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 "pnm.h"
  27
  28 typedef struct PNMParseContext {
  29     ParseContext pc;
  30     int remaining_bytes;
  31     int ascii_scan;
  32 }PNMParseContext;
  33
  34 static int pnm_parse(AVCodecParserContext *s, AVCodecContext *avctx,
  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 && pnmctx.half)
 115             ret >>= 1;
 116         if (ret >= 0 && next + (uint64_t)ret <= INT_MAX)
 117             next += ret;
 118     }
 119     if (next != END_NOT_FOUND && pnmctx.bytestream_start != buf + skip)
 120         next -= pc->index;
 121     if (next > buf_size) {
 122         pnmpc->remaining_bytes = next - buf_size;
 123         next = END_NOT_FOUND;
 124     }
 125 end:
 126     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 127         *poutbuf      = NULL;
 128         *poutbuf_size = 0;
 129         return buf_size;
 130     }
 131     *poutbuf      = buf;
 132     *poutbuf_size = buf_size;
 133     return next;
 134 }
 135
 136 const AVCodecParser ff_pnm_parser = {
 137     .codec_ids      = { AV_CODEC_ID_PGM, AV_CODEC_ID_PGMYUV, AV_CODEC_ID_PPM,
 138                         AV_CODEC_ID_PBM, AV_CODEC_ID_PAM, AV_CODEC_ID_PFM,
 139                         AV_CODEC_ID_PHM },
 140     .priv_data_size = sizeof(PNMParseContext),
 141     .parser_parse   = pnm_parse,
 142     .parser_close   = ff_parse_close,
 143 };