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demux: make the parse a bit more strict

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* VP8L shouldn't have an alpha chunk
 * expect an animation to only contain frames, not a mix of image chunks
 * enforce ANIM/ANMF order
 * expect a full frame in a complete file

Change-Id: I953a8b6058f9bc00f1d042635548f158abdf6fce
This commit is contained in:
James Zern
2013-03-16 16:32:30 -07:00
parent 42b611a491
commit d851cd1d85
1 changed files with 10 additions and 1 deletions
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11
src/demux/demux.c
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@@ -235,8 +235,10 @@ static ParseStatus StoreFrame(int frame_num, uint32_t min_size,
goto Done;
}
break;
case MKFOURCC('V', 'P', '8', ' '):
case MKFOURCC('V', 'P', '8', 'L'):
if (alpha_chunks > 0) return PARSE_ERROR; // VP8L has its own alpha
// fall through
case MKFOURCC('V', 'P', '8', ' '):
if (image_chunks == 0) {
// Extract the bitstream features, tolerating failures when the data
// is incomplete.
@@ -506,6 +508,9 @@ static ParseStatus ParseVP8X(WebPDemuxer* const dmux) {
case MKFOURCC('A', 'L', 'P', 'H'):
case MKFOURCC('V', 'P', '8', ' '):
case MKFOURCC('V', 'P', '8', 'L'): {
// check that this isn't an animation (all frames should be in an ANMF).
if (anim_chunks > 0) return PARSE_ERROR;
Rewind(mem, CHUNK_HEADER_SIZE);
status = ParseSingleImage(dmux);
break;
@@ -527,6 +532,7 @@ static ParseStatus ParseVP8X(WebPDemuxer* const dmux) {
break;
}
case MKFOURCC('A', 'N', 'M', 'F'): {
if (anim_chunks == 0) return PARSE_ERROR; // 'ANIM' precedes frames.
status = ParseFrame(dmux, chunk_size_padded);
break;
}
@@ -623,6 +629,9 @@ static int IsValidExtendedFormat(const WebPDemuxer* const dmux) {
if (f->width_ <= 0 || f->height_ <= 0) return 0;
} else {
// There shouldn't be a partial frame in a complete file.
if (dmux->state_ == WEBP_DEMUX_DONE) return 0;
// Ensure alpha precedes image bitstream.
if (alpha->size_ > 0 && image->size_ > 0 &&
alpha->offset_ > image->offset_) {