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mirror of https://github.com/FFmpeg/FFmpeg.git synced 2024-12-07 11:13:41 +02:00
FFmpeg/libavformat/srtdec.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

227 lines
7.2 KiB
C

/*
* SubRip subtitle demuxer
* Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.org>
* Copyright (c) 2015 Clément Bœsch <u pkh me>
*
* 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 "avformat.h"
#include "internal.h"
#include "subtitles.h"
#include "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
typedef struct {
FFDemuxSubtitlesQueue q;
} SRTContext;
static int srt_probe(const AVProbeData *p)
{
int v;
char buf[64], *pbuf;
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);
/* Check if the first non-empty line is a number. We do not check what the
* number is because in practice it can be anything.
* Also, that number can be followed by random garbage, so we can not
* unfortunately check that we only have a number. */
if (ff_subtitles_read_line(&tr, buf, sizeof(buf)) < 0 ||
strtol(buf, &pbuf, 10) < 0 || pbuf == buf)
return 0;
/* Check if the next line matches a SRT timestamp */
if (ff_subtitles_read_line(&tr, buf, sizeof(buf)) < 0)
return 0;
pbuf = buf;
if (buf[0] == '-')
pbuf++;
if (pbuf[0] >= '0' && pbuf[0] <= '9' && strstr(buf, " --> ")
&& sscanf(buf, "%*d:%*d:%*d%*1[,.]%*d --> %*d:%*d:%*d%*1[,.]%d", &v) == 1)
return AVPROBE_SCORE_MAX;
return 0;
}
struct event_info {
int32_t x1, x2, y1, y2;
int duration;
int64_t pts;
int64_t pos;
};
static int get_event_info(const char *line, struct event_info *ei)
{
int hh1, mm1, ss1, ms1;
int hh2, mm2, ss2, ms2;
ei->x1 = ei->x2 = ei->y1 = ei->y2 = ei->duration = -1;
ei->pts = AV_NOPTS_VALUE;
ei->pos = -1;
if (sscanf(line, "%d:%d:%d%*1[,.]%d --> %d:%d:%d%*1[,.]%d"
"%*[ ]X1:%"PRId32" X2:%"PRId32" Y1:%"PRId32" Y2:%"PRId32,
&hh1, &mm1, &ss1, &ms1,
&hh2, &mm2, &ss2, &ms2,
&ei->x1, &ei->x2, &ei->y1, &ei->y2) >= 8) {
const int64_t start = (hh1*3600LL + mm1*60LL + ss1) * 1000LL + ms1;
const int64_t end = (hh2*3600LL + mm2*60LL + ss2) * 1000LL + ms2;
ei->duration = end - start;
ei->pts = start;
return 0;
}
return -1;
}
static int add_event(FFDemuxSubtitlesQueue *q, AVBPrint *buf, char *line_cache,
const struct event_info *ei, int append_cache)
{
if (append_cache && line_cache[0])
av_bprintf(buf, "%s\n", line_cache);
line_cache[0] = 0;
if (!av_bprint_is_complete(buf))
return AVERROR(ENOMEM);
while (buf->len > 0 && buf->str[buf->len - 1] == '\n')
buf->str[--buf->len] = 0;
if (buf->len) {
AVPacket *sub = ff_subtitles_queue_insert_bprint(q, buf, 0);
if (!sub)
return AVERROR(ENOMEM);
av_bprint_clear(buf);
sub->pos = ei->pos;
sub->pts = ei->pts;
sub->duration = ei->duration;
if (ei->x1 != -1) {
uint8_t *p = av_packet_new_side_data(sub, AV_PKT_DATA_SUBTITLE_POSITION, 16);
if (p) {
AV_WL32(p, ei->x1);
AV_WL32(p + 4, ei->y1);
AV_WL32(p + 8, ei->x2);
AV_WL32(p + 12, ei->y2);
}
}
}
return 0;
}
static int srt_read_header(AVFormatContext *s)
{
SRTContext *srt = s->priv_data;
AVBPrint buf;
AVStream *st = avformat_new_stream(s, NULL);
int res = 0;
char line[4096], line_cache[4096];
int has_event_info = 0;
struct event_info ei;
FFTextReader tr;
ff_text_init_avio(s, &tr, s->pb);
if (!st)
return AVERROR(ENOMEM);
avpriv_set_pts_info(st, 64, 1, 1000);
st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
st->codecpar->codec_id = AV_CODEC_ID_SUBRIP;
av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
line_cache[0] = 0;
while (!ff_text_eof(&tr)) {
struct event_info tmp_ei;
const int64_t pos = ff_text_pos(&tr);
ptrdiff_t len = ff_subtitles_read_line(&tr, line, sizeof(line));
if (len < 0)
break;
if (!len || !line[0])
continue;
if (get_event_info(line, &tmp_ei) < 0) {
char *pline;
if (!has_event_info)
continue;
if (line_cache[0]) {
/* We got some cache and a new line so we assume the cached
* line was actually part of the payload */
av_bprintf(&buf, "%s\n", line_cache);
line_cache[0] = 0;
}
/* If the line doesn't start with a number, we assume it's part of
* the payload, otherwise is likely an event number preceding the
* timing information... but we can't be sure of this yet, so we
* cache it */
if (strtol(line, &pline, 10) < 0 || line == pline)
av_bprintf(&buf, "%s\n", line);
else
strcpy(line_cache, line);
} else {
if (has_event_info) {
/* We have the information of previous event, append it to the
* queue. We insert the cached line if and only if the payload
* is empty and the cached line is not a standalone number. */
char *pline = NULL;
const int standalone_number = strtol(line_cache, &pline, 10) >= 0 && pline && !*pline;
res = add_event(&srt->q, &buf, line_cache, &ei, !buf.len && !standalone_number);
if (res < 0)
goto end;
} else {
has_event_info = 1;
}
tmp_ei.pos = pos;
ei = tmp_ei;
}
}
/* Append the last event. Here we force the cache to be flushed, because a
* trailing number is more likely to be geniune (for example a copyright
* date) and not the event index of an inexistant event */
if (has_event_info) {
res = add_event(&srt->q, &buf, line_cache, &ei, 1);
if (res < 0)
goto end;
}
ff_subtitles_queue_finalize(s, &srt->q);
end:
av_bprint_finalize(&buf, NULL);
return res;
}
const AVInputFormat ff_srt_demuxer = {
.name = "srt",
.long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
.priv_data_size = sizeof(SRTContext),
.flags_internal = FF_FMT_INIT_CLEANUP,
.read_probe = srt_probe,
.read_header = srt_read_header,
.read_packet = ff_subtitles_read_packet,
.read_seek2 = ff_subtitles_read_seek,
.read_close = ff_subtitles_read_close,
};