vorbiscomment.c : Do not write empty vorbiscomment fields.
[flac.git] / src / flac / vorbiscomment.c
1 /* flac - Command-line FLAC encoder/decoder
2  * Copyright (C) 2002-2009  Josh Coalson
3  * Copyright (C) 2011-2013  Xiph.Org Foundation
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License
7  * as published by the Free Software Foundation; either version 2
8  * of the License, or (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License along
16  * with this program; if not, write to the Free Software Foundation, Inc.,
17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18  */
19
20 #ifdef HAVE_CONFIG_H
21 #  include <config.h>
22 #endif
23
24 #include "vorbiscomment.h"
25 #include "FLAC/assert.h"
26 #include "FLAC/metadata.h"
27 #include "share/grabbag.h" /* for grabbag__file_get_filesize() */
28 #include "share/utf8.h"
29 #include <ctype.h>
30 #include <stdio.h>
31 #include <stdlib.h>
32 #include <string.h>
33 #include "share/compat.h"
34
35
36 /*
37  * This struct and the following 4 static functions are copied from
38  * ../metaflac/.  Maybe someday there will be a convenience
39  * library for Vorbis comment parsing.
40  */
41 typedef struct {
42         char *field; /* the whole field as passed on the command line, i.e. "NAME=VALUE" */
43         char *field_name;
44         /* according to the vorbis spec, field values can contain \0 so simple C strings are not enough here */
45         unsigned field_value_length;
46         char *field_value;
47         FLAC__bool field_value_from_file; /* true if field_value holds a filename for the value, false for plain value */
48 } Argument_VcField;
49
50 static void die(const char *message)
51 {
52         FLAC__ASSERT(0 != message);
53         fprintf(stderr, "ERROR: %s\n", message);
54         exit(1);
55 }
56
57 static char *local_strdup(const char *source)
58 {
59         char *ret;
60         FLAC__ASSERT(0 != source);
61         if(0 == (ret = strdup(source)))
62                 die("out of memory during strdup()");
63         return ret;
64 }
65
66 static FLAC__bool parse_vorbis_comment_field(const char *field_ref, char **field, char **name, char **value, unsigned *length, const char **violation)
67 {
68         static const char * const violations[] = {
69                 "field name contains invalid character",
70                 "field contains no '=' character"
71         };
72
73         char *p, *q, *s;
74
75         if(0 != field)
76                 *field = local_strdup(field_ref);
77
78         s = local_strdup(field_ref);
79
80         if(0 == (p = strchr(s, '='))) {
81                 free(s);
82                 *violation = violations[1];
83                 return false;
84         }
85         *p++ = '\0';
86
87         for(q = s; *q; q++) {
88                 if(*q < 0x20 || *q > 0x7d || *q == 0x3d) {
89                         free(s);
90                         *violation = violations[0];
91                         return false;
92                 }
93         }
94
95         *name = local_strdup(s);
96         *value = local_strdup(p);
97         *length = strlen(p);
98
99         free(s);
100         return true;
101 }
102
103 /* slight modification: no 'filename' arg, and errors are passed back in 'violation' instead of printed to stderr */
104 static FLAC__bool set_vc_field(FLAC__StreamMetadata *block, const Argument_VcField *field, FLAC__bool *needs_write, FLAC__bool raw, const char **violation)
105 {
106         FLAC__StreamMetadata_VorbisComment_Entry entry;
107         char *converted;
108
109         FLAC__ASSERT(0 != block);
110         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
111         FLAC__ASSERT(0 != field);
112         FLAC__ASSERT(0 != needs_write);
113
114         if(field->field_value_from_file) {
115                 /* read the file into 'data' */
116                 FILE *f = 0;
117                 char *data = 0;
118                 const FLAC__off_t size = grabbag__file_get_filesize(field->field_value);
119                 if(size < 0) {
120                         *violation = "can't open file for tag value";
121                         return false;
122                 }
123                 if(size >= 0x100000) { /* magic arbitrary limit, actual format limit is near 16MB */
124                         *violation = "file for tag value is too large";
125                         return false;
126                 }
127                 if(0 == (data = malloc(size+1)))
128                         die("out of memory allocating tag value");
129                 data[size] = '\0';
130                 if(0 == (f = flac_fopen(field->field_value, "rb")) || fread(data, 1, size, f) != (size_t)size) {
131                         free(data);
132                         if(f)
133                                 fclose(f);
134                         *violation = "error while reading file for tag value";
135                         return false;
136                 }
137                 fclose(f);
138                 if(strlen(data) != (size_t)size) {
139                         free(data);
140                         *violation = "file for tag value has embedded NULs";
141                         return false;
142                 }
143
144                 /* move 'data' into 'converted', converting to UTF-8 if necessary */
145                 if(raw) {
146                         converted = data;
147                 }
148                 else if(utf8_encode(data, &converted) >= 0) {
149                         free(data);
150                 }
151                 else {
152                         free(data);
153                         *violation = "error converting file contents to UTF-8 for tag value";
154                         return false;
155                 }
156
157                 /* create and entry and append it */
158                 if(!FLAC__metadata_object_vorbiscomment_entry_from_name_value_pair(&entry, field->field_name, converted)) {
159                         free(converted);
160                         *violation = "file for tag value is not valid UTF-8";
161                         return false;
162                 }
163                 free(converted);
164                 if(!FLAC__metadata_object_vorbiscomment_append_comment(block, entry, /*copy=*/false)) {
165                         *violation = "memory allocation failure";
166                         return false;
167                 }
168
169                 *needs_write = true;
170                 return true;
171         }
172         else {
173                 FLAC__bool needs_free = false;
174 #ifdef _WIN32 /* everything in UTF-8 already. Must not alter */
175                 entry.entry = (FLAC__byte *)field->field;
176 #else
177                 if(raw) {
178                         entry.entry = (FLAC__byte *)field->field;
179                 }
180                 else if(utf8_encode(field->field, &converted) >= 0) {
181                         entry.entry = (FLAC__byte *)converted;
182                         needs_free = true;
183                 }
184                 else {
185                         *violation = "error converting comment to UTF-8";
186                         return false;
187                 }
188 #endif
189                 entry.length = strlen((const char *)entry.entry);
190                 if(!FLAC__format_vorbiscomment_entry_is_legal(entry.entry, entry.length)) {
191                         if(needs_free)
192                                 free(converted);
193                         /*
194                          * our previous parsing has already established that the field
195                          * name is OK, so it must be the field value
196                          */
197                         *violation = "tag value for is not valid UTF-8";
198                         return false;
199                 }
200
201                 if(!FLAC__metadata_object_vorbiscomment_append_comment(block, entry, /*copy=*/true)) {
202                         if(needs_free)
203                                 free(converted);
204                         *violation = "memory allocation failure";
205                         return false;
206                 }
207
208                 *needs_write = true;
209                 if(needs_free)
210                         free(converted);
211                 return true;
212         }
213 }
214
215 /*
216  * The rest of the code is novel
217  */
218
219 static void free_field(Argument_VcField *obj)
220 {
221         if(0 != obj->field)
222                 free(obj->field);
223         if(0 != obj->field_name)
224                 free(obj->field_name);
225         if(0 != obj->field_value)
226                 free(obj->field_value);
227 }
228
229 FLAC__bool flac__vorbiscomment_add(FLAC__StreamMetadata *block, const char *comment, FLAC__bool value_from_file, FLAC__bool raw, const char **violation)
230 {
231         Argument_VcField parsed;
232         FLAC__bool dummy;
233
234         FLAC__ASSERT(0 != block);
235         FLAC__ASSERT(block->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
236         FLAC__ASSERT(0 != comment);
237
238         memset(&parsed, 0, sizeof(parsed));
239
240         parsed.field_value_from_file = value_from_file;
241         if(!parse_vorbis_comment_field(comment, &(parsed.field), &(parsed.field_name), &(parsed.field_value), &(parsed.field_value_length), violation)) {
242                 free_field(&parsed);
243                 return false;
244         }
245
246         if(parsed.field_value_length > 0 && !set_vc_field(block, &parsed, &dummy, raw, violation)) {
247                 free_field(&parsed);
248                 return false;
249         }
250         else {
251                 free_field(&parsed);
252                 return true;
253         }
254 }