diff options
Diffstat (limited to 'lib/lz4.h')
| -rw-r--r-- | lib/lz4.h | 368 |
1 files changed, 208 insertions, 160 deletions
@@ -51,19 +51,23 @@ extern "C" { multiple GB/s per core, typically reaching RAM speed limits on multi-core systems. The LZ4 compression library provides in-memory compression and decompression functions. + It gives full buffer control to user. Compression can be done in: - a single step (described as Simple Functions) - a single step, reusing a context (described in Advanced Functions) - unbounded multiple steps (described as Streaming compression) - lz4.h provides block compression functions. It gives full buffer control to user. - Decompressing an lz4-compressed block also requires metadata (such as compressed size). - Each application is free to encode such metadata in whichever way it wants. + lz4.h generates and decodes LZ4-compressed blocks (doc/lz4_Block_format.md). + Decompressing a block requires additional metadata, such as its compressed size. + Each application is free to encode and pass such metadata in whichever way it wants. - An additional format, called LZ4 frame specification (doc/lz4_Frame_format.md), - take care of encoding standard metadata alongside LZ4-compressed blocks. - Frame format is required for interoperability. - It is delivered through a companion API, declared in lz4frame.h. + lz4.h only handle blocks, it can not generate Frames. + + Blocks are different from Frames (doc/lz4_Frame_format.md). + Frames bundle both blocks and metadata in a specified manner. + This are required for compressed data to be self-contained and portable. + Frame format is delivered through a companion API, declared in lz4frame.h. + Note that the `lz4` CLI can only manage frames. */ /*^*************************************************************** @@ -92,8 +96,8 @@ extern "C" { /*------ Version ------*/ #define LZ4_VERSION_MAJOR 1 /* for breaking interface changes */ -#define LZ4_VERSION_MINOR 8 /* for new (non-breaking) interface capabilities */ -#define LZ4_VERSION_RELEASE 3 /* for tweaks, bug-fixes, or development */ +#define LZ4_VERSION_MINOR 9 /* for new (non-breaking) interface capabilities */ +#define LZ4_VERSION_RELEASE 0 /* for tweaks, bug-fixes, or development */ #define LZ4_VERSION_NUMBER (LZ4_VERSION_MAJOR *100*100 + LZ4_VERSION_MINOR *100 + LZ4_VERSION_RELEASE) @@ -103,7 +107,7 @@ extern "C" { #define LZ4_VERSION_STRING LZ4_EXPAND_AND_QUOTE(LZ4_LIB_VERSION) LZ4LIB_API int LZ4_versionNumber (void); /**< library version number; useful to check dll version */ -LZ4LIB_API const char* LZ4_versionString (void); /**< library version string; unseful to check dll version */ +LZ4LIB_API const char* LZ4_versionString (void); /**< library version string; useful to check dll version */ /*-************************************ @@ -112,14 +116,15 @@ LZ4LIB_API const char* LZ4_versionString (void); /**< library version string; /*! * LZ4_MEMORY_USAGE : * Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.) - * Increasing memory usage improves compression ratio - * Reduced memory usage may improve speed, thanks to cache effect + * Increasing memory usage improves compression ratio. + * Reduced memory usage may improve speed, thanks to better cache locality. * Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */ #ifndef LZ4_MEMORY_USAGE # define LZ4_MEMORY_USAGE 14 #endif + /*-************************************ * Simple Functions **************************************/ @@ -130,21 +135,22 @@ LZ4LIB_API const char* LZ4_versionString (void); /**< library version string; It also runs faster, so it's a recommended setting. If the function cannot compress 'src' into a more limited 'dst' budget, compression stops *immediately*, and the function result is zero. - Note : as a consequence, 'dst' content is not valid. - Note 2 : This function is protected against buffer overflow scenarios (never writes outside 'dst' buffer, nor read outside 'source' buffer). + In which case, 'dst' content is undefined (invalid). srcSize : max supported value is LZ4_MAX_INPUT_SIZE. dstCapacity : size of buffer 'dst' (which must be already allocated) - return : the number of bytes written into buffer 'dst' (necessarily <= dstCapacity) - or 0 if compression fails */ + @return : the number of bytes written into buffer 'dst' (necessarily <= dstCapacity) + or 0 if compression fails + Note : This function is protected against buffer overflow scenarios (never writes outside 'dst' buffer, nor read outside 'source' buffer). +*/ LZ4LIB_API int LZ4_compress_default(const char* src, char* dst, int srcSize, int dstCapacity); /*! LZ4_decompress_safe() : compressedSize : is the exact complete size of the compressed block. dstCapacity : is the size of destination buffer, which must be already allocated. - return : the number of bytes decompressed into destination buffer (necessarily <= dstCapacity) + @return : the number of bytes decompressed into destination buffer (necessarily <= dstCapacity) If destination buffer is not large enough, decoding will stop and output an error code (negative value). If the source stream is detected malformed, the function will stop decoding and return a negative result. - This function is protected against malicious data packets. + Note : This function is protected against malicious data packets (never writes outside 'dst' buffer, nor read outside 'source' buffer). */ LZ4LIB_API int LZ4_decompress_safe (const char* src, char* dst, int compressedSize, int dstCapacity); @@ -155,8 +161,7 @@ LZ4LIB_API int LZ4_decompress_safe (const char* src, char* dst, int compressedSi #define LZ4_MAX_INPUT_SIZE 0x7E000000 /* 2 113 929 216 bytes */ #define LZ4_COMPRESSBOUND(isize) ((unsigned)(isize) > (unsigned)LZ4_MAX_INPUT_SIZE ? 0 : (isize) + ((isize)/255) + 16) -/*! -LZ4_compressBound() : +/*! LZ4_compressBound() : Provides the maximum size that LZ4 compression may output in a "worst case" scenario (input data not compressible) This function is primarily useful for memory allocation purposes (destination buffer size). Macro LZ4_COMPRESSBOUND() is also provided for compilation-time evaluation (stack memory allocation for example). @@ -167,8 +172,7 @@ LZ4_compressBound() : */ LZ4LIB_API int LZ4_compressBound(int inputSize); -/*! -LZ4_compress_fast() : +/*! LZ4_compress_fast() : Same as LZ4_compress_default(), but allows selection of "acceleration" factor. The larger the acceleration value, the faster the algorithm, but also the lesser the compression. It's a trade-off. It can be fine tuned, with each successive value providing roughly +~3% to speed. @@ -178,13 +182,12 @@ LZ4_compress_fast() : LZ4LIB_API int LZ4_compress_fast (const char* src, char* dst, int srcSize, int dstCapacity, int acceleration); -/*! -LZ4_compress_fast_extState() : - Same compression function, just using an externally allocated memory space to store compression state. - Use LZ4_sizeofState() to know how much memory must be allocated, - and allocate it on 8-bytes boundaries (using malloc() typically). - Then, provide this buffer as 'void* state' to compression function. -*/ +/*! LZ4_compress_fast_extState() : + * Same as LZ4_compress_fast(), using an externally allocated memory space for its state. + * Use LZ4_sizeofState() to know how much memory must be allocated, + * and allocate it on 8-bytes boundaries (using `malloc()` typically). + * Then, provide this buffer as `void* state` to compression function. + */ LZ4LIB_API int LZ4_sizeofState(void); LZ4LIB_API int LZ4_compress_fast_extState (void* state, const char* src, char* dst, int srcSize, int dstCapacity, int acceleration); @@ -204,27 +207,6 @@ LZ4LIB_API int LZ4_compress_fast_extState (void* state, const char* src, char* d LZ4LIB_API int LZ4_compress_destSize (const char* src, char* dst, int* srcSizePtr, int targetDstSize); -/*! LZ4_decompress_fast() : **unsafe!** - * This function used to be a bit faster than LZ4_decompress_safe(), - * though situation has changed in recent versions, - * and now `LZ4_decompress_safe()` can be as fast and sometimes faster than `LZ4_decompress_fast()`. - * Moreover, LZ4_decompress_fast() is not protected vs malformed input, as it doesn't perform full validation of compressed data. - * As a consequence, this function is no longer recommended, and may be deprecated in future versions. - * It's only remaining specificity is that it can decompress data without knowing its compressed size. - * - * originalSize : is the uncompressed size to regenerate. - * `dst` must be already allocated, its size must be >= 'originalSize' bytes. - * @return : number of bytes read from source buffer (== compressed size). - * If the source stream is detected malformed, the function stops decoding and returns a negative result. - * note : This function requires uncompressed originalSize to be known in advance. - * The function never writes past the output buffer. - * However, since it doesn't know its 'src' size, it may read past the intended input. - * Also, because match offsets are not validated during decoding, - * reads from 'src' may underflow. - * Use this function in trusted environment **only**. - */ -LZ4LIB_API int LZ4_decompress_fast (const char* src, char* dst, int originalSize); - /*! LZ4_decompress_safe_partial() : * Decompress an LZ4 compressed block, of size 'srcSize' at position 'src', * into destination buffer 'dst' of size 'dstCapacity'. @@ -257,30 +239,49 @@ LZ4LIB_API int LZ4_decompress_safe_partial (const char* src, char* dst, int srcS ***********************************************/ typedef union LZ4_stream_u LZ4_stream_t; /* incomplete type (defined later) */ -/*! LZ4_createStream() and LZ4_freeStream() : - * LZ4_createStream() will allocate and initialize an `LZ4_stream_t` structure. - * LZ4_freeStream() releases its memory. - */ LZ4LIB_API LZ4_stream_t* LZ4_createStream(void); LZ4LIB_API int LZ4_freeStream (LZ4_stream_t* streamPtr); -/*! LZ4_resetStream() : - * An LZ4_stream_t structure can be allocated once and re-used multiple times. - * Use this function to start compressing a new stream. +/*! LZ4_resetStream_fast() : v1.9.0+ + * Use this to prepare an LZ4_stream_t for a new chain of dependent blocks + * (e.g., LZ4_compress_fast_continue()). + * + * An LZ4_stream_t must be initialized once before usage. + * This is automatically done when created by LZ4_createStream(). + * However, should the LZ4_stream_t be simply declared on stack (for example), + * it's necessary to initialize it first, using LZ4_initStream(). + * + * After init, start any new stream with LZ4_resetStream_fast(). + * A same LZ4_stream_t can be re-used multiple times consecutively + * and compress multiple streams, + * provided that it starts each new stream with LZ4_resetStream_fast(). + * + * LZ4_resetStream_fast() is much faster than LZ4_initStream(), + * but is not compatible with memory regions containing garbage data. + * + * Note: it's only useful to call LZ4_resetStream_fast() + * in the context of streaming compression. + * The *extState* functions perform their own resets. + * Invoking LZ4_resetStream_fast() before is redundant, and even counterproductive. */ -LZ4LIB_API void LZ4_resetStream (LZ4_stream_t* streamPtr); +LZ4LIB_API void LZ4_resetStream_fast (LZ4_stream_t* streamPtr); /*! LZ4_loadDict() : - * Use this function to load a static dictionary into LZ4_stream_t. - * Any previous data will be forgotten, only 'dictionary' will remain in memory. + * Use this function to reference a static dictionary into LZ4_stream_t. + * The dictionary must remain available during compression. + * LZ4_loadDict() triggers a reset, so any previous data will be forgotten. + * The same dictionary will have to be loaded on decompression side for successful decoding. + * Dictionary are useful for better compression of small data (KB range). + * While LZ4 accept any input as dictionary, + * results are generally better when using Zstandard's Dictionary Builder. * Loading a size of 0 is allowed, and is the same as reset. - * @return : dictionary size, in bytes (necessarily <= 64 KB) + * @return : loaded dictionary size, in bytes (necessarily <= 64 KB) */ LZ4LIB_API int LZ4_loadDict (LZ4_stream_t* streamPtr, const char* dictionary, int dictSize); /*! LZ4_compress_fast_continue() : * Compress 'src' content using data from previously compressed blocks, for better compression ratio. - * 'dst' buffer must be already allocated. + * 'dst' buffer must be already allocated. * If dstCapacity >= LZ4_compressBound(srcSize), compression is guaranteed to succeed, and runs faster. * * @return : size of compressed block @@ -288,10 +289,10 @@ LZ4LIB_API int LZ4_loadDict (LZ4_stream_t* streamPtr, const char* dictionary, in * * Note 1 : Each invocation to LZ4_compress_fast_continue() generates a new block. * Each block has precise boundaries. + * Each block must be decompressed separately, calling LZ4_decompress_*() with relevant metadata. * It's not possible to append blocks together and expect a single invocation of LZ4_decompress_*() to decompress them together. - * Each block must be decompressed separately, calling LZ4_decompress_*() with associated metadata. * - * Note 2 : The previous 64KB of source data is __assumed__ to remain present, unmodified, at same address in memory! + * Note 2 : The previous 64KB of source data is __assumed__ to remain present, unmodified, at same address in memory ! * * Note 3 : When input is structured as a double-buffer, each buffer can have any size, including < 64 KB. * Make sure that buffers are separated, by at least one byte. @@ -299,7 +300,7 @@ LZ4LIB_API int LZ4_loadDict (LZ4_stream_t* streamPtr, const char* dictionary, in * * Note 4 : If input buffer is a ring-buffer, it can have any size, including < 64 KB. * - * Note 5 : After an error, the stream status is invalid, it can only be reset or freed. + * Note 5 : After an error, the stream status is undefined (invalid), it can only be reset or freed. */ LZ4LIB_API int LZ4_compress_fast_continue (LZ4_stream_t* streamPtr, const char* src, char* dst, int srcSize, int dstCapacity, int acceleration); @@ -335,7 +336,7 @@ LZ4LIB_API int LZ4_freeStreamDecode (LZ4_streamDecode_t* LZ4_str */ LZ4LIB_API int LZ4_setStreamDecode (LZ4_streamDecode_t* LZ4_streamDecode, const char* dictionary, int dictSize); -/*! LZ4_decoderRingBufferSize() : v1.8.2 +/*! LZ4_decoderRingBufferSize() : v1.8.2+ * Note : in a ring buffer scenario (optional), * blocks are presumed decompressed next to each other * up to the moment there is not enough remaining space for next block (remainingSize < maxBlockSize), @@ -347,7 +348,7 @@ LZ4LIB_API int LZ4_setStreamDecode (LZ4_streamDecode_t* LZ4_streamDecode, const * or 0 if there is an error (invalid maxBlockSize). */ LZ4LIB_API int LZ4_decoderRingBufferSize(int maxBlockSize); -#define LZ4_DECODER_RING_BUFFER_SIZE(mbs) (65536 + 14 + (mbs)) /* for static allocation; mbs presumed valid */ +#define LZ4_DECODER_RING_BUFFER_SIZE(maxBlockSize) (65536 + 14 + (maxBlockSize)) /* for static allocation; maxBlockSize presumed valid */ /*! LZ4_decompress_*_continue() : * These decoding functions allow decompression of consecutive blocks in "streaming" mode. @@ -375,83 +376,67 @@ LZ4LIB_API int LZ4_decoderRingBufferSize(int maxBlockSize); * then indicate where this data is saved using LZ4_setStreamDecode(), before decompressing next block. */ LZ4LIB_API int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int srcSize, int dstCapacity); -LZ4LIB_API int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int originalSize); /*! LZ4_decompress_*_usingDict() : * These decoding functions work the same as * a combination of LZ4_setStreamDecode() followed by LZ4_decompress_*_continue() * They are stand-alone, and don't need an LZ4_streamDecode_t structure. - * Dictionary is presumed stable : it must remain accessible and unmodified during next decompression. + * Dictionary is presumed stable : it must remain accessible and unmodified during decompression. + * Performance tip : Decompression speed can be substantially increased + * when dst == dictStart + dictSize. */ LZ4LIB_API int LZ4_decompress_safe_usingDict (const char* src, char* dst, int srcSize, int dstCapcity, const char* dictStart, int dictSize); -LZ4LIB_API int LZ4_decompress_fast_usingDict (const char* src, char* dst, int originalSize, const char* dictStart, int dictSize); -/*^********************************************** +/*^************************************* * !!!!!! STATIC LINKING ONLY !!!!!! - ***********************************************/ + ***************************************/ -/*-************************************ - * Unstable declarations - ************************************** - * Declarations in this section should be considered unstable. - * Use at your own peril, etc., etc. - * They may be removed in the future. - * Their signatures may change. - **************************************/ +/*-**************************************************************************** + * Experimental section + * + * Symbols declared in this section must be considered unstable. Their + * signatures or semantics may change, or they may be removed altogether in the + * future. They are therefore only safe to depend on when the caller is + * statically linked against the library. + * + * To protect against unsafe usage, not only are the declarations guarded, + * the definitions are hidden by default + * when building LZ4 as a shared/dynamic library. + * + * In order to access these declarations, + * define LZ4_STATIC_LINKING_ONLY in your application + * before including LZ4's headers. + * + * In order to make their implementations accessible dynamically, you must + * define LZ4_PUBLISH_STATIC_FUNCTIONS when building the LZ4 library. + ******************************************************************************/ + +#ifdef LZ4_PUBLISH_STATIC_FUNCTIONS +#define LZ4LIB_STATIC_API LZ4LIB_API +#else +#define LZ4LIB_STATIC_API +#endif #ifdef LZ4_STATIC_LINKING_ONLY -/*! LZ4_resetStream_fast() : - * Use this, like LZ4_resetStream(), to prepare a context for a new chain of - * calls to a streaming API (e.g., LZ4_compress_fast_continue()). - * - * Note: - * Using this in advance of a non- streaming-compression function is redundant, - * and potentially bad for performance, since they all perform their own custom - * reset internally. - * - * Differences from LZ4_resetStream(): - * When an LZ4_stream_t is known to be in a internally coherent state, - * it can often be prepared for a new compression with almost no work, only - * sometimes falling back to the full, expensive reset that is always required - * when the stream is in an indeterminate state (i.e., the reset performed by - * LZ4_resetStream()). - * - * LZ4_streams are guaranteed to be in a valid state when: - * - returned from LZ4_createStream() - * - reset by LZ4_resetStream() - * - memset(stream, 0, sizeof(LZ4_stream_t)), though this is discouraged - * - the stream was in a valid state and was reset by LZ4_resetStream_fast() - * - the stream was in a valid state and was then used in any compression call - * that returned success - * - the stream was in an indeterminate state and was used in a compression - * call that fully reset the state (e.g., LZ4_compress_fast_extState()) and - * that returned success - * - * When a stream isn't known to be in a valid state, it is not safe to pass to - * any fastReset or streaming function. It must first be cleansed by the full - * LZ4_resetStream(). - */ -LZ4LIB_API void LZ4_resetStream_fast (LZ4_stream_t* streamPtr); /*! LZ4_compress_fast_extState_fastReset() : * A variant of LZ4_compress_fast_extState(). * - * Using this variant avoids an expensive initialization step. It is only safe - * to call if the state buffer is known to be correctly initialized already - * (see above comment on LZ4_resetStream_fast() for a definition of "correctly - * initialized"). From a high level, the difference is that this function - * initializes the provided state with a call to something like - * LZ4_resetStream_fast() while LZ4_compress_fast_extState() starts with a - * call to LZ4_resetStream(). + * Using this variant avoids an expensive initialization step. + * It is only safe to call if the state buffer is known to be correctly initialized already + * (see above comment on LZ4_resetStream_fast() for a definition of "correctly initialized"). + * From a high level, the difference is that + * this function initializes the provided state with a call to something like LZ4_resetStream_fast() + * while LZ4_compress_fast_extState() starts with a call to LZ4_resetStream(). */ -LZ4LIB_API int LZ4_compress_fast_extState_fastReset (void* state, const char* src, char* dst, int srcSize, int dstCapacity, int acceleration); +LZ4LIB_STATIC_API int LZ4_compress_fast_extState_fastReset (void* state, const char* src, char* dst, int srcSize, int dstCapacity, int acceleration); /*! LZ4_attach_dictionary() : - * This is an experimental API that allows for the efficient use of a - * static dictionary many times. + * This is an experimental API that allows + * efficient use of a static dictionary many times. * * Rather than re-loading the dictionary buffer into a working context before * each compression, or copying a pre-loaded dictionary's LZ4_stream_t into a @@ -462,8 +447,8 @@ LZ4LIB_API int LZ4_compress_fast_extState_fastReset (void* state, const char* sr * Currently, only streams which have been prepared by LZ4_loadDict() should * be expected to work. * - * Alternatively, the provided dictionary stream pointer may be NULL, in which - * case any existing dictionary stream is unset. + * Alternatively, the provided dictionaryStream may be NULL, + * in which case any existing dictionary stream is unset. * * If a dictionary is provided, it replaces any pre-existing stream history. * The dictionary contents are the only history that can be referenced and @@ -475,17 +460,18 @@ LZ4LIB_API int LZ4_compress_fast_extState_fastReset (void* state, const char* sr * stream (and source buffer) must remain in-place / accessible / unchanged * through the completion of the first compression call on the stream. */ -LZ4LIB_API void LZ4_attach_dictionary(LZ4_stream_t *working_stream, const LZ4_stream_t *dictionary_stream); +LZ4LIB_STATIC_API void LZ4_attach_dictionary(LZ4_stream_t* workingStream, const LZ4_stream_t* dictionaryStream); #endif -/*-************************************ - * Private definitions - ************************************** - * Do not use these definitions. - * They are exposed to allow static allocation of `LZ4_stream_t` and `LZ4_streamDecode_t`. - * Using these definitions will expose code to API and/or ABI break in future versions of the library. - **************************************/ + +/*-************************************************************ + * PRIVATE DEFINITIONS + ************************************************************** + * Do not use these definitions directly. + * They are only exposed to allow static allocation of `LZ4_stream_t` and `LZ4_streamDecode_t`. + * Accessing members will expose code to API and/or ABI break in future versions of the library. + **************************************************************/ #define LZ4_HASHLOG (LZ4_MEMORY_USAGE-2) #define LZ4_HASHTABLESIZE (1 << LZ4_MEMORY_USAGE) #define LZ4_HASH_SIZE_U32 (1 << LZ4_HASHLOG) /* required as macro for static allocation */ @@ -497,7 +483,7 @@ typedef struct LZ4_stream_t_internal LZ4_stream_t_internal; struct LZ4_stream_t_internal { uint32_t hashTable[LZ4_HASH_SIZE_U32]; uint32_t currentOffset; - uint16_t initCheck; + uint16_t dirty; uint16_t tableType; const uint8_t* dictionary; const LZ4_stream_t_internal* dictCtx; @@ -517,7 +503,7 @@ typedef struct LZ4_stream_t_internal LZ4_stream_t_internal; struct LZ4_stream_t_internal { unsigned int hashTable[LZ4_HASH_SIZE_U32]; unsigned int currentOffset; - unsigned short initCheck; + unsigned short dirty; unsigned short tableType; const unsigned char* dictionary; const LZ4_stream_t_internal* dictCtx; @@ -526,38 +512,54 @@ struct LZ4_stream_t_internal { typedef struct { const unsigned char* externalDict; - size_t extDictSize; const unsigned char* prefixEnd; + size_t extDictSize; size_t prefixSize; } LZ4_streamDecode_t_internal; #endif -/*! - * LZ4_stream_t : - * information structure to track an LZ4 stream. - * init this structure before first use. - * note : only use in association with static linking ! - * this definition is not API/ABI safe, - * it may change in a future version ! +/*! LZ4_stream_t : + * information structure to track an LZ4 stream. + * LZ4_stream_t can also be created using LZ4_createStream(), which is recommended. + * The structure definition can be convenient for static allocation + * (on stack, or as part of larger structure). + * Init this structure with LZ4_initStream() before first use. + * note : only use this definition in association with static linking ! + * this definition is not API/ABI safe, and may change in a future version. */ -#define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE-3)) + 4) +#define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE-3)) + 4 + ((sizeof(void*)==16) ? 4 : 0) /*AS-400*/ ) #define LZ4_STREAMSIZE (LZ4_STREAMSIZE_U64 * sizeof(unsigned long long)) union LZ4_stream_u { unsigned long long table[LZ4_STREAMSIZE_U64]; LZ4_stream_t_internal internal_donotuse; } ; /* previously typedef'd to LZ4_stream_t */ +/*! LZ4_initStream() : v1.9.0+ + * An LZ4_stream_t structure must be initialized at least once. + * This is automatically done when invoking LZ4_createStream(), + * but it's not when the structure is simply declared on stack (for example). + * + * Use LZ4_initStream() to properly initialize a newly declared LZ4_stream_t. + * It can also initialize any arbitrary buffer of sufficient size, + * and will @return a pointer of proper type upon initialization. + * + * Note : initialization fails if size and alignment conditions are not respected. + * In which case, the function will @return NULL. + * Note2: An LZ4_stream_t structure guarantees correct alignment and size. + * Note3: Before v1.9.0, use LZ4_resetStream() instead + */ +LZ4LIB_API LZ4_stream_t* LZ4_initStream (void* buffer, size_t size); -/*! - * LZ4_streamDecode_t : - * information structure to track an LZ4 stream during decompression. - * init this structure using LZ4_setStreamDecode (or memset()) before first use - * note : only use in association with static linking ! - * this definition is not API/ABI safe, - * and may change in a future version ! + +/*! LZ4_streamDecode_t : + * information structure to track an LZ4 stream during decompression. + * init this structure using LZ4_setStreamDecode() before first use. + * note : only use in association with static linking ! + * this definition is not API/ABI safe, + * and may change in a future version ! */ -#define LZ4_STREAMDECODESIZE_U64 4 +#define LZ4_STREAMDECODESIZE_U64 (4 + ((sizeof(void*)==16) ? 2 : 0) /*AS-400*/ ) #define LZ4_STREAMDECODESIZE (LZ4_STREAMDECODESIZE_U64 * sizeof(unsigned long long)) union LZ4_streamDecode_u { unsigned long long table[LZ4_STREAMDECODESIZE_U64]; @@ -570,11 +572,16 @@ union LZ4_streamDecode_u { **************************************/ /*! Deprecation warnings - Should deprecation warnings be a problem, - it is generally possible to disable them, - typically with -Wno-deprecated-declarations for gcc - or _CRT_SECURE_NO_WARNINGS in Visual. - Otherwise, it's also possible to define LZ4_DISABLE_DEPRECATE_WARNINGS */ + * + * Deprecated functions make the compiler generate a warning when invoked. + * This is meant to invite users to update their source code. + * Should deprecation warnings be a problem, it is generally possible to disable them, + * typically with -Wno-deprecated-declarations for gcc + * or _CRT_SECURE_NO_WARNINGS in Visual. + * + * Another method is to define LZ4_DISABLE_DEPRECATE_WARNINGS + * before including the header file. + */ #ifdef LZ4_DISABLE_DEPRECATE_WARNINGS # define LZ4_DEPRECATED(message) /* disable deprecation warnings */ #else @@ -594,8 +601,8 @@ union LZ4_streamDecode_u { #endif /* LZ4_DISABLE_DEPRECATE_WARNINGS */ /* Obsolete compression functions */ -LZ4_DEPRECATED("use LZ4_compress_default() instead") LZ4LIB_API int LZ4_compress (const char* source, char* dest, int sourceSize); -LZ4_DEPRECATED("use LZ4_compress_default() instead") LZ4LIB_API int LZ4_compress_limitedOutput (const char* source, char* dest, int sourceSize, int maxOutputSize); +LZ4_DEPRECATED("use LZ4_compress_default() instead") LZ4LIB_API int LZ4_compress (const char* source, char* dest, int sourceSize); +LZ4_DEPRECATED("use LZ4_compress_default() instead") LZ4LIB_API int LZ4_compress_limitedOutput (const char* source, char* dest, int sourceSize, int maxOutputSize); LZ4_DEPRECATED("use LZ4_compress_fast_extState() instead") LZ4LIB_API int LZ4_compress_withState (void* state, const char* source, char* dest, int inputSize); LZ4_DEPRECATED("use LZ4_compress_fast_extState() instead") LZ4LIB_API int LZ4_compress_limitedOutput_withState (void* state, const char* source, char* dest, int inputSize, int maxOutputSize); LZ4_DEPRECATED("use LZ4_compress_fast_continue() instead") LZ4LIB_API int LZ4_compress_continue (LZ4_stream_t* LZ4_streamPtr, const char* source, char* dest, int inputSize); @@ -616,13 +623,54 @@ LZ4_DEPRECATED("use LZ4_decompress_safe() instead") LZ4LIB_API int LZ4_uncompres */ LZ4_DEPRECATED("Use LZ4_createStream() instead") LZ4LIB_API void* LZ4_create (char* inputBuffer); LZ4_DEPRECATED("Use LZ4_createStream() instead") LZ4LIB_API int LZ4_sizeofStreamState(void); -LZ4_DEPRECATED("Use LZ4_resetStream() instead") LZ4LIB_API int LZ4_resetStreamState(void* state, char* inputBuffer); -LZ4_DEPRECATED("Use LZ4_saveDict() instead") LZ4LIB_API char* LZ4_slideInputBuffer (void* state); +LZ4_DEPRECATED("Use LZ4_resetStream() instead") LZ4LIB_API int LZ4_resetStreamState(void* state, char* inputBuffer); +LZ4_DEPRECATED("Use LZ4_saveDict() instead") LZ4LIB_API char* LZ4_slideInputBuffer (void* state); /* Obsolete streaming decoding functions */ LZ4_DEPRECATED("use LZ4_decompress_safe_usingDict() instead") LZ4LIB_API int LZ4_decompress_safe_withPrefix64k (const char* src, char* dst, int compressedSize, int maxDstSize); LZ4_DEPRECATED("use LZ4_decompress_fast_usingDict() instead") LZ4LIB_API int LZ4_decompress_fast_withPrefix64k (const char* src, char* dst, int originalSize); +/*! LZ4_decompress_fast() : **unsafe!** + * These functions are generally slightly faster than LZ4_decompress_safe(), + * though the difference is small (generally ~5%). + * However, the real cost is a risk : LZ4_decompress_safe() is protected vs malformed input, while `LZ4_decompress_fast()` is not, making it a security liability. + * As a consequence, LZ4_decompress_fast() is strongly discouraged, and deprecated. + * These functions will generate a deprecation warning in the future. + * + * Last LZ4_decompress_fast() specificity is that it can decompress a block without knowing its compressed size. + * Note that even that functionality could be achieved in a more secure manner if need be, + * though it would require new prototypes, and adaptation of the implementation to this new use case. + * + * Parameters: + * originalSize : is the uncompressed size to regenerate. + * `dst` must be already allocated, its size must be >= 'originalSize' bytes. + * @return : number of bytes read from source buffer (== compressed size). + * The function expects to finish at block's end exactly. + * If the source stream is detected malformed, the function stops decoding and returns a negative result. + * note : LZ4_decompress_fast*() requires originalSize. Thanks to this information, it never writes past the output buffer. + * However, since it doesn't know its 'src' size, it may read an unknown amount of input, past input buffer bounds. + * Also, since match offsets are not validated, match reads from 'src' may underflow too. + * These issues never happen if input (compressed) data is correct. + * But they may happen if input data is invalid (error or intentional tampering). + * As a consequence, use these functions in trusted environments with trusted data **only**. + */ + +/* LZ4_DEPRECATED("This function is deprecated and unsafe. Consider using LZ4_decompress_safe() instead") */ +LZ4LIB_API int LZ4_decompress_fast (const char* src, char* dst, int originalSize); +/* LZ4_DEPRECATED("This function is deprecated and unsafe. Consider using LZ4_decompress_safe_continue() instead") */ +LZ4LIB_API int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int originalSize); +/* LZ4_DEPRECATED("This function is deprecated and unsafe. Consider using LZ4_decompress_safe_usingDict() instead") */ +LZ4LIB_API int LZ4_decompress_fast_usingDict (const char* src, char* dst, int originalSize, const char* dictStart, int dictSize); + +/*! LZ4_resetStream() : + * An LZ4_stream_t structure must be initialized at least once. + * This is done with LZ4_initStream(), or LZ4_resetStream(). + * Consider switching to LZ4_initStream(), + * invoking LZ4_resetStream() will trigger deprecation warnings in the future. + */ +LZ4LIB_API void LZ4_resetStream (LZ4_stream_t* streamPtr); + + #endif /* LZ4_H_2983827168210 */ |