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[libzstd] Require ZSTD_MULTITHREAD to create a ZSTDMT_CCtx 

ZSTDMT was broken when compiled without ZSTD_MULTITHREAD defined,
because `ZSTD_CCtx_setParameter(cctx, ZSTD_c_nbWorkers, nbWorkerss)`
failed. It was detected by the MSVC test which runs the fuzzer with
multithreading disabled.

This is a very niche use case of a deprecated API, because the API is
inefficient and synchronous, since `threading.h` will be synchronous.
Users almost certainly don't want this, and anyone who tested their code
should realize that it is broken. Therefore, I think it is safe to
require `ZSTD_MULTITHREAD` to be defined to use ZSTDMT.
dev
Nick Terrell 2019-04-15 22:49:44 -07:00
parent a821aee3b1
commit de0499f7fa
3 changed files with 12 additions and 1 deletions
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1
CHANGELOG
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@ -5,6 +5,7 @@ api: Make ZSTD_e_flush and ZSTD_e_end block for maximum forward progress
api: Rename ZSTD_CCtxParam_getParameter to ZSTD_CCtxParams_getParameter
api: Rename ZSTD_CCtxParam_setParameter to ZSTD_CCtxParams_setParameter
api: Don't export ZSTDMT functions from the shared library by default
api: Require ZSTD_MULTITHREAD to be defined to use ZSTDMT
api: Add ZSTD_decompressBound() to provide an upper bound on decompressed size by @shakeelrao
api: Fix ZSTD_decompressDCtx() corner cases with a dictionary
api: Move ZSTD_getDictID_*() functions to the stable section

4
lib/compress/zstdmt_compress.c
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@ -874,6 +874,10 @@ ZSTDMT_CCtx* ZSTDMT_createCCtx_advanced(unsigned nbWorkers, ZSTD_customMem cMem)
int initError;
DEBUGLOG(3, "ZSTDMT_createCCtx_advanced (nbWorkers = %u)", nbWorkers);
#ifndef ZSTD_MULTITHREAD
return NULL;
#endif
if (nbWorkers < 1) return NULL;
nbWorkers = MIN(nbWorkers , ZSTDMT_NBWORKERS_MAX);
if ((cMem.customAlloc!=NULL) ^ (cMem.customFree!=NULL))

8
lib/compress/zstdmt_compress.h
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@ -19,12 +19,16 @@
/* Note : This is an internal API.
* These APIs used to be exposed with ZSTDLIB_API,
* because it used to be the only way to invoke MT compression.
* Now, it's recommended to use ZSTD_compress_generic() instead.
* Now, it's recommended to use ZSTD_compress2 and ZSTD_compressStream2()
* instead.
*
* If you depend on these APIs and can't switch, then define
* ZSTD_LEGACY_MULTITHREADED_API when making the dynamic library.
* However, we may completely remove these functions in a future
* release, so please switch soon.
*
* This API requires ZSTD_MULTITHREAD to be defined during compilation,
* otherwise ZSTDMT_createCCtx*() will fail.
*/
#ifdef ZSTD_LEGACY_MULTITHREADED_API
@ -51,7 +55,9 @@
/* === Memory management === */
typedef struct ZSTDMT_CCtx_s ZSTDMT_CCtx;
/* Requires ZSTD_MULTITHREAD to be defined during compilation, otherwise it will return NULL. */
ZSTDMT_API ZSTDMT_CCtx* ZSTDMT_createCCtx(unsigned nbWorkers);
/* Requires ZSTD_MULTITHREAD to be defined during compilation, otherwise it will return NULL. */
ZSTDMT_API ZSTDMT_CCtx* ZSTDMT_createCCtx_advanced(unsigned nbWorkers,
ZSTD_customMem cMem);
ZSTDMT_API size_t ZSTDMT_freeCCtx(ZSTDMT_CCtx* mtctx);