FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/gif_parser.c
Date: 2026-01-16 07:34:38
Exec Total Coverage
Lines: 102 112 91.1%
Functions: 2 2 100.0%
Branches: 66 76 86.8%
Line Branch Exec Source
1 /*
2 * GIF parser
3 * Copyright (c) 2018 Paul B Mahol
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 * GIF parser
25 */
26
27 #include "gif.h"
28 #include "parser.h"
29 #include "parser_internal.h"
30
31 typedef enum GIFParseStates {
32 GIF_HEADER = 1,
33 GIF_EXTENSION,
34 GIF_EXTENSION_BLOCK,
35 GIF_IMAGE,
36 GIF_IMAGE_BLOCK,
37 } gif_states;
38
39 typedef struct GIFParseContext {
40 ParseContext pc;
41 unsigned found_sig;
42 int found_start;
43 int found_end;
44 int index;
45 int state;
46 int gct_flag;
47 int gct_size;
48 int block_size;
49 int etype;
50 int delay;
51 int keyframe;
52 } GIFParseContext;
53
54 44654 static int gif_find_frame_end(GIFParseContext *g, const uint8_t *buf,
55 int buf_size, void *logctx)
56 {
57 44654 ParseContext *pc = &g->pc;
58 44654 int index, next = END_NOT_FOUND;
59
60
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 43852416 for (index = 0; index < buf_size; index++) {
61
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 43809551 if (!g->state) {
62
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 5596 if (!memcmp(buf + index, gif87a_sig, 6) ||
63
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 5596 !memcmp(buf + index, gif89a_sig, 6)) {
64 50 g->state = GIF_HEADER;
65 50 g->found_sig++;
66 50 g->keyframe = 1;
67
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 5546 } else if (buf[index] == GIF_EXTENSION_INTRODUCER) {
68 3674 g->state = GIF_EXTENSION;
69 3674 g->found_start = pc->frame_start_found = 1;
70
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 1872 } else if (buf[index] == GIF_IMAGE_SEPARATOR) {
71
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 1839 if (g->state != GIF_EXTENSION_BLOCK && g->found_start &&
72
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 1839 g->found_end && g->found_sig) {
73 ✗ next = index;
74 ✗ g->found_start = pc->frame_start_found = 1;
75 ✗ g->found_end = 0;
76 ✗ g->index = 0;
77 ✗ g->gct_flag = 0;
78 ✗ g->gct_size = 0;
79 ✗ g->state = GIF_IMAGE;
80 ✗ break;
81 }
82 1839 g->state = GIF_IMAGE;
83
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 33 } else if (buf[index] == GIF_TRAILER) {
84 33 g->state = 0;
85 33 g->found_end = 1;
86 33 g->found_sig = 0;
87 } else {
88 ✗ g->found_sig = 0;
89 }
90 }
91
92
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 43809551 if (g->state == GIF_HEADER) {
93
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 33098 if (g->index == 10) {
94 50 g->gct_flag = !!(buf[index] & 0x80);
95 50 g->gct_size = 3 * (1 << ((buf[index] & 0x07) + 1));
96 }
97
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 33098 if (g->index >= 12 + g->gct_flag * g->gct_size) {
98 50 g->state = 0;
99 50 g->index = 0;
100 50 g->gct_flag = 0;
101 50 g->gct_size = 0;
102 50 continue;
103 }
104 33048 g->index++;
105
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 43776453 } else if (g->state == GIF_EXTENSION) {
106
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 7444 if (g->found_start && g->found_end && g->found_sig) {
107 1789 next = index;
108 1789 g->found_start = pc->frame_start_found = 0;
109 1789 g->found_end = 0;
110 1789 g->index = 0;
111 1789 g->gct_flag = 0;
112 1789 g->gct_size = 0;
113 1789 g->state = 0;
114 1789 break;
115 }
116
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 5655 if (g->index == 1) {
117 1885 g->etype = buf[index];
118 }
119
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 5655 if (g->index >= 2) {
120 1885 g->block_size = buf[index];
121 1885 g->index = 0;
122 1885 g->state = GIF_EXTENSION_BLOCK;
123 1885 continue;
124 }
125 3770 g->index++;
126
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 43769009 } else if (g->state == GIF_IMAGE_BLOCK) {
127
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 42843797 if (!g->index)
128 170506 g->block_size = buf[index];
129
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 42843797 if (g->index >= g->block_size) {
130 170489 g->index = 0;
131
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 170489 if (!g->block_size) {
132 1822 g->state = 0;
133 1822 g->found_end = 1;
134 }
135 170489 continue;
136 }
137 42673308 g->index++;
138
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 925212 } else if (g->state == GIF_EXTENSION_BLOCK) {
139
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 10998 if (g->etype == GIF_GCE_EXT_LABEL) {
140
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 9195 if (g->index == 0)
141 1839 g->delay = 0;
142
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 9195 if (g->index >= 1 && g->index <= 2) {
143 3678 g->delay |= buf[index] << (8 * (g->index - 1));
144 }
145 }
146
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 10998 if (g->index >= g->block_size) {
147 1940 g->block_size = buf[index];
148 1940 g->index = 0;
149
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 1940 if (!g->block_size)
150 1885 g->state = 0;
151 1940 continue;
152 }
153 9058 g->index++;
154
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 914214 } else if (g->state == GIF_IMAGE) {
155
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 914181 if (g->index == 9) {
156 1839 g->gct_flag = !!(buf[index] & 0x80);
157 1839 g->gct_size = 3 * (1 << ((buf[index] & 0x07) + 1));
158 }
159
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 914181 if (g->index >= 10 + g->gct_flag * g->gct_size) {
160 1839 g->state = GIF_IMAGE_BLOCK;
161 1839 g->index = 0;
162 1839 g->gct_flag = 0;
163 1839 g->gct_size = 0;
164 1839 continue;
165 }
166 912342 g->index++;
167 }
168 }
169
170 44654 return next;
171 }
172
173 44654 static int gif_parse(AVCodecParserContext *s, AVCodecContext *avctx,
174 const uint8_t **poutbuf, int *poutbuf_size,
175 const uint8_t *buf, int buf_size)
176 {
177 44654 GIFParseContext *g = s->priv_data;
178 int next;
179
180 44654 *poutbuf_size = 0;
181 44654 *poutbuf = NULL;
182
183
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 44654 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
184 ✗ next = buf_size;
185 } else {
186 44654 next = gif_find_frame_end(g, buf, buf_size, avctx);
187
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 44654 if (ff_combine_frame(&g->pc, next, &buf, &buf_size) < 0) {
188 42799 *poutbuf = NULL;
189 42799 *poutbuf_size = 0;
190 42799 return buf_size;
191 }
192 }
193
194
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 1855 s->duration = g->delay ? g->delay : 10;
195 1855 s->key_frame = g->keyframe;
196
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 1855 s->pict_type = g->keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
197 1855 g->keyframe = 0;
198
199 1855 *poutbuf = buf;
200 1855 *poutbuf_size = buf_size;
201 1855 return next;
202 }
203
204 const FFCodecParser ff_gif_parser = {
205 PARSER_CODEC_LIST(AV_CODEC_ID_GIF),
206 .priv_data_size = sizeof(GIFParseContext),
207 .parse = gif_parse,
208 .close = ff_parse_close,
209 };
210