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
33static int ape_tag_read_field(AVFormatContext *s)
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    }
54    if (size >= UINT_MAX)
55        return -1;
56    value = av_malloc(size+1);
57    if (!value)
58        return AVERROR(ENOMEM);
59    avio_read(pb, value, size);
60    value[size] = 0;
61    av_dict_set(&s->metadata, key, value, AV_DICT_DONT_STRDUP_VAL);
62    return 0;
63}
64
65void ff_ape_parse_tag(AVFormatContext *s)
66{
67    AVIOContext *pb = s->pb;
68    int64_t file_size = avio_size(pb);
69    uint32_t val, fields, tag_bytes;
70    uint8_t buf[8];
71    int i;
72
73    if (file_size < APE_TAG_FOOTER_BYTES)
74        return;
75
76    avio_seek(pb, file_size - APE_TAG_FOOTER_BYTES, SEEK_SET);
77
78    avio_read(pb, buf, 8);     /* APETAGEX */
79    if (strncmp(buf, "APETAGEX", 8)) {
80        return;
81    }
82
83    val = avio_rl32(pb);       /* APE tag version */
84    if (val > APE_TAG_VERSION) {
85        av_log(s, AV_LOG_ERROR, "Unsupported tag version. (>=%d)\n", APE_TAG_VERSION);
86        return;
87    }
88
89    tag_bytes = avio_rl32(pb); /* tag size */
90    if (tag_bytes - APE_TAG_FOOTER_BYTES > (1024 * 1024 * 16)) {
91        av_log(s, AV_LOG_ERROR, "Tag size is way too big\n");
92        return;
93    }
94
95    fields = avio_rl32(pb);    /* number of fields */
96    if (fields > 65536) {
97        av_log(s, AV_LOG_ERROR, "Too many tag fields (%d)\n", fields);
98        return;
99    }
100
101    val = avio_rl32(pb);       /* flags */
102    if (val & APE_TAG_FLAG_IS_HEADER) {
103        av_log(s, AV_LOG_ERROR, "APE Tag is a header\n");
104        return;
105    }
106
107    avio_seek(pb, file_size - tag_bytes, SEEK_SET);
108
109    for (i=0; i<fields; i++)
110        if (ape_tag_read_field(s) < 0) break;
111}
112