GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/gifdec.c Lines: 203 274 74.1 %
Date: 2019-11-22 03:34:36 Branches: 89 139 64.0 %

Line Branch Exec Source
1
/*
2
 * GIF decoder
3
 * Copyright (c) 2003 Fabrice Bellard
4
 * Copyright (c) 2006 Baptiste Coudurier
5
 * Copyright (c) 2012 Vitaliy E Sugrobov
6
 *
7
 * This file is part of FFmpeg.
8
 *
9
 * FFmpeg is free software; you can redistribute it and/or
10
 * modify it under the terms of the GNU Lesser General Public
11
 * License as published by the Free Software Foundation; either
12
 * version 2.1 of the License, or (at your option) any later version.
13
 *
14
 * FFmpeg is distributed in the hope that it will be useful,
15
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17
 * Lesser General Public License for more details.
18
 *
19
 * You should have received a copy of the GNU Lesser General Public
20
 * License along with FFmpeg; if not, write to the Free Software
21
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22
 */
23
24
#include "libavutil/imgutils.h"
25
#include "libavutil/opt.h"
26
#include "avcodec.h"
27
#include "bytestream.h"
28
#include "internal.h"
29
#include "lzw.h"
30
#include "gif.h"
31
32
/* This value is intentionally set to "transparent white" color.
33
 * It is much better to have white background instead of black
34
 * when gif image converted to format which not support transparency.
35
 */
36
#define GIF_TRANSPARENT_COLOR    0x00ffffff
37
38
typedef struct GifState {
39
    const AVClass *class;
40
    AVFrame *frame;
41
    int screen_width;
42
    int screen_height;
43
    int has_global_palette;
44
    int bits_per_pixel;
45
    uint32_t bg_color;
46
    int background_color_index;
47
    int transparent_color_index;
48
    int color_resolution;
49
    /* intermediate buffer for storing color indices
50
     * obtained from lzw-encoded data stream */
51
    uint8_t *idx_line;
52
    int idx_line_size;
53
54
    /* after the frame is displayed, the disposal method is used */
55
    int gce_prev_disposal;
56
    int gce_disposal;
57
    /* rectangle describing area that must be disposed */
58
    int gce_l, gce_t, gce_w, gce_h;
59
    /* depending on disposal method we store either part of the image
60
     * drawn on the canvas or background color that
61
     * should be used upon disposal */
62
    uint32_t * stored_img;
63
    int stored_img_size;
64
    int stored_bg_color;
65
66
    GetByteContext gb;
67
    LZWState *lzw;
68
69
    /* aux buffers */
70
    uint32_t global_palette[256];
71
    uint32_t local_palette[256];
72
73
    AVCodecContext *avctx;
74
    int keyframe;
75
    int keyframe_ok;
76
    int trans_color;    /**< color value that is used instead of transparent color */
77
} GifState;
78
79
1219
static void gif_read_palette(GifState *s, uint32_t *pal, int nb)
80
{
81
    int i;
82
83
300547
    for (i = 0; i < nb; i++, pal++)
84
299328
        *pal = (0xffu << 24) | bytestream2_get_be24u(&s->gb);
85
1219
}
86
87
13
static void gif_fill(AVFrame *picture, uint32_t color)
88
{
89
13
    uint32_t *p = (uint32_t *)picture->data[0];
90
13
    uint32_t *p_end = p + (picture->linesize[0] / sizeof(uint32_t)) * picture->height;
91
92
727197
    for (; p < p_end; p++)
93
727184
        *p = color;
94
13
}
95
96
6
static void gif_fill_rect(AVFrame *picture, uint32_t color, int l, int t, int w, int h)
97
{
98
6
    const int linesize = picture->linesize[0] / sizeof(uint32_t);
99
6
    const uint32_t *py = (uint32_t *)picture->data[0] + t * linesize;
100
6
    const uint32_t *pr, *pb = py + h * linesize;
101
    uint32_t *px;
102
103
222
    for (; py < pb; py += linesize) {
104
216
        px = (uint32_t *)py + l;
105
216
        pr = px + w;
106
107
15768
        for (; px < pr; px++)
108
15552
            *px = color;
109
    }
110
6
}
111
112
3
static void gif_copy_img_rect(const uint32_t *src, uint32_t *dst,
113
                              int linesize, int l, int t, int w, int h)
114
{
115
3
    const int y_start = t * linesize;
116
    const uint32_t *src_px,
117
3
                   *src_py = src + y_start,
118
3
                   *dst_py = dst + y_start;
119
3
    const uint32_t *src_pb = src_py + h * linesize;
120
    uint32_t *dst_px;
121
122
183
    for (; src_py < src_pb; src_py += linesize, dst_py += linesize) {
123
180
        src_px = src_py + l;
124
180
        dst_px = (uint32_t *)dst_py + l;
125
126
180
        memcpy(dst_px, src_px, w * sizeof(uint32_t));
127
    }
128
3
}
129
130
1294
static int gif_read_image(GifState *s, AVFrame *frame)
131
{
132
    int left, top, width, height, bits_per_pixel, code_size, flags, pw;
133
    int is_interleaved, has_local_palette, y, pass, y1, linesize, pal_size, lzwed_len;
134
    uint32_t *ptr, *pal, *px, *pr, *ptr1;
135
    int ret;
136
    uint8_t *idx;
137
138
    /* At least 9 bytes of Image Descriptor. */
139
1294
    if (bytestream2_get_bytes_left(&s->gb) < 9)
140
        return AVERROR_INVALIDDATA;
141
142
1294
    left   = bytestream2_get_le16u(&s->gb);
143
1294
    top    = bytestream2_get_le16u(&s->gb);
144
1294
    width  = bytestream2_get_le16u(&s->gb);
145
1294
    height = bytestream2_get_le16u(&s->gb);
146
1294
    flags  = bytestream2_get_byteu(&s->gb);
147
1294
    is_interleaved = flags & 0x40;
148
1294
    has_local_palette = flags & 0x80;
149
1294
    bits_per_pixel = (flags & 0x07) + 1;
150
151
    ff_dlog(s->avctx, "image x=%d y=%d w=%d h=%d\n", left, top, width, height);
152
153
1294
    if (has_local_palette) {
154
1213
        pal_size = 1 << bits_per_pixel;
155
156
1213
        if (bytestream2_get_bytes_left(&s->gb) < pal_size * 3)
157
            return AVERROR_INVALIDDATA;
158
159
1213
        gif_read_palette(s, s->local_palette, pal_size);
160
1213
        pal = s->local_palette;
161
    } else {
162
81
        if (!s->has_global_palette) {
163
            av_log(s->avctx, AV_LOG_ERROR, "picture doesn't have either global or local palette.\n");
164
            return AVERROR_INVALIDDATA;
165
        }
166
167
81
        pal = s->global_palette;
168
    }
169
170
1294
    if (s->keyframe) {
171

13
        if (s->transparent_color_index == -1 && s->has_global_palette) {
172
            /* transparency wasn't set before the first frame, fill with background color */
173
5
            gif_fill(frame, s->bg_color);
174
        } else {
175
            /* otherwise fill with transparent color.
176
             * this is necessary since by default picture filled with 0x80808080. */
177
8
            gif_fill(frame, s->trans_color);
178
        }
179
    }
180
181
    /* verify that all the image is inside the screen dimensions */
182

1294
    if (!width || width > s->screen_width) {
183
        av_log(s->avctx, AV_LOG_WARNING, "Invalid image width: %d, truncating.\n", width);
184
        width = s->screen_width;
185
    }
186
1294
    if (left >= s->screen_width) {
187
        av_log(s->avctx, AV_LOG_ERROR, "Invalid left position: %d.\n", left);
188
        return AVERROR_INVALIDDATA;
189
    }
190

1294
    if (!height || height > s->screen_height) {
191
        av_log(s->avctx, AV_LOG_WARNING, "Invalid image height: %d, truncating.\n", height);
192
        height = s->screen_height;
193
    }
194
1294
    if (top >= s->screen_height) {
195
        av_log(s->avctx, AV_LOG_ERROR, "Invalid top position: %d.\n", top);
196
        return AVERROR_INVALIDDATA;
197
    }
198
1294
    if (left + width > s->screen_width) {
199
        /* width must be kept around to avoid lzw vs line desync */
200
        pw = s->screen_width - left;
201
        av_log(s->avctx, AV_LOG_WARNING, "Image too wide by %d, truncating.\n",
202
               left + width - s->screen_width);
203
    } else {
204
1294
        pw = width;
205
    }
206
1294
    if (top + height > s->screen_height) {
207
        /* we don't care about the extra invisible lines */
208
        av_log(s->avctx, AV_LOG_WARNING, "Image too high by %d, truncating.\n",
209
               top + height - s->screen_height);
210
        height = s->screen_height - top;
211
    }
212
213
    /* process disposal method */
214
1294
    if (s->gce_prev_disposal == GCE_DISPOSAL_BACKGROUND) {
215
6
        gif_fill_rect(frame, s->stored_bg_color, s->gce_l, s->gce_t, s->gce_w, s->gce_h);
216
1288
    } else if (s->gce_prev_disposal == GCE_DISPOSAL_RESTORE) {
217
1
        gif_copy_img_rect(s->stored_img, (uint32_t *)frame->data[0],
218
1
            frame->linesize[0] / sizeof(uint32_t), s->gce_l, s->gce_t, s->gce_w, s->gce_h);
219
    }
220
221
1294
    s->gce_prev_disposal = s->gce_disposal;
222
223
1294
    if (s->gce_disposal != GCE_DISPOSAL_NONE) {
224
1293
        s->gce_l = left;  s->gce_t = top;
225
1293
        s->gce_w = pw;    s->gce_h = height;
226
227
1293
        if (s->gce_disposal == GCE_DISPOSAL_BACKGROUND) {
228
8
            if (s->transparent_color_index >= 0)
229
8
                s->stored_bg_color = s->trans_color;
230
            else
231
                s->stored_bg_color = s->bg_color;
232
1285
        } else if (s->gce_disposal == GCE_DISPOSAL_RESTORE) {
233
2
            av_fast_malloc(&s->stored_img, &s->stored_img_size, frame->linesize[0] * frame->height);
234
2
            if (!s->stored_img)
235
                return AVERROR(ENOMEM);
236
237
2
            gif_copy_img_rect((uint32_t *)frame->data[0], s->stored_img,
238
2
                frame->linesize[0] / sizeof(uint32_t), left, top, pw, height);
239
        }
240
    }
241
242
    /* Expect at least 2 bytes: 1 for lzw code size and 1 for block size. */
243
1294
    if (bytestream2_get_bytes_left(&s->gb) < 2)
244
        return AVERROR_INVALIDDATA;
245
246
    /* now get the image data */
247
1294
    code_size = bytestream2_get_byteu(&s->gb);
248
1294
    if ((ret = ff_lzw_decode_init(s->lzw, code_size, s->gb.buffer,
249
1294
                                  bytestream2_get_bytes_left(&s->gb), FF_LZW_GIF)) < 0) {
250
        av_log(s->avctx, AV_LOG_ERROR, "LZW init failed\n");
251
        return ret;
252
    }
253
254
    /* read all the image */
255
1294
    linesize = frame->linesize[0] / sizeof(uint32_t);
256
1294
    ptr1 = (uint32_t *)frame->data[0] + top * linesize + left;
257
1294
    ptr = ptr1;
258
1294
    pass = 0;
259
1294
    y1 = 0;
260
39267
    for (y = 0; y < height; y++) {
261
37973
        int count = ff_lzw_decode(s->lzw, s->idx_line, width);
262
37973
        if (count != width) {
263
            if (count)
264
                av_log(s->avctx, AV_LOG_ERROR, "LZW decode failed\n");
265
            goto decode_tail;
266
        }
267
268
37973
        pr = ptr + pw;
269
270
5366572
        for (px = ptr, idx = s->idx_line; px < pr; px++, idx++) {
271
5328599
            if (*idx != s->transparent_color_index)
272
3988325
                *px = pal[*idx];
273
        }
274
275
37973
        if (is_interleaved) {
276
            switch(pass) {
277
            default:
278
            case 0:
279
            case 1:
280
                y1 += 8;
281
                ptr += linesize * 8;
282
                break;
283
            case 2:
284
                y1 += 4;
285
                ptr += linesize * 4;
286
                break;
287
            case 3:
288
                y1 += 2;
289
                ptr += linesize * 2;
290
                break;
291
            }
292
            while (y1 >= height) {
293
                y1  = 4 >> pass;
294
                ptr = ptr1 + linesize * y1;
295
                pass++;
296
            }
297
        } else {
298
37973
            ptr += linesize;
299
        }
300
    }
301
302
1294
 decode_tail:
303
    /* read the garbage data until end marker is found */
304
1294
    lzwed_len = ff_lzw_decode_tail(s->lzw);
305
1294
    bytestream2_skipu(&s->gb, lzwed_len);
306
307
    /* Graphic Control Extension's scope is single frame.
308
     * Remove its influence. */
309
1294
    s->transparent_color_index = -1;
310
1294
    s->gce_disposal = GCE_DISPOSAL_NONE;
311
312
1294
    return 0;
313
}
314
315
1303
static int gif_read_extension(GifState *s)
316
{
317
    int ext_code, ext_len, gce_flags, gce_transparent_index;
318
319
    /* There must be at least 2 bytes:
320
     * 1 for extension label and 1 for extension length. */
321
1303
    if (bytestream2_get_bytes_left(&s->gb) < 2)
322
        return AVERROR_INVALIDDATA;
323
324
1303
    ext_code = bytestream2_get_byteu(&s->gb);
325
1303
    ext_len  = bytestream2_get_byteu(&s->gb);
326
327
    ff_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len);
328
329
1303
    switch(ext_code) {
330
1294
    case GIF_GCE_EXT_LABEL:
331
1294
        if (ext_len != 4)
332
            goto discard_ext;
333
334
        /* We need at least 5 bytes more: 4 is for extension body
335
         * and 1 for next block size. */
336
1294
        if (bytestream2_get_bytes_left(&s->gb) < 5)
337
            return AVERROR_INVALIDDATA;
338
339
1294
        gce_flags    = bytestream2_get_byteu(&s->gb);
340
1294
        bytestream2_skipu(&s->gb, 2);    // delay during which the frame is shown
341
1294
        gce_transparent_index = bytestream2_get_byteu(&s->gb);
342
1294
        if (gce_flags & 0x01)
343
46
            s->transparent_color_index = gce_transparent_index;
344
        else
345
1248
            s->transparent_color_index = -1;
346
1294
        s->gce_disposal = (gce_flags >> 2) & 0x7;
347
348
        ff_dlog(s->avctx, "gce_flags=%x tcolor=%d disposal=%d\n",
349
               gce_flags,
350
               s->transparent_color_index, s->gce_disposal);
351
352
1294
        if (s->gce_disposal > 3) {
353
            s->gce_disposal = GCE_DISPOSAL_NONE;
354
            ff_dlog(s->avctx, "invalid value in gce_disposal (%d). Using default value of 0.\n", ext_len);
355
        }
356
357
1294
        ext_len = bytestream2_get_byteu(&s->gb);
358
1294
        break;
359
    }
360
361
    /* NOTE: many extension blocks can come after */
362
1303
 discard_ext:
363
1330
    while (ext_len) {
364
        /* There must be at least ext_len bytes and 1 for next block size byte. */
365
27
        if (bytestream2_get_bytes_left(&s->gb) < ext_len + 1)
366
            return AVERROR_INVALIDDATA;
367
368
27
        bytestream2_skipu(&s->gb, ext_len);
369
27
        ext_len = bytestream2_get_byteu(&s->gb);
370
371
        ff_dlog(s->avctx, "ext_len1=%d\n", ext_len);
372
    }
373
1303
    return 0;
374
}
375
376
13
static int gif_read_header1(GifState *s)
377
{
378
    uint8_t sig[6];
379
    int v, n;
380
    int background_color_index;
381
382
13
    if (bytestream2_get_bytes_left(&s->gb) < 13)
383
        return AVERROR_INVALIDDATA;
384
385
    /* read gif signature */
386
13
    bytestream2_get_bufferu(&s->gb, sig, 6);
387
13
    if (memcmp(sig, gif87a_sig, 6) &&
388
13
        memcmp(sig, gif89a_sig, 6))
389
        return AVERROR_INVALIDDATA;
390
391
    /* read screen header */
392
13
    s->transparent_color_index = -1;
393
13
    s->screen_width  = bytestream2_get_le16u(&s->gb);
394
13
    s->screen_height = bytestream2_get_le16u(&s->gb);
395
396
13
    v = bytestream2_get_byteu(&s->gb);
397
13
    s->color_resolution = ((v & 0x70) >> 4) + 1;
398
13
    s->has_global_palette = (v & 0x80);
399
13
    s->bits_per_pixel = (v & 0x07) + 1;
400
13
    background_color_index = bytestream2_get_byteu(&s->gb);
401
13
    n = bytestream2_get_byteu(&s->gb);
402
13
    if (n) {
403
        s->avctx->sample_aspect_ratio.num = n + 15;
404
        s->avctx->sample_aspect_ratio.den = 64;
405
    }
406
407
    ff_dlog(s->avctx, "screen_w=%d screen_h=%d bpp=%d global_palette=%d\n",
408
           s->screen_width, s->screen_height, s->bits_per_pixel,
409
           s->has_global_palette);
410
411
13
    if (s->has_global_palette) {
412
6
        s->background_color_index = background_color_index;
413
6
        n = 1 << s->bits_per_pixel;
414
6
        if (bytestream2_get_bytes_left(&s->gb) < n * 3)
415
            return AVERROR_INVALIDDATA;
416
417
6
        gif_read_palette(s, s->global_palette, n);
418
6
        s->bg_color = s->global_palette[s->background_color_index];
419
    } else
420
7
        s->background_color_index = -1;
421
422
13
    return 0;
423
}
424
425
1294
static int gif_parse_next_image(GifState *s, AVFrame *frame)
426
{
427
2597
    while (bytestream2_get_bytes_left(&s->gb) > 0) {
428
2597
        int code = bytestream2_get_byte(&s->gb);
429
        int ret;
430
431
2597
        av_log(s->avctx, AV_LOG_DEBUG, "code=%02x '%c'\n", code, code);
432
433

2597
        switch (code) {
434
1294
        case GIF_IMAGE_SEPARATOR:
435
1294
            return gif_read_image(s, frame);
436
1303
        case GIF_EXTENSION_INTRODUCER:
437
1303
            if ((ret = gif_read_extension(s)) < 0)
438
                return ret;
439
1303
            break;
440
        case GIF_TRAILER:
441
            /* end of image */
442
            return AVERROR_EOF;
443
        default:
444
            /* erroneous block label */
445
            return AVERROR_INVALIDDATA;
446
        }
447
    }
448
    return AVERROR_EOF;
449
}
450
451
28
static av_cold int gif_decode_init(AVCodecContext *avctx)
452
{
453
28
    GifState *s = avctx->priv_data;
454
455
28
    s->avctx = avctx;
456
457
28
    avctx->pix_fmt = AV_PIX_FMT_RGB32;
458
28
    s->frame = av_frame_alloc();
459
28
    if (!s->frame)
460
        return AVERROR(ENOMEM);
461
28
    ff_lzw_decode_open(&s->lzw);
462
28
    if (!s->lzw)
463
        return AVERROR(ENOMEM);
464
28
    return 0;
465
}
466
467
1294
static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
468
{
469
1294
    GifState *s = avctx->priv_data;
470
    int ret;
471
472
1294
    bytestream2_init(&s->gb, avpkt->data, avpkt->size);
473
474
1294
    s->frame->pts     = avpkt->pts;
475
#if FF_API_PKT_PTS
476
FF_DISABLE_DEPRECATION_WARNINGS
477
1294
    s->frame->pkt_pts = avpkt->pts;
478
FF_ENABLE_DEPRECATION_WARNINGS
479
#endif
480
1294
    s->frame->pkt_dts = avpkt->dts;
481
1294
    s->frame->pkt_duration = avpkt->duration;
482
483
1294
    if (avpkt->size >= 6) {
484
2588
        s->keyframe = memcmp(avpkt->data, gif87a_sig, 6) == 0 ||
485
1294
                      memcmp(avpkt->data, gif89a_sig, 6) == 0;
486
    } else {
487
        s->keyframe = 0;
488
    }
489
490
1294
    if (s->keyframe) {
491
13
        s->keyframe_ok = 0;
492
13
        s->gce_prev_disposal = GCE_DISPOSAL_NONE;
493
13
        if ((ret = gif_read_header1(s)) < 0)
494
            return ret;
495
496
13
        if ((ret = ff_set_dimensions(avctx, s->screen_width, s->screen_height)) < 0)
497
            return ret;
498
499
13
        av_frame_unref(s->frame);
500
13
        if ((ret = ff_get_buffer(avctx, s->frame, 0)) < 0)
501
            return ret;
502
503
13
        av_fast_malloc(&s->idx_line, &s->idx_line_size, s->screen_width);
504
13
        if (!s->idx_line)
505
            return AVERROR(ENOMEM);
506
507
13
        s->frame->pict_type = AV_PICTURE_TYPE_I;
508
13
        s->frame->key_frame = 1;
509
13
        s->keyframe_ok = 1;
510
    } else {
511
1281
        if (!s->keyframe_ok) {
512
            av_log(avctx, AV_LOG_ERROR, "cannot decode frame without keyframe\n");
513
            return AVERROR_INVALIDDATA;
514
        }
515
516
1281
        if ((ret = ff_reget_buffer(avctx, s->frame, 0)) < 0)
517
            return ret;
518
519
1281
        s->frame->pict_type = AV_PICTURE_TYPE_P;
520
1281
        s->frame->key_frame = 0;
521
    }
522
523
1294
    ret = gif_parse_next_image(s, s->frame);
524
1294
    if (ret < 0)
525
        return ret;
526
527
1294
    if ((ret = av_frame_ref(data, s->frame)) < 0)
528
        return ret;
529
1294
    *got_frame = 1;
530
531
1294
    return bytestream2_tell(&s->gb);
532
}
533
534
28
static av_cold int gif_decode_close(AVCodecContext *avctx)
535
{
536
28
    GifState *s = avctx->priv_data;
537
538
28
    ff_lzw_decode_close(&s->lzw);
539
28
    av_frame_free(&s->frame);
540
28
    av_freep(&s->idx_line);
541
28
    av_freep(&s->stored_img);
542
543
28
    return 0;
544
}
545
546
static const AVOption options[] = {
547
    { "trans_color", "color value (ARGB) that is used instead of transparent color",
548
      offsetof(GifState, trans_color), AV_OPT_TYPE_INT,
549
      {.i64 = GIF_TRANSPARENT_COLOR}, 0, 0xffffffff,
550
      AV_OPT_FLAG_DECODING_PARAM|AV_OPT_FLAG_VIDEO_PARAM },
551
    { NULL },
552
};
553
554
static const AVClass decoder_class = {
555
    .class_name = "gif decoder",
556
    .item_name  = av_default_item_name,
557
    .option     = options,
558
    .version    = LIBAVUTIL_VERSION_INT,
559
    .category   = AV_CLASS_CATEGORY_DECODER,
560
};
561
562
AVCodec ff_gif_decoder = {
563
    .name           = "gif",
564
    .long_name      = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
565
    .type           = AVMEDIA_TYPE_VIDEO,
566
    .id             = AV_CODEC_ID_GIF,
567
    .priv_data_size = sizeof(GifState),
568
    .init           = gif_decode_init,
569
    .close          = gif_decode_close,
570
    .decode         = gif_decode_frame,
571
    .capabilities   = AV_CODEC_CAP_DR1,
572
    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |
573
                      FF_CODEC_CAP_INIT_CLEANUP,
574
    .priv_class     = &decoder_class,
575
};