cannam@85: /*
cannam@85:  * libid3tag - ID3 tag manipulation library
cannam@85:  * Copyright (C) 2000-2004 Underbit Technologies, Inc.
cannam@85:  *
cannam@85:  * This program is free software; you can redistribute it and/or modify
cannam@85:  * it under the terms of the GNU General Public License as published by
cannam@85:  * the Free Software Foundation; either version 2 of the License, or
cannam@85:  * (at your option) any later version.
cannam@85:  *
cannam@85:  * This program is distributed in the hope that it will be useful,
cannam@85:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
cannam@85:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
cannam@85:  * GNU General Public License for more details.
cannam@85:  *
cannam@85:  * You should have received a copy of the GNU General Public License
cannam@85:  * along with this program; if not, write to the Free Software
cannam@85:  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
cannam@85:  *
cannam@85:  * $Id: frame.c,v 1.15 2004/01/23 09:41:32 rob Exp $
cannam@85:  */
cannam@85: 
cannam@85: # ifdef HAVE_CONFIG_H
cannam@85: #  include "config.h"
cannam@85: # endif
cannam@85: 
cannam@85: # include "global.h"
cannam@85: 
cannam@85: # include <stdlib.h>
cannam@85: # include <string.h>
cannam@85: 
cannam@85: # ifdef HAVE_ASSERT_H
cannam@85: #  include <assert.h>
cannam@85: # endif
cannam@85: 
cannam@85: # include "id3tag.h"
cannam@85: # include "frame.h"
cannam@85: # include "frametype.h"
cannam@85: # include "compat.h"
cannam@85: # include "field.h"
cannam@85: # include "render.h"
cannam@85: # include "parse.h"
cannam@85: # include "util.h"
cannam@85: 
cannam@85: static
cannam@85: int valid_idchar(char c)
cannam@85: {
cannam@85:   return (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9');
cannam@85: }
cannam@85: 
cannam@85: /*
cannam@85:  * NAME:	frame->validid()
cannam@85:  * DESCRIPTION:	return true if the parameter string is a legal frame ID
cannam@85:  */
cannam@85: int id3_frame_validid(char const *id)
cannam@85: {
cannam@85:   return id &&
cannam@85:     valid_idchar(id[0]) &&
cannam@85:     valid_idchar(id[1]) &&
cannam@85:     valid_idchar(id[2]) &&
cannam@85:     valid_idchar(id[3]);
cannam@85: }
cannam@85: 
cannam@85: /*
cannam@85:  * NAME:	frame->new()
cannam@85:  * DESCRIPTION:	allocate and return a new frame
cannam@85:  */
cannam@85: struct id3_frame *id3_frame_new(char const *id)
cannam@85: {
cannam@85:   struct id3_frametype const *frametype;
cannam@85:   struct id3_frame *frame;
cannam@85:   unsigned int i;
cannam@85: 
cannam@85:   if (!id3_frame_validid(id))
cannam@85:     return 0;
cannam@85: 
cannam@85:   frametype = id3_frametype_lookup(id, 4);
cannam@85:   if (frametype == 0) {
cannam@85:     switch (id[0]) {
cannam@85:     case 'T':
cannam@85:       frametype = &id3_frametype_text;
cannam@85:       break;
cannam@85: 
cannam@85:     case 'W':
cannam@85:       frametype = &id3_frametype_url;
cannam@85:       break;
cannam@85: 
cannam@85:     case 'X':
cannam@85:     case 'Y':
cannam@85:     case 'Z':
cannam@85:       frametype = &id3_frametype_experimental;
cannam@85:       break;
cannam@85: 
cannam@85:     default:
cannam@85:       frametype = &id3_frametype_unknown;
cannam@85:       if (id3_compat_lookup(id, 4))
cannam@85: 	frametype = &id3_frametype_obsolete;
cannam@85:       break;
cannam@85:     }
cannam@85:   }
cannam@85: 
cannam@85:   frame = malloc(sizeof(*frame) + frametype->nfields * sizeof(*frame->fields));
cannam@85:   if (frame) {
cannam@85:     frame->id[0] = id[0];
cannam@85:     frame->id[1] = id[1];
cannam@85:     frame->id[2] = id[2];
cannam@85:     frame->id[3] = id[3];
cannam@85:     frame->id[4] = 0;
cannam@85: 
cannam@85:     frame->description       = frametype->description;
cannam@85:     frame->refcount          = 0;
cannam@85:     frame->flags             = frametype->defaultflags;
cannam@85:     frame->group_id          = 0;
cannam@85:     frame->encryption_method = 0;
cannam@85:     frame->encoded           = 0;
cannam@85:     frame->encoded_length    = 0;
cannam@85:     frame->decoded_length    = 0;
cannam@85:     frame->nfields           = frametype->nfields;
cannam@85:     frame->fields            = (union id3_field *) &frame[1];
cannam@85: 
cannam@85:     for (i = 0; i < frame->nfields; ++i)
cannam@85:       id3_field_init(&frame->fields[i], frametype->fields[i]);
cannam@85:   }
cannam@85: 
cannam@85:   return frame;
cannam@85: }
cannam@85: 
cannam@85: void id3_frame_delete(struct id3_frame *frame)
cannam@85: {
cannam@85:   assert(frame);
cannam@85: 
cannam@85:   if (frame->refcount == 0) {
cannam@85:     unsigned int i;
cannam@85: 
cannam@85:     for (i = 0; i < frame->nfields; ++i)
cannam@85:       id3_field_finish(&frame->fields[i]);
cannam@85: 
cannam@85:     if (frame->encoded)
cannam@85:       free(frame->encoded);
cannam@85: 
cannam@85:     free(frame);
cannam@85:   }
cannam@85: }
cannam@85: 
cannam@85: /*
cannam@85:  * NAME:	frame->addref()
cannam@85:  * DESCRIPTION:	add an external reference to a frame
cannam@85:  */
cannam@85: void id3_frame_addref(struct id3_frame *frame)
cannam@85: {
cannam@85:   assert(frame);
cannam@85: 
cannam@85:   ++frame->refcount;
cannam@85: }
cannam@85: 
cannam@85: /*
cannam@85:  * NAME:	frame->delref()
cannam@85:  * DESCRIPTION:	remove an external reference to a frame
cannam@85:  */
cannam@85: void id3_frame_delref(struct id3_frame *frame)
cannam@85: {
cannam@85:   assert(frame && frame->refcount > 0);
cannam@85: 
cannam@85:   --frame->refcount;
cannam@85: }
cannam@85: 
cannam@85: /*
cannam@85:  * NAME:	frame->field()
cannam@85:  * DESCRIPTION:	return a pointer to a field in a frame
cannam@85:  */
cannam@85: union id3_field *id3_frame_field(struct id3_frame const *frame,
cannam@85: 				 unsigned int index)
cannam@85: {
cannam@85:   assert(frame);
cannam@85: 
cannam@85:   return (index < frame->nfields) ? &frame->fields[index] : 0;
cannam@85: }
cannam@85: 
cannam@85: static
cannam@85: struct id3_frame *obsolete(char const *id, id3_byte_t const *data,
cannam@85: 			   id3_length_t length)
cannam@85: {
cannam@85:   struct id3_frame *frame;
cannam@85: 
cannam@85:   frame = id3_frame_new(ID3_FRAME_OBSOLETE);
cannam@85:   if (frame) {
cannam@85:     if (id3_field_setframeid(&frame->fields[0], id) == -1 ||
cannam@85: 	id3_field_setbinarydata(&frame->fields[1], data, length) == -1)
cannam@85:       goto fail;
cannam@85:   }
cannam@85: 
cannam@85:   if (0) {
cannam@85:   fail:
cannam@85:     if (frame) {
cannam@85:       id3_frame_delete(frame);
cannam@85:       frame = 0;
cannam@85:     }
cannam@85:   }
cannam@85: 
cannam@85:   return frame;
cannam@85: }
cannam@85: 
cannam@85: static
cannam@85: struct id3_frame *unparseable(char const *id, id3_byte_t const **ptr,
cannam@85: 			      id3_length_t length, int flags,
cannam@85: 			      int group_id, int encryption_method,
cannam@85: 			      id3_length_t decoded_length)
cannam@85: {
cannam@85:   struct id3_frame *frame = 0;
cannam@85:   id3_byte_t *mem;
cannam@85: 
cannam@85:   mem = malloc(length ? length : 1);
cannam@85:   if (mem == 0)
cannam@85:     goto fail;
cannam@85: 
cannam@85:   frame = id3_frame_new(id);
cannam@85:   if (frame == 0)
cannam@85:     free(mem);
cannam@85:   else {
cannam@85:     memcpy(mem, *ptr, length);
cannam@85: 
cannam@85:     frame->flags             = flags;
cannam@85:     frame->group_id          = group_id;
cannam@85:     frame->encryption_method = encryption_method;
cannam@85:     frame->encoded           = mem;
cannam@85:     frame->encoded_length    = length;
cannam@85:     frame->decoded_length    = decoded_length;
cannam@85:   }
cannam@85: 
cannam@85:   if (0) {
cannam@85:   fail:
cannam@85:     ;
cannam@85:   }
cannam@85: 
cannam@85:   *ptr += length;
cannam@85: 
cannam@85:   return frame;
cannam@85: }
cannam@85: 
cannam@85: static
cannam@85: int parse_data(struct id3_frame *frame,
cannam@85: 	       id3_byte_t const *data, id3_length_t length)
cannam@85: {
cannam@85:   enum id3_field_textencoding encoding;
cannam@85:   id3_byte_t const *end;
cannam@85:   unsigned int i;
cannam@85: 
cannam@85:   encoding = ID3_FIELD_TEXTENCODING_ISO_8859_1;
cannam@85: 
cannam@85:   end = data + length;
cannam@85: 
cannam@85:   for (i = 0; i < frame->nfields; ++i) {
cannam@85:     if (id3_field_parse(&frame->fields[i], &data, end - data, &encoding) == -1)
cannam@85:       return -1;
cannam@85:   }
cannam@85: 
cannam@85:   return 0;
cannam@85: }
cannam@85: 
cannam@85: /*
cannam@85:  * NAME:	frame->parse()
cannam@85:  * DESCRIPTION:	parse raw frame data according to the specified ID3 tag version
cannam@85:  */
cannam@85: struct id3_frame *id3_frame_parse(id3_byte_t const **ptr, id3_length_t length,
cannam@85: 				  unsigned int version)
cannam@85: {
cannam@85:   struct id3_frame *frame = 0;
cannam@85:   id3_byte_t const *id, *end, *data;
cannam@85:   id3_length_t size, decoded_length = 0;
cannam@85:   int flags = 0, group_id = 0, encryption_method = 0;
cannam@85:   struct id3_compat const *compat = 0;
cannam@85:   id3_byte_t *mem = 0;
cannam@85:   char xid[4];
cannam@85: 
cannam@85:   id  = *ptr;
cannam@85:   end = *ptr + length;
cannam@85: 
cannam@85:   if (ID3_TAG_VERSION_MAJOR(version) < 4) {
cannam@85:     switch (ID3_TAG_VERSION_MAJOR(version)) {
cannam@85:     case 2:
cannam@85:       if (length < 6)
cannam@85: 	goto fail;
cannam@85: 
cannam@85:       compat = id3_compat_lookup(id, 3);
cannam@85: 
cannam@85:       *ptr += 3;
cannam@85:       size  = id3_parse_uint(ptr, 3);
cannam@85: 
cannam@85:       if (size > end - *ptr)
cannam@85: 	goto fail;
cannam@85: 
cannam@85:       end = *ptr + size;
cannam@85: 
cannam@85:       break;
cannam@85: 
cannam@85:     case 3:
cannam@85:       if (length < 10)
cannam@85: 	goto fail;
cannam@85: 
cannam@85:       compat = id3_compat_lookup(id, 4);
cannam@85: 
cannam@85:       *ptr += 4;
cannam@85:       size  = id3_parse_uint(ptr, 4);
cannam@85:       flags = id3_parse_uint(ptr, 2);
cannam@85: 
cannam@85:       if (size > end - *ptr)
cannam@85: 	goto fail;
cannam@85: 
cannam@85:       end = *ptr + size;
cannam@85: 
cannam@85:       if (flags & (ID3_FRAME_FLAG_FORMATFLAGS & ~0x00e0)) {
cannam@85: 	frame = unparseable(id, ptr, end - *ptr, 0, 0, 0, 0);
cannam@85: 	goto done;
cannam@85:       }
cannam@85: 
cannam@85:       flags =
cannam@85: 	((flags >> 1) & ID3_FRAME_FLAG_STATUSFLAGS) |
cannam@85: 	((flags >> 4) & (ID3_FRAME_FLAG_COMPRESSION |
cannam@85: 			 ID3_FRAME_FLAG_ENCRYPTION)) |
cannam@85: 	((flags << 1) & ID3_FRAME_FLAG_GROUPINGIDENTITY);
cannam@85: 
cannam@85:       if (flags & ID3_FRAME_FLAG_COMPRESSION) {
cannam@85: 	if (end - *ptr < 4)
cannam@85: 	  goto fail;
cannam@85: 
cannam@85: 	decoded_length = id3_parse_uint(ptr, 4);
cannam@85:       }
cannam@85: 
cannam@85:       if (flags & ID3_FRAME_FLAG_ENCRYPTION) {
cannam@85: 	if (end - *ptr < 1)
cannam@85: 	  goto fail;
cannam@85: 
cannam@85: 	encryption_method = id3_parse_uint(ptr, 1);
cannam@85:       }
cannam@85: 
cannam@85:       if (flags & ID3_FRAME_FLAG_GROUPINGIDENTITY) {
cannam@85: 	if (end - *ptr < 1)
cannam@85: 	  goto fail;
cannam@85: 
cannam@85: 	group_id = id3_parse_uint(ptr, 1);
cannam@85:       }
cannam@85: 
cannam@85:       break;
cannam@85: 
cannam@85:     default:
cannam@85:       goto fail;
cannam@85:     }
cannam@85: 
cannam@85:     /* canonicalize frame ID for ID3v2.4 */
cannam@85: 
cannam@85:     if (compat && compat->equiv)
cannam@85:       id = compat->equiv;
cannam@85:     else if (ID3_TAG_VERSION_MAJOR(version) == 2) {
cannam@85:       xid[0] = 'Y';
cannam@85:       xid[1] = id[0];
cannam@85:       xid[2] = id[1];
cannam@85:       xid[3] = id[2];
cannam@85: 
cannam@85:       id = xid;
cannam@85: 
cannam@85:       flags |=
cannam@85: 	ID3_FRAME_FLAG_TAGALTERPRESERVATION |
cannam@85: 	ID3_FRAME_FLAG_FILEALTERPRESERVATION;
cannam@85:     }
cannam@85:   }
cannam@85:   else {  /* ID3v2.4 */
cannam@85:     if (length < 10)
cannam@85:       goto fail;
cannam@85: 
cannam@85:     *ptr += 4;
cannam@85:     size  = id3_parse_syncsafe(ptr, 4);
cannam@85:     flags = id3_parse_uint(ptr, 2);
cannam@85: 
cannam@85:     if (size > end - *ptr)
cannam@85:       goto fail;
cannam@85: 
cannam@85:     end = *ptr + size;
cannam@85: 
cannam@85:     if (flags & (ID3_FRAME_FLAG_FORMATFLAGS & ~ID3_FRAME_FLAG_KNOWNFLAGS)) {
cannam@85:       frame = unparseable(id, ptr, end - *ptr, flags, 0, 0, 0);
cannam@85:       goto done;
cannam@85:     }
cannam@85: 
cannam@85:     if (flags & ID3_FRAME_FLAG_GROUPINGIDENTITY) {
cannam@85:       if (end - *ptr < 1)
cannam@85: 	goto fail;
cannam@85: 
cannam@85:       group_id = id3_parse_uint(ptr, 1);
cannam@85:     }
cannam@85: 
cannam@85:     if ((flags & ID3_FRAME_FLAG_COMPRESSION) &&
cannam@85: 	!(flags & ID3_FRAME_FLAG_DATALENGTHINDICATOR))
cannam@85:       goto fail;
cannam@85: 
cannam@85:     if (flags & ID3_FRAME_FLAG_ENCRYPTION) {
cannam@85:       if (end - *ptr < 1)
cannam@85: 	goto fail;
cannam@85: 
cannam@85:       encryption_method = id3_parse_uint(ptr, 1);
cannam@85:     }
cannam@85: 
cannam@85:     if (flags & ID3_FRAME_FLAG_DATALENGTHINDICATOR) {
cannam@85:       if (end - *ptr < 4)
cannam@85: 	goto fail;
cannam@85: 
cannam@85:       decoded_length = id3_parse_syncsafe(ptr, 4);
cannam@85:     }
cannam@85:   }
cannam@85: 
cannam@85:   data = *ptr;
cannam@85:   *ptr = end;
cannam@85: 
cannam@85:   /* undo frame encodings */
cannam@85: 
cannam@85:   if ((flags & ID3_FRAME_FLAG_UNSYNCHRONISATION) && end - data > 0) {
cannam@85:     mem = malloc(end - data);
cannam@85:     if (mem == 0)
cannam@85:       goto fail;
cannam@85: 
cannam@85:     memcpy(mem, data, end - data);
cannam@85: 
cannam@85:     end  = mem + id3_util_deunsynchronise(mem, end - data);
cannam@85:     data = mem;
cannam@85:   }
cannam@85: 
cannam@85:   if (flags & ID3_FRAME_FLAG_ENCRYPTION) {
cannam@85:     frame = unparseable(id, &data, end - data, flags,
cannam@85: 			group_id, encryption_method, decoded_length);
cannam@85:     goto done;
cannam@85:   }
cannam@85: 
cannam@85:   if (flags & ID3_FRAME_FLAG_COMPRESSION) {
cannam@85:     id3_byte_t *decomp;
cannam@85: 
cannam@85:     decomp = id3_util_decompress(data, end - data, decoded_length);
cannam@85:     if (decomp == 0)
cannam@85:       goto fail;
cannam@85: 
cannam@85:     if (mem)
cannam@85:       free(mem);
cannam@85: 
cannam@85:     data = mem = decomp;
cannam@85:     end  = data + decoded_length;
cannam@85:   }
cannam@85: 
cannam@85:   /* check for obsolescence */
cannam@85: 
cannam@85:   if (compat && !compat->equiv) {
cannam@85:     frame = obsolete(id, data, end - data);
cannam@85:     goto done;
cannam@85:   }
cannam@85: 
cannam@85:   /* generate the internal frame structure */
cannam@85: 
cannam@85:   frame = id3_frame_new(id);
cannam@85:   if (frame) {
cannam@85:     frame->flags    = flags;
cannam@85:     frame->group_id = group_id;
cannam@85: 
cannam@85:     if (compat && compat->translate) {
cannam@85:       if (compat->translate(frame, compat->id, data, end - data) == -1)
cannam@85: 	goto fail;
cannam@85:     }
cannam@85:     else {
cannam@85:       if (parse_data(frame, data, end - data) == -1)
cannam@85: 	goto fail;
cannam@85:     }
cannam@85:   }
cannam@85: 
cannam@85:   if (0) {
cannam@85:   fail:
cannam@85:     if (frame) {
cannam@85:       id3_frame_delete(frame);
cannam@85:       frame = 0;
cannam@85:     }
cannam@85:   }
cannam@85: 
cannam@85:  done:
cannam@85:   if (mem)
cannam@85:     free(mem);
cannam@85: 
cannam@85:   return frame;
cannam@85: }
cannam@85: 
cannam@85: static
cannam@85: id3_length_t render_data(id3_byte_t **ptr,
cannam@85: 			 union id3_field *fields, unsigned int length)
cannam@85: {
cannam@85:   id3_length_t size = 0;
cannam@85:   enum id3_field_textencoding encoding;
cannam@85:   unsigned int i;
cannam@85: 
cannam@85:   encoding = ID3_FIELD_TEXTENCODING_ISO_8859_1;
cannam@85: 
cannam@85:   for (i = 0; i < length; ++i)
cannam@85:     size += id3_field_render(&fields[i], ptr, &encoding, i < length - 1);
cannam@85: 
cannam@85:   return size;
cannam@85: }
cannam@85: 
cannam@85: /*
cannam@85:  * NAME:	frame->render()
cannam@85:  * DESCRIPTION:	render a single, complete frame
cannam@85:  */
cannam@85: id3_length_t id3_frame_render(struct id3_frame const *frame,
cannam@85: 			      id3_byte_t **ptr, int options)
cannam@85: {
cannam@85:   id3_length_t size = 0, decoded_length, datalen;
cannam@85:   id3_byte_t *size_ptr = 0, *flags_ptr = 0, *data = 0;
cannam@85:   int flags;
cannam@85: 
cannam@85:   assert(frame);
cannam@85: 
cannam@85:   if ((frame->flags & ID3_FRAME_FLAG_TAGALTERPRESERVATION) ||
cannam@85:       ((options & ID3_TAG_OPTION_FILEALTERED) &&
cannam@85:        (frame->flags & ID3_FRAME_FLAG_FILEALTERPRESERVATION)))
cannam@85:     return 0;
cannam@85: 
cannam@85:   /* a frame must be at least 1 byte big, excluding the header */
cannam@85: 
cannam@85:   decoded_length = render_data(0, frame->fields, frame->nfields);
cannam@85:   if (decoded_length == 0 && frame->encoded == 0)
cannam@85:     return 0;
cannam@85: 
cannam@85:   /* header */
cannam@85: 
cannam@85:   size += id3_render_immediate(ptr, frame->id, 4);
cannam@85: 
cannam@85:   if (ptr)
cannam@85:     size_ptr = *ptr;
cannam@85: 
cannam@85:   size += id3_render_syncsafe(ptr, 0, 4);
cannam@85: 
cannam@85:   if (ptr)
cannam@85:     flags_ptr = *ptr;
cannam@85: 
cannam@85:   flags = frame->flags;
cannam@85: 
cannam@85:   size += id3_render_int(ptr, flags, 2);
cannam@85: 
cannam@85:   if (flags & (ID3_FRAME_FLAG_FORMATFLAGS & ~ID3_FRAME_FLAG_KNOWNFLAGS)) {
cannam@85:     size += id3_render_binary(ptr, frame->encoded, frame->encoded_length);
cannam@85:     if (size_ptr)
cannam@85:       id3_render_syncsafe(&size_ptr, size - 10, 4);
cannam@85: 
cannam@85:     return size;
cannam@85:   }
cannam@85: 
cannam@85:   flags &= ID3_FRAME_FLAG_KNOWNFLAGS;
cannam@85: 
cannam@85:   flags &= ~ID3_FRAME_FLAG_UNSYNCHRONISATION;
cannam@85:   if (options & ID3_TAG_OPTION_UNSYNCHRONISATION)
cannam@85:     flags |= ID3_FRAME_FLAG_UNSYNCHRONISATION;
cannam@85: 
cannam@85:   if (!(flags & ID3_FRAME_FLAG_ENCRYPTION)) {
cannam@85:     flags &= ~ID3_FRAME_FLAG_COMPRESSION;
cannam@85:     if (options & ID3_TAG_OPTION_COMPRESSION)
cannam@85:       flags |= ID3_FRAME_FLAG_COMPRESSION | ID3_FRAME_FLAG_DATALENGTHINDICATOR;
cannam@85:   }
cannam@85: 
cannam@85:   if (flags & ID3_FRAME_FLAG_GROUPINGIDENTITY)
cannam@85:     size += id3_render_int(ptr, frame->group_id, 1);
cannam@85:   if (flags & ID3_FRAME_FLAG_ENCRYPTION)
cannam@85:     size += id3_render_int(ptr, frame->encryption_method, 1);
cannam@85:   if (flags & ID3_FRAME_FLAG_DATALENGTHINDICATOR) {
cannam@85:     if (flags & ID3_FRAME_FLAG_ENCRYPTION)
cannam@85:       decoded_length = frame->decoded_length;
cannam@85:     size += id3_render_syncsafe(ptr, decoded_length, 4);
cannam@85:   }
cannam@85: 
cannam@85:   if (ptr)
cannam@85:     data = *ptr;
cannam@85: 
cannam@85:   if (flags & ID3_FRAME_FLAG_ENCRYPTION)
cannam@85:     datalen = id3_render_binary(ptr, frame->encoded, frame->encoded_length);
cannam@85:   else {
cannam@85:     if (ptr == 0)
cannam@85:       datalen = decoded_length;
cannam@85:     else {
cannam@85:       datalen = render_data(ptr, frame->fields, frame->nfields);
cannam@85: 
cannam@85:       if (flags & ID3_FRAME_FLAG_COMPRESSION) {
cannam@85: 	id3_byte_t *comp;
cannam@85: 	id3_length_t complen;
cannam@85: 
cannam@85: 	comp = id3_util_compress(data, datalen, &complen);
cannam@85: 	if (comp == 0)
cannam@85: 	  flags &= ~ID3_FRAME_FLAG_COMPRESSION;
cannam@85: 	else {
cannam@85: 	  *ptr = data;
cannam@85: 	  datalen = id3_render_binary(ptr, comp, complen);
cannam@85: 
cannam@85: 	  free(comp);
cannam@85: 	}
cannam@85:       }
cannam@85:     }
cannam@85:   }
cannam@85: 
cannam@85:   /* unsynchronisation */
cannam@85: 
cannam@85:   if (flags & ID3_FRAME_FLAG_UNSYNCHRONISATION) {
cannam@85:     if (data == 0)
cannam@85:       datalen *= 2;
cannam@85:     else {
cannam@85:       id3_length_t newlen;
cannam@85: 
cannam@85:       newlen = id3_util_unsynchronise(data, datalen);
cannam@85:       if (newlen == datalen)
cannam@85: 	flags &= ~ID3_FRAME_FLAG_UNSYNCHRONISATION;
cannam@85:       else {
cannam@85: 	*ptr   += newlen - datalen;
cannam@85: 	datalen = newlen;
cannam@85:       }
cannam@85:     }
cannam@85:   }
cannam@85: 
cannam@85:   size += datalen;
cannam@85: 
cannam@85:   /* patch size and flags */
cannam@85: 
cannam@85:   if (size_ptr)
cannam@85:     id3_render_syncsafe(&size_ptr, size - 10, 4);
cannam@85:   if (flags_ptr)
cannam@85:     id3_render_int(&flags_ptr, flags, 2);
cannam@85: 
cannam@85:   return size;
cannam@85: }