From 2a32f16108e6a424b20a15be4e06ebe6e92535a9 Mon Sep 17 00:00:00 2001
From: Lynne <dev@lynne.ee>
Date: Tue, 28 Apr 2020 12:41:34 +0100
Subject: [PATCH 1/3] oggdec: eliminate copies and extra buffers
This also makes implementing CRC checking far simpler and more robust.
---
libavformat/oggdec.c | 127 ++++++++++++++++++++-----------------------
1 file changed, 58 insertions(+), 69 deletions(-)
@@ -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;
- ogg->page_pos =
- os->page_pos = avio_tell(bc) - 27;
+ os = ogg->streams + idx;
- if (os->psize > 0) {
- ret = ogg_new_buf(ogg, idx);
- if (ret < 0)
- return ret;
+ memcpy(os->buf + os->bufpos, readout_buf, size);
+ av_free(readout_buf);
}
- 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;
}
--
2.26.2