FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/gif_parser.c
Date: 2023-09-24 13:02:57
Exec Total Coverage
Lines: 100 102 98.0%
Functions: 2 2 100.0%
Branches: 63 68 92.6%
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
30 typedef enum GIFParseStates {
31 GIF_HEADER = 1,
32 GIF_EXTENSION,
33 GIF_EXTENSION_BLOCK,
34 GIF_IMAGE,
35 GIF_IMAGE_BLOCK,
36 } gif_states;
37
38 typedef struct GIFParseContext {
39 ParseContext pc;
40 unsigned found_sig;
41 int found_start;
42 int found_end;
43 int index;
44 int state;
45 int gct_flag;
46 int gct_size;
47 int block_size;
48 int etype;
49 int delay;
50 int keyframe;
51 } GIFParseContext;
52
53 44654 static int gif_find_frame_end(GIFParseContext *g, const uint8_t *buf,
54 int buf_size, void *logctx)
55 {
56 44654 ParseContext *pc = &g->pc;
57 44654 int index, next = END_NOT_FOUND;
58
59
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 43852416 for (index = 0; index < buf_size; index++) {
60
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 43809551 if (!g->state) {
61
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 5596 if (!memcmp(buf + index, gif87a_sig, 6) ||
62
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 5596 !memcmp(buf + index, gif89a_sig, 6)) {
63 50 g->state = GIF_HEADER;
64 50 g->found_sig++;
65 50 g->keyframe = 1;
66
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 5546 } else if (buf[index] == GIF_EXTENSION_INTRODUCER) {
67 3674 g->state = GIF_EXTENSION;
68 3674 g->found_start = pc->frame_start_found = 1;
69
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 1872 } else if (buf[index] == GIF_IMAGE_SEPARATOR) {
70 1839 g->state = GIF_IMAGE;
71
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 33 } else if (buf[index] == GIF_TRAILER) {
72 33 g->state = 0;
73 33 g->found_end = 1;
74 33 g->found_sig = 0;
75 } else {
76 ✗ g->found_sig = 0;
77 }
78 }
79
80
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 43809551 if (g->state == GIF_HEADER) {
81
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 33098 if (g->index == 10) {
82 50 g->gct_flag = !!(buf[index] & 0x80);
83 50 g->gct_size = 3 * (1 << ((buf[index] & 0x07) + 1));
84 }
85
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 33098 if (g->index >= 12 + g->gct_flag * g->gct_size) {
86 50 g->state = 0;
87 50 g->index = 0;
88 50 g->gct_flag = 0;
89 50 g->gct_size = 0;
90 50 continue;
91 }
92 33048 g->index++;
93
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 43776453 } else if (g->state == GIF_EXTENSION) {
94
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 7444 if (g->found_start && g->found_end && g->found_sig) {
95 1789 next = index;
96 1789 g->found_start = pc->frame_start_found = 0;
97 1789 g->found_end = 0;
98 1789 g->index = 0;
99 1789 g->gct_flag = 0;
100 1789 g->gct_size = 0;
101 1789 g->state = 0;
102 1789 break;
103 }
104
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 5655 if (g->index == 1) {
105 1885 g->etype = buf[index];
106 }
107
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 5655 if (g->index >= 2) {
108 1885 g->block_size = buf[index];
109 1885 g->index = 0;
110 1885 g->state = GIF_EXTENSION_BLOCK;
111 1885 continue;
112 }
113 3770 g->index++;
114
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 43769009 } else if (g->state == GIF_IMAGE_BLOCK) {
115
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 42843797 if (!g->index)
116 170506 g->block_size = buf[index];
117
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 42843797 if (g->index >= g->block_size) {
118 170489 g->index = 0;
119
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 170489 if (!g->block_size) {
120 1822 g->state = 0;
121 1822 g->found_end = 1;
122 }
123 170489 continue;
124 }
125 42673308 g->index++;
126
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 925212 } else if (g->state == GIF_EXTENSION_BLOCK) {
127
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 10998 if (g->etype == GIF_GCE_EXT_LABEL) {
128
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 9195 if (g->index == 0)
129 1839 g->delay = 0;
130
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 9195 if (g->index >= 1 && g->index <= 2) {
131 3678 g->delay |= buf[index] << (8 * (g->index - 1));
132 }
133 }
134
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 10998 if (g->index >= g->block_size) {
135 1940 g->block_size = buf[index];
136 1940 g->index = 0;
137
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 1940 if (!g->block_size)
138 1885 g->state = 0;
139 1940 continue;
140 }
141 9058 g->index++;
142
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 914214 } else if (g->state == GIF_IMAGE) {
143
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 914181 if (g->index == 9) {
144 1839 g->gct_flag = !!(buf[index] & 0x80);
145 1839 g->gct_size = 3 * (1 << ((buf[index] & 0x07) + 1));
146 }
147
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 914181 if (g->index >= 10 + g->gct_flag * g->gct_size) {
148 1839 g->state = GIF_IMAGE_BLOCK;
149 1839 g->index = 0;
150 1839 g->gct_flag = 0;
151 1839 g->gct_size = 0;
152 1839 continue;
153 }
154 912342 g->index++;
155 }
156 }
157
158 44654 return next;
159 }
160
161 44654 static int gif_parse(AVCodecParserContext *s, AVCodecContext *avctx,
162 const uint8_t **poutbuf, int *poutbuf_size,
163 const uint8_t *buf, int buf_size)
164 {
165 44654 GIFParseContext *g = s->priv_data;
166 int next;
167
168 44654 *poutbuf_size = 0;
169 44654 *poutbuf = NULL;
170
171
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 44654 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
172 ✗ next = buf_size;
173 } else {
174 44654 next = gif_find_frame_end(g, buf, buf_size, avctx);
175
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 44654 if (ff_combine_frame(&g->pc, next, &buf, &buf_size) < 0) {
176 42799 *poutbuf = NULL;
177 42799 *poutbuf_size = 0;
178 42799 return buf_size;
179 }
180 }
181
182
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 1855 s->duration = g->delay ? g->delay : 10;
183 1855 s->key_frame = g->keyframe;
184
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 1855 s->pict_type = g->keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
185 1855 g->keyframe = 0;
186
187 1855 *poutbuf = buf;
188 1855 *poutbuf_size = buf_size;
189 1855 return next;
190 }
191
192 const AVCodecParser ff_gif_parser = {
193 .codec_ids = { AV_CODEC_ID_GIF },
194 .priv_data_size = sizeof(GIFParseContext),
195 .parser_parse = gif_parse,
196 .parser_close = ff_parse_close,
197 };
198