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Fixing undefined behavior vp9_peek_si().

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Bitwise OR operation doesn't guarantee any subexpression evaluation order.
Just reading one bit now and ignoring the next one. For reference look at
vp9_decode_frame() implementation.

Change-Id: I4971686929838ae5ded8f43a38a2934db5e1d462
This commit is contained in:
Dmitry Kovalev 2014-02-07 14:21:19 -08:00
parent 4f8a30b116
commit 0f3cffa685
1 changed files with 3 additions and 1 deletions
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4
vp9/vp9_dx_iface.c
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@ -148,7 +148,9 @@ static vpx_codec_err_t vp9_peek_si(const uint8_t *data, unsigned int data_sz,
{
struct vp9_read_bit_buffer rb = { data, data + data_sz, 0, NULL, NULL };
const int frame_marker = vp9_rb_read_literal(&rb, 2);
const int version = vp9_rb_read_bit(&rb) | (vp9_rb_read_bit(&rb) << 1);
const int version = vp9_rb_read_bit(&rb);
(void) vp9_rb_read_bit(&rb); // unused version bit
if (frame_marker != VP9_FRAME_MARKER)
return VPX_CODEC_UNSUP_BITSTREAM;
#if CONFIG_NON420