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Commit df9e6aaf authored by Robert Shih's avatar Robert Shih
Browse files

ARTPSource: avoid over/underflow in seq # recovery 

Bug: 25801317
Change-Id: Id9a5ad2d6c27f64b502c78f06174b29edb486134
parent 436ae0b8

media/libstagefright/rtsp/ARTPSource.cpp

+9 −2
Original line number Diff line number Diff line
@@ -116,8 +116,15 @@ bool ARTPSource::queuePacket(const sp<ABuffer> &buffer) { 
    // to the highest sequence number (extended to 32 bits) received so far.



    uint32_t seq1 = seqNum | (mHighestSeqNumber & 0xffff0000);

    uint32_t seq2 = seqNum | ((mHighestSeqNumber & 0xffff0000) + 0x10000);

    uint32_t seq3 = seqNum | ((mHighestSeqNumber & 0xffff0000) - 0x10000);



    // non-overflowing version of:

    // uint32_t seq2 = seqNum | ((mHighestSeqNumber & 0xffff0000) + 0x10000);

    uint32_t seq2 = seqNum | (((mHighestSeqNumber >> 16) + 1) << 16);



    // non-underflowing version of:

    // uint32_t seq2 = seqNum | ((mHighestSeqNumber & 0xffff0000) - 0x10000);

    uint32_t seq3 = seqNum | ((((mHighestSeqNumber >> 16) | 0x10000) - 1) << 16);



    uint32_t diff1 = AbsDiff(seq1, mHighestSeqNumber);

    uint32_t diff2 = AbsDiff(seq2, mHighestSeqNumber);

    uint32_t diff3 = AbsDiff(seq3, mHighestSeqNumber);