libavcodec/dvdsub_parser.c

   1 /*
   2  * DVD subtitle decoding
   3  * Copyright (c) 2005 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 <string.h>
  23
  24 #include "libavutil/intreadwrite.h"
  25 #include "libavutil/mem.h"
  26 #include "avcodec.h"
  27
  28 /* parser definition */
  29 typedef struct DVDSubParseContext {
  30     uint8_t *packet;
  31     int packet_len;
  32     int packet_index;
  33 } DVDSubParseContext;
  34
  35 static int dvdsub_parse(AVCodecParserContext *s,
  36                         AVCodecContext *avctx,
  37                         const uint8_t **poutbuf, int *poutbuf_size,
  38                         const uint8_t *buf, int buf_size)
  39 {
  40     DVDSubParseContext *pc = s->priv_data;
  41
  42     *poutbuf      = buf;
  43     *poutbuf_size = buf_size;
  44
  45     if (pc->packet_index == 0) {
  46         if (buf_size < 2 || (AV_RB16(buf) == 0 && buf_size < 6)) {
  47             if (buf_size)
  48                 av_log(avctx, AV_LOG_DEBUG, "Parser input %d too small\n", buf_size);
  49             return buf_size;
  50         }
  51         pc->packet_len = AV_RB16(buf);
  52         if (pc->packet_len == 0) /* HD-DVD subpicture packet */
  53             pc->packet_len = AV_RB32(buf+2);
  54         av_freep(&pc->packet);
  55         if ((unsigned)pc->packet_len > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE) {
  56             av_log(avctx, AV_LOG_ERROR, "packet length %d is invalid\n", pc->packet_len);
  57             return buf_size;
  58         }
  59         pc->packet = av_malloc(pc->packet_len + AV_INPUT_BUFFER_PADDING_SIZE);
  60     }
  61     if (pc->packet) {
  62         if (pc->packet_index + buf_size <= pc->packet_len) {
  63             memcpy(pc->packet + pc->packet_index, buf, buf_size);
  64             pc->packet_index += buf_size;
  65             if (pc->packet_index >= pc->packet_len) {
  66                 *poutbuf = pc->packet;
  67                 *poutbuf_size = pc->packet_len;
  68                 pc->packet_index = 0;
  69                 return buf_size;
  70             }
  71         } else {
  72             /* erroneous size */
  73             pc->packet_index = 0;
  74         }
  75     }
  76     *poutbuf = NULL;
  77     *poutbuf_size = 0;
  78     return buf_size;
  79 }
  80
  81 static av_cold void dvdsub_parse_close(AVCodecParserContext *s)
  82 {
  83     DVDSubParseContext *pc = s->priv_data;
  84     av_freep(&pc->packet);
  85 }
  86
  87 const AVCodecParser ff_dvdsub_parser = {
  88     .codec_ids      = { AV_CODEC_ID_DVD_SUBTITLE },
  89     .priv_data_size = sizeof(DVDSubParseContext),
  90     .parser_parse   = dvdsub_parse,
  91     .parser_close   = dvdsub_parse_close,
  92 };