src/libFLAC/metadata_object.c

   1 /* libFLAC - Free Lossless Audio Codec library
   2  * Copyright (C) 2001,2002  Josh Coalson
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA  02111-1307, USA.
  18  */
  19
  20 #include <stdlib.h>
  21 #include <string.h>
  22
  23 #include "private/metadata.h"
  24
  25 #include "FLAC/assert.h"
  26
  27
  28 /****************************************************************************
  29  *
  30  * Local routines
  31  *
  32  ***************************************************************************/
  33
  34 static FLAC__bool copy_bytes_(FLAC__byte **to, const FLAC__byte *from, unsigned bytes)
  35 {
  36         if(bytes > 0 && 0 != from) {
  37                 FLAC__byte *x;
  38                 if(0 == (x = malloc(bytes)))
  39                         return false;
  40                 memcpy(x, from, bytes);
  41                 *to = x;
  42         }
  43         else {
  44                 FLAC__ASSERT(0 == from);
  45                 FLAC__ASSERT(bytes == 0);
  46                 *to = 0;
  47         }
  48         return true;
  49 }
  50
  51 static FLAC__bool copy_vcentry_(FLAC__StreamMetaData_VorbisComment_Entry *to, const FLAC__StreamMetaData_VorbisComment_Entry *from)
  52 {
  53         to->length = from->length;
  54         if(0 == from->entry) {
  55                 FLAC__ASSERT(from->length == 0);
  56                 to->entry = 0;
  57         }
  58         else {
  59                 FLAC__byte *x;
  60                 FLAC__ASSERT(from->length > 0);
  61                 if(0 == (x = malloc(from->length)))
  62                         return false;
  63                 memcpy(x, from->entry, from->length);
  64                 to->entry = x;
  65         }
  66         return true;
  67 }
  68
  69 static void seektable_calculate_length_(FLAC__StreamMetaData *object)
  70 {
  71         FLAC__ASSERT(0 != object);
  72         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
  73
  74         object->length = object->data.seek_table.num_points * FLAC__STREAM_METADATA_SEEKPOINT_LENGTH;
  75 }
  76
  77 static FLAC__StreamMetaData_SeekPoint *seekpoint_array_new_(unsigned num_points)
  78 {
  79         FLAC__StreamMetaData_SeekPoint *object_array;
  80
  81         FLAC__ASSERT(num_points > 0);
  82
  83         object_array = malloc(num_points * sizeof(FLAC__StreamMetaData_SeekPoint));
  84
  85         if(0 != object_array) {
  86                 unsigned i;
  87                 for(i = 0; i < num_points; i++) {
  88                         object_array[i].sample_number = FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER;
  89                         object_array[i].stream_offset = 0;
  90                         object_array[i].frame_samples = 0;
  91                 }
  92         }
  93
  94         return object_array;
  95 }
  96
  97 static void vorbiscomment_calculate_length_(FLAC__StreamMetaData *object)
  98 {
  99         unsigned i;
 100
 101         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 102
 103         object->length = (FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN) / 8;
 104         object->length += object->data.vorbis_comment.vendor_string.length;
 105         object->length += (FLAC__STREAM_METADATA_VORBIS_COMMENT_NUM_COMMENTS_LEN) / 8;
 106         for(i = 0; i < object->data.vorbis_comment.num_comments; i++) {
 107                 object->length += (FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN / 8);
 108                 object->length += object->data.vorbis_comment.comments[i].length;
 109         }
 110 }
 111
 112 static FLAC__StreamMetaData_VorbisComment_Entry *vorbiscomment_entry_array_new_(unsigned num_comments)
 113 {
 114         FLAC__StreamMetaData_VorbisComment_Entry *object_array;
 115
 116         FLAC__ASSERT(num_comments > 0);
 117
 118         object_array = malloc(num_comments * sizeof(FLAC__StreamMetaData_VorbisComment_Entry));
 119
 120         if(0 != object_array)
 121                 memset(object_array, 0, num_comments * sizeof(FLAC__StreamMetaData_VorbisComment_Entry));
 122
 123         return object_array;
 124 }
 125
 126 static void vorbiscomment_entry_array_delete_(FLAC__StreamMetaData_VorbisComment_Entry *object_array, unsigned num_comments)
 127 {
 128         unsigned i;
 129
 130         FLAC__ASSERT(0 != object_array && num_comments > 0);
 131
 132         for(i = 0; i < num_comments; i++)
 133                 if(0 != object_array[i].entry)
 134                         free(object_array[i].entry);
 135
 136         if(0 != object_array)
 137                 free(object_array);
 138 }
 139
 140 static FLAC__StreamMetaData_VorbisComment_Entry *vorbiscomment_entry_array_copy_(const FLAC__StreamMetaData_VorbisComment_Entry *object_array, unsigned num_comments)
 141 {
 142         FLAC__StreamMetaData_VorbisComment_Entry *return_array;
 143
 144         FLAC__ASSERT(0 != object_array);
 145         FLAC__ASSERT(num_comments > 0);
 146
 147         return_array = vorbiscomment_entry_array_new_(num_comments);
 148
 149         if(0 != return_array) {
 150                 unsigned i;
 151
 152                 /* Need to do this to set the pointers inside the comments to 0.
 153                  * In case of an error in the following loop, the object will be
 154                  * deleted and we don't want the destructor freeing uninitialized
 155                  * pointers.
 156                  */
 157                 memset(return_array, 0, num_comments * sizeof(FLAC__StreamMetaData_VorbisComment_Entry));
 158
 159                 for(i = 0; i < num_comments; i++) {
 160                         if(!copy_vcentry_(return_array+i, object_array+i)) {
 161                                 vorbiscomment_entry_array_delete_(return_array, num_comments);
 162                                 return 0;
 163                         }
 164                 }
 165         }
 166
 167         return return_array;
 168 }
 169
 170 static FLAC__bool vorbiscomment_set_entry_(FLAC__StreamMetaData *object, FLAC__StreamMetaData_VorbisComment_Entry *dest, const FLAC__StreamMetaData_VorbisComment_Entry *src, FLAC__bool copy)
 171 {
 172         FLAC__byte *save;
 173
 174         FLAC__ASSERT(0 != object);
 175         FLAC__ASSERT(0 != dest);
 176         FLAC__ASSERT(0 != src);
 177         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 178         FLAC__ASSERT((0 != src->entry && src->length > 0) || (0 == src->entry && src->length == 0 && copy == false));
 179
 180         save = dest->entry;
 181
 182         /* do the copy first so that if we fail we leave the object untouched */
 183         if(copy) {
 184                 if(!copy_vcentry_(dest, src))
 185                         return false;
 186         }
 187         else {
 188                 *dest = *src;
 189         }
 190
 191         if(0 != save)
 192                 free(save);
 193
 194         vorbiscomment_calculate_length_(object);
 195         return true;
 196 }
 197
 198
 199 /****************************************************************************
 200  *
 201  * Metadata object routines
 202  *
 203  ***************************************************************************/
 204
 205 /*@@@@move
 206 will return pointer to new empty object of type 'type', or 0 if malloc failed
 207 type is valid type
 208 */
 209 FLAC__StreamMetaData *FLAC__metadata_object_new(FLAC__MetaDataType type)
 210 {
 211         FLAC__StreamMetaData *object = malloc(sizeof(FLAC__StreamMetaData));
 212         if(0 != object) {
 213                 memset(object, 0, sizeof(FLAC__StreamMetaData));
 214                 object->is_last = false;
 215                 object->type = type;
 216                 switch(type) {
 217                         case FLAC__METADATA_TYPE_STREAMINFO:
 218                                 object->length = FLAC__STREAM_METADATA_STREAMINFO_LENGTH;
 219                                 break;
 220                         case FLAC__METADATA_TYPE_PADDING:
 221                                 break;
 222                         case FLAC__METADATA_TYPE_APPLICATION:
 223                                 object->length = FLAC__STREAM_METADATA_APPLICATION_ID_LEN / 8;
 224                                 break;
 225                         case FLAC__METADATA_TYPE_SEEKTABLE:
 226                                 break;
 227                         case FLAC__METADATA_TYPE_VORBIS_COMMENT:
 228                                 object->length = (FLAC__STREAM_METADATA_VORBIS_COMMENT_ENTRY_LENGTH_LEN + FLAC__STREAM_METADATA_VORBIS_COMMENT_NUM_COMMENTS_LEN) / 8;
 229                                 break;
 230                         default:
 231                                 /* double protection: */
 232                                 FLAC__ASSERT(0);
 233                                 free(object);
 234                                 return 0;
 235                 }
 236         }
 237
 238         return object;
 239 }
 240
 241 /*@@@@move
 242 return a pointer to a copy of 'object', or 0 if any malloc failed.  does a deep copy.  user gets ownership of object.
 243     FLAC__ASSERT(0 != object);
 244 */
 245 FLAC__StreamMetaData *FLAC__metadata_object_copy(const FLAC__StreamMetaData *object)
 246 {
 247         FLAC__StreamMetaData *to;
 248
 249         FLAC__ASSERT(0 != object);
 250
 251         if(0 != (to = FLAC__metadata_object_new(object->type))) {
 252                 to->is_last = object->is_last;
 253                 to->type = object->type;
 254                 to->length = object->length;
 255                 switch(to->type) {
 256                         case FLAC__METADATA_TYPE_STREAMINFO:
 257                                 memcpy(&to->data.stream_info, &object->data.stream_info, sizeof(FLAC__StreamMetaData_StreamInfo));
 258                                 break;
 259                         case FLAC__METADATA_TYPE_PADDING:
 260                                 break;
 261                         case FLAC__METADATA_TYPE_APPLICATION:
 262                                 memcpy(&to->data.application.id, &object->data.application.id, FLAC__STREAM_METADATA_APPLICATION_ID_LEN / 8);
 263                                 if(!copy_bytes_(&to->data.application.data, object->data.application.data, object->length - FLAC__STREAM_METADATA_APPLICATION_ID_LEN / 8)) {
 264                                         FLAC__metadata_object_delete(to);
 265                                         return 0;
 266                                 }
 267                                 break;
 268                         case FLAC__METADATA_TYPE_SEEKTABLE:
 269                                 to->data.seek_table.num_points = object->data.seek_table.num_points;
 270                                 if(!copy_bytes_((FLAC__byte**)&to->data.seek_table.points, (FLAC__byte*)object->data.seek_table.points, object->data.seek_table.num_points * sizeof(FLAC__StreamMetaData_SeekPoint))) {
 271                                         FLAC__metadata_object_delete(to);
 272                                         return 0;
 273                                 }
 274                                 break;
 275                         case FLAC__METADATA_TYPE_VORBIS_COMMENT:
 276                                 if(!copy_vcentry_(&to->data.vorbis_comment.vendor_string, &object->data.vorbis_comment.vendor_string)) {
 277                                         FLAC__metadata_object_delete(to);
 278                                         return 0;
 279                                 }
 280                                 if(object->data.vorbis_comment.num_comments == 0) {
 281                                         FLAC__ASSERT(0 == object->data.vorbis_comment.comments);
 282                                         to->data.vorbis_comment.comments = 0;
 283                                 }
 284                                 else {
 285                                         FLAC__ASSERT(0 != object->data.vorbis_comment.comments);
 286                                         to->data.vorbis_comment.comments = vorbiscomment_entry_array_copy_(object->data.vorbis_comment.comments, object->data.vorbis_comment.num_comments);
 287                                         if(0 == to->data.vorbis_comment.comments) {
 288                                                 FLAC__metadata_object_delete(to);
 289                                                 return 0;
 290                                         }
 291                                 }
 292                                 to->data.vorbis_comment.num_comments = object->data.vorbis_comment.num_comments;
 293                                 break;
 294                         default:
 295                                 /* double protection: */
 296                                 FLAC__ASSERT(0);
 297                                 free(to);
 298                                 return 0;
 299                 }
 300         }
 301
 302         return to;
 303 }
 304
 305 void FLAC__metadata_object_delete_data(FLAC__StreamMetaData *object)
 306 {
 307         FLAC__ASSERT(0 != object);
 308
 309         switch(object->type) {
 310                 case FLAC__METADATA_TYPE_STREAMINFO:
 311                 case FLAC__METADATA_TYPE_PADDING:
 312                         break;
 313                 case FLAC__METADATA_TYPE_APPLICATION:
 314                         if(0 != object->data.application.data)
 315                                 free(object->data.application.data);
 316                         break;
 317                 case FLAC__METADATA_TYPE_SEEKTABLE:
 318                         if(0 != object->data.seek_table.points)
 319                                 free(object->data.seek_table.points);
 320                         break;
 321                 case FLAC__METADATA_TYPE_VORBIS_COMMENT:
 322                         if(0 != object->data.vorbis_comment.vendor_string.entry)
 323                                 free(object->data.vorbis_comment.vendor_string.entry);
 324                         if(0 != object->data.vorbis_comment.comments) {
 325                                 FLAC__ASSERT(object->data.vorbis_comment.num_comments > 0);
 326                                 vorbiscomment_entry_array_delete_(object->data.vorbis_comment.comments, object->data.vorbis_comment.num_comments);
 327                         }
 328                         break;
 329                 default:
 330                         FLAC__ASSERT(0);
 331         }
 332 }
 333
 334 /*@@@@move
 335 frees 'object'.  does a deep delete.
 336 */
 337 void FLAC__metadata_object_delete(FLAC__StreamMetaData *object)
 338 {
 339         FLAC__metadata_object_delete_data(object);
 340         free(object);
 341 }
 342
 343 /*@@@@move
 344 sets the application data to 'data'.  if 'copy' is true, makes, copy, else takes ownership of pointer.  returns false if copy==true and malloc fails.
 345     FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_APPLICATION);
 346     FLAC__ASSERT((0 != data && length > 0) || (0 == data && length == 0 && copy == false));
 347 */
 348 FLAC__bool FLAC__metadata_object_application_set_data(FLAC__StreamMetaData *object, FLAC__byte *data, unsigned length, FLAC__bool copy)
 349 {
 350         FLAC__byte *save;
 351
 352         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_APPLICATION);
 353         FLAC__ASSERT((0 != data && length > 0) || (0 == data && length == 0 && copy == false));
 354
 355         save = object->data.application.data;
 356
 357         /* do the copy first so that if we fail we leave the object untouched */
 358         if(copy) {
 359                 if(!copy_bytes_(&object->data.application.data, data, length))
 360                         return false;
 361         }
 362         else {
 363                 object->data.application.data = data;
 364         }
 365
 366         if(0 != save)
 367                 free(save);
 368
 369         object->length = FLAC__STREAM_METADATA_APPLICATION_ID_LEN / 8 + length;
 370         return true;
 371 }
 372
 373 FLAC__bool FLAC__metadata_object_seektable_resize_points(FLAC__StreamMetaData *object, unsigned new_num_points)
 374 {
 375         FLAC__ASSERT(0 != object);
 376         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
 377
 378         if(0 == object->data.seek_table.points) {
 379                 FLAC__ASSERT(object->data.seek_table.num_points == 0);
 380                 if(0 == new_num_points)
 381                         return true;
 382                 else if(0 == (object->data.seek_table.points = seekpoint_array_new_(new_num_points)))
 383                         return false;
 384         }
 385         else {
 386                 const unsigned old_size = object->data.seek_table.num_points * sizeof(FLAC__StreamMetaData_SeekPoint);
 387                 const unsigned new_size = new_num_points * sizeof(FLAC__StreamMetaData_SeekPoint);
 388
 389                 FLAC__ASSERT(object->data.seek_table.num_points > 0);
 390
 391                 if(new_size == 0) {
 392                         free(object->data.seek_table.points);
 393                         object->data.seek_table.points = 0;
 394                 }
 395                 else if(0 == (object->data.seek_table.points = realloc(object->data.seek_table.points, new_size)))
 396                         return false;
 397
 398                 /* if growing, set new elements to placeholders */
 399                 if(new_size > old_size) {
 400                         unsigned i;
 401                         for(i = object->data.seek_table.num_points; i < new_num_points; i++) {
 402                                 object->data.seek_table.points[i].sample_number = FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER;
 403                                 object->data.seek_table.points[i].stream_offset = 0;
 404                                 object->data.seek_table.points[i].frame_samples = 0;
 405                         }
 406                 }
 407         }
 408
 409         object->data.seek_table.num_points = new_num_points;
 410
 411         seektable_calculate_length_(object);
 412         return true;
 413 }
 414
 415 void FLAC__metadata_object_seektable_set_point(FLAC__StreamMetaData *object, unsigned point_num, FLAC__StreamMetaData_SeekPoint point)
 416 {
 417         FLAC__ASSERT(0 != object);
 418         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
 419         FLAC__ASSERT(object->data.seek_table.num_points > point_num);
 420
 421         object->data.seek_table.points[point_num] = point;
 422 }
 423
 424 FLAC__bool FLAC__metadata_object_seektable_insert_point(FLAC__StreamMetaData *object, unsigned point_num, FLAC__StreamMetaData_SeekPoint point)
 425 {
 426         int i;
 427
 428         FLAC__ASSERT(0 != object);
 429         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
 430         FLAC__ASSERT(object->data.seek_table.num_points >= point_num);
 431
 432         if(!FLAC__metadata_object_seektable_resize_points(object, object->data.seek_table.num_points+1))
 433                 return false;
 434
 435         /* move all points >= point_num forward one space */
 436         for(i = (int)object->data.seek_table.num_points-1; i > (int)point_num; i--)
 437                 object->data.seek_table.points[i] = object->data.seek_table.points[i-1];
 438
 439         FLAC__metadata_object_seektable_set_point(object, point_num, point);
 440         seektable_calculate_length_(object);
 441         return true;
 442 }
 443
 444 FLAC__bool FLAC__metadata_object_seektable_delete_point(FLAC__StreamMetaData *object, unsigned point_num)
 445 {
 446         unsigned i;
 447
 448         FLAC__ASSERT(0 != object);
 449         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
 450         FLAC__ASSERT(object->data.seek_table.num_points > point_num);
 451
 452         /* move all points > point_num backward one space */
 453         for(i = point_num; i < object->data.seek_table.num_points-1; i++)
 454                 object->data.seek_table.points[i] = object->data.seek_table.points[i+1];
 455
 456         return FLAC__metadata_object_seektable_resize_points(object, object->data.seek_table.num_points-1);
 457 }
 458
 459 FLAC__bool FLAC__metadata_object_seektable_is_legal(const FLAC__StreamMetaData *object)
 460 {
 461         unsigned i;
 462         FLAC__uint64 last_sample_number = 0;
 463         FLAC__bool got_last = false;
 464
 465         FLAC__ASSERT(0 != object);
 466         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_SEEKTABLE);
 467
 468         {
 469                 const FLAC__StreamMetaData_SeekTable *seek_table = &object->data.seek_table;
 470
 471                 for(i = 0; i < seek_table->num_points; i++) {
 472                         if(seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER) {
 473                                 if(got_last) {
 474                                         if(seek_table->points[i].sample_number <= last_sample_number)
 475                                                 return false;
 476                                 }
 477                                 last_sample_number = seek_table->points[i].sample_number;
 478                                 got_last = true;
 479                         }
 480                 }
 481         }
 482
 483         return true;
 484 }
 485
 486 FLAC__bool FLAC__metadata_object_vorbiscomment_set_vendor_string(FLAC__StreamMetaData *object, FLAC__StreamMetaData_VorbisComment_Entry entry, FLAC__bool copy)
 487 {
 488         return vorbiscomment_set_entry_(object, &object->data.vorbis_comment.vendor_string, &entry, copy);
 489 }
 490
 491 FLAC__bool FLAC__metadata_object_vorbiscomment_resize_comments(FLAC__StreamMetaData *object, unsigned new_num_comments)
 492 {
 493         FLAC__ASSERT(0 != object);
 494         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 495
 496         if(0 == object->data.vorbis_comment.comments) {
 497                 FLAC__ASSERT(object->data.vorbis_comment.num_comments == 0);
 498                 if(0 == new_num_comments)
 499                         return true;
 500                 else if(0 == (object->data.vorbis_comment.comments = vorbiscomment_entry_array_new_(new_num_comments)))
 501                         return false;
 502         }
 503         else {
 504                 const unsigned old_size = object->data.vorbis_comment.num_comments * sizeof(FLAC__StreamMetaData_VorbisComment_Entry);
 505                 const unsigned new_size = new_num_comments * sizeof(FLAC__StreamMetaData_VorbisComment_Entry);
 506
 507                 FLAC__ASSERT(object->data.vorbis_comment.num_comments > 0);
 508
 509                 /* if shrinking, free the truncated entries */
 510                 if(new_num_comments < object->data.vorbis_comment.num_comments) {
 511                         unsigned i;
 512                         for(i = new_num_comments; i < object->data.vorbis_comment.num_comments; i++)
 513                                 if(0 != object->data.vorbis_comment.comments[i].entry)
 514                                         free(object->data.vorbis_comment.comments[i].entry);
 515                 }
 516
 517                 if(new_size == 0) {
 518                         free(object->data.vorbis_comment.comments);
 519                         object->data.vorbis_comment.comments = 0;
 520                 }
 521                 else if(0 == (object->data.vorbis_comment.comments = realloc(object->data.vorbis_comment.comments, new_size)))
 522                         return false;
 523
 524                 /* if growing, zero all the length/pointers of new elements */
 525                 if(new_size > old_size)
 526                         memset(object->data.vorbis_comment.comments + object->data.vorbis_comment.num_comments, 0, new_size - old_size);
 527         }
 528
 529         object->data.vorbis_comment.num_comments = new_num_comments;
 530
 531         vorbiscomment_calculate_length_(object);
 532         return true;
 533 }
 534
 535 FLAC__bool FLAC__metadata_object_vorbiscomment_set_comment(FLAC__StreamMetaData *object, unsigned comment_num, FLAC__StreamMetaData_VorbisComment_Entry entry, FLAC__bool copy)
 536 {
 537         return vorbiscomment_set_entry_(object, &object->data.vorbis_comment.comments[comment_num], &entry, copy);
 538 }
 539
 540 FLAC__bool FLAC__metadata_object_vorbiscomment_insert_comment(FLAC__StreamMetaData *object, unsigned comment_num, FLAC__StreamMetaData_VorbisComment_Entry entry, FLAC__bool copy)
 541 {
 542         FLAC__StreamMetaData_VorbisComment *vc;
 543
 544         FLAC__ASSERT(0 != object);
 545         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 546         FLAC__ASSERT(object->data.vorbis_comment.num_comments >= comment_num);
 547
 548         vc = &object->data.vorbis_comment;
 549
 550         if(!FLAC__metadata_object_vorbiscomment_resize_comments(object, vc->num_comments+1))
 551                 return false;
 552
 553         /* move all comments >= comment_num forward one space */
 554         memmove(&vc->comments[comment_num+1], &vc->comments[comment_num], sizeof(FLAC__StreamMetaData_VorbisComment_Entry)*(vc->num_comments-1-comment_num));
 555         vc->comments[comment_num].length = 0;
 556         vc->comments[comment_num].entry = 0;
 557
 558         return FLAC__metadata_object_vorbiscomment_set_comment(object, comment_num, entry, copy);
 559 }
 560
 561 FLAC__bool FLAC__metadata_object_vorbiscomment_delete_comment(FLAC__StreamMetaData *object, unsigned comment_num)
 562 {
 563         FLAC__StreamMetaData_VorbisComment *vc;
 564
 565         FLAC__ASSERT(0 != object);
 566         FLAC__ASSERT(object->type == FLAC__METADATA_TYPE_VORBIS_COMMENT);
 567         FLAC__ASSERT(object->data.vorbis_comment.num_comments > comment_num);
 568
 569         vc = &object->data.vorbis_comment;
 570
 571         /* free the comment at comment_num */
 572         if(0 != vc->comments[comment_num].entry)
 573                 free(vc->comments[comment_num].entry);
 574
 575         /* move all comments > comment_num backward one space */
 576         memmove(&vc->comments[comment_num], &vc->comments[comment_num+1], sizeof(FLAC__StreamMetaData_VorbisComment_Entry)*(vc->num_comments-comment_num-1));
 577         vc->comments[vc->num_comments-1].length = 0;
 578         vc->comments[vc->num_comments-1].entry = 0;
 579
 580         return FLAC__metadata_object_vorbiscomment_resize_comments(object, vc->num_comments-1);
 581 }