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mxfdec: Parse PreviousPartition in mxf_seek_to_previous_partition() 

Without this patch the demuxer can get stuck in a loop if PreviousPartition
points somewhere where there's no PartitionPack, or if klv_read_packet() syncs
back up to the current partition.

This should fix Ticket3278 properly and unbreak Ticket4040.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Tomas Härdin 2014-10-28 13:38:18 +01:00 committed by Michael Niedermayer
parent fc1b89d887
commit 37c3686155
1 changed files with 34 additions and 1 deletions
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35
libavformat/mxfdec.c
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@ -89,6 +89,7 @@ typedef struct {
int64_t header_byte_count;
int64_t index_byte_count;
int pack_length;
int64_t pack_ofs; ///< absolute offset of pack in file, including run-in
} MXFPartition;
typedef struct {
@ -472,6 +473,7 @@ static int mxf_read_partition_pack(void *arg, AVIOContext *pb, int tag, int size
memset(partition, 0, sizeof(*partition));
mxf->partitions_count++;
partition->pack_length = avio_tell(pb) - klv_offset + size;
partition->pack_ofs = klv_offset;
switch(uid[13]) {
case 2:
@ -547,6 +549,7 @@ static int mxf_read_partition_pack(void *arg, AVIOContext *pb, int tag, int size
partition->index_sid, partition->body_sid);
/* sanity check PreviousPartition if set */
//NOTE: this isn't actually enough, see mxf_seek_to_previous_partition()
if (partition->previous_partition &&
mxf->run_in + partition->previous_partition >= klv_offset) {
av_log(mxf->fc, AV_LOG_ERROR,
@ -2076,23 +2079,53 @@ static int mxf_parse_klv(MXFContext *mxf, KLVPacket klv, MXFMetadataReadFunc *re
}
/**
* Seeks to the previous partition, if possible
* Seeks to the previous partition and parses it, if possible
* @return <= 0 if we should stop parsing, > 0 if we should keep going
*/
static int mxf_seek_to_previous_partition(MXFContext *mxf)
{
AVIOContext *pb = mxf->fc->pb;
KLVPacket klv;
int64_t current_partition_ofs;
int ret;
if (!mxf->current_partition ||
mxf->run_in + mxf->current_partition->previous_partition <= mxf->last_forward_tell)
return 0; /* we've parsed all partitions */
/* seek to previous partition */
current_partition_ofs = mxf->current_partition->pack_ofs; //includes run-in
avio_seek(pb, mxf->run_in + mxf->current_partition->previous_partition, SEEK_SET);
mxf->current_partition = NULL;
av_dlog(mxf->fc, "seeking to previous partition\n");
/* Make sure this is actually a PartitionPack, and if so parse it.
* See deadlock2.mxf
*/
if ((ret = klv_read_packet(&klv, pb)) < 0) {
av_log(mxf->fc, AV_LOG_ERROR, "failed to read PartitionPack KLV\n");
return ret;
}
if (!mxf_is_partition_pack_key(klv.key)) {
av_log(mxf->fc, AV_LOG_ERROR, "PreviousPartition @ %" PRIx64 " isn't a PartitionPack\n", klv.offset);
return AVERROR_INVALIDDATA;
}
/* We can't just check ofs >= current_partition_ofs because PreviousPartition
* can point to just before the current partition, causing klv_read_packet()
* to sync back up to it. See deadlock3.mxf
*/
if (klv.offset >= current_partition_ofs) {
av_log(mxf->fc, AV_LOG_ERROR, "PreviousPartition for PartitionPack @ %"
PRIx64 " indirectly points to itself\n", current_partition_ofs);
return AVERROR_INVALIDDATA;
}
if ((ret = mxf_parse_klv(mxf, klv, mxf_read_partition_pack, 0, 0)) < 0)
return ret;
return 1;
}