From 4d61ebc9c8738fc79301d8ef7e27920d4b300913 Mon Sep 17 00:00:00 2001 From: Yann Collet Date: Sat, 13 Jan 2018 22:39:39 -0800 Subject: modified formulation for LZ4F_compressBound() previous version used an intentional overflow, which is defined since it uses unsigned type, but static analyzer complain about it. --- lib/lz4frame.c | 10 +++++----- lib/lz4frame.h | 38 +++++++++++++++++++------------------- 2 files changed, 24 insertions(+), 24 deletions(-) diff --git a/lib/lz4frame.c b/lib/lz4frame.c index 488ab75..62e7010 100644 --- a/lib/lz4frame.c +++ b/lib/lz4frame.c @@ -281,7 +281,7 @@ static size_t LZ4F_compressBound_internal(size_t srcSize, size_t const bufferedSize = MIN(alreadyBuffered, maxBuffered); size_t const maxSrcSize = srcSize + bufferedSize; unsigned const nbFullBlocks = (unsigned)(maxSrcSize / blockSize); - size_t const partialBlockSize = (srcSize - (srcSize==0)) & (blockSize-1); /* 0 => -1 == MAX => blockSize-1 */ + size_t const partialBlockSize = maxSrcSize & (blockSize-1); size_t const lastBlockSize = flush ? partialBlockSize : 0; unsigned const nbBlocks = nbFullBlocks + (lastBlockSize>0); @@ -604,10 +604,10 @@ size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, } -/* LZ4F_compressBound() : - * @ return size of Dst buffer given a srcSize to handle worst case situations. - * The LZ4F_frameInfo_t structure is optional : if NULL, preferences will be set to cover worst case situations. - * This function cannot fail. +/* LZ4F_compressBound() : + * @return minimum capacity of dstBuffer for a given srcSize to handle worst case scenario. + * LZ4F_preferences_t structure is optional : if NULL, preferences will be set to cover worst case scenario. + * This function cannot fail. */ size_t LZ4F_compressBound(size_t srcSize, const LZ4F_preferences_t* preferencesPtr) { diff --git a/lib/lz4frame.h b/lib/lz4frame.h index 675aeeb..eb55e45 100644 --- a/lib/lz4frame.h +++ b/lib/lz4frame.h @@ -248,19 +248,19 @@ LZ4FLIB_API size_t LZ4F_compressBegin(LZ4F_cctx* cctx, const LZ4F_preferences_t* prefsPtr); /*! LZ4F_compressBound() : - * Provides dstCapacity given a srcSize to guarantee operation success in worst case situations. - * prefsPtr is optional : you can provide NULL as argument, preferences will be set to cover worst case scenario. - * Result is always the same for a srcSize and prefsPtr, so it can be trusted to size reusable buffers. - * When srcSize==0, LZ4F_compressBound() provides an upper bound for LZ4F_flush() and LZ4F_compressEnd() operations. + * Provides minimum dstCapacity for a given srcSize to guarantee operation success in worst case situations. + * prefsPtr is optional : when NULL is provided, preferences will be set to cover worst case scenario. + * Result is always the same for a srcSize and prefsPtr, so it can be trusted to size reusable buffers. + * When srcSize==0, LZ4F_compressBound() provides an upper bound for LZ4F_flush() and LZ4F_compressEnd() operations. */ LZ4FLIB_API size_t LZ4F_compressBound(size_t srcSize, const LZ4F_preferences_t* prefsPtr); /*! LZ4F_compressUpdate() : - * LZ4F_compressUpdate() can be called repetitively to compress as much data as necessary. - * An important rule is that dstCapacity MUST be large enough to ensure operation success even in worst case situations. - * This value is provided by LZ4F_compressBound(). - * If this condition is not respected, LZ4F_compress() will fail (result is an errorCode). - * LZ4F_compressUpdate() doesn't guarantee error recovery. When an error occurs, compression context must be freed or resized. + * LZ4F_compressUpdate() can be called repetitively to compress as much data as necessary. + * An important rule is that dstCapacity MUST be large enough to ensure operation success even in worst case situations. + * This value is provided by LZ4F_compressBound(). + * If this condition is not respected, LZ4F_compress() will fail (result is an errorCode). + * LZ4F_compressUpdate() doesn't guarantee error recovery. When an error occurs, compression context must be freed or resized. * `cOptPtr` is optional : NULL can be provided, in which case all options are set to default. * @return : number of bytes written into `dstBuffer` (it can be zero, meaning input data was just buffered). * or an error code if it fails (which can be tested using LZ4F_isError()) @@ -268,8 +268,8 @@ LZ4FLIB_API size_t LZ4F_compressBound(size_t srcSize, const LZ4F_preferences_t* LZ4FLIB_API size_t LZ4F_compressUpdate(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapacity, const void* srcBuffer, size_t srcSize, const LZ4F_compressOptions_t* cOptPtr); /*! LZ4F_flush() : - * When data must be generated and sent immediately, without waiting for a block to be completely filled, - * it's possible to call LZ4_flush(). It will immediately compress any data buffered within cctx. + * When data must be generated and sent immediately, without waiting for a block to be completely filled, + * it's possible to call LZ4_flush(). It will immediately compress any data buffered within cctx. * `dstCapacity` must be large enough to ensure the operation will be successful. * `cOptPtr` is optional : it's possible to provide NULL, all options will be set to default. * @return : number of bytes written into dstBuffer (it can be zero, which means there was no data stored within cctx) @@ -303,14 +303,14 @@ typedef struct { /* Resource management */ -/*!LZ4F_createDecompressionContext() : - * Create an LZ4F_dctx object, to track all decompression operations. - * The version provided MUST be LZ4F_VERSION. - * The function provides a pointer to an allocated and initialized LZ4F_dctx object. - * The result is an errorCode, which can be tested using LZ4F_isError(). - * dctx memory can be released using LZ4F_freeDecompressionContext(); - * The result of LZ4F_freeDecompressionContext() is indicative of the current state of decompressionContext when being released. - * That is, it should be == 0 if decompression has been completed fully and correctly. +/*! LZ4F_createDecompressionContext() : + * Create an LZ4F_dctx object, to track all decompression operations. + * The version provided MUST be LZ4F_VERSION. + * The function provides a pointer to an allocated and initialized LZ4F_dctx object. + * The result is an errorCode, which can be tested using LZ4F_isError(). + * dctx memory can be released using LZ4F_freeDecompressionContext(); + * The result of LZ4F_freeDecompressionContext() is indicative of the current state of decompressionContext when being released. + * That is, it should be == 0 if decompression has been completed fully and correctly. */ LZ4FLIB_API LZ4F_errorCode_t LZ4F_createDecompressionContext(LZ4F_dctx** dctxPtr, unsigned version); LZ4FLIB_API LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx); -- cgit v0.12