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lavc: introduce the convenience function init_get_bits8

Accept the buffer size in bytes and check for overflow before passing
the value in bits to init_get_bits.
(cherry picked from commit e28ac6e)

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
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lu-zero committed Jan 13, 2013
1 parent 7a2ee77 commit 71e00caeab89d9beeef9c947673f72e992bd109c
Showing with 16 additions and 0 deletions.
  1. +16 −0 libavcodec/get_bits.h
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@@ -393,6 +393,22 @@ static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,
return ret;
}
+/**
+ * Initialize GetBitContext.
+ * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes
+ * larger than the actual read bits because some optimized bitstream
+ * readers read 32 or 64 bit at once and could read over the end
+ * @param byte_size the size of the buffer in bytes
+ * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
+ */
+static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer,
+ int byte_size)
+{
+ if (byte_size > INT_MAX / 8)
+ return AVERROR_INVALIDDATA;
+ return init_get_bits(s, buffer, byte_size * 8);
+}
+
static inline void align_get_bits(GetBitContext *s)
{
int n = -get_bits_count(s) & 7;

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