libavcodec/pnm_parser.c

   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 "parser_internal.h"
  27 #include "pnm.h"
  28
  29 typedef struct PNMParseContext {
  30     ParseContext pc;
  31     int remaining_bytes;
  32     int ascii_scan;
  33 }PNMParseContext;
  34
  35 static int pnm_parse(AVCodecParserContext *s, AVCodecContext *avctx,
  36                      const uint8_t **poutbuf, int *poutbuf_size,
  37                      const uint8_t *buf, int buf_size)
  38 {
  39     PNMParseContext *pnmpc = s->priv_data;
  40     ParseContext *pc = &pnmpc->pc;
  41     PNMContext pnmctx;
  42     int next = END_NOT_FOUND;
  43     int skip = 0;
  44
  45     if (pc->overread > 0) {
  46         memmove(pc->buffer + pc->index, pc->buffer + pc->overread_index, pc->overread);
  47         pc->index          += pc->overread;
  48         pc->overread_index += pc->overread;
  49         pc->overread = 0;
  50     }
  51
  52     if (pnmpc->remaining_bytes) {
  53         int inc = FFMIN(pnmpc->remaining_bytes, buf_size);
  54         skip += inc;
  55         pnmpc->remaining_bytes -= inc;
  56
  57         if (!pnmpc->remaining_bytes)
  58             next = skip;
  59         goto end;
  60     }
  61
  62 retry:
  63     if (pc->index) {
  64         pnmctx.bytestream_start =
  65         pnmctx.bytestream       = pc->buffer;
  66         pnmctx.bytestream_end   = pc->buffer + pc->index;
  67     } else {
  68         pnmctx.bytestream_start =
  69         pnmctx.bytestream       = buf + skip;
  70         pnmctx.bytestream_end   = buf + buf_size - skip;
  71     }
  72     if (ff_pnm_decode_header(avctx, &pnmctx) < 0) {
  73         if (pnmctx.bytestream < pnmctx.bytestream_end) {
  74             if (pc->index) {
  75                 pc->index = 0;
  76                 pnmpc->ascii_scan = 0;
  77             } else {
  78                 unsigned step = FFMAX(1, pnmctx.bytestream - pnmctx.bytestream_start);
  79
  80                 skip += step;
  81             }
  82             goto retry;
  83         }
  84     } else if (pnmctx.type < 4) {
  85         const uint8_t *bs   = pnmctx.bytestream;
  86         const uint8_t *end = pnmctx.bytestream_end;
  87         const uint8_t *sync = bs;
  88
  89         if (pc->index) {
  90             av_assert0(pnmpc->ascii_scan <= end - bs);
  91             bs += pnmpc->ascii_scan;
  92         }
  93
  94         while (bs < end) {
  95             int c;
  96             sync = bs;
  97             c = *bs++;
  98             if (c == '#')  {
  99                 uint8_t *match = memchr(bs, '\n', end-bs);
 100                 if (match)
 101                     bs = match + 1;
 102                 else
 103                     break;
 104             } else if (c == 'P') {
 105                 next = bs - pnmctx.bytestream_start + skip - 1;
 106                 pnmpc->ascii_scan = 0;
 107                 break;
 108             }
 109         }
 110         if (next == END_NOT_FOUND)
 111             pnmpc->ascii_scan = sync - pnmctx.bytestream + skip;
 112     } else {
 113         int ret = av_image_get_buffer_size(avctx->pix_fmt, avctx->width, avctx->height, 1);
 114         next = pnmctx.bytestream - pnmctx.bytestream_start + skip;
 115         if (ret > 0 && pnmctx.half)
 116             ret >>= 1;
 117         if (ret >= 0 && next + (uint64_t)ret <= INT_MAX)
 118             next += ret;
 119     }
 120     if (next != END_NOT_FOUND && pnmctx.bytestream_start != buf + skip)
 121         next -= pc->index;
 122     if (next > buf_size) {
 123         pnmpc->remaining_bytes = next - buf_size;
 124         next = END_NOT_FOUND;
 125     }
 126 end:
 127     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 128         *poutbuf      = NULL;
 129         *poutbuf_size = 0;
 130         return buf_size;
 131     }
 132     *poutbuf      = buf;
 133     *poutbuf_size = buf_size;
 134     return next;
 135 }
 136
 137 const FFCodecParser ff_pnm_parser = {
 138     PARSER_CODEC_LIST(AV_CODEC_ID_PGM, AV_CODEC_ID_PGMYUV, AV_CODEC_ID_PPM,
 139                       AV_CODEC_ID_PBM, AV_CODEC_ID_PAM, AV_CODEC_ID_PFM,
 140                       AV_CODEC_ID_PHM),
 141     .priv_data_size = sizeof(PNMParseContext),
 142     .parse          = pnm_parse,
 143     .close          = ff_parse_close,
 144 };