[FFmpeg-cvslog] avformat/mpjpegdec: ensure seekback for latest chunk

[Moritz Barsnick]

ffmpeg | branch: master | Moritz Barsnick <barsnick at gmx.net> | Mon Oct  7 00:19:30 2019 +0200| [f76a899abc80512959ec7deab25bc9642c4feb73] | committer: Michael Niedermayer

avformat/mpjpegdec: ensure seekback for latest chunk

Not only the first, but each latest chunk must be cached to allow
seekback after finding the mime boundary.

Fixes trac #5023 and #5921.

Signed-off-by: Moritz Barsnick <barsnick at gmx.net>
Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f76a899abc80512959ec7deab25bc9642c4feb73
---

 libavformat/mpjpegdec.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/libavformat/mpjpegdec.c b/libavformat/mpjpegdec.c
index 24bf232db2..c79a39c69d 100644
--- a/libavformat/mpjpegdec.c
+++ b/libavformat/mpjpegdec.c
@@ -336,10 +336,8 @@ static int mpjpeg_read_packet(AVFormatContext *s, AVPacket *pkt)
         pkt->size = 0;
         pkt->pos  = avio_tell(s->pb);
 
-        /* we may need to return as much as all we've read back to the buffer */
-        ffio_ensure_seekback(s->pb, read_chunk);
-
-        while ((ret = av_append_packet(s->pb, pkt, read_chunk - remaining)) >= 0) {
+        while ((ret = ffio_ensure_seekback(s->pb, read_chunk - remaining)) >= 0 && /* we may need to return as much as all we've read back to the buffer */
+               (ret = av_append_packet(s->pb, pkt, read_chunk - remaining)) >= 0) {
             /* scan the new data */
             char *start;