1/*
2 * EXIF metadata parser
3 * Copyright (c) 2013 Thilo Borgmann <thilo.borgmann _at_ mail.de>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22/**
23 * @file
24 * EXIF metadata parser
25 * @author Thilo Borgmann <thilo.borgmann _at_ mail.de>
26 */
27
28#include "exif.h"
29
30
31static const char *exif_get_tag_name(uint16_t id)
32{
33    int i;
34
35    for (i = 0; i < FF_ARRAY_ELEMS(tag_list); i++) {
36        if (tag_list[i].id == id)
37            return tag_list[i].name;
38    }
39
40    return NULL;
41}
42
43
44static int exif_add_metadata(AVCodecContext *avctx, int count, int type,
45                             const char *name, const char *sep,
46                             GetByteContext *gb, int le,
47                             AVDictionary **metadata)
48{
49    switch(type) {
50    case TIFF_DOUBLE   : return ff_tadd_doubles_metadata(count, name, sep, gb, le, metadata);
51    case TIFF_SSHORT   : return ff_tadd_shorts_metadata(count, name, sep, gb, le, 1, metadata);
52    case TIFF_SHORT    : return ff_tadd_shorts_metadata(count, name, sep, gb, le, 0, metadata);
53    case TIFF_SBYTE    : return ff_tadd_bytes_metadata(count, name, sep, gb, le, 1, metadata);
54    case TIFF_BYTE     :
55    case TIFF_UNDEFINED: return ff_tadd_bytes_metadata(count, name, sep, gb, le, 0, metadata);
56    case TIFF_STRING   : return ff_tadd_string_metadata(count, name, gb, le, metadata);
57    case TIFF_SRATIONAL:
58    case TIFF_RATIONAL : return ff_tadd_rational_metadata(count, name, sep, gb, le, metadata);
59    case TIFF_SLONG    :
60    case TIFF_LONG     : return ff_tadd_long_metadata(count, name, sep, gb, le, metadata);
61    default:
62        avpriv_request_sample(avctx, "TIFF tag type (%u)", type);
63        return 0;
64    };
65}
66
67
68static int exif_decode_tag(AVCodecContext *avctx, GetByteContext *gbytes, int le,
69                           int depth, AVDictionary **metadata)
70{
71    int ret, cur_pos;
72    unsigned id, count;
73    enum TiffTypes type;
74
75    if (depth > 2) {
76        return 0;
77    }
78
79    ff_tread_tag(gbytes, le, &id, &type, &count, &cur_pos);
80
81    if (!bytestream2_tell(gbytes)) {
82        bytestream2_seek(gbytes, cur_pos, SEEK_SET);
83        return 0;
84    }
85
86    // read count values and add it metadata
87    // store metadata or proceed with next IFD
88    ret = ff_tis_ifd(id);
89    if (ret) {
90        ret = avpriv_exif_decode_ifd(avctx, gbytes, le, depth + 1, metadata);
91    } else {
92        const char *name = exif_get_tag_name(id);
93        char *use_name   = (char*) name;
94
95        if (!use_name) {
96            use_name = av_malloc(7);
97            if (!use_name) {
98                return AVERROR(ENOMEM);
99            }
100            snprintf(use_name, 7, "0x%04X", id);
101        }
102
103        ret = exif_add_metadata(avctx, count, type, use_name, NULL,
104                                gbytes, le, metadata);
105
106        if (!name) {
107            av_freep(&use_name);
108        }
109    }
110
111    bytestream2_seek(gbytes, cur_pos, SEEK_SET);
112
113    return ret;
114}
115
116
117int avpriv_exif_decode_ifd(AVCodecContext *avctx, GetByteContext *gbytes, int le,
118                           int depth, AVDictionary **metadata)
119{
120    int i, ret;
121    int entries;
122
123    entries = ff_tget_short(gbytes, le);
124
125    if (bytestream2_get_bytes_left(gbytes) < entries * 12) {
126        return AVERROR_INVALIDDATA;
127    }
128
129    for (i = 0; i < entries; i++) {
130        if ((ret = exif_decode_tag(avctx, gbytes, le, depth, metadata)) < 0) {
131            return ret;
132        }
133    }
134
135    // return next IDF offset or 0x000000000 or a value < 0 for failure
136    return ff_tget_long(gbytes, le);
137}
138