in-place

so as not to create empty files

README.md

@@ -3,6 +3,12 @@ opustags
 
 View and edit Opus comments.
 
+Requirements
+------------
+
+* A POSIX-compliant system,
+* libogg.
+
 Installing
 ----------
 

opustags.1

@@ -1,4 +1,4 @@
-.TH opustags 1 "January 1st 2013"
+.TH opustags 1 "January 2013"
 .SH NAME
 opustags \- Opus comment editor
 .SH SYNOPSIS
@@ -26,6 +26,7 @@ This could be useful to preview some changes before writing them.
 As for the edition mode, you need to specify an output file (or \fB-\fP for
 \fBstdout\fP). 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 can be made with the \fB--add\fP, \fB--delete\fP and \fB--set\fP
 options. They can be written in any order and don’t conflict with each other.
@@ -57,6 +58,14 @@ specified output file. If \fIFILE\fP is \fB-\fP then the resulting Opus file
 will be written to \fBstdout\fP. As the input file is read incrementally, 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. This creates a
+temporary file with the specified suffix (.otmp 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 actually
+\fBstdin\fP.
+.TP
 .B \-y, \-\-overwrite
 By default, \fBopustags\fP refuses to overwrite an already existent file. Use
 this option to allow that. Note that this doesn’t allow in-place edition, the
@@ -89,10 +98,9 @@ or \fB--set\fP, which, in that case, are equivalent.
 .B \-S, \-\-set-all
 Sets the tags from scratch. All the original tags are deleted and new ones are
 read from \fBstdin\fP. Each line must specify a \fIFIELD=VALUE\fP pair and be
-LF-terminated. If the last line isn’t terminated when the end of the stream is
-reached, it is ignored. Invalid lines are skipped and cause a warning to be
-issued.  This could be useful for batch processing tags through an utility like
-\fBsed\fP.
+LF-terminated (except for the last line). 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 SEE ALSO
 .BR vorbiscomment (1),
 .BR sed (1)

opustags.c

@@ -156,7 +156,7 @@ int write_page(ogg_page *og, FILE *stream){
     return 0;
 }
 
-const char *version = "opustags version 1.0\n";
+const char *version = "opustags version 1.1\n";
 
 const char *usage =
     "Usage: opustags --help\n"
@@ -167,6 +167,7 @@ const char *help =
     "Options:\n"
     "  -h, --help              print this help\n"
     "  -o, --output            write the modified tags to a 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"
     "  -d, --delete FIELD      delete all the fields of a specified type\n"
     "  -a, --add FIELD=VALUE   add a field\n"
@@ -177,12 +178,14 @@ const char *help =
 struct option 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'}
+    {"set-all", no_argument, 0, 'S'},
+    {NULL, 0, 0, 0}
 };
 
 int main(int argc, char **argv){
@@ -191,7 +194,7 @@ int main(int argc, char **argv){
         fputs(usage, stdout);
         return EXIT_SUCCESS;
     }
-    const char *path_in, *path_out = NULL;
+    char *path_in, *path_out = NULL, *inplace = NULL;
     const char* to_add[argc];
     const char* to_delete[argc];
     int count_add = 0, count_delete = 0;
@@ -200,7 +203,7 @@ int main(int argc, char **argv){
     int overwrite = 0;
     int print_help = 0;
     int c;
-    while((c = getopt_long(argc, argv, "ho:yd:a:s:DS", options, NULL)) != -1){
+    while((c = getopt_long(argc, argv, "ho:i::yd:a:s:DS", options, NULL)) != -1){
         switch(c){
             case 'h':
                 print_help = 1;
@@ -208,6 +211,9 @@ int main(int argc, char **argv){
             case 'o':
                 path_out = optarg;
                 break;
+            case 'i':
+                inplace = optarg == NULL ? ".otmp" : optarg;
+                break;
             case 'y':
                 overwrite = 1;
                 break;
@@ -248,6 +254,10 @@ int main(int argc, char **argv){
         fputs("invalid arguments\n", stderr);
         return EXIT_FAILURE;
     }
+    if(inplace && path_out){
+        fputs("cannot combine --in-place and --output\n", stderr);
+        return EXIT_FAILURE;
+    }
     path_in = argv[optind];
     if(path_out != NULL && strcmp(path_in, "-") != 0){
         char canon_in[PATH_MAX+1], canon_out[PATH_MAX+1];
@@ -258,30 +268,14 @@ int main(int argc, char **argv){
             }
         }
     }
-    FILE *out = NULL;
-    if(path_out != NULL){
-        if(strcmp(path_out, "-") == 0)
-            out = stdout;
-        else{
-            if(!overwrite){
-                if(access(path_out, F_OK) == 0){
-                    fprintf(stderr, "'%s' already exists (use -y to overwrite)\n", path_out);
-                    return EXIT_FAILURE;
-                }
-            }
-            out = fopen(path_out, "w");
-            if(!out){
-                perror("fopen");
-                return EXIT_FAILURE;
-            }
-        }
-    }
     FILE *in;
     if(strcmp(path_in, "-") == 0){
         if(set_all){
             fputs("can't open stdin for input when -S is specified\n", stderr);
-            if(out)
-                fclose(out);
+            return EXIT_FAILURE;
+        }
+        if(inplace){
+            fputs("cannot modify stdin 'in-place'\n", stderr);
             return EXIT_FAILURE;
         }
         in = stdin;
@@ -290,10 +284,40 @@ int main(int argc, char **argv){
         in = fopen(path_in, "r");
     if(!in){
         perror("fopen");
-        if(out)
-            fclose(out);
         return EXIT_FAILURE;
     }
+    FILE *out = NULL;
+    if(inplace != NULL){
+        path_out = malloc(strlen(path_in) + strlen(inplace) + 1);
+        if(path_out == NULL){
+            fputs("failure to allocate memory\n", stderr);
+            fclose(in);
+            return EXIT_FAILURE;
+        }
+        strcpy(path_out, path_in);
+        strcat(path_out, inplace);
+    }
+    if(path_out != NULL){
+        if(strcmp(path_out, "-") == 0)
+            out = stdout;
+        else{
+            if(!overwrite && !inplace){
+                if(access(path_out, F_OK) == 0){
+                    fprintf(stderr, "'%s' already exists (use -y to overwrite)\n", path_out);
+                    fclose(in);
+                    return EXIT_FAILURE;
+                }
+            }
+            out = fopen(path_out, "w");
+            if(!out){
+                perror("fopen");
+                fclose(in);
+                if(inplace)
+                    free(path_out);
+                return EXIT_FAILURE;
+            }
+        }
+    }
     ogg_sync_state oy;
     ogg_stream_state os, enc;
     ogg_page og;
@@ -380,16 +404,19 @@ int main(int argc, char **argv){
                     }
                     else{
                         char *raw_comment[256];
-                        size_t raw_len = fread(raw_tags, 1, 16384, stdin);
-                        if(raw_len == 16384)
+                        size_t raw_len = fread(raw_tags, 1, 16383, stdin);
+                        if(raw_len == 16383)
                             fputs("warning: truncating comment to 16 KiB\n", stderr);
+                        raw_tags[raw_len] = '\0';
                         uint32_t raw_count = 0;
                         size_t field_len = 0;
                         int caught_eq = 0;
                         size_t i = 0;
                         char *cursor = raw_tags;
-                        for(i=0; i<raw_len && raw_count < 256; i++){
-                            if(raw_tags[i] == '\n'){
+                        for(i=0; i <= raw_len && raw_count < 256; i++){
+                            if(raw_tags[i] == '\n' || raw_tags[i] == '\0'){
+                                if(field_len == 0)
+                                    continue;
                                 if(caught_eq)
                                     raw_comment[raw_count++] = cursor;
                                 else
@@ -460,7 +487,19 @@ int main(int argc, char **argv){
         error = "opustags: invalid file";
     if(error){
         fprintf(stderr, "%s\n", error);
+        if(path_out != NULL && out != stdout)
+            remove(path_out);
+        if(inplace)
+            free(path_out);
         return EXIT_FAILURE;
     }
+    else if(inplace){
+        if(rename(path_out, path_in) == -1){
+            perror("rename");
+            free(path_out);
+            return EXIT_FAILURE;
+        }
+        free(path_out);
+    }
     return EXIT_SUCCESS;
 }