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liblzma: Fix lzma_memlimit_set(strm, 0).

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The 0 got treated specially in a buggy way and as a result
the function did nothing. The API doc said that 0 was supposed
to return LZMA_PROG_ERROR but it didn't.

Now 0 is treated as if 1 had been specified. This is done because
0 is already used to indicate an error from lzma_memlimit_get()
and lzma_memusage().

In addition, lzma_memlimit_set() no longer checks that the new
limit is at least LZMA_MEMUSAGE_BASE. It's counter-productive
for the Index decoder and was actually needed only by the
auto decoder. Auto decoder has now been modified to check for
LZMA_MEMUSAGE_BASE.
This commit is contained in:
Lasse Collin 2017-03-30 19:47:45 +03:00
parent 84462afaad
commit a0b1dda409
3 changed files with 13 additions and 3 deletions
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7
src/liblzma/api/lzma/base.h
View file

@ -644,11 +644,16 @@ extern LZMA_API(uint64_t) lzma_memlimit_get(const lzma_stream *strm)
* This function is supported only when *strm has been initialized with * This function is supported only when *strm has been initialized with
* a function that takes a memlimit argument. * a function that takes a memlimit argument.
* *
* liblzma 5.2.3 and earlier has a bug where memlimit value of 0 causes
* this function to do nothing (leaving the limit unchanged) and still
* return LZMA_OK. Later versions treat 0 as if 1 had been specified (so
* lzma_memlimit_get() will return 1 even if you specify 0 here).
*
* \return - LZMA_OK: New memory usage limit successfully set. * \return - LZMA_OK: New memory usage limit successfully set.
* - LZMA_MEMLIMIT_ERROR: The new limit is too small. * - LZMA_MEMLIMIT_ERROR: The new limit is too small.
* The limit was not changed. * The limit was not changed.
* - LZMA_PROG_ERROR: Invalid arguments, e.g. *strm doesn't * - LZMA_PROG_ERROR: Invalid arguments, e.g. *strm doesn't
* support memory usage limit or memlimit was zero. * support memory usage limit.
*/ */
extern LZMA_API(lzma_ret) lzma_memlimit_set( extern LZMA_API(lzma_ret) lzma_memlimit_set(
lzma_stream *strm, uint64_t memlimit) lzma_nothrow; lzma_stream *strm, uint64_t memlimit) lzma_nothrow;

3
src/liblzma/common/auto_decoder.c
View file

@ -139,7 +139,10 @@ auto_decoder_memconfig(void *coder_ptr, uint64_t *memusage,
// the current memory usage. // the current memory usage.
*memusage = LZMA_MEMUSAGE_BASE; *memusage = LZMA_MEMUSAGE_BASE;
*old_memlimit = coder->memlimit; *old_memlimit = coder->memlimit;
ret = LZMA_OK; ret = LZMA_OK;
if (new_memlimit != 0 && new_memlimit < *memusage)
ret = LZMA_MEMLIMIT_ERROR;
} }
if (ret == LZMA_OK && new_memlimit != 0) if (ret == LZMA_OK && new_memlimit != 0)

6
src/liblzma/common/common.c
View file

@ -435,8 +435,10 @@ lzma_memlimit_set(lzma_stream *strm, uint64_t new_memlimit)
|| strm->internal->next.memconfig == NULL) || strm->internal->next.memconfig == NULL)
return LZMA_PROG_ERROR; return LZMA_PROG_ERROR;
if (new_memlimit != 0 && new_memlimit < LZMA_MEMUSAGE_BASE) // Zero is a special value that cannot be used as an actual limit.
return LZMA_MEMLIMIT_ERROR; // If 0 was specified, use 1 instead.
if (new_memlimit == 0)
new_memlimit = 1;
return strm->internal->next.memconfig(strm->internal->next.coder, return strm->internal->next.memconfig(strm->internal->next.coder,
&memusage, &old_memlimit, new_memlimit); &memusage, &old_memlimit, new_memlimit);