FFmpeg  4.3.6
pnm_parser.c
Go to the documentation of this file.
1 /*
2  * PNM image parser
3  * Copyright (c) 2002, 2003 Fabrice Bellard
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 #include "libavutil/avassert.h"
23 #include "libavutil/imgutils.h"
24 
25 #include "parser.h" //for ParseContext
26 #include "pnm.h"
27 
28 typedef struct PNMParseContext {
33 
35  const uint8_t **poutbuf, int *poutbuf_size,
36  const uint8_t *buf, int buf_size)
37 {
38  PNMParseContext *pnmpc = s->priv_data;
39  ParseContext *pc = &pnmpc->pc;
40  PNMContext pnmctx;
41  int next = END_NOT_FOUND;
42  int skip = 0;
43 
44  if (pc->overread > 0) {
45  memmove(pc->buffer + pc->index, pc->buffer + pc->overread_index, pc->overread);
46  pc->index += pc->overread;
47  pc->overread_index += pc->overread;
48  pc->overread = 0;
49  }
50 
51  if (pnmpc->remaining_bytes) {
52  int inc = FFMIN(pnmpc->remaining_bytes, buf_size);
53  skip += inc;
54  pnmpc->remaining_bytes -= inc;
55 
56  if (!pnmpc->remaining_bytes)
57  next = skip;
58  goto end;
59  }
60 
61 retry:
62  if (pc->index) {
63  pnmctx.bytestream_start =
64  pnmctx.bytestream = pc->buffer;
65  pnmctx.bytestream_end = pc->buffer + pc->index;
66  } else {
67  pnmctx.bytestream_start =
68  pnmctx.bytestream = (uint8_t *) buf + skip; /* casts avoid warnings */
69  pnmctx.bytestream_end = (uint8_t *) buf + buf_size - skip;
70  }
71  if (ff_pnm_decode_header(avctx, &pnmctx) < 0) {
72  if (pnmctx.bytestream < pnmctx.bytestream_end) {
73  if (pc->index) {
74  pc->index = 0;
75  pnmpc->ascii_scan = 0;
76  } else {
77  unsigned step = FFMAX(1, pnmctx.bytestream - pnmctx.bytestream_start);
78 
79  skip += step;
80  }
81  goto retry;
82  }
83  } else if (pnmctx.type < 4) {
84  uint8_t *bs = pnmctx.bytestream;
85  const uint8_t *end = pnmctx.bytestream_end;
86  uint8_t *sync = bs;
87 
88  if (pc->index) {
89  av_assert0(pnmpc->ascii_scan <= end - bs);
90  bs += pnmpc->ascii_scan;
91  }
92 
93  while (bs < end) {
94  int c;
95  sync = bs;
96  c = *bs++;
97  if (c == '#') {
98  uint8_t *match = memchr(bs, '\n', end-bs);
99  if (match)
100  bs = match + 1;
101  else
102  break;
103  } else if (c == 'P') {
104  next = bs - pnmctx.bytestream_start + skip - 1;
105  pnmpc->ascii_scan = 0;
106  break;
107  }
108  }
109  if (next == END_NOT_FOUND)
110  pnmpc->ascii_scan = sync - pnmctx.bytestream + skip;
111  } else {
112  int ret = av_image_get_buffer_size(avctx->pix_fmt, avctx->width, avctx->height, 1);
113  next = pnmctx.bytestream - pnmctx.bytestream_start + skip;
114  if (ret >= 0 && next + (uint64_t)ret <= INT_MAX)
115  next += ret;
116  }
117  if (next != END_NOT_FOUND && pnmctx.bytestream_start != buf + skip)
118  next -= pc->index;
119  if (next > buf_size) {
120  pnmpc->remaining_bytes = next - buf_size;
121  next = END_NOT_FOUND;
122  }
123 end:
124  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
125  *poutbuf = NULL;
126  *poutbuf_size = 0;
127  return buf_size;
128  }
129  *poutbuf = buf;
130  *poutbuf_size = buf_size;
131  return next;
132 }
133 
137  .priv_data_size = sizeof(PNMParseContext),
138  .parser_parse = pnm_parse,
139  .parser_close = ff_parse_close,
140 };
#define NULL
Definition: coverity.c:32
misc image utilities
int codec_ids[5]
Definition: avcodec.h:3521
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:736
uint8_t * bytestream
Definition: pnm.h:28
AVCodecParser ff_pnm_parser
Definition: pnm_parser.c:134
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
uint8_t
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:92
int av_image_get_buffer_size(enum AVPixelFormat pix_fmt, int width, int height, int align)
Return the size in bytes of the amount of data required to store an image with the given parameters...
Definition: imgutils.c:431
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
Combine the (truncated) bitstream to a complete frame.
Definition: parser.c:234
simple assert() macros that are a bit more flexible than ISO C assert().
int overread_index
the index into ParseContext.buffer of the overread bytes
Definition: parser.h:36
uint8_t * bytestream_end
Definition: pnm.h:30
#define FFMAX(a, b)
Definition: common.h:94
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:319
int overread
the number of bytes which where irreversibly read from the next frame
Definition: parser.h:35
#define FFMIN(a, b)
Definition: common.h:96
int width
picture width / height.
Definition: avcodec.h:699
#define s(width, name)
Definition: cbs_vp9.c:257
Definition: pnm.h:27
uint8_t * buffer
Definition: parser.h:29
int ff_pnm_decode_header(AVCodecContext *avctx, PNMContext *const s)
Definition: pnm.c:65
main external API structure.
Definition: avcodec.h:526
#define END_NOT_FOUND
Definition: parser.h:40
static int pnm_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: pnm_parser.c:34
ParseContext pc
Definition: pnm_parser.c:29
static double c[64]
int index
Definition: parser.h:30
uint8_t * bytestream_start
Definition: pnm.h:29
int type
Definition: pnm.h:32