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![Clément Bœsch](/assets/img/avatar_default.png)
This fixes a bunch of possible overread in avformat with the idiom p += strcspn(p, "\n") + 1 (strcspn() can focus on the trailing '\0' if no '\n' is found, so the +1 leads to an overread). Note on lavf/matroskaenc: no extra subtitles.o Makefile dependency is added because only the header is required for ff_subtitles_next_line(). Note on lavf/mpsubdec: code gets slightly complex to avoid an infinite loop in the probing since there is no more forced increment.
166 lines
5.0 KiB
C
166 lines
5.0 KiB
C
/*
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* SubRip subtitle demuxer
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* Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.org>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avformat.h"
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#include "internal.h"
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#include "subtitles.h"
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#include "libavutil/bprint.h"
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#include "libavutil/intreadwrite.h"
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typedef struct {
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FFDemuxSubtitlesQueue q;
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} SRTContext;
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static int srt_probe(AVProbeData *p)
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{
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const unsigned char *ptr = p->buf;
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int i, v, num = 0;
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if (AV_RB24(ptr) == 0xEFBBBF)
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ptr += 3; /* skip UTF-8 BOM */
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while (*ptr == '\r' || *ptr == '\n')
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ptr++;
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for (i=0; i<2; i++) {
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if ((num == i || num + 1 == i)
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&& sscanf(ptr, "%*d:%*2d:%*2d%*1[,.]%*3d --> %*d:%*2d:%*2d%*1[,.]%3d", &v) == 1)
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return AVPROBE_SCORE_MAX;
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num = atoi(ptr);
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ptr += ff_subtitles_next_line(ptr);
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}
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return 0;
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}
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static int64_t get_pts(const char **buf, int *duration,
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int32_t *x1, int32_t *y1, int32_t *x2, int32_t *y2)
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{
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int i;
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for (i=0; i<2; i++) {
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int hh1, mm1, ss1, ms1;
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int hh2, mm2, ss2, ms2;
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if (sscanf(*buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
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"%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
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&hh1, &mm1, &ss1, &ms1,
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&hh2, &mm2, &ss2, &ms2,
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x1, x2, y1, y2) >= 8) {
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int64_t start = (hh1*3600LL + mm1*60LL + ss1) * 1000LL + ms1;
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int64_t end = (hh2*3600LL + mm2*60LL + ss2) * 1000LL + ms2;
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*duration = end - start;
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*buf += ff_subtitles_next_line(*buf);
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return start;
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}
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*buf += ff_subtitles_next_line(*buf);
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}
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return AV_NOPTS_VALUE;
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}
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static int srt_read_header(AVFormatContext *s)
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{
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SRTContext *srt = s->priv_data;
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AVBPrint buf;
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AVStream *st = avformat_new_stream(s, NULL);
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int res = 0;
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if (!st)
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return AVERROR(ENOMEM);
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avpriv_set_pts_info(st, 64, 1, 1000);
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st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
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st->codec->codec_id = AV_CODEC_ID_SUBRIP;
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av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
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while (!url_feof(s->pb)) {
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ff_subtitles_read_chunk(s->pb, &buf);
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if (buf.len) {
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int64_t pos = avio_tell(s->pb);
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int64_t pts;
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int duration;
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const char *ptr = buf.str;
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int32_t x1 = -1, y1 = -1, x2 = -1, y2 = -1;
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AVPacket *sub;
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pts = get_pts(&ptr, &duration, &x1, &y1, &x2, &y2);
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if (pts != AV_NOPTS_VALUE) {
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int len = buf.len - (ptr - buf.str);
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if (len <= 0)
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continue;
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sub = ff_subtitles_queue_insert(&srt->q, ptr, len, 0);
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if (!sub) {
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res = AVERROR(ENOMEM);
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goto end;
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}
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sub->pos = pos;
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sub->pts = pts;
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sub->duration = duration;
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if (x1 != -1) {
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uint8_t *p = av_packet_new_side_data(sub, AV_PKT_DATA_SUBTITLE_POSITION, 16);
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if (p) {
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AV_WL32(p, x1);
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AV_WL32(p + 4, y1);
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AV_WL32(p + 8, x2);
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AV_WL32(p + 12, y2);
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}
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}
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}
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}
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}
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ff_subtitles_queue_finalize(&srt->q);
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end:
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av_bprint_finalize(&buf, NULL);
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return res;
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}
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static int srt_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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SRTContext *srt = s->priv_data;
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return ff_subtitles_queue_read_packet(&srt->q, pkt);
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}
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static int srt_read_seek(AVFormatContext *s, int stream_index,
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int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
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{
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SRTContext *srt = s->priv_data;
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return ff_subtitles_queue_seek(&srt->q, s, stream_index,
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min_ts, ts, max_ts, flags);
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}
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static int srt_read_close(AVFormatContext *s)
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{
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SRTContext *srt = s->priv_data;
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ff_subtitles_queue_clean(&srt->q);
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return 0;
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}
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AVInputFormat ff_srt_demuxer = {
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.name = "srt",
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.long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
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.priv_data_size = sizeof(SRTContext),
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.read_probe = srt_probe,
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.read_header = srt_read_header,
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.read_packet = srt_read_packet,
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.read_seek2 = srt_read_seek,
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.read_close = srt_read_close,
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};
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