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FFmpeg/libavformat/assdec.c
Reimar Döffinger c0f867bf50 libavformat: fix incorrect handling of incomplete AVBPrint.
Change some internal APIs a bit to make it harder to make
such mistakes.
In particular, have the read chunk functions return an error
when the result is incomplete.
This might be less flexible, but since there has been no
use-case for that so far, avoiding coding mistakes seems better.
Add a function to queue a AVBPrint directly (ff_subtitles_queue_insert_bprint).
Also fixes a leak in lrcdec when ff_subtitles_queue_insert fails.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
2023-07-29 16:05:29 +02:00

174 lines
4.9 KiB
C

/*
* SSA/ASS demuxer
* Copyright (c) 2008 Michael Niedermayer
* Copyright (c) 2014 Clément Bœsch
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdint.h>
#include "avformat.h"
#include "internal.h"
#include "subtitles.h"
#include "libavutil/bprint.h"
typedef struct ASSContext {
FFDemuxSubtitlesQueue q;
unsigned readorder;
} ASSContext;
static int ass_probe(const AVProbeData *p)
{
char buf[13];
FFTextReader tr;
ff_text_init_buf(&tr, p->buf, p->buf_size);
while (ff_text_peek_r8(&tr) == '\r' || ff_text_peek_r8(&tr) == '\n')
ff_text_r8(&tr);
ff_text_read(&tr, buf, sizeof(buf));
if (!memcmp(buf, "[Script Info]", 13))
return AVPROBE_SCORE_MAX;
return 0;
}
static int read_dialogue(ASSContext *ass, AVBPrint *dst, const uint8_t *p,
int64_t *start, int *duration)
{
int pos = 0;
int64_t end;
int hh1, mm1, ss1, ms1;
int hh2, mm2, ss2, ms2;
if (sscanf(p, "Dialogue: %*[^,],%d:%d:%d%*c%d,%d:%d:%d%*c%d,%n",
&hh1, &mm1, &ss1, &ms1,
&hh2, &mm2, &ss2, &ms2, &pos) >= 8 && pos > 0) {
/* This is not part of the sscanf itself in order to handle an actual
* number (which would be the Layer) or the form "Marked=N" (which is
* the old SSA field, now replaced by Layer, and will lead to Layer
* being 0 here). */
const int layer = atoi(p + 10);
end = (hh2*3600LL + mm2*60LL + ss2) * 100LL + ms2;
*start = (hh1*3600LL + mm1*60LL + ss1) * 100LL + ms1;
*duration = end - *start;
av_bprint_clear(dst);
av_bprintf(dst, "%u,%d,%s", ass->readorder++, layer, p + pos);
if (!av_bprint_is_complete(dst))
return AVERROR(ENOMEM);
/* right strip the buffer */
while (dst->len > 0 &&
dst->str[dst->len - 1] == '\r' ||
dst->str[dst->len - 1] == '\n')
dst->str[--dst->len] = 0;
return 0;
}
return -1;
}
static int64_t get_line(AVBPrint *buf, FFTextReader *tr)
{
int64_t pos = ff_text_pos(tr);
av_bprint_clear(buf);
for (;;) {
char c = ff_text_r8(tr);
if (!c)
break;
av_bprint_chars(buf, c, 1);
if (c == '\n')
break;
}
return pos;
}
static int ass_read_header(AVFormatContext *s)
{
ASSContext *ass = s->priv_data;
AVBPrint header, line, rline;
int res = 0;
AVStream *st;
FFTextReader tr;
ff_text_init_avio(s, &tr, s->pb);
st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
avpriv_set_pts_info(st, 64, 1, 100);
st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
st->codecpar->codec_id = AV_CODEC_ID_ASS;
av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED);
av_bprint_init(&line, 0, AV_BPRINT_SIZE_UNLIMITED);
av_bprint_init(&rline, 0, AV_BPRINT_SIZE_UNLIMITED);
ass->q.keep_duplicates = 1;
for (;;) {
int64_t pos = get_line(&line, &tr);
int64_t ts_start = AV_NOPTS_VALUE;
int duration = -1;
AVPacket *sub;
if (!line.str[0]) // EOF
break;
if (read_dialogue(ass, &rline, line.str, &ts_start, &duration) < 0) {
av_bprintf(&header, "%s", line.str);
continue;
}
sub = ff_subtitles_queue_insert_bprint(&ass->q, &rline, 0);
if (!sub) {
res = AVERROR(ENOMEM);
goto end;
}
sub->pos = pos;
sub->pts = ts_start;
sub->duration = duration;
}
res = ff_bprint_to_codecpar_extradata(st->codecpar, &header);
if (res < 0)
goto end;
ff_subtitles_queue_finalize(s, &ass->q);
end:
av_bprint_finalize(&header, NULL);
av_bprint_finalize(&line, NULL);
av_bprint_finalize(&rline, NULL);
return res;
}
const AVInputFormat ff_ass_demuxer = {
.name = "ass",
.long_name = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),
.flags_internal = FF_FMT_INIT_CLEANUP,
.priv_data_size = sizeof(ASSContext),
.read_probe = ass_probe,
.read_header = ass_read_header,
.read_packet = ff_subtitles_read_packet,
.read_close = ff_subtitles_read_close,
.read_seek2 = ff_subtitles_read_seek,
};