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FFmpeg/libavformat/tedcaptionsdec.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

370 lines
11 KiB
C

/*
* TED Talks captions format decoder
* Copyright (c) 2012 Nicolas George
*
* 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 "libavutil/bprint.h"
#include "libavutil/log.h"
#include "libavutil/opt.h"
#include "avformat.h"
#include "internal.h"
#include "subtitles.h"
typedef struct {
AVClass *class;
int64_t start_time;
FFDemuxSubtitlesQueue subs;
} TEDCaptionsDemuxer;
static const AVOption tedcaptions_options[] = {
{ "start_time", "set the start time (offset) of the subtitles, in ms",
offsetof(TEDCaptionsDemuxer, start_time), AV_OPT_TYPE_INT64,
{ .i64 = 15000 }, INT64_MIN, INT64_MAX,
AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM },
{ NULL },
};
static const AVClass tedcaptions_demuxer_class = {
.class_name = "tedcaptions_demuxer",
.item_name = av_default_item_name,
.option = tedcaptions_options,
.version = LIBAVUTIL_VERSION_INT,
};
#define BETWEEN(a, amin, amax) ((unsigned)((a) - (amin)) <= (amax) - (amin))
#define HEX_DIGIT_TEST(c) (BETWEEN(c, '0', '9') || BETWEEN((c) | 32, 'a', 'z'))
#define HEX_DIGIT_VAL(c) ((c) <= '9' ? (c) - '0' : ((c) | 32) - 'a' + 10)
#define ERR_CODE(c) ((c) < 0 ? (c) : AVERROR_INVALIDDATA)
static void av_bprint_utf8(AVBPrint *bp, unsigned c)
{
int bytes, i;
if (c <= 0x7F) {
av_bprint_chars(bp, c, 1);
return;
}
bytes = (av_log2(c) - 2) / 5;
av_bprint_chars(bp, (c >> (bytes * 6)) | ((0xFF80 >> bytes) & 0xFF), 1);
for (i = bytes - 1; i >= 0; i--)
av_bprint_chars(bp, ((c >> (i * 6)) & 0x3F) | 0x80, 1);
}
static void next_byte(AVIOContext *pb, int *cur_byte)
{
uint8_t b;
int ret = avio_read(pb, &b, 1);
*cur_byte = ret > 0 ? b : ret == 0 ? AVERROR_EOF : ret;
}
static void skip_spaces(AVIOContext *pb, int *cur_byte)
{
while (*cur_byte == ' ' || *cur_byte == '\t' ||
*cur_byte == '\n' || *cur_byte == '\r')
next_byte(pb, cur_byte);
}
static int expect_byte(AVIOContext *pb, int *cur_byte, uint8_t c)
{
skip_spaces(pb, cur_byte);
if (*cur_byte != c)
return ERR_CODE(*cur_byte);
next_byte(pb, cur_byte);
return 0;
}
static int parse_string(AVIOContext *pb, int *cur_byte, AVBPrint *bp, int full)
{
int ret;
ret = expect_byte(pb, cur_byte, '"');
if (ret < 0)
return ret;
while (*cur_byte > 0 && *cur_byte != '"') {
if (*cur_byte == '\\') {
next_byte(pb, cur_byte);
if (*cur_byte < 0)
return AVERROR_INVALIDDATA;
if ((*cur_byte | 32) == 'u') {
unsigned chr = 0, i;
for (i = 0; i < 4; i++) {
next_byte(pb, cur_byte);
if (!HEX_DIGIT_TEST(*cur_byte))
return ERR_CODE(*cur_byte);
chr = chr * 16 + HEX_DIGIT_VAL(*cur_byte);
}
av_bprint_utf8(bp, chr);
} else {
av_bprint_chars(bp, *cur_byte, 1);
}
} else {
av_bprint_chars(bp, *cur_byte, 1);
}
next_byte(pb, cur_byte);
}
ret = expect_byte(pb, cur_byte, '"');
if (ret < 0)
return ret;
if (full && !av_bprint_is_complete(bp))
return AVERROR(ENOMEM);
return 0;
}
static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp)
{
int ret;
av_bprint_init(bp, 0, AV_BPRINT_SIZE_AUTOMATIC);
ret = parse_string(pb, cur_byte, bp, 0);
if (ret < 0)
return ret;
ret = expect_byte(pb, cur_byte, ':');
if (ret < 0)
return ret;
return 0;
}
static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result)
{
static const char * const text[] = { "false", "true" };
const char *p;
int i;
skip_spaces(pb, cur_byte);
for (i = 0; i < 2; i++) {
p = text[i];
if (*cur_byte != *p)
continue;
for (; *p; p++, next_byte(pb, cur_byte))
if (*cur_byte != *p)
return AVERROR_INVALIDDATA;
if (BETWEEN(*cur_byte | 32, 'a', 'z'))
return AVERROR_INVALIDDATA;
*result = i;
return 0;
}
return AVERROR_INVALIDDATA;
}
static int parse_int(AVIOContext *pb, int *cur_byte, int64_t *result)
{
int64_t val = 0;
skip_spaces(pb, cur_byte);
if ((unsigned)*cur_byte - '0' > 9)
return AVERROR_INVALIDDATA;
while (BETWEEN(*cur_byte, '0', '9')) {
if (val > INT_MAX/10 - (*cur_byte - '0'))
return AVERROR_INVALIDDATA;
val = val * 10 + (*cur_byte - '0');
next_byte(pb, cur_byte);
}
*result = val;
return 0;
}
static int parse_file(AVIOContext *pb, FFDemuxSubtitlesQueue *subs)
{
int ret, cur_byte, start_of_par;
AVBPrint label, content;
int64_t pos, start, duration;
AVPacket *pkt;
av_bprint_init(&content, 0, AV_BPRINT_SIZE_UNLIMITED);
next_byte(pb, &cur_byte);
ret = expect_byte(pb, &cur_byte, '{');
if (ret < 0)
return AVERROR_INVALIDDATA;
ret = parse_label(pb, &cur_byte, &label);
if (ret < 0 || strcmp(label.str, "captions"))
return AVERROR_INVALIDDATA;
ret = expect_byte(pb, &cur_byte, '[');
if (ret < 0)
return AVERROR_INVALIDDATA;
while (1) {
start = duration = AV_NOPTS_VALUE;
ret = expect_byte(pb, &cur_byte, '{');
if (ret < 0)
goto fail;
pos = avio_tell(pb) - 1;
while (1) {
ret = parse_label(pb, &cur_byte, &label);
if (ret < 0)
goto fail;
if (!strcmp(label.str, "startOfParagraph")) {
ret = parse_boolean(pb, &cur_byte, &start_of_par);
if (ret < 0)
goto fail;
} else if (!strcmp(label.str, "content")) {
ret = parse_string(pb, &cur_byte, &content, 1);
if (ret < 0)
goto fail;
} else if (!strcmp(label.str, "startTime")) {
ret = parse_int(pb, &cur_byte, &start);
if (ret < 0)
goto fail;
} else if (!strcmp(label.str, "duration")) {
ret = parse_int(pb, &cur_byte, &duration);
if (ret < 0)
goto fail;
} else {
ret = AVERROR_INVALIDDATA;
goto fail;
}
skip_spaces(pb, &cur_byte);
if (cur_byte != ',')
break;
next_byte(pb, &cur_byte);
}
ret = expect_byte(pb, &cur_byte, '}');
if (ret < 0)
goto fail;
if (!content.size || start == AV_NOPTS_VALUE ||
duration == AV_NOPTS_VALUE) {
ret = AVERROR_INVALIDDATA;
goto fail;
}
pkt = ff_subtitles_queue_insert_bprint(subs, &content, 0);
if (!pkt) {
ret = AVERROR(ENOMEM);
goto fail;
}
pkt->pos = pos;
pkt->pts = start;
pkt->duration = duration;
av_bprint_clear(&content);
skip_spaces(pb, &cur_byte);
if (cur_byte != ',')
break;
next_byte(pb, &cur_byte);
}
ret = expect_byte(pb, &cur_byte, ']');
if (ret < 0)
goto fail;
ret = expect_byte(pb, &cur_byte, '}');
if (ret < 0)
goto fail;
skip_spaces(pb, &cur_byte);
if (cur_byte != AVERROR_EOF)
ret = ERR_CODE(cur_byte);
fail:
av_bprint_finalize(&content, NULL);
return ret;
}
static av_cold int tedcaptions_read_header(AVFormatContext *avf)
{
TEDCaptionsDemuxer *tc = avf->priv_data;
AVStream *st = avformat_new_stream(avf, NULL);
FFStream *sti;
int ret, i;
AVPacket *last;
if (!st)
return AVERROR(ENOMEM);
sti = ffstream(st);
ret = parse_file(avf->pb, &tc->subs);
if (ret < 0) {
if (ret == AVERROR_INVALIDDATA)
av_log(avf, AV_LOG_ERROR, "Syntax error near offset %"PRId64".\n",
avio_tell(avf->pb));
return ret;
}
ff_subtitles_queue_finalize(avf, &tc->subs);
for (i = 0; i < tc->subs.nb_subs; i++)
tc->subs.subs[i]->pts += tc->start_time;
last = tc->subs.subs[tc->subs.nb_subs - 1];
st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
st->codecpar->codec_id = AV_CODEC_ID_TEXT;
avpriv_set_pts_info(st, 64, 1, 1000);
sti->probe_packets = 0;
st->start_time = 0;
st->duration = last->pts + last->duration;
sti->cur_dts = 0;
return 0;
}
static int tedcaptions_read_packet(AVFormatContext *avf, AVPacket *packet)
{
TEDCaptionsDemuxer *tc = avf->priv_data;
return ff_subtitles_queue_read_packet(&tc->subs, packet);
}
static int tedcaptions_read_close(AVFormatContext *avf)
{
TEDCaptionsDemuxer *tc = avf->priv_data;
ff_subtitles_queue_clean(&tc->subs);
return 0;
}
static av_cold int tedcaptions_read_probe(const AVProbeData *p)
{
static const char *const tags[] = {
"\"captions\"", "\"duration\"", "\"content\"",
"\"startOfParagraph\"", "\"startTime\"",
};
unsigned i, count = 0;
const char *t;
if (p->buf[strspn(p->buf, " \t\r\n")] != '{')
return 0;
for (i = 0; i < FF_ARRAY_ELEMS(tags); i++) {
if (!(t = strstr(p->buf, tags[i])))
continue;
t += strlen(tags[i]);
t += strspn(t, " \t\r\n");
if (*t == ':')
count++;
}
return count == FF_ARRAY_ELEMS(tags) ? AVPROBE_SCORE_MAX :
count ? AVPROBE_SCORE_EXTENSION : 0;
}
static int tedcaptions_read_seek(AVFormatContext *avf, int stream_index,
int64_t min_ts, int64_t ts, int64_t max_ts,
int flags)
{
TEDCaptionsDemuxer *tc = avf->priv_data;
return ff_subtitles_queue_seek(&tc->subs, avf, stream_index,
min_ts, ts, max_ts, flags);
}
const AVInputFormat ff_tedcaptions_demuxer = {
.name = "tedcaptions",
.long_name = NULL_IF_CONFIG_SMALL("TED Talks captions"),
.priv_data_size = sizeof(TEDCaptionsDemuxer),
.flags_internal = FF_FMT_INIT_CLEANUP,
.priv_class = &tedcaptions_demuxer_class,
.read_header = tedcaptions_read_header,
.read_packet = tedcaptions_read_packet,
.read_close = tedcaptions_read_close,
.read_probe = tedcaptions_read_probe,
.read_seek2 = tedcaptions_read_seek,
};