apetag.c
Go to the documentation of this file.
1 /*
2  * APE tag handling
3  * Copyright (c) 2007 Benjamin Zores <ben@geexbox.org>
4  * based upon libdemac from Dave Chapman.
5  *
6  * This file is part of Libav.
7  *
8  * Libav is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * Libav is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with Libav; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "libavutil/intreadwrite.h"
24 #include "libavutil/dict.h"
25 #include "avformat.h"
26 #include "apetag.h"
27 
28 #define APE_TAG_VERSION 2000
29 #define APE_TAG_FOOTER_BYTES 32
30 #define APE_TAG_FLAG_CONTAINS_HEADER (1 << 31)
31 #define APE_TAG_FLAG_IS_HEADER (1 << 29)
32 
34 {
35  AVIOContext *pb = s->pb;
36  uint8_t key[1024], *value;
37  uint32_t size;
38  int i, c;
39 
40  size = avio_rl32(pb); /* field size */
41  avio_skip(pb, 4); /* field flags */
42  for (i = 0; i < sizeof(key) - 1; i++) {
43  c = avio_r8(pb);
44  if (c < 0x20 || c > 0x7E)
45  break;
46  else
47  key[i] = c;
48  }
49  key[i] = 0;
50  if (c != 0) {
51  av_log(s, AV_LOG_WARNING, "Invalid APE tag key '%s'.\n", key);
52  return -1;
53  }
55  av_log(s, AV_LOG_ERROR, "APE tag size too large.\n");
56  return AVERROR_INVALIDDATA;
57  }
58  value = av_malloc(size+1);
59  if (!value)
60  return AVERROR(ENOMEM);
61  avio_read(pb, value, size);
62  value[size] = 0;
64  return 0;
65 }
66 
68 {
69  AVIOContext *pb = s->pb;
70  int64_t file_size = avio_size(pb);
71  uint32_t val, fields, tag_bytes;
72  uint8_t buf[8];
73  int i;
74 
75  if (file_size < APE_TAG_FOOTER_BYTES)
76  return;
77 
78  avio_seek(pb, file_size - APE_TAG_FOOTER_BYTES, SEEK_SET);
79 
80  avio_read(pb, buf, 8); /* APETAGEX */
81  if (strncmp(buf, "APETAGEX", 8)) {
82  return;
83  }
84 
85  val = avio_rl32(pb); /* APE tag version */
86  if (val > APE_TAG_VERSION) {
87  av_log(s, AV_LOG_ERROR, "Unsupported tag version. (>=%d)\n", APE_TAG_VERSION);
88  return;
89  }
90 
91  tag_bytes = avio_rl32(pb); /* tag size */
92  if (tag_bytes - APE_TAG_FOOTER_BYTES > (1024 * 1024 * 16)) {
93  av_log(s, AV_LOG_ERROR, "Tag size is way too big\n");
94  return;
95  }
96 
97  fields = avio_rl32(pb); /* number of fields */
98  if (fields > 65536) {
99  av_log(s, AV_LOG_ERROR, "Too many tag fields (%d)\n", fields);
100  return;
101  }
102 
103  val = avio_rl32(pb); /* flags */
104  if (val & APE_TAG_FLAG_IS_HEADER) {
105  av_log(s, AV_LOG_ERROR, "APE Tag is a header\n");
106  return;
107  }
108 
109  avio_seek(pb, file_size - tag_bytes, SEEK_SET);
110 
111  for (i=0; i<fields; i++)
112  if (ape_tag_read_field(s) < 0) break;
113 }