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oggdec: eliminate copies and extra buffers

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This also makes implementing CRC checking far simpler and more robust.
This commit is contained in:
Lynne 2020-04-28 12:41:34 +01:00
parent 8afa03a5f6
commit f619e1ec66
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GPG Key ID: A2FEA5F03F034464
1 changed files with 60 additions and 71 deletions
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131
libavformat/oggdec.c
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@ -205,7 +205,7 @@ static const struct ogg_codec *ogg_find_codec(uint8_t *buf, int size)
* situation where a new audio stream spawn (identified with a new serial) and
* must replace the previous one (track switch).
*/
static int ogg_replace_stream(AVFormatContext *s, uint32_t serial, int nsegs)
static int ogg_replace_stream(AVFormatContext *s, uint32_t serial, int size)
{
struct ogg *ogg = s->priv_data;
struct ogg_stream *os;
@ -214,11 +214,10 @@ static int ogg_replace_stream(AVFormatContext *s, uint32_t serial, int nsegs)
if (s->pb->seekable & AVIO_SEEKABLE_NORMAL) {
uint8_t magic[8];
int64_t pos = avio_tell(s->pb);
avio_skip(s->pb, nsegs);
avio_seek(s->pb, -size, SEEK_CUR);
if (avio_read(s->pb, magic, sizeof(magic)) != sizeof(magic))
return AVERROR_INVALIDDATA;
avio_seek(s->pb, pos, SEEK_SET);
avio_seek(s->pb, size - sizeof(magic), SEEK_CUR);
codec = ogg_find_codec(magic, sizeof(magic));
if (!codec) {
av_log(s, AV_LOG_ERROR, "Cannot identify new stream\n");
@ -303,27 +302,6 @@ static int ogg_new_stream(AVFormatContext *s, uint32_t serial)
return idx;
}
static int ogg_new_buf(struct ogg *ogg, int idx)
{
struct ogg_stream *os = ogg->streams + idx;
uint8_t *nb = av_malloc(os->bufsize + AV_INPUT_BUFFER_PADDING_SIZE);
int size = os->bufpos - os->pstart;
if (!nb)
return AVERROR(ENOMEM);
if (os->buf) {
memcpy(nb, os->buf + os->pstart, size);
av_free(os->buf);
}
os->buf = nb;
os->bufpos = size;
os->pstart = 0;
return 0;
}
static int data_packets_seen(const struct ogg *ogg)
{
int i;
@ -343,8 +321,11 @@ static int ogg_read_page(AVFormatContext *s, int *sid)
int flags, nsegs;
uint64_t gp;
uint32_t serial;
int size, idx;
int size = 0, idx;
int64_t page_pos;
uint8_t sync[4];
uint8_t segments[255];
uint8_t *readout_buf;
int sp = 0;
ret = avio_read(bc, sync, 4);
@ -387,47 +368,73 @@ static int ogg_read_page(AVFormatContext *s, int *sid)
gp = avio_rl64(bc);
serial = avio_rl32(bc);
avio_skip(bc, 8); /* seq, crc */
nsegs = avio_r8(bc);
nsegs = avio_r8(bc);
page_pos = avio_tell(bc) - 27;
ret = avio_read(bc, segments, nsegs);
if (ret < nsegs)
return ret < 0 ? ret : AVERROR_EOF;
if (avio_feof(bc))
return AVERROR_EOF;
for (i = 0; i < nsegs; i++)
size += segments[i];
idx = ogg_find_stream(ogg, serial);
if (idx >= 0) {
os = ogg->streams + idx;
/* Even if invalid guarantee there's enough memory to read the page */
if (os->bufsize - os->bufpos < size) {
uint8_t *nb = av_realloc(os->buf, 2*os->bufsize + AV_INPUT_BUFFER_PADDING_SIZE);
if (!nb)
return AVERROR(ENOMEM);
os->buf = nb;
os->bufsize *= 2;
}
readout_buf = os->buf + os->bufpos;
} else {
readout_buf = av_malloc(size);
}
ret = avio_read(bc, readout_buf, size);
if (ret < size) {
if (idx < 0)
av_free(readout_buf);
return ret < 0 ? ret : AVERROR_EOF;
}
if (idx < 0) {
if (data_packets_seen(ogg))
idx = ogg_replace_stream(s, serial, nsegs);
idx = ogg_replace_stream(s, serial, size);
else
idx = ogg_new_stream(s, serial);
if (idx < 0) {
av_log(s, AV_LOG_ERROR, "failed to create or replace stream\n");
av_free(readout_buf);
return idx;
}
os = ogg->streams + idx;
memcpy(os->buf + os->bufpos, readout_buf, size);
av_free(readout_buf);
}
os = ogg->streams + idx;
ogg->page_pos =
os->page_pos = avio_tell(bc) - 27;
if (os->psize > 0) {
ret = ogg_new_buf(ogg, idx);
if (ret < 0)
return ret;
}
ret = avio_read(bc, os->segments, nsegs);
if (ret < nsegs)
return ret < 0 ? ret : AVERROR_EOF;
os->nsegs = nsegs;
os->segp = 0;
size = 0;
for (i = 0; i < nsegs; i++)
size += os->segments[i];
if (!(flags & OGG_FLAG_BOS))
os->got_data = 1;
ogg->page_pos = page_pos;
os->page_pos = page_pos;
os->nsegs = nsegs;
os->segp = 0;
os->got_data = !(flags & OGG_FLAG_BOS);
os->bufpos += size;
os->granule = gp;
os->flags = flags;
memcpy(os->segments, segments, nsegs);
memset(os->buf + os->bufpos, 0, AV_INPUT_BUFFER_PADDING_SIZE);
if (flags & OGG_FLAG_CONT || os->incomplete) {
if (!os->psize) {
@ -447,26 +454,8 @@ static int ogg_read_page(AVFormatContext *s, int *sid)
os->sync_pos = os->page_pos;
}
if (os->bufsize - os->bufpos < size) {
uint8_t *nb = av_malloc((os->bufsize *= 2) + AV_INPUT_BUFFER_PADDING_SIZE);
if (!nb)
return AVERROR(ENOMEM);
memcpy(nb, os->buf, os->bufpos);
av_free(os->buf);
os->buf = nb;
}
ret = avio_read(bc, os->buf + os->bufpos, size);
if (ret < size)
return ret < 0 ? ret : AVERROR_EOF;
os->bufpos += size;
os->granule = gp;
os->flags = flags;
memset(os->buf + os->bufpos, 0, AV_INPUT_BUFFER_PADDING_SIZE);
if (sid)
*sid = idx;
/* This function is always called with sid != NULL */
*sid = idx;
return 0;
}