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liblzma: Check that the first byte of range encoded data is 0x00.

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It is just to be more pedantic and thus perhaps catch broken
files slightly earlier.
This commit is contained in:
Lasse Collin 2012-06-28 10:47:49 +03:00
parent eccd8017ff
commit 1403707fc6
2 changed files with 15 additions and 5 deletions
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8
src/liblzma/lzma/lzma_decoder.c
View file

@ -289,8 +289,12 @@ lzma_decode(lzma_coder *restrict coder, lzma_dict *restrict dictptr,
// Initialization //
////////////////////
if (!rc_read_init(&coder->rc, in, in_pos, in_size))
return LZMA_OK;
{
const lzma_ret ret = rc_read_init(
&coder->rc, in, in_pos, in_size);
if (ret != LZMA_STREAM_END)
return ret;
}
///////////////
// Variables //

12
src/liblzma/rangecoder/range_decoder.h
View file

@ -25,20 +25,26 @@ typedef struct {
/// Reads the first five bytes to initialize the range decoder.
static inline bool
static inline lzma_ret
rc_read_init(lzma_range_decoder *rc, const uint8_t *restrict in,
size_t *restrict in_pos, size_t in_size)
{
while (rc->init_bytes_left > 0) {
if (*in_pos == in_size)
return false;
return LZMA_OK;
// The first byte is always 0x00. It could have been omitted
// in LZMA2 but it wasn't, so one byte is wasted in every
// LZMA2 chunk.
if (rc->init_bytes_left == 5 && in[*in_pos] != 0x00)
return LZMA_DATA_ERROR;
rc->code = (rc->code << 8) | in[*in_pos];
++*in_pos;
--rc->init_bytes_left;
}
return true;
return LZMA_STREAM_END;
}