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

.gitignore

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

CHANGELOG.md

@@ -1,34 +0,0 @@
-opustags changelog
-==================
-
-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

@@ -1,36 +1,78 @@
-cmake_minimum_required(VERSION 3.9)
-
-project(
-	opustags
-	VERSION 1.2.0
-	LANGUAGES CXX
-)
-
+cmake_minimum_required (VERSION 2.8.8)
+project (opustags)
 set(CMAKE_CXX_STANDARD 14)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_STANDARD_REQUIRED on)
+set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/modules/")
+set(CMAKE_SOURCE_DIR "${CMAKE_BINARY_DIR}/../")
 
-find_package(PkgConfig REQUIRED)
-pkg_check_modules(OGG REQUIRED ogg)
-add_compile_options(${OGG_CFLAGS})
+# ------------
+# Dependencies
+# ------------
+find_package(Ogg REQUIRED)
+include_directories(${Ogg_INCLUDE_DIR})
+link_directories(${Ogg_LIBRARY_DIRS})
 
-configure_file(src/config.h.in config.h @ONLY)
-include_directories(BEFORE src "${CMAKE_BINARY_DIR}")
+# --------------------
+# Global build options
+# --------------------
+if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX)
+    set(CMAKE_CXX_FLAGS "${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()
 
-add_library(
-	libopustags
-	OBJECT
-	src/cli.cc
-	src/ogg.cc
-	src/opus.cc
-)
-target_link_libraries(libopustags PUBLIC ${OGG_LIBRARIES})
+# -------
+# Version
+# -------
+execute_process(COMMAND git describe --tags --abbrev=0 OUTPUT_VARIABLE VERSION_SHORT OUTPUT_STRIP_TRAILING_WHITESPACE)
+execute_process(COMMAND git describe --always --dirty --long --tags OUTPUT_VARIABLE VERSION_LONG OUTPUT_STRIP_TRAILING_WHITESPACE)
+if("${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)
 
-add_executable(opustags src/opustags.cc)
-target_link_libraries(opustags libopustags)
+# ------------
+# 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(GNUInstallDirs)
-install(TARGETS opustags DESTINATION "${CMAKE_INSTALL_BINDIR}")
-configure_file(opustags.1 . @ONLY)
-install(FILES "${CMAKE_BINARY_DIR}/opustags.1" DESTINATION "${CMAKE_INSTALL_MANDIR}/man1")
+# -------------------
+# 3rd party libraries
+# -------------------
+# Catch
+set(CATCH_PATH "${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()
 
-add_subdirectory(t)
+# ------------
+# 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" )
+
+# -------------------
+# 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

@@ -1,59 +0,0 @@
-# Contributing to opustags
-
-opustags is slowing getting more mature, and contributions 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.
-
-## 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++14 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.
-
-The next release will focus on correctness, with the following technical
-objectives:
-
-1. Validate the comments: field name in ASCII and value in UTF-8.
-2. Allow selecting the stream to edit, instead of assuming the Ogg contains only
-   one Opus stream.
-3. Provide an --escape option for escaping the newlines inside comment strings.
-4. Take into account the system's encoding: the tags must always be stored as
-   UTF-8, and converted from and to the console encoding when reading input or
-   printing.
-5. Maybe provide a --binary option to dump the raw OpusTags packet, that can be
-   combined to --set-all to read it back.

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2013-2018, Frédéric Mangano-Tarumi
+Copyright (c) 2013, Frédéric Mangano
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without modification,

README.md

@@ -3,63 +3,43 @@ opustags
 
 View and edit Opus comments.
 
-The current code quality of this project is getting better, and is suitable for reliably editing any
-Opus file provided it does not contain other multiplexed streams. Only UTF-8 is currently supported.
-
-Until opustags becomes top-quality software, if it ever does, you might want to
-check out these more mature tag editors:
-
-- [EasyTAG](https://wiki.gnome.org/Apps/EasyTAG)
-- [Beets](http://beets.io/)
-- [Picard](https://picard.musicbrainz.org/)
-- [puddletag](http://docs.puddletag.net/)
-- [Quod Libet](https://quodlibet.readthedocs.io/en/latest/)
-- [Goggles Music Manager](https://gogglesmm.github.io/)
-
-See also these libraries if you need a lower-level access:
-
-- [TagLib](http://taglib.org/)
-- [mutagen](https://mutagen.readthedocs.io/en/latest/)
-
 Requirements
 ------------
 
-* a C++14 compiler,
-* CMake,
-* a POSIX-compliant system,
-* libogg.
+* 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 FILE -o FILE
+           opustags [OPTIONS] INPUT
+           opustags [OPTIONS] -o OUTPUT INPUT
 
     Options:
       -h, --help              print this help
-      -o, --output FILE       set the output file
-      -i, --in-place          overwrite the input file instead of writing a different output file
+      -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
-      -a, --add FIELD=VALUE   add a comment
-      -d, --delete FIELD      delete all previously existing comments of a specific type
-      -D, --delete-all        delete all the previously existing comments
-      -s, --set FIELD=VALUE   replace a comment (shorthand for --delete FIELD --add FIELD=VALUE)
-      -S, --set-all           replace all the comments with the ones read from standard input
+          --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

@@ -1,116 +0,0 @@
-.TH opustags 1 "November 2018" "@PROJECT_NAME@ @PROJECT_VERSION@"
-.SH NAME
-opustags \- Opus comment editor
-.SH SYNOPSIS
-.B opustags --help
-.br
-.B opustags
-.RI [ OPTIONS ]
-.I INPUT
-.br
-.B opustags
-.I OPTIONS
-.B -o
-.I OUTPUT INPUT
-.SH DESCRIPTION
-.PP
-\fBopustags\fP can read and edit the comment header of an Opus file.
-It basically has two modes: read-only, and read-write for tag edition.
-.PP
-In read-only mode, only the beginning of \fIINPUT\fP is read, and the tags are
-printed on standard output.
-\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 edition mode, you need to specify an output file (or \fB-\fP for standard output). It must be
-different from the input file. To overwrite the input file, use \fB--in-place\fP.
-.PP
-Tag edition 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
-\fBWarning:\fP the Opus format specifications requires tags to be encoded in
-\fBUTF-8\fP. This tool ignores the system locale, assuming the encoding is
-set to UTF-8, and assume that tags are already encoded in UTF-8.
-.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\fR[=\fP\fISUFFIX\fP\fR]\fP
-Use this when you want to modify the input file in-place. opustags will create a temporary output
-file with the specified suffix (.otmp by default), and move it to the location of the input file on
-success. If a file with the same name as the temporary file already exists, it will be overwritten
-without warning.
-This option conflicts with \fB--output\fP.
-.TP
-.B \-y, \-\-overwrite
-By default, \fBopustags\fP 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. They may be several one of them, though usually
-there is only one of each type.
-.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.
-Invalid lines are skipped and cause a warning to be issued. Blank lines are ignored.
-This mode could be useful for batch processing tags through an utility like \fBsed\fP.
-.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
-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
-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
-.SH SEE ALSO
-.BR vorbiscomment (1),
-.BR sed (1)
-.SH AUTHOR
-Frédéric Mangano-Tarumi <fmang@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/cli.cc

@@ -1,331 +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.
- *
- * \todo Use a safer temporary file name for in-place editing, like tmpnam.
- * \todo Abort editing with --set-all if one comment is invalid?
- */
-
-#include <config.h>
-#include <opustags.h>
-
-#include <getopt.h>
-#include <limits.h>
-#include <string.h>
-#include <unistd.h>
-
-static const char* version = PROJECT_NAME " version " PROJECT_VERSION "\n";
-
-static const char* usage = 1 + R"raw(
-Usage: opustags --help
-       opustags [OPTIONS] FILE
-       opustags OPTIONS FILE -o FILE
-)raw";
-
-static const char* help = 1 + R"raw(
-Options:
-  -h, --help              print this help
-  -o, --output FILE       set the output file
-  -i, --in-place          overwrite the input file instead of writing a different output file
-  -y, --overwrite         overwrite the output file if it already exists
-  -a, --add FIELD=VALUE   add a comment
-  -d, --delete FIELD      delete all previously existing comments of a specific type
-  -D, --delete-all        delete all the previously existing comments
-  -s, --set FIELD=VALUE   replace a comment (shorthand for --delete FIELD --add FIELD=VALUE)
-  -S, --set-all           replace all the comments with the ones read from standard input
-)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'},
-	{NULL, 0, 0, 0}
-};
-
-ot::status ot::process_options(int argc, char** argv, ot::options& opt)
-{
-	if (argc == 1) {
-		fputs(version, stdout);
-		fputs(usage, stdout);
-		return st::exit_now;
-	}
-	int c;
-	while ((c = getopt_long(argc, argv, "ho:i::yd:a:s:DS", getopt_options, NULL)) != -1) {
-		switch (c) {
-		case 'h':
-			opt.print_help = true;
-			break;
-		case 'o':
-			opt.path_out = optarg;
-			if (opt.path_out.empty()) {
-				fputs("output's file path cannot be empty\n", stderr);
-				return st::bad_arguments;
-			}
-			break;
-		case 'i':
-			opt.inplace = optarg == nullptr ? ".otmp" : optarg;
-			if (strcmp(opt.inplace, "") == 0) {
-				fputs("the in-place suffix cannot be empty\n", stderr);
-				return st::bad_arguments;
-			}
-			break;
-		case 'y':
-			opt.overwrite = true;
-			break;
-		case 'd':
-			if (strchr(optarg, '=') != nullptr) {
-				fprintf(stderr, "invalid field name: '%s'\n", optarg);
-				return st::bad_arguments;
-			}
-			opt.to_delete.emplace_back(optarg);
-			break;
-		case 'a':
-		case 's':
-			if (strchr(optarg, '=') == NULL) {
-				fprintf(stderr, "invalid comment: '%s'\n", optarg);
-				return st::bad_arguments;
-			}
-			opt.to_add.emplace_back(optarg);
-			if (c == 's')
-				opt.to_delete.emplace_back(optarg);
-			break;
-		case 'S':
-			opt.set_all = true;
-			/* fall through */
-		case 'D':
-			opt.delete_all = true;
-			break;
-		default:
-			/* getopt printed a message */
-			return st::bad_arguments;
-		}
-	}
-	if (opt.print_help) {
-		puts(version);
-		puts(usage);
-		puts(help);
-		puts("See the man page for extensive documentation.");
-		return st::exit_now;
-	}
-	if (optind != argc - 1) {
-		fputs("exactly one input file must be specified\n", stderr);
-		return st::bad_arguments;
-	}
-	opt.path_in = argv[optind];
-	if (opt.path_in.empty()) {
-		fputs("input's file path cannot be empty\n", stderr);
-		return st::bad_arguments;
-	}
-	if (opt.inplace != nullptr) {
-		if (!opt.path_out.empty()) {
-			fputs("cannot combine --in-place and --output\n", stderr);
-			return st::bad_arguments;
-		}
-		opt.path_out = opt.path_in + opt.inplace;
-	}
-	if (opt.path_in == "-" && opt.set_all) {
-		fputs("can't open standard input for input when --set-all is specified\n", stderr);
-		return st::bad_arguments;
-	}
-	if (opt.path_in == "-" && opt.inplace) {
-		fputs("cannot modify standard input in-place\n", stderr);
-		return st::bad_arguments;
-	}
-	return st::ok;
-}
-
-/**
- * \todo Escape new lines.
- */
-void ot::print_comments(const std::list<std::string>& comments, FILE* output)
-{
-	for (const std::string& comment : comments) {
-		fwrite(comment.data(), 1, comment.size(), output);
-		puts("");
-	}
-}
-
-std::list<std::string> ot::read_comments(FILE* input)
-{
-	std::list<std::string> comments;
-	char* line = nullptr;
-	size_t buflen = 0;
-	ssize_t nread;
-	while ((nread = getline(&line, &buflen, input)) != -1) {
-		if (nread > 0 && line[nread - 1] == '\n')
-			--nread;
-		if (nread == 0)
-			continue;
-		if (memchr(line, '=', nread) == nullptr) {
-			fputs("warning: skipping malformed tag\n", stderr);
-			continue;
-		}
-		comments.emplace_back(line, nread);
-	}
-	free(line);
-	return comments;
-}
-
-/**
- * Parse the packet as an OpusTags comment header, apply the user's modifications, and write the new
- * packet to the writer.
- */
-static ot::status process_tags(const ogg_packet& packet, const ot::options& opt, ot::ogg_writer* writer)
-{
-	ot::opus_tags tags;
-	ot::status rc = ot::parse_tags(packet, tags);
-	if (rc != ot::st::ok)
-		return rc;
-
-	if (opt.delete_all) {
-		tags.comments.clear();
-	} else {
-		for (const std::string& name : opt.to_delete)
-			ot::delete_comments(tags, name.c_str());
-	}
-
-	if (opt.set_all)
-		tags.comments = ot::read_comments(stdin);
-	for (const std::string& comment : opt.to_add)
-		tags.comments.emplace_back(comment);
-
-	if (writer) {
-		auto packet = ot::render_tags(tags);
-		return writer->write_packet(packet);
-	} else {
-		ot::print_comments(tags.comments, stdout);
-		return ot::st::ok;
-	}
-}
-
-ot::status ot::process(ogg_reader& reader, ogg_writer* writer, const ot::options &opt)
-{
-	int packet_count = 0;
-	for (;;) {
-		// Read the next page.
-		ot::status rc = reader.read_page();
-		if (rc == ot::st::end_of_stream)
-			break;
-		else if (rc != ot::st::ok)
-			return rc;
-		// Short-circuit when the relevant packets have been read.
-		if (packet_count >= 2 && writer) {
-			if ((rc = writer->write_page(reader.page)) != ot::st::ok)
-				return rc;
-			continue;
-		}
-		auto serialno = ogg_page_serialno(&reader.page);
-		if (writer && (rc = writer->prepare_stream(serialno)) != ot::st::ok)
-			return rc;
-		// Read all the packets.
-		for (;;) {
-			rc = reader.read_packet();
-			if (rc == ot::st::end_of_page)
-				break;
-			else if (rc != ot::st::ok)
-				return rc;
-			packet_count++;
-			if (packet_count == 1) { // Identification header
-				rc = ot::validate_identification_header(reader.packet);
-				if (rc != ot::st::ok)
-					return rc;
-			} else if (packet_count == 2) { // Comment header
-				rc = process_tags(reader.packet, opt, writer);
-				if (rc != ot::st::ok)
-					return rc;
-				if (!writer)
-					return ot::st::ok; /* nothing else to do */
-				else
-					continue; /* process_tags wrote the new packet */
-			}
-			if (writer && (rc = writer->write_packet(reader.packet)) != ot::st::ok)
-				return rc;
-		}
-		// Write the assembled page.
-		if (writer && (rc = writer->flush_page()) != ot::st::ok)
-			return rc;
-	}
-	if (packet_count < 2)
-		return {ot::st::fatal_error, "Expected at least 2 Ogg packets"};
-	return ot::st::ok;
-}
-
-/**
- * Check if two filepaths point to the same file, after path canonicalization.
- * The path "-" is treated specially, meaning stdin for path_in and stdout for path_out.
- */
-static bool same_file(const std::string& path_in, const std::string& path_out)
-{
-	if (path_in == "-" || path_out == "-")
-		return false;
-	char canon_in[PATH_MAX+1], canon_out[PATH_MAX+1];
-	if (realpath(path_in.c_str(), canon_in) && realpath(path_out.c_str(), canon_out)) {
-		return (strcmp(canon_in, canon_out) == 0);
-	}
-	return false;
-}
-
-ot::status ot::run(ot::options& opt)
-{
-	if (!opt.path_out.empty() && same_file(opt.path_in, opt.path_out))
-		return {ot::st::fatal_error, "Input and output files are the same"};
-
-	ot::file input;
-	if (opt.path_in == "-") {
-		input = stdin;
-	} else {
-		input = fopen(opt.path_in.c_str(), "r");
-		if (input == nullptr)
-			return {ot::st::standard_error,
-			        "Could not open '" + opt.path_in + "' for reading: " + strerror(errno)};
-	}
-
-	ot::file output;
-	if (opt.path_out == "-") {
-		output.reset(stdout);
-	} else if (!opt.path_out.empty()) {
-		if (!opt.overwrite && access(opt.path_out.c_str(), F_OK) == 0)
-			return {ot::st::fatal_error,
-			        "'" + opt.path_out + "' already exists (use -y to overwrite)"};
-		output = fopen(opt.path_out.c_str(), "w");
-		if (output == nullptr)
-			return {ot::st::standard_error,
-				"Could not open '" + opt.path_out + "' for writing: " + strerror(errno)};
-	}
-
-	ot::status rc;
-	{
-		ot::ogg_reader reader(input.get());
-		std::unique_ptr<ot::ogg_writer> writer;
-		if (output != nullptr)
-			writer = std::make_unique<ot::ogg_writer>(output.get());
-		rc = process(reader, writer.get(), opt);
-		/* delete reader and writer before closing the files */
-	}
-
-	input.reset();
-	output.reset();
-
-	if (rc != ot::st::ok) {
-		if (!opt.path_out.empty() && opt.path_out != "-")
-			remove(opt.path_out.c_str());
-		return rc;
-	}
-
-	if (opt.inplace) {
-		if (rename(opt.path_out.c_str(), opt.path_in.c_str()) == -1)
-			return {ot::st::fatal_error,
-			        "Could not move the result to '" + opt.path_in + "': " + strerror(errno)};
-	}
-
-	return ot::st::ok;
-}

src/config.h.in

@@ -1,2 +0,0 @@
-#cmakedefine PROJECT_NAME "@PROJECT_NAME@"
-#cmakedefine PROJECT_VERSION "@PROJECT_VERSION@"

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

@@ -1,124 +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 <string.h>
+using namespace opustags;
 
-using namespace std::literals::string_literals;
+////////////////////////////////////////////////////////////////////////////////
+// ogg::Stream
 
-ot::ogg_reader::ogg_reader(FILE* input)
-	: file(input)
+ogg::Stream::Stream(int streamno)
 {
-	ogg_sync_init(&sync);
+    state = ogg::BEGIN_OF_STREAM;
+    type = ogg::UNKNOWN_STREAM;
+    if (ogg_stream_init(&stream, streamno) != 0)
+        throw std::runtime_error("ogg_stream_init failed");
 }
 
-ot::ogg_reader::~ogg_reader()
+ogg::Stream::~Stream()
 {
-	if (stream_ready)
-		ogg_stream_clear(&stream);
-	ogg_sync_clear(&sync);
+    ogg_stream_clear(&stream);
 }
 
-ot::status ot::ogg_reader::read_page()
+void ogg::Stream::flush_packets()
 {
-	while (ogg_sync_pageout(&sync, &page) != 1) {
-		if (feof(file))
-			return {st::end_of_stream, "End of stream was reached"};
-		char* buf = ogg_sync_buffer(&sync, 65536);
-		if (buf == nullptr)
-			return {st::libogg_error, "ogg_sync_buffer failed"};
-		size_t len = fread(buf, 1, 65536, file);
-		if (ferror(file))
-			return {st::standard_error, "fread error: "s + strerror(errno)};
-		if (ogg_sync_wrote(&sync, len) != 0)
-			return {st::libogg_error, "ogg_sync_wrote failed"};
-		if (ogg_sync_check(&sync) != 0)
-			return {st::libogg_error, "ogg_sync_check failed"};
-	}
-	/* at this point, we've got a good page */
-	if (!stream_ready) {
-		if (ogg_stream_init(&stream, ogg_page_serialno(&page)) != 0)
-			return {st::libogg_error, "ogg_stream_init failed"};
-		stream_ready = true;
-	}
-	stream_in_sync = false;
-	return st::ok;
+    ogg_packet op;
+    while (ogg_stream_packetout(&stream, &op) > 0);
 }
 
-ot::status ot::ogg_reader::read_packet()
+bool ogg::Stream::page_in(ogg_page &og)
 {
-	if (!stream_ready)
-		return {st::stream_not_ready, "Stream was not initialized"};
-	if (!stream_in_sync) {
-		if (ogg_stream_pagein(&stream, &page) != 0)
-			return {st::libogg_error, "ogg_stream_pagein failed"};
-		stream_in_sync = true;
-	}
-	int rc = ogg_stream_packetout(&stream, &packet);
-	if (rc == 1)
-		return st::ok;
-	else if (rc == 0 && ogg_stream_check(&stream) == 0)
-		return {st::end_of_page, "End of page was reached"};
-	else
-		return {st::libogg_error, "ogg_stream_packetout failed"};
+    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");
+
+    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;
+    }
 }
 
-ot::ogg_writer::ogg_writer(FILE* output)
-	: file(output)
+// Read the first packet of the page and parses it.
+bool ogg::Stream::handle_page()
 {
-	if (ogg_stream_init(&stream, 0) != 0)
-		throw std::bad_alloc();
+    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;
 }
 
-ot::ogg_writer::~ogg_writer()
+void ogg::Stream::handle_packet(const ogg_packet &op)
 {
-	ogg_stream_clear(&stream);
+    if (state == ogg::BEGIN_OF_STREAM)
+        parse_header(op);
+    else if (state == ogg::HEADER_READY)
+        parse_opustags(op);
+    // else shrug
 }
 
-ot::status ot::ogg_writer::write_page(const ogg_page& page)
+void ogg::Stream::parse_header(const ogg_packet &op)
 {
-	if (page.header_len < 0 || page.body_len < 0)
-		return {st::int_overflow, "Overflowing page length"};
-	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)
-		return {st::standard_error, "fwrite error: "s + strerror(errno)};
-	if (fwrite(page.body, 1, body_len, file) < body_len)
-		return {st::standard_error, "fwrite error: "s + strerror(errno)};
-	return st::ok;
+    if (op.bytes >= 8 && memcmp(op.packet, "OpusHead", 8) == 0)
+        type = OPUS_STREAM;
+    else
+        type = UNKNOWN_STREAM;
+    state = HEADER_READY;
 }
 
-ot::status ot::ogg_writer::prepare_stream(long serialno)
+// For reference:
+// https://tools.ietf.org/html/draft-ietf-codec-oggopus-14#section-5.2
+void ogg::Stream::parse_opustags(const ogg_packet &op)
 {
-	if (stream.serialno != serialno) {
-		if (ogg_stream_reset_serialno(&stream, serialno) != 0)
-			return {st::libogg_error, "ogg_stream_reset_serialno failed"};
-	}
-	return st::ok;
+    // 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;
 }
 
-ot::status ot::ogg_writer::write_packet(const ogg_packet& packet)
+void ogg::Stream::downgrade()
 {
-	if (ogg_stream_packetin(&stream, const_cast<ogg_packet*>(&packet)) != 0)
-		return {st::libogg_error, "ogg_stream_packetin failed"};
-	else
-		return st::ok;
+    type = ogg::UNKNOWN_STREAM;
+    if (state != ogg::BEGIN_OF_STREAM && state != ogg::END_OF_STREAM)
+        state = RAW_READY;
 }
 
-ot::status ot::ogg_writer::flush_page()
+////////////////////////////////////////////////////////////////////////////////
+// ogg::Decoder
+
+ogg::Decoder::Decoder(std::istream &in)
+    : input(in)
 {
-	ogg_page page;
-	if (ogg_stream_flush(&stream, &page) != 0)
-		return write_page(page);
-	if (ogg_stream_check(&stream) != 0)
-		return {st::libogg_error, "ogg_stream_check failed"};
-	return st::ok; /* nothing was done */
+    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

@@ -1,163 +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 7584](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.
- * \todo Field names are case insensitive, respect that.
- *
- */
-
-#include <opustags.h>
-
-#include <string.h>
-
-#ifdef __APPLE__
-#include <libkern/OSByteOrder.h>
-#define htole32(x) OSSwapHostToLittleInt32(x)
-#define le32toh(x) OSSwapLittleToHostInt32(x)
-#endif
-
-/**
- * \todo Validate more properties of the packet, like the sequence number.
- */
-ot::status ot::validate_identification_header(const ogg_packet& packet)
-{
-	if (packet.bytes < 8)
-		return {ot::st::cut_magic_number,
-		        "Identification header too short for the magic number"};
-	if (memcmp(packet.packet, "OpusHead", 8) != 0)
-		return {ot::st::bad_magic_number,
-		        "Identification header did not start with OpusHead"};
-	return ot::st::ok;
-}
-
-/**
- * \todo See if the packet's data could be casted more nicely into a string.
- */
-ot::status ot::parse_tags(const ogg_packet& packet, opus_tags& tags)
-{
-	if (packet.bytes < 0)
-		return {st::int_overflow, "Overflowing comment header length"};
-	size_t size = static_cast<size_t>(packet.bytes);
-	const char* data = reinterpret_cast<char*>(packet.packet);
-	size_t pos = 0;
-	opus_tags my_tags;
-
-	// Magic number
-	if (8 > size)
-		return {st::cut_magic_number, "Comment header too short for the magic number"};
-	if (memcmp(data, "OpusTags", 8) != 0)
-		return {st::bad_magic_number, "Comment header did not start with OpusTags"};
-
-	// Vendor
-	pos = 8;
-	if (pos + 4 > size)
-		return {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)
-		return {st::cut_vendor_data, "Vendor string did not fit the comment header"};
-	my_tags.vendor = std::string(data + pos + 4, vendor_length);
-	pos += 4 + my_tags.vendor.size();
-
-	// Comment count
-	if (pos + 4 > size)
-		return {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)
-			return {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)
-			return {st::cut_comment_data,
-			        "Comment string did not fit the comment header"};
-		const char *comment_value = data + pos + 4;
-		my_tags.comments.emplace_back(comment_value, comment_length);
-		pos += 4 + comment_length;
-	}
-
-	// Extra data
-	my_tags.extra_data = std::string(data + pos, size - pos);
-
-	tags = std::move(my_tags);
-	return st::ok;
-}
-
-ot::dynamic_ogg_packet ot::render_tags(const opus_tags& tags)
-{
-	size_t size = 8 + 4 + tags.vendor.size() + 4;
-	for (const std::string& 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::string& 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;
-}
-
-/**
- * \todo Make the field name case-insensitive?
- */
-static int match_field(const char *comment, uint32_t len, const char *field)
-{
-	size_t field_len;
-	for (field_len = 0; field[field_len] != '\0' && field[field_len] != '='; field_len++);
-	if (len <= field_len)
-		return 0;
-	if (comment[field_len] != '=')
-		return 0;
-	if (strncmp(comment, field, field_len) != 0)
-		return 0;
-	return 1;
-}
-
-void ot::delete_comments(opus_tags& tags, const char* field_name)
-{
-	auto it = tags.comments.begin(), end = tags.comments.end();
-	while (it != end) {
-		auto current = it++;
-		if (match_field(current->data(), current->size(), field_name))
-			tags.comments.erase(current);
-	}
-}

src/opustags.cc

@@ -1,35 +0,0 @@
-/**
- * \file src/opustags.cc
- * \brief Main function for opustags.
- *
- * See opustags.h for the program's documentation.
- */
-
-#include <opustags.h>
-
-/**
- * Main entry point to the opustags binary.
- *
- * Does practically nothing but call the cli module.
- */
-int main(int argc, char** argv) {
-	ot::status rc;
-	ot::options opt;
-	rc = process_options(argc, argv, opt);
-	if (rc == ot::st::exit_now) {
-		return EXIT_SUCCESS;
-	} else if (rc != ot::st::ok) {
-		if (!rc.message.empty())
-			fprintf(stderr, "error: %s\n", rc.message.c_str());
-		return EXIT_FAILURE;
-	}
-
-	rc = run(opt);
-	if (rc != ot::st::ok && rc != ot::st::exit_now) {
-		if (!rc.message.empty())
-			fprintf(stderr, "error: %s\n", rc.message.c_str());
-		return EXIT_FAILURE;
-	}
-
-	return EXIT_SUCCESS;
-}

src/opustags.h

@@ -1,475 +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 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 <ogg/ogg.h>
-#include <stdio.h>
-
-#include <list>
-#include <memory>
-#include <string>
-#include <vector>
-
-namespace ot {
-
-/**
- * Possible return status code, ranging from errors to special statuses. They are usually
- * accompanied with a message with the #status structure.
- *
- * Functions that return non-ok status codes to signal special conditions like #end_of_stream should
- * have it explictly mentionned in their documentation. By default, a non-ok status should be
- * handled like an error.
- *
- * 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,
-	int_overflow,
-	standard_error,
-	/* Ogg */
-	end_of_stream,
-	end_of_page,
-	stream_not_ready,
-	libogg_error,
-	/* Opus */
-	bad_magic_number,
-	cut_magic_number,
-	cut_vendor_length,
-	cut_vendor_data,
-	cut_comment_count,
-	cut_comment_length,
-	cut_comment_data,
-	/* CLI */
-	bad_arguments,
-	exit_now, /**< The program should terminate successfully. */
-	fatal_error,
-};
-
-/**
- * Wraps a status code with an optional message. It is implictly converted to and from a
- * #status_code.
- *
- * 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() { return code; }
-	st code;
-	std::string message;
-};
-
-/**
- * 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) {}
-};
-
-/***********************************************************************************************//**
- * \defgroup ogg Ogg
- * \{
- */
-
-/**
- * Ogg reader, combining a FILE input, an ogg_sync_state reading the pages, and an ogg_stream_state
- * extracting the packets from the page.
- *
- * Call #read_page repeatedly until #status::end_of_stream to consume the stream, and use #page to
- * check its content. To extract its packets, call #read_packet until #status::end_of_packet.
- */
-class ogg_reader {
-public:
-	/**
-	 * 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);
-	/**
-	 * 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();
-	/**
-	 * Read the next page from the input file. The result, provided the status is #status::ok,
-	 * is made available in the #page field, is owned by the Ogg reader, and is valid until the
-	 * next call to #read_page.
-	 *
-	 * After the last page was read, return #status::end_of_stream.
-	 */
-	status read_page();
-	/**
-	 * Read the next available packet from the current #page. The packet is made available in
-	 * the #packet field.
-	 *
-	 * No packet can be read until a page has been loaded with #read_page. If that happens,
-	 * return #status::stream_not_ready.
-	 *
-	 * After the last packet was read, return #status::end_of_page.
-	 */
-	status read_packet();
-	/**
-	 * 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;
-	/**
-	 * Current packet from the stream state.
-	 *
-	 * Its memory is managed by libogg, inside the stream state, and is valid until the next
-	 * call to ogg_stream_packetout, wrapped by #read_packet.
-	 */
-	ogg_packet packet;
-private:
-	/**
-	 * 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;
-	/**
-	 * Indicates whether the stream has been initialized or not.
-	 *
-	 * To initialize it properly, we need the serialno of the stream, which is available only
-	 * after the first page was read.
-	 */
-	bool stream_ready = false;
-	/**
-	 * Indicates if the stream's last fed page is the current one.
-	 *
-	 * Its state is irrelevant if the stream is not ready.
-	 */
-	bool stream_in_sync;
-	/**
-	 * The stream layer receives pages and yields a sequence of packets.
-	 *
-	 * A single page may contain several packets, and a single packet may span on multiple
-	 * pages. The 2 packets we're interested in occupy whole pages though, in theory, but we'd
-	 * better ensure there are no extra packets anyway.
-	 *
-	 * After we've read OpusHead and OpusTags, we don't need the stream layer anymore.
-	 */
-	ogg_stream_state stream;
-};
-
-/**
- * An Ogg writer lets you write ogg_page objets to an output file, and assemble packets into pages.
- *
- * It has two modes of operations :
- *   1. call #write_page, or
- *   2. call #prepare_stream, then #write_packet one or more times, followed by #flush_page.
- *
- * You can switch between the two modes, but must not start writing packets and then pages without
- * flushing.
- */
-class ogg_writer {
-public:
-	/**
-	 * Initialize the writer with the given output file handle. The caller is responsible for
-	 * keeping the file handle alive, and to close it.
-	 */
-	ogg_writer(FILE* output);
-	/**
-	 * Clears the stream state and any internal memory. Does not close the output file.
-	 */
-	~ogg_writer();
-	/**
-	 * 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.
-	 */
-	status write_page(const ogg_page& page);
-	/**
-	 * Prepare the stream with the given Ogg serial number.
-	 *
-	 * If the stream is already configured with the right serial number, it doesn't do anything
-	 * and is cheap to call.
-	 *
-	 * If the stream contains unflushed packets, they will be lost.
-	 */
-	status prepare_stream(long serialno);
-	/**
-	 * Add a packet to the current page under assembly.
-	 *
-	 * If the packet is coming from a different page, make sure the serial number fits by
-	 * calling #prepare_stream.
-	 *
-	 * When the page is complete, you should call #flush_page to finalize the page.
-	 *
-	 * You must not call #write_page after it, until you call #flush_page.
-	 */
-	status write_packet(const ogg_packet& packet);
-	/**
-	 * Write the page under assembly. Future calls to #write_packet will be written in a new
-	 * page.
-	 */
-	status flush_page();
-private:
-	/**
-	 * The stream state receives packets and generates pages.
-	 *
-	 * In our specific use case, we only need it to put the OpusHead and OpusTags packets into
-	 * their own pages. The other pages are naively written to the output stream.
-	 */
-	ogg_stream_state stream;
-	/**
-	 * 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;
-};
-
-/**
- * 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;
-};
-
-/** \} */
-
-/***********************************************************************************************//**
- * \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 should be an arbitrary UTF-8 string.
-	 */
-	std::string vendor;
-	/**
-	 * Comments. These are a list of string following the NAME=Value format.  A comment may also
-	 * be called a field, or a tag.
-	 *
-	 * The field name in vorbis comment is 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::string> 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.
-	 */
-	std::string extra_data;
-};
-
-/**
- * Validate the content of the first packet of an Ogg stream to ensure it's a valid OpusHead.
- *
- * Returns #ot::status::ok on success, #ot::status::bad_identification_header on error.
- */
-status validate_identification_header(const ogg_packet& packet);
-
-/**
- * Read the given OpusTags packet and extract its content into an opus_tags object.
- *
- * On error, the tags object is left unchanged.
- */
-status parse_tags(const ogg_packet& packet, opus_tags& tags);
-
-/**
- * Serialize an #opus_tags object into an OpusTags Ogg packet.
- */
-dynamic_ogg_packet render_tags(const opus_tags& tags);
-
-/**
- * Remove all the comments whose field name is equal to the special one, case-sensitive.
- */
-void delete_comments(opus_tags& tags, const char* field_name);
-
-/** \} */
-
-/***********************************************************************************************//**
- * \defgroup cli Command-Line Interface
- * \{
- */
-
-/**
- * Structured representation of the arguments to opustags.
- */
-struct options {
-	/**
-	 * Path to the input file. It cannot be empty. The special "-" string means stdin.
-	 *
-	 * This is the mandatory non-flagged parameter.
-	 */
-	std::string path_in;
-	/**
-	 * Path to the optional file. The special "-" string means stdout. When empty, opustags runs
-	 * in read-only mode.
-	 *
-	 * Option: --output
-	 */
-	std::string path_out;
-	/**
-	 * If null, in-place editing is disabled. Otherwise, it points to the suffix to add to the
-	 * file name.
-	 *
-	 * Option: --in-place
-	 */
-	const char* inplace = nullptr;
-	/**
-	 * List of field names to delete. `{"ARTIST"}` will delete *all* the comments `ARTIST=*`. It
-	 * is currently case-sensitive. When #delete_all is true, it becomes 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.
-	 *
-	 * \todo Consider making it case-insensitive.
-	 * \todo Allow values like `ARTIST=x` to delete only the ARTIST comment whose value is x.
-	 *
-	 * Option: --delete, --set
-	 */
-	std::vector<std::string> to_delete;
-	/**
-	 * 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::vector<std::string> to_add;
-	/**
-	 * Delete all the existing comments.
-	 *
-	 * Option: --delete-all
-	 */
-	bool delete_all = false;
-	/**
-	 * Replace the previous comments by the ones supplied by the user.
-	 *
-	 * Read a list of comments from stdin and populate #to_add. Implies #delete_all. Further
-	 * comments may be added with the --add option.
-	 *
-	 * Option: --set-all
-	 */
-	bool set_all = false;
-	/**
-	 * By default, opustags won't overwrite the output file if it already exists.
-	 *
-	 * Option: --overwrite
-	 */
-	bool overwrite = false;
-	/**
-	 * When true, opustags prints a detailed help and exits. All the other options are ignored.
-	 *
-	 * Option: --help
-	 */
-	bool print_help = false;
-};
-
-/**
- * Process the command-line arguments.
- *
- * This function does not perform I/O related validations, but checks the consistency of its
- * arguments.
- *
- * It returns one of :
- * - #ot::st::ok, meaning the process may continue normally.
- * - #ot::st::exit_now, meaning there is nothing to do and process should exit successfully.
- *   This happens when all the user wants is see the help or usage.
- * - #ot::st::bad_arguments, meaning the arguments were invalid and the process should exit with
- *   an error.
- *
- * Help messages are written on standard output, and error messages on standard error.
- */
-status process_options(int argc, char** argv, options& opt);
-
-/**
- * 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 output generated is meant to be parseable by #ot::read_tags.
- */
-void print_comments(const std::list<std::string>& comments, FILE* output);
-
-/**
- * Parse the comments outputted by #ot::print_comments.
- */
-std::list<std::string> read_comments(FILE* input);
-
-/**
- * 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.
- */
-status process(ogg_reader& reader, ogg_writer* writer, const options &opt);
-
-/**
- * Open the input and output streams, then call #ot::process.
- *
- * This is the main entry point to the opustags program, and pretty much the same as calling
- * opustags from the command-line.
- */
-status run(options& opt);
-
-/** \} */
-
-}

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

@@ -1,16 +0,0 @@
-add_executable(opus.t EXCLUDE_FROM_ALL opus.cc)
-target_link_libraries(opus.t libopustags)
-
-add_executable(ogg.t EXCLUDE_FROM_ALL ogg.cc)
-target_link_libraries(ogg.t libopustags)
-
-add_executable(cli.t EXCLUDE_FROM_ALL cli.cc)
-target_link_libraries(cli.t libopustags)
-
-configure_file(gobble.opus . COPYONLY)
-
-add_custom_target(
-	check
-	COMMAND prove "${CMAKE_CURRENT_SOURCE_DIR}" "${CMAKE_CURRENT_BINARY_DIR}"
-	DEPENDS opustags gobble.opus opus.t ogg.t cli.t
-)

t/cli.cc

@@ -1,26 +0,0 @@
-#include <opustags.h>
-#include "tap.h"
-
-#include <string.h>
-
-const char *user_comments = R"raw(
-TITLE=a b c
-
-ARTIST=X
-Artist=Y)raw";
-
-void check_read_comments()
-{
-	ot::file input = fmemopen(const_cast<char*>(user_comments), strlen(user_comments), "r");
-	auto comments = ot::read_comments(input.get());
-	auto&& expected = {"TITLE=a b c", "ARTIST=X", "Artist=Y"};
-	if (!std::equal(comments.begin(), comments.end(), expected.begin(), expected.end()))
-		throw failure("parsed user comments did not match expectations");
-}
-
-int main(int argc, char **argv)
-{
-	std::cout << "1..1\n";
-	run(check_read_comments, "check tags parsing");
-	return 0;
-}

t/ogg.cc

@@ -1,148 +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());
-
-	ot::status rc = reader.read_page();
-	if (rc != ot::st::ok)
-		throw failure("could not read the first page");
-	rc = reader.read_packet();
-	if (rc != ot::st::ok)
-		throw failure("could not read the first packet");
-	if (reader.packet.bytes != 19)
-		throw failure("unexpected length for the first packet");
-	rc = reader.read_packet();
-	if (rc != ot::st::end_of_page)
-		throw failure("got an unexpected second packet on the first page");
-
-	rc = reader.read_page();
-	if (rc != ot::st::ok)
-		throw failure("could not read the second page");
-	rc = reader.read_packet();
-	if (rc != ot::st::ok)
-		throw failure("could not read the second packet");
-	if (reader.packet.bytes != 62)
-		throw failure("unexpected length for the first packet");
-	rc = reader.read_packet();
-	if (rc != ot::st::end_of_page)
-		throw failure("got an unexpected second packet on the second page");
-
-	while (!ogg_page_eos(&reader.page)) {
-		rc = reader.read_page();
-		if (rc != ot::st::ok)
-			throw failure("failure reading a page");
-	}
-	rc = reader.read_page();
-	if (rc != ot::st::end_of_stream)
-		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()
-{
-	const ogg_packet first_packet  = make_packet("First");
-	const ogg_packet second_packet = make_packet("Second");
-	const ogg_packet third_packet  = make_packet("Third");
-	std::vector<unsigned char> my_ogg(128);
-	size_t my_ogg_size;
-	ot::status rc;
-
-	{
-		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());
-		rc = writer.prepare_stream(1234);
-		if (rc != ot::st::ok)
-			throw failure("could not prepare the stream for the first page");
-		writer.write_packet(first_packet);
-		if (rc != ot::st::ok)
-			throw failure("could not write the first packet");
-		writer.flush_page();
-		if (rc != ot::st::ok)
-			throw failure("could not flush the first page");
-		writer.prepare_stream(1234);
-		if (rc != ot::st::ok)
-			throw failure("could not prepare the stream for the second page");
-		writer.write_packet(second_packet);
-		if (rc != ot::st::ok)
-			throw failure("could not write the second packet");
-		writer.write_packet(third_packet);
-		if (rc != ot::st::ok)
-			throw failure("could not write the third packet");
-		writer.flush_page();
-		if (rc != ot::st::ok)
-			throw failure("could not flush the second page");
-		my_ogg_size = ftell(output.get());
-		if (my_ogg_size != 73)
-			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());
-		rc = reader.read_page();
-		if (rc != ot::st::ok)
-			throw failure("could not read the first page");
-		rc = reader.read_packet();
-		if (rc != ot::st::ok)
-			throw failure("could not read the first packet");
-		if (!same_packet(reader.packet, first_packet))
-			throw failure("unexpected content in the first packet");
-		rc = reader.read_packet();
-		if (rc != ot::st::end_of_page)
-			throw failure("unexpected second packet in the first page");
-		rc = reader.read_page();
-		if (rc != ot::st::ok)
-			throw failure("could not read the second page");
-		rc = reader.read_packet();
-		if (rc != ot::st::ok)
-			throw failure("could not read the second packet");
-		if (!same_packet(reader.packet, second_packet))
-			throw failure("unexpected content in the second packet");
-		rc = reader.read_packet();
-		if (rc != ot::st::ok)
-			throw failure("could not read the third packet");
-		if (!same_packet(reader.packet, third_packet))
-			throw failure("unexpected content in the third packet");
-		rc = reader.read_packet();
-		if (rc != ot::st::end_of_page)
-			throw failure("unexpected third packet in the second page");
-		rc = reader.read_page();
-		if (rc != ot::st::end_of_stream)
-			throw failure("unexpected third page");
-	}
-}
-
-int main(int argc, char **argv)
-{
-	std::cout << "1..2\n";
-	run(check_ref_ogg, "check a reference ogg stream");
-	run(check_memory_ogg, "build and check a fresh stream");
-	return 0;
-}

t/opus.cc

@@ -1,166 +0,0 @@
-#include <opustags.h>
-#include "tap.h"
-
-#include <string.h>
-
-using namespace std::literals::string_literals;
-
-static void check_identification()
-{
-	ogg_packet packet {};
-	packet.packet = (unsigned char*) "OpusHead..";
-	packet.bytes = 10;
-	if (ot::validate_identification_header(packet) != ot::st::ok)
-		throw failure("did not accept a good OpusHead");
-
-	packet.bytes = 7;
-	if (ot::validate_identification_header(packet) != ot::st::cut_magic_number)
-		throw failure("accepted an OpusHead that is too short");
-
-	packet.packet = (unsigned char*) "NotOpusHead";
-	packet.bytes = 11;
-	if (ot::validate_identification_header(packet) != ot::st::bad_magic_number)
-		throw failure("did not report the right status for a bad OpusHead");
-}
-
-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()
-{
-	ot::opus_tags tags;
-	ogg_packet op;
-	op.bytes = sizeof(standard_OpusTags) - 1;
-	op.packet = (unsigned char*) standard_OpusTags;
-	auto rc = ot::parse_tags(op, tags);
-	if (rc != ot::st::ok)
-		throw failure("ot::parse_tags did not return ok");
-	if (tags.vendor != "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 != "TITLE=Foo")
-		throw failure("bad title");
-	++it;
-	if (*it != "ARTIST=Bar")
-		throw failure("bad artist");
-	if (tags.extra_data.size() != 0)
-		throw failure("found mysterious padding data");
-}
-
-/**
- * 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 (ot::parse_tags(op, tags) != ot::st::cut_magic_number)
-		throw failure("did not detect the overflowing magic number");
-	op.bytes = 11;
-	if (ot::parse_tags(op, tags) != ot::st::cut_vendor_length)
-		throw failure("did not detect the overflowing vendor string length");
-	op.bytes = size;
-
-	header_data[0] = 'o';
-	if (ot::parse_tags(op, tags) != 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 (ot::parse_tags(op, tags) != ot::st::cut_vendor_data)
-		throw failure("did not detect the overflowing vendor string");
-	*vendor_length = end - vendor_string - 3;
-	if (ot::parse_tags(op, tags) != ot::st::cut_comment_count)
-		throw failure("did not detect the overflowing comment count");
-	*vendor_length = comment_count - vendor_string;
-
-	++*comment_count;
-	if (ot::parse_tags(op, tags) != ot::st::cut_comment_length)
-		throw failure("did not detect the overflowing comment length");
-	*first_comment_length = end - first_comment_data + 1;
-	if (ot::parse_tags(op, tags) != ot::st::cut_comment_data)
-		throw failure("did not detect the overflowing comment data");
-}
-
-static void recode_standard()
-{
-	ot::opus_tags tags;
-	ogg_packet op;
-	op.bytes = sizeof(standard_OpusTags) - 1;
-	op.packet = (unsigned char*) standard_OpusTags;
-	auto rc = ot::parse_tags(op, tags);
-	if (rc != ot::st::ok)
-		throw failure("ot::parse_tags did not return ok");
-	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()
-{
-	ot::opus_tags tags;
-	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();
-
-	auto rc = ot::parse_tags(op, tags);
-	if (rc != ot::st::ok)
-		throw failure("ot::parse_tags did not return ok");
-	if (tags.extra_data != "\0hello"s)
-		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");
-}
-
-int main()
-{
-	std::cout << "1..5\n";
-	run(check_identification, "check the OpusHead packet");
-	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");
-	return 0;
-}

t/opustags.t

@@ -1,193 +0,0 @@
-#!/usr/bin/env perl
-
-use strict;
-use warnings;
-use utf8;
-
-use Test::More tests => 27;
-
-use Digest::MD5;
-use File::Basename;
-use IPC::Open3;
-use Symbol 'gensym';
-
-my $opustags = '../opustags';
-BAIL_OUT("$opustags does not exist or is not executable") if (! -x $opustags);
-
-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.
-
-my $usage = opustags();
-$usage->[0] =~ /^([^\n]*+)/;
-my $version = $1;
-like($version, qr/^opustags version (\d+\.\d+\.\d+)/, 'get the version string');
-
-is_deeply($usage, [<<"EOF", "", 0], 'no options show the usage');
-$version
-Usage: opustags --help
-       opustags [OPTIONS] FILE
-       opustags OPTIONS FILE -o FILE
-EOF
-
-my $help = <<"EOF";
-$version
-
-Usage: opustags --help
-       opustags [OPTIONS] FILE
-       opustags OPTIONS FILE -o FILE
-
-Options:
-  -h, --help              print this help
-  -o, --output FILE       set the output file
-  -i, --in-place          overwrite the input file instead of writing a different output file
-  -y, --overwrite         overwrite the output file if it already exists
-  -a, --add FIELD=VALUE   add a comment
-  -d, --delete FIELD      delete all previously existing comments of a specific type
-  -D, --delete-all        delete all the previously existing comments
-  -s, --set FIELD=VALUE   replace a comment (shorthand for --delete FIELD --add FIELD=VALUE)
-  -S, --set-all           replace all the comments with the ones read from standard input
-
-See the man page for extensive documentation.
-EOF
-
-is_deeply(opustags('--help'), [$help, '', 0], '--help displays the help message');
-is_deeply(opustags('-h'), [$help, '', 0], '-h displays the help message too');
-
-is_deeply(opustags('--derp'), ['', <<"EOF", 256], 'unrecognized option shows an error');
-$opustags: unrecognized option '--derp'
-EOF
-
-####################################################################################################
-# Test the main features of opustags on an Ogg Opus sample file.
-
-sub md5 {
-	my ($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');
-is_deeply(opustags(qw(gobble.opus -o out.opus)), ['', '', 0], 'copy the file without changes');
-is(md5('out.opus'), '111a483596ac32352fbce4d14d16abd2', 'the copy is faithful');
-
-# 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');
-error: 'out.opus' already exists (use -y to overwrite)
-EOF
-is(md5('out.opus'), 'd41d8cd98f00b204e9800998ecf8427e', 'the output wasn\'t written');
-
-is_deeply(opustags(qw(out.opus -o out.opus)), ['', <<'EOF', 256], 'output and input can\'t be the same');
-error: Input and output files are the same
-EOF
-
-is_deeply(opustags(qw(gobble.opus -o out.opus --overwrite)), ['', '', 0], 'overwrite');
-is(md5('out.opus'), '111a483596ac32352fbce4d14d16abd2', 'successfully overwritten');
-
-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_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)), [<<'EOF', '', 0], 'dry editing');
-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', 256], 'bad tag with --add');
-invalid comment: 'FOO'
-EOF
-is(md5('out.opus'), '66780307a6081523dc9040f3c47b0448', 'the file did not change');
-
-is_deeply(opustags(qw(-i out.opus -s fatal=yes -s FOO -s BAR)), ['', <<'EOF', 256], 'bad tag with --set');
-invalid comment: '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
-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', 0], 'set all with bad tags');
-whatever
-
-# thing
-!
-wrong=yes
-END_IN
-wrong=yes
-END_OUT
-warning: skipping malformed tag
-warning: skipping malformed tag
-warning: skipping malformed tag
-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');

t/tap.h

@@ -1,29 +0,0 @@
-/**
- * \file t/tap.h
- *
- * \brief
- * Helpers for following the Test Anything Protocol.
- */
-
-#pragma once
-
-#include <exception>
-#include <iostream>
-
-class failure : public std::runtime_error {
-public:
-	failure(const char *message) : std::runtime_error(message) {}
-};
-
-template <typename F>
-static void run(F test, const char *name)
-{
-	bool ok = false;
-	try {
-		test();
-		ok = true;
-	} catch (failure& e) {
-		std::cout << "# " << e.what() << "\n";
-	}
-	std::cout << (ok ? "ok" : "not ok") << " - " << name << "\n";
-}

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());
+    }
+}