throw failure(name);
-}
-
-template <>
-void is(const ot::status& got, const ot::st& expected, const char* name)
-{
-	if (got.code != expected) {
-		if (got.code == ot::st::ok)
-			std::cerr << "# unexpected success\n";
-		else
-			std::cerr << "# unexpected error: " << got.message << "\n";
-		throw failure(name);
-	}
-}
-
-}

tests/actions_test.cc

@@ -0,0 +1,169 @@
+#include "actions.h"
+#include "catch.h"
+
+#include "ogg.h"
+#include "tags_handlers/insertion_tags_handler.h"
+#include "tags_handlers/stream_tags_handler.h"
+
+#include <fstream>
+#include <cstring>
+
+using namespace opustags;
+
+static bool same_streams(ogg::Decoder &a, ogg::Decoder &b)
+{
+    std::shared_ptr<ogg::Stream> sa, sb;
+    ogg_packet pa, pb;
+    int ra, rb;
+
+    for (;;) {
+        sa = a.read_page();
+        sb = b.read_page();
+        if (!sa && !sb)
+            break; // both reached the end at the same time
+        if (!sa || !sb)
+            return false; // one stream is shorter than the other
+        if (sa->stream.serialno != sb->stream.serialno)
+            return false;
+        for (;;) {
+            ra = ogg_stream_packetout(&sa->stream, &pa);
+            rb = ogg_stream_packetout(&sb->stream, &pb);
+            if (ra != rb)
+                return false;
+            else if (ra == 0)
+                break;
+            else if (ra < 0)
+                throw std::runtime_error("ogg_stream_packetout failed");
+            // otherwise we got a valid packet on both sides
+            if (pa.bytes != pb.bytes || pa.b_o_s != pb.b_o_s || pa.e_o_s != pb.e_o_s)
+                return false;
+            if (pa.granulepos != pb.granulepos || pa.packetno != pb.packetno)
+                return false;
+            if (memcmp(pa.packet, pb.packet, pa.bytes) != 0)
+                return false;
+        }
+    }
+    return true;
+}
+
+static bool same_files(std::istream &a, std::istream &b)
+{
+    static const size_t block = 1024;
+    char ba[block], bb[block];
+    while (a && b) {
+        a.read(ba, block);
+        b.read(bb, block);
+        if (a.gcount() != b.gcount())
+            return false;
+        if (memcmp(ba, bb, a.gcount()) != 0)
+            return false;
+    }
+    if (a || b)
+        return false; // one of them is shorter
+    return true;
+}
+
+TEST_CASE("editing an unknown stream should do nothing", "[actions]")
+{
+    std::ifstream in("../tests/samples/beep.ogg");
+    std::stringstream out;
+    ogg::Decoder dec(in);
+    ogg::Encoder enc(out);
+
+    StreamTagsHandler editor(StreamTagsHandler::ALL_STREAMS);
+    edit_tags(dec, enc, editor);
+
+    in.clear();
+    in.seekg(0, in.beg);
+    out.clear();
+    out.seekg(0, out.beg);
+    REQUIRE(same_files(in, out));
+}
+
+TEST_CASE("fake editing of an Opus stream should preserve the stream", "[actions]")
+{
+    std::ifstream in("../tests/samples/mystery-beep.ogg");
+    std::stringstream out;
+    ogg::Decoder dec(in);
+    ogg::Encoder enc(out);
+
+    StreamTagsHandler editor(StreamTagsHandler::ALL_STREAMS);
+    edit_tags(dec, enc, editor);
+
+    in.clear();
+    in.seekg(0, in.beg);
+    out.clear();
+    out.seekg(0, out.beg);
+    REQUIRE(same_files(in, out));
+}
+
+TEST_CASE("editing a specific stream", "[actions]")
+{
+    std::ifstream in("../tests/samples/mystery-beep.ogg");
+    std::stringstream out;
+
+    {
+        ogg::Decoder dec(in);
+        ogg::Encoder enc(out);
+        InsertionTagsHandler editor(3, "pwnd", "yes");
+        edit_tags(dec, enc, editor);
+    }
+
+    in.clear();
+    in.seekg(0, in.beg);
+    out.clear();
+    out.seekg(0, out.beg);
+
+    {
+        ogg::Decoder a(in);
+        ogg::Decoder b(out);
+        std::shared_ptr<ogg::Stream> s2[6];
+        for (int i = 0; i < 6; i++) {
+            // get the headers
+            a.read_page();
+            s2[i] = b.read_page();
+        }
+
+        REQUIRE(s2[0]->type == ogg::OPUS_STREAM);
+        REQUIRE(s2[1]->type == ogg::UNKNOWN_STREAM);
+        REQUIRE(s2[2]->type == ogg::OPUS_STREAM);
+        REQUIRE(!s2[0]->tags.contains("pwnd"));
+        REQUIRE(s2[2]->tags.get("pwnd") == "yes");
+
+        REQUIRE(same_streams(a, b));
+    }
+}
+
+class GetLanguages : public StreamTagsHandler {
+public:
+    GetLanguages() : StreamTagsHandler(StreamTagsHandler::ALL_STREAMS) {}
+    std::vector<std::string> languages;
+protected:
+    void list_impl(const Tags &tags) {
+        languages.push_back(tags.get("LANGUAGE"));
+    }
+};
+
+TEST_CASE("listing tags", "[actions]")
+{
+    std::ifstream in("../tests/samples/mystery-beep.ogg");
+    ogg::Decoder dec(in);
+    GetLanguages lister;
+    list_tags(dec, lister);
+
+    REQUIRE(lister.languages.size() == 2);
+    REQUIRE(lister.languages[0] == "und");
+    REQUIRE(lister.languages[1] == "und");
+}
+
+TEST_CASE("listing tags, full scan", "[actions]")
+{
+    std::ifstream in("../tests/samples/mystery-beep.ogg");
+    ogg::Decoder dec(in);
+    GetLanguages lister;
+    list_tags(dec, lister, true);
+
+    REQUIRE(lister.languages.size() == 2);
+    REQUIRE(lister.languages[0] == "und");
+    REQUIRE(lister.languages[1] == "und");
+}

tests/main.cc

@@ -0,0 +1,2 @@
+#define CATCH_CONFIG_MAIN
+#include "catch.h"

tests/ogg_test.cc

@@ -0,0 +1,148 @@
+#include "ogg.h"
+#include "catch.h"
+
+#include <fstream>
+
+using namespace opustags;
+
+TEST_CASE("decoding a single-stream Ogg Opus file", "[ogg]")
+{
+    std::ifstream src("../tests/samples/mystery.ogg");
+    ogg::Decoder dec(src);
+
+    std::shared_ptr<ogg::Stream> s = dec.read_page();
+    REQUIRE(s != nullptr);
+    REQUIRE(s->state == ogg::HEADER_READY);
+    REQUIRE(s->type == ogg::OPUS_STREAM);
+
+    std::shared_ptr<ogg::Stream> s2 = dec.read_page();
+    REQUIRE(s2 == s);
+    REQUIRE(s->state == ogg::TAGS_READY);
+    REQUIRE(s->type == ogg::OPUS_STREAM);
+    REQUIRE(s->tags.get("encoder") == "Lavc57.24.102 libopus");
+}
+
+TEST_CASE("decoding garbage", "[ogg]")
+{
+    std::ifstream src("Makefile");
+    ogg::Decoder dec(src);
+    REQUIRE_THROWS(dec.read_page());
+}
+
+TEST_CASE("decoding an Ogg Vorbis file", "[ogg]")
+{
+    std::ifstream src("../tests/samples/beep.ogg");
+    ogg::Decoder dec(src);
+
+    std::shared_ptr<ogg::Stream> s = dec.read_page();
+    REQUIRE(s != nullptr);
+    REQUIRE(s->state == ogg::HEADER_READY);
+    REQUIRE(s->type == ogg::UNKNOWN_STREAM);
+
+    s = dec.read_page();
+    REQUIRE(s != nullptr);
+    REQUIRE(s->state == ogg::RAW_READY);
+}
+
+TEST_CASE("decoding a multi-stream file", "[ogg]")
+{
+    std::ifstream src("../tests/samples/mystery-beep.ogg");
+    ogg::Decoder dec(src);
+    std::shared_ptr<ogg::Stream> first, second, third, s;
+
+    s = dec.read_page();
+    first = s;
+    REQUIRE(s != nullptr);
+    REQUIRE(s->state == ogg::HEADER_READY);
+    REQUIRE(s->type == ogg::OPUS_STREAM);
+
+    s = dec.read_page();
+    second = s;
+    REQUIRE(s != nullptr);
+    REQUIRE(s != first);
+    REQUIRE(s->state == ogg::HEADER_READY);
+    REQUIRE(s->type == ogg::UNKNOWN_STREAM);
+
+    s = dec.read_page();
+    third = s;
+    REQUIRE(s != nullptr);
+    REQUIRE(s != first);
+    REQUIRE(s != second);
+    REQUIRE(s->state == ogg::HEADER_READY);
+    REQUIRE(s->type == ogg::OPUS_STREAM);
+
+    s = dec.read_page();
+    REQUIRE(s == first);
+    REQUIRE(s->state == ogg::TAGS_READY);
+
+    s = dec.read_page();
+    REQUIRE(s == second);
+    REQUIRE(s->state == ogg::RAW_READY);
+
+    s = dec.read_page();
+    REQUIRE(s == third);
+    REQUIRE(s->state == ogg::TAGS_READY);
+}
+
+static void craft_stream(std::ostream &out, const std::string &tags_data)
+{
+    ogg::Encoder enc(out);
+    ogg_stream_state os;
+    ogg_page og;
+    ogg_packet op;
+    ogg_stream_init(&os, 0);
+
+    op.packet = reinterpret_cast<unsigned char*>(const_cast<char*>("OpusHead"));
+    op.bytes = 8;
+    op.b_o_s = 1;
+    op.e_o_s = 0;
+    op.granulepos = 0;
+    op.packetno = 0;
+    ogg_stream_packetin(&os, &op);
+    ogg_stream_flush(&os, &og);
+    enc.write_raw_page(og);
+
+    op.packet = reinterpret_cast<unsigned char*>(const_cast<char*>(tags_data.data()));
+    op.bytes = tags_data.size();
+    op.b_o_s = 0;
+    op.e_o_s = 1;
+    op.granulepos = 0;
+    op.packetno = 1;
+    ogg_stream_packetin(&os, &op);
+    ogg_stream_flush(&os, &og);
+    enc.write_raw_page(og);
+
+    ogg_stream_clear(&os);
+}
+
+const char *evil_tags =
+    "OpusTags"
+    "\x00\x00\x00\x00" "" /* vendor */
+    "\x01\x00\x00\x00" /* one comment */
+    "\xFA\x00\x00\x00" "TITLE=Evil"
+    /* ^ should be \x0A as the length of the comment is 10 */
+;
+
+TEST_CASE("decoding a malicious Ogg Opus file", "[ogg]")
+{
+    std::stringstream buf;
+    craft_stream(buf, std::string(evil_tags, 8 + 4 + 4 + 4 + 10));
+    buf.seekg(0, buf.beg);
+    ogg::Decoder dec(buf);
+
+    std::shared_ptr<ogg::Stream> s = dec.read_page();
+    REQUIRE(s != nullptr);
+    REQUIRE(s->state == ogg::HEADER_READY);
+    REQUIRE(s->type == ogg::OPUS_STREAM);
+
+    REQUIRE_THROWS(dec.read_page());
+}
+
+TEST_CASE("decoding a bad stream", "[ogg]")
+{
+    std::ifstream in("uioprheuio");
+    REQUIRE_THROWS(std::make_shared<ogg::Decoder>(in));
+}
+
+// Encoding is trickier, and might as well be done in actions_test.cc, given
+// opustags::edit_tags covers all of Encoder's regular code.

tests/options_test.cc

@@ -0,0 +1,205 @@
+#include "options.h"
+#include "catch.h"
+
+#include "tags_handlers/export_tags_handler.h"
+#include "tags_handlers/external_edit_tags_handler.h"
+#include "tags_handlers/import_tags_handler.h"
+#include "tags_handlers/insertion_tags_handler.h"
+#include "tags_handlers/listing_tags_handler.h"
+#include "tags_handlers/modification_tags_handler.h"
+#include "tags_handlers/removal_tags_handler.h"
+
+#include <memory>
+
+using namespace opustags;
+
+static std::unique_ptr<char[]> string_to_uptr(const std::string &str)
+{
+    auto ret = std::make_unique<char[]>(str.size() + 1);
+    for (size_t i = 0; i < str.size(); i++)
+        ret[i] = str[i];
+    ret[str.size()] = 0;
+    return ret;
+}
+
+static Options retrieve_options(
+    std::vector<std::string> args, bool fake_input_path = true)
+{
+    // need to pass non-const char*, but we got const objects. make copies
+    std::vector<std::unique_ptr<char[]>> arg_holders;
+    arg_holders.push_back(string_to_uptr("fake/path/to/program"));
+    for (size_t i = 0; i < args.size(); i++)
+        arg_holders.push_back(string_to_uptr(args[i]));
+    if (fake_input_path)
+        arg_holders.push_back(string_to_uptr("fake/path/to/input"));
+
+    auto plain_args = std::make_unique<char*[]>(arg_holders.size());
+    for (size_t i = 0; i < arg_holders.size(); i++)
+        plain_args[i] = arg_holders[i].get();
+
+    return parse_args(arg_holders.size(), plain_args.get());
+}
+
+// retrieve a specific TagsHandler from the CompositeTagsHandler in options
+template<typename T> static T *get_handler(
+    const Options &options, const size_t index)
+{
+    const auto handlers = options.tags_handler.get_handlers();
+    const auto handler = dynamic_cast<T*>(handlers.at(index).get());
+    REQUIRE(handler);
+    return handler;
+}
+
+TEST_CASE("option parsing", "[options]")
+{
+    SECTION("--help") {
+        REQUIRE(retrieve_options({"--help"}).show_help);
+        REQUIRE(retrieve_options({"-h"}).show_help);
+        REQUIRE(!retrieve_options({}).show_help);
+    }
+
+    SECTION("--version") {
+        REQUIRE(retrieve_options({"--version"}).show_version);
+        REQUIRE(retrieve_options({"-V"}).show_version);
+        REQUIRE(!retrieve_options({}).show_version);
+    }
+
+    SECTION("--overwrite") {
+        REQUIRE(retrieve_options({"--overwrite"}).overwrite);
+        REQUIRE(retrieve_options({"-y"}).overwrite);
+        REQUIRE(!retrieve_options({}).overwrite);
+    }
+
+    SECTION("--full") {
+        REQUIRE(retrieve_options({"--full"}).full);
+        REQUIRE(!retrieve_options({}).full);
+    }
+
+    SECTION("--in-place") {
+        REQUIRE(!retrieve_options({}).in_place);
+        REQUIRE(retrieve_options({}).path_out.empty());
+        REQUIRE(retrieve_options({"--in-place", "ABC"}, false).in_place);
+        REQUIRE(
+            retrieve_options({"--in-place", "ABC"}, false).path_out == ".otmp");
+        REQUIRE(retrieve_options({"--in-place"}).in_place);
+        REQUIRE(retrieve_options({"--in-place"}).path_out == ".otmp");
+        REQUIRE(retrieve_options({"--in-place=ABC"}).in_place);
+        REQUIRE(retrieve_options({"--in-place=ABC"}).path_out == "ABC");
+        REQUIRE(retrieve_options({"-i", "ABC"}, false).in_place);
+        REQUIRE(retrieve_options({"-i", "ABC"}, false).path_out == ".otmp");
+        REQUIRE(retrieve_options({"-i"}).in_place);
+        REQUIRE(retrieve_options({"-i"}).path_out == ".otmp");
+        REQUIRE(retrieve_options({"-iABC"}).in_place);
+        REQUIRE(retrieve_options({"-iABC"}).path_out == "ABC");
+    }
+
+    SECTION("input") {
+        REQUIRE_THROWS(retrieve_options({}, false));
+        REQUIRE_THROWS(retrieve_options({""}, false));
+        REQUIRE(retrieve_options({"input"}, false).path_in == "input");
+        REQUIRE_THROWS(retrieve_options({"input", "extra argument"}, false));
+    }
+
+    SECTION("--output") {
+        REQUIRE(retrieve_options({"--output", "ABC"}).path_out == "ABC");
+        REQUIRE(retrieve_options({"-o", "ABC"}).path_out == "ABC");
+        REQUIRE_THROWS(retrieve_options({"--output", ""}));
+        REQUIRE_THROWS(retrieve_options({"-o", ""}));
+    }
+
+    SECTION("--import") {
+        get_handler<ImportTagsHandler>(retrieve_options({"--import"}), 0);
+    }
+
+    SECTION("--export") {
+        get_handler<ExportTagsHandler>(retrieve_options({"--export"}), 0);
+    }
+
+    SECTION("--edit") {
+        get_handler<ExternalEditTagsHandler>(retrieve_options({"--edit"}), 0);
+        get_handler<ExternalEditTagsHandler>(retrieve_options({"-e"}), 0);
+    }
+
+    SECTION("--list") {
+        get_handler<ListingTagsHandler>(retrieve_options({"--list"}), 0);
+        get_handler<ListingTagsHandler>(retrieve_options({"-l"}), 0);
+        // TODO:
+        // test enabling / disabling colors, which should be
+        // contained inside the state of ListingTagsHandler
+        // TODO:
+        // it should be the default operation for readonly mode - test this too
+    }
+
+    SECTION("--delete-all") {
+        REQUIRE(get_handler<RemovalTagsHandler>(
+            retrieve_options({"--delete-all"}), 0)->get_tag_key().empty());
+
+        REQUIRE(get_handler<RemovalTagsHandler>(
+            retrieve_options({"-D"}), 0)->get_tag_key().empty());
+    }
+
+    SECTION("--delete") {
+        const auto opts = retrieve_options({"--delete", "A", "-d", "B"});
+        REQUIRE(get_handler<RemovalTagsHandler>(opts, 0)->get_tag_key() == "A");
+        REQUIRE(get_handler<RemovalTagsHandler>(opts, 1)->get_tag_key() == "B");
+        REQUIRE_THROWS(retrieve_options({"--delete", "invalid="}));
+    }
+
+    SECTION("--add") {
+        const auto opts = retrieve_options({"--add", "A=1", "-a", "B=2"});
+        const auto handler1 = get_handler<InsertionTagsHandler>(opts, 0);
+        const auto handler2 = get_handler<InsertionTagsHandler>(opts, 1);
+        REQUIRE(handler1->get_tag_key() == "A");
+        REQUIRE(handler1->get_tag_value() == "1");
+        REQUIRE(handler2->get_tag_key() == "B");
+        REQUIRE(handler2->get_tag_value() == "2");
+        REQUIRE_THROWS(retrieve_options({"--add", "invalid"}));
+    }
+
+    SECTION("--set") {
+        const auto opts = retrieve_options({"--set", "A=1", "-s", "B=2"});
+        const auto handler1 = get_handler<ModificationTagsHandler>(opts, 0);
+        const auto handler2 = get_handler<ModificationTagsHandler>(opts, 1);
+        REQUIRE(handler1->get_tag_key() == "A");
+        REQUIRE(handler1->get_tag_value() == "1");
+        REQUIRE(handler2->get_tag_key() == "B");
+        REQUIRE(handler2->get_tag_value() == "2");
+        REQUIRE_THROWS(retrieve_options({"--set", "invalid"}));
+    }
+
+    SECTION("--stream") {
+        // by default, use all the streams
+        REQUIRE(
+            get_handler<RemovalTagsHandler>(retrieve_options({"-d", "xyz"}), 0)
+            ->get_streamno() == StreamTagsHandler::ALL_STREAMS);
+
+        // ...unless the user supplies an option to use a specific stream
+        REQUIRE(
+            get_handler<RemovalTagsHandler>(
+                retrieve_options({"--stream", "1", "-d", "xyz"}), 0)
+            ->get_streamno() == 1);
+
+        // ...which can be combined multiple times
+        {
+            const auto opts = retrieve_options({
+                "--stream", "1",
+                "-d", "xyz",
+                "--stream", "2",
+                "-d", "abc"});
+            const auto handler1 = get_handler<RemovalTagsHandler>(opts, 0);
+            const auto handler2 = get_handler<RemovalTagsHandler>(opts, 1);
+            REQUIRE(handler1->get_streamno() == 1);
+            REQUIRE(handler2->get_streamno() == 2);
+        }
+
+        // ...or contain comma separated values
+        {
+            const auto opts = retrieve_options({
+                "--stream", "1,2", "-d", "xyz"});
+            const auto handler1 = get_handler<RemovalTagsHandler>(opts, 0);
+            const auto handler2 = get_handler<RemovalTagsHandler>(opts, 1);
+            REQUIRE(handler1->get_streamno() == 1);
+            REQUIRE(handler2->get_streamno() == 2);
+        }
+    }
+}

tests/tags_handlers/composite_tags_handler_test.cc

@@ -0,0 +1,96 @@
+#include "tags_handlers/composite_tags_handler.h"
+#include "catch.h"
+
+using namespace opustags;
+
+namespace
+{
+    struct DummyTagsHandler : ITagsHandler
+    {
+        DummyTagsHandler();
+
+        bool relevant(const int streamno) override;
+        void list(const int streamno, const Tags &) override;
+        bool edit(const int streamno, Tags &) override;
+        bool done() override;
+
+        bool relevant_ret, edit_ret, done_ret, list_fired;
+    };
+}
+
+DummyTagsHandler::DummyTagsHandler()
+    : relevant_ret(true), edit_ret(true), done_ret(true), list_fired(false)
+{
+}
+
+bool DummyTagsHandler::relevant(const int)
+{
+    return relevant_ret;
+}
+
+void DummyTagsHandler::list(const int, const Tags &)
+{
+    list_fired = true;
+}
+
+bool DummyTagsHandler::edit(const int, Tags &)
+{
+    return edit_ret;
+}
+
+bool DummyTagsHandler::done()
+{
+    return done_ret;
+}
+
+TEST_CASE("composite tags handler", "[tags_handlers]")
+{
+    auto handler1 = std::make_shared<DummyTagsHandler>();
+    auto handler2 = std::make_shared<DummyTagsHandler>();
+    CompositeTagsHandler composite_handler;
+    composite_handler.add_handler(handler1);
+    composite_handler.add_handler(handler2);
+
+    SECTION("relevance") {
+        const int dummy_streamno = 1;
+        handler1->relevant_ret = true;
+        handler2->relevant_ret = true;
+        REQUIRE(composite_handler.relevant(dummy_streamno));
+        handler1->relevant_ret = false;
+        REQUIRE(composite_handler.relevant(dummy_streamno));
+        handler2->relevant_ret = false;
+        REQUIRE(!composite_handler.relevant(dummy_streamno));
+    }
+
+    SECTION("listing") {
+        const int dummy_streamno = 1;
+        Tags dummy_tags;
+        REQUIRE(!handler1->list_fired);
+        REQUIRE(!handler2->list_fired);
+        composite_handler.list(dummy_streamno, dummy_tags);
+        REQUIRE(handler1->list_fired);
+        REQUIRE(handler2->list_fired);
+    }
+
+    SECTION("editing") {
+        const int dummy_streamno = 1;
+        Tags dummy_tags;
+        handler1->edit_ret = true;
+        handler2->edit_ret = true;
+        REQUIRE(composite_handler.edit(dummy_streamno, dummy_tags));
+        handler1->edit_ret = false;
+        REQUIRE(composite_handler.edit(dummy_streamno, dummy_tags));
+        handler2->edit_ret = false;
+        REQUIRE(!composite_handler.edit(dummy_streamno, dummy_tags));
+    }
+
+    SECTION("finish") {
+        handler1->done_ret = true;
+        handler2->done_ret = true;
+        REQUIRE(composite_handler.done());
+        handler1->done_ret = false;
+        REQUIRE(!composite_handler.done());
+        handler2->done_ret = false;
+        REQUIRE(!composite_handler.done());
+    }
+}

tests/tags_handlers/export_tags_handler_test.cc

@@ -0,0 +1,23 @@
+#include "tags_handlers/export_tags_handler.h"
+#include "catch.h"
+#include <sstream>
+
+using namespace opustags;
+
+TEST_CASE("export tags handler", "[tags_handlers]")
+{
+    std::stringstream ss;
+    ExportTagsHandler handler(ss);
+    handler.list(1, {{{"a", "value1"}, {"b", "value2"}}});
+    handler.list(2, {{{"c", "value3"}, {"d", "value4"}}});
+
+    REQUIRE(ss.str() == R"([Stream 1]
+a=value1
+b=value2
+
+[Stream 2]
+c=value3
+d=value4
+
+)");
+}

tests/tags_handlers/import_tags_handler_test.cc

@@ -0,0 +1,142 @@
+#include "tags_handlers/import_tags_handler.h"
+#include "catch.h"
+#include <sstream>
+
+using namespace opustags;
+
+TEST_CASE("import tags handler", "[tags_handlers]")
+{
+    SECTION("tags for streams not mentioned in import get emptied")
+    {
+        Tags tags = {{{"remove", "me"}}};
+        std::stringstream ss;
+        ImportTagsHandler handler(ss);
+        REQUIRE(handler.edit(1, tags));
+        REQUIRE(tags.get_all().empty());
+    }
+
+    SECTION("streams that do not exist in the input file are ignored")
+    {
+        // TODO: rather than ignoring, at least print a warning
+        // requires #6
+
+        Tags tags;
+        std::stringstream ss;
+        ss << "[Stream 5]\nkey = value\n";
+        ImportTagsHandler handler(ss);
+        REQUIRE(!handler.edit(1, tags));
+        REQUIRE(tags.get_all().empty());
+    }
+
+    SECTION("adding unique tags")
+    {
+        Tags tags;
+        std::stringstream ss;
+        ss << "[Stream 1]\nkey = value\nkey2 = value2\n";
+        ImportTagsHandler handler(ss);
+        REQUIRE(handler.edit(1, tags));
+        REQUIRE(tags.get_all().size() == 2);
+        REQUIRE(tags.get("key") == "value");
+        REQUIRE(tags.get("key2") == "value2");
+    }
+
+    SECTION("adding tags with the same key")
+    {
+        Tags tags;
+        std::stringstream ss;
+        ss << "[Stream 1]\nkey = value1\nkey = value2\n";
+        ImportTagsHandler handler(ss);
+        REQUIRE(handler.edit(1, tags));
+        REQUIRE(tags.get_all().size() == 2);
+        REQUIRE(tags.get_all().at(0).key == "key");
+        REQUIRE(tags.get_all().at(1).key == "key");
+        REQUIRE(tags.get_all().at(0).value == "value1");
+        REQUIRE(tags.get_all().at(1).value == "value2");
+    }
+
+    SECTION("overwriting existing tags")
+    {
+        Tags tags = {{{"remove", "me"}}};
+        std::stringstream ss;
+        ss << "[Stream 1]\nkey = value\nkey2 = value2\n";
+        ImportTagsHandler handler(ss);
+        REQUIRE(handler.edit(1, tags));
+        REQUIRE(tags.get_all().size() == 2);
+        REQUIRE(tags.get("key") == "value");
+        REQUIRE(tags.get("key2") == "value2");
+    }
+
+    SECTION("various whitespace issues are worked around")
+    {
+        Tags tags;
+        std::stringstream ss;
+        ss << " [StrEaM  1] \n\n  key = value  \nkey2=value2\n";
+        ImportTagsHandler handler(ss);
+        REQUIRE(handler.edit(1, tags));
+        REQUIRE(tags.get_all().size() == 2);
+        REQUIRE(tags.get("key") == "value");
+        REQUIRE(tags.get("key2") == "value2");
+    }
+
+    SECTION("not specifying stream assumes first stream")
+    {
+        Tags tags;
+        std::stringstream ss;
+        ss << "key=value";
+        ImportTagsHandler handler(ss);
+        REQUIRE(handler.edit(1, tags));
+        REQUIRE(tags.get_all().size() == 1);
+        REQUIRE(tags.get("key") == "value");
+    }
+
+    SECTION("multiple streams")
+    {
+        Tags tags1;
+        Tags tags2;
+        std::stringstream ss;
+        ss << "[stream 1]\nkey=value\n[stream 2]\nkey2=value2";
+        ImportTagsHandler handler(ss);
+        REQUIRE(handler.edit(1, tags1));
+        REQUIRE(handler.edit(2, tags2));
+        REQUIRE(tags1.get_all().size() == 1);
+        REQUIRE(tags2.get_all().size() == 1);
+        REQUIRE(tags1.get("key") == "value");
+        REQUIRE(tags2.get("key2") == "value2");
+    }
+
+    SECTION("sections listed twice are concatenated")
+    {
+        Tags tags;
+        std::stringstream ss;
+        ss << "[stream 1]\nkey=value\n"
+            "[stream 2]\nkey=irrelevant\n"
+            "[Stream 1]\nkey2=value2";
+        ImportTagsHandler handler(ss);
+        REQUIRE(handler.edit(1, tags));
+        REQUIRE(tags.get_all().size() == 2);
+        REQUIRE(tags.get("key") == "value");
+        REQUIRE(tags.get("key2") == "value2");
+    }
+
+    SECTION("weird input throws errors - malformed section headers")
+    {
+        Tags tags;
+        std::stringstream ss;
+        ss << "[stream huh]\n";
+        REQUIRE_THROWS({
+            ImportTagsHandler handler(ss);
+            handler.edit(1, tags);
+        });
+    }
+
+    SECTION("weird input throws errors - malformed lines")
+    {
+        Tags tags;
+        std::stringstream ss;
+        ss << "tag huh\n";
+        REQUIRE_THROWS({
+            ImportTagsHandler handler(ss);
+            handler.edit(1, tags);
+        });
+    }
+}

tests/tags_handlers/insertion_tags_handler_test.cc

@@ -0,0 +1,22 @@
+#include "tags_handlers/insertion_tags_handler.h"
+#include "catch.h"
+
+using namespace opustags;
+
+TEST_CASE("insertion tags handler", "[tags_handlers]")
+{
+    Tags tags;
+    const auto streamno = 1;
+    const auto expected_tag_key = "tag_key";
+    const auto expected_tag_value = "tag_value";
+    InsertionTagsHandler handler(
+        streamno, expected_tag_key, expected_tag_value);
+
+    REQUIRE(handler.edit(streamno, tags));
+    REQUIRE(tags.get_all().size() == 1);
+    REQUIRE(tags.get(expected_tag_key) == expected_tag_value);
+
+    REQUIRE(handler.edit(streamno, tags));
+    REQUIRE(tags.get_all().size() == 2);
+    REQUIRE(tags.get(expected_tag_key) == expected_tag_value);
+}

tests/tags_handlers/listing_tags_handler_test.cc

@@ -0,0 +1,22 @@
+#include "tags_handlers/listing_tags_handler.h"
+#include "catch.h"
+#include <sstream>
+
+using namespace opustags;
+
+TEST_CASE("listing tags handler", "[tags_handlers]")
+{
+    const auto streamno = 1;
+
+    Tags tags;
+    tags.add("z", "value1");
+    tags.add("a", "value2");
+    tags.add("y", "value3");
+    tags.add("c", "value4");
+
+    std::stringstream ss;
+    ListingTagsHandler handler(streamno, ss);
+    handler.list(streamno, tags);
+
+    REQUIRE(ss.str() == "z=value1\na=value2\ny=value3\nc=value4\n");
+}

tests/tags_handlers/modification_tags_handler_test.cc

@@ -0,0 +1,33 @@
+#include "tags_handlers/modification_tags_handler.h"
+#include "catch.h"
+
+using namespace opustags;
+
+TEST_CASE("modification tags handler", "[tags_handlers]")
+{
+    const auto streamno = 1;
+    const auto first_tag_key = "tag_key";
+    const auto other_tag_key = "other_tag_key";
+    const auto dummy_value = "dummy";
+    const auto new_value = "dummy 2";
+
+    Tags tags;
+    tags.add(first_tag_key, dummy_value);
+
+    REQUIRE(tags.get_all().size() == 1);
+
+    // setting nonexistent keys adds them
+    ModificationTagsHandler handler1(streamno, other_tag_key, dummy_value);
+    REQUIRE(handler1.edit(streamno, tags));
+    REQUIRE(tags.get_all().size() == 2);
+    REQUIRE(tags.get(other_tag_key) == dummy_value);
+
+    // setting existing keys overrides their values
+    ModificationTagsHandler handler2(streamno, other_tag_key, new_value);
+    REQUIRE(handler2.edit(streamno, tags));
+    REQUIRE(tags.get_all().size() == 2);
+    REQUIRE(tags.get(other_tag_key) == new_value);
+
+    // setting existing keys reports no modifications if values are the same
+    REQUIRE(!handler2.edit(streamno, tags));
+}

tests/tags_handlers/removal_tags_handler_test.cc

@@ -0,0 +1,43 @@
+#include "tags_handlers/removal_tags_handler.h"
+#include "catch.h"
+
+using namespace opustags;
+
+TEST_CASE("removal tags handler", "[tags_handlers]")
+{
+    const auto streamno = 1;
+
+    SECTION("removing a single tag")
+    {
+        const auto expected_tag_key = "tag_key";
+        const auto other_tag_key = "other_tag_key";
+        const auto dummy_value = "dummy";
+        RemovalTagsHandler handler(streamno, expected_tag_key);
+
+        Tags tags;
+        tags.add(expected_tag_key, dummy_value);
+        tags.add(other_tag_key, dummy_value);
+
+        REQUIRE(tags.get_all().size() == 2);
+        REQUIRE(handler.edit(streamno, tags));
+        REQUIRE(tags.get_all().size() == 1);
+        REQUIRE(tags.contains(other_tag_key));
+        REQUIRE(!handler.edit(streamno, tags));
+    }
+
+    SECTION("removing all tags")
+    {
+        RemovalTagsHandler handler(streamno);
+
+        Tags tags;
+        tags.add("z", "value1");
+        tags.add("a", "value2");
+        tags.add("y", "value3");
+        tags.add("c", "value4");
+
+        REQUIRE(tags.get_all().size() == 4);
+        REQUIRE(handler.edit(streamno, tags));
+        REQUIRE(tags.get_all().size() == 0);
+        REQUIRE(!handler.edit(streamno, tags));
+    }
+}

tests/tags_handlers/stream_tags_handler_test.cc

@@ -0,0 +1,92 @@
+#include "tags_handlers/stream_tags_handler.h"
+#include "catch.h"
+
+using namespace opustags;
+
+namespace
+{
+    class DummyTagsHandler final : public StreamTagsHandler
+    {
+    public:
+        DummyTagsHandler(const int streamno);
+
+    protected:
+        void list_impl(const Tags &) override;
+        bool edit_impl(Tags &) override;
+
+    public:
+        bool list_fired, edit_fired;
+    };
+}
+
+DummyTagsHandler::DummyTagsHandler(const int streamno)
+    : StreamTagsHandler(streamno), list_fired(false), edit_fired(false)
+{
+}
+
+void DummyTagsHandler::list_impl(const Tags &)
+{
+    list_fired = true;
+}
+
+bool DummyTagsHandler::edit_impl(Tags &)
+{
+    edit_fired = true;
+    return true;
+}
+
+TEST_CASE("stream-based tags handler", "[tags_handlers]")
+{
+    SECTION("concrete stream") {
+        const auto relevant_stream_number = 1;
+        const auto irrelevant_stream_number = 2;
+        Tags dummy_tags;
+        DummyTagsHandler handler(relevant_stream_number);
+
+        SECTION("relevance") {
+            REQUIRE(!handler.relevant(irrelevant_stream_number));
+            REQUIRE(handler.relevant(relevant_stream_number));
+        }
+
+        SECTION("listing") {
+            handler.list(irrelevant_stream_number, dummy_tags);
+            REQUIRE(!handler.list_fired);
+            handler.list(relevant_stream_number, dummy_tags);
+            REQUIRE(handler.list_fired);
+        }
+
+        SECTION("Editing") {
+            REQUIRE(!handler.edit(irrelevant_stream_number, dummy_tags));
+            REQUIRE(!handler.edit_fired);
+            REQUIRE(handler.edit(relevant_stream_number, dummy_tags));
+            REQUIRE(handler.edit_fired);
+        }
+
+        SECTION("finish through listing") {
+            REQUIRE(!handler.edit(irrelevant_stream_number, dummy_tags));
+            REQUIRE(!handler.done());
+            REQUIRE(handler.edit(relevant_stream_number, dummy_tags));
+            REQUIRE(handler.done());
+        }
+
+        SECTION("finish through editing") {
+            handler.list(irrelevant_stream_number, dummy_tags);
+            REQUIRE(!handler.done());
+            handler.list(relevant_stream_number, dummy_tags);
+            REQUIRE(handler.done());
+        }
+    }
+
+    SECTION("any stream") {
+        Tags dummy_tags;
+        DummyTagsHandler handler(StreamTagsHandler::ALL_STREAMS);
+        REQUIRE(handler.relevant(1));
+        REQUIRE(handler.relevant(2));
+        REQUIRE(handler.relevant(3));
+        REQUIRE(!handler.done());
+        handler.list(1, dummy_tags);
+        REQUIRE(!handler.done());
+        handler.list(2, dummy_tags);
+        REQUIRE(!handler.done());
+    }
+}

tests/tags_test.cc

@@ -0,0 +1,85 @@
+#include "tags.h"
+#include "catch.h"
+
+using namespace opustags;
+
+TEST_CASE("tag manipulation", "[tags]")
+{
+    SECTION("basic operations") {
+        Tags tags;
+        REQUIRE(!tags.contains("a"));
+        tags.add("a", "1");
+        REQUIRE(tags.get("a") == "1");
+        REQUIRE(tags.contains("a"));
+        tags.remove("a");
+        REQUIRE(!tags.contains("a"));
+        REQUIRE_THROWS(tags.get("a"));
+    }
+
+    SECTION("clearing") {
+        Tags tags;
+        tags.add("a", "1");
+        tags.add("b", "2");
+        REQUIRE(tags.get_all().size() == 2);
+        tags.clear();
+        REQUIRE(tags.get_all().empty());
+    }
+
+    SECTION("maintaing order of insertions") {
+        Tags tags;
+        tags.add("z", "1");
+        tags.add("y", "2");
+        tags.add("x", "3");
+        tags.add("y", "4");
+
+        REQUIRE(tags.get_all().size() == 4);
+        REQUIRE(tags.get_all()[0].key == "z");
+        REQUIRE(tags.get_all()[1].key == "y");
+        REQUIRE(tags.get_all()[2].key == "x");
+        REQUIRE(tags.get_all()[3].key == "y");
+
+        tags.remove("z");
+        REQUIRE(tags.get_all().size() == 3);
+        REQUIRE(tags.get_all()[0].key == "y");
+        REQUIRE(tags.get_all()[1].key == "x");
+        REQUIRE(tags.get_all()[2].key == "y");
+
+        tags.add("gamma", "5");
+        REQUIRE(tags.get_all().size() == 4);
+        REQUIRE(tags.get_all()[0].key == "y");
+        REQUIRE(tags.get_all()[1].key == "x");
+        REQUIRE(tags.get_all()[2].key == "y");
+        REQUIRE(tags.get_all()[3].key == "gamma");
+    }
+
+    SECTION("key to multiple values") {
+        // ARTIST is set once per artist.
+        // https://www.xiph.org/vorbis/doc/v-comment.html
+        Tags tags;
+        tags.add("ARTIST", "You");
+        tags.add("ARTIST", "Me");
+        REQUIRE(tags.get_all().size() == 2);
+    }
+
+    SECTION("removing multivalues should remove all of them") {
+        Tags tags;
+        tags.add("ARTIST", "You");
+        tags.add("ARTIST", "Me");
+        tags.remove("ARTIST");
+        REQUIRE(tags.get_all().empty());
+    }
+
+    SECTION("tag parsing") {
+        Tag t = parse_tag("TITLE=Foo=Bar");
+        REQUIRE(t.key == "TITLE");
+        REQUIRE(t.value == "Foo=Bar");
+    }
+
+    SECTION("case insensitiveness for keys") {
+        Tags tags;
+        tags.add("TITLE", "Boop");
+        REQUIRE(tags.get("title") == "Boop");
+        tags.remove("titLE");
+        REQUIRE(tags.get_all().empty());
+    }
+}