Crate `zstd_sys`

Low-level bindings to the zstd library.

Structs

Enums

ZSTD_EndDirective
ZSTD_ErrorCode
ZSTD_ResetDirective
ZSTD_cParameter
ZSTD_dParameter Advanced decompression API (Requires v1.4.0+)
ZSTD_strategy Advanced compression API (Requires v1.4.0+)

Functions

ZSTD_CCtx_loadDictionary ZSTD_CCtx_loadDictionary() : Requires v1.4.0+ Create an internal CDict from dict buffer. Decompression will have to use same dictionary. @result : 0, or an error code (which can be tested with ZSTD_isError()). Special: Loading a NULL (or 0-size) dictionary invalidates previous dictionary, meaning "return to no-dictionary mode". Note 1 : Dictionary is sticky, it will be used for all future compressed frames, until parameters are reset, a new dictionary is loaded, or the dictionary is explicitly invalidated by loading a NULL dictionary. Note 2 : Loading a dictionary involves building tables. It's also a CPU consuming operation, with non-negligible impact on latency. Tables are dependent on compression parameters, and for this reason, compression parameters can no longer be changed after loading a dictionary. Note 3 :dict content will be copied internally. Use experimental ZSTD_CCtx_loadDictionary_byReference() to reference content instead. In such a case, dictionary buffer must outlive its users. Note 4 : Use ZSTD_CCtx_loadDictionary_advanced() to precisely select how dictionary content must be interpreted. Note 5 : This method does not benefit from LDM (long distance mode). If you want to employ LDM on some large dictionary content, prefer employing ZSTD_CCtx_refPrefix() described below.
ZSTD_CCtx_refCDict ZSTD_CCtx_refCDict() : Requires v1.4.0+ Reference a prepared dictionary, to be used for all future compressed frames. Note that compression parameters are enforced from within CDict, and supersede any compression parameter previously set within CCtx. The parameters ignored are labelled as "superseded-by-cdict" in the ZSTD_cParameter enum docs. The ignored parameters will be used again if the CCtx is returned to no-dictionary mode. The dictionary will remain valid for future compressed frames using same CCtx. @result : 0, or an error code (which can be tested with ZSTD_isError()). Special : Referencing a NULL CDict means "return to no-dictionary mode". Note 1 : Currently, only one dictionary can be managed. Referencing a new dictionary effectively "discards" any previous one. Note 2 : CDict is just referenced, its lifetime must outlive its usage within CCtx.
ZSTD_CCtx_refPrefix ZSTD_CCtx_refPrefix() : Requires v1.4.0+ Reference a prefix (single-usage dictionary) for next compressed frame. A prefix is only used once. Tables are discarded at end of frame (ZSTD_e_end). Decompression will need same prefix to properly regenerate data. Compressing with a prefix is similar in outcome as performing a diff and compressing it, but performs much faster, especially during decompression (compression speed is tunable with compression level). This method is compatible with LDM (long distance mode). @result : 0, or an error code (which can be tested with ZSTD_isError()). Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary Note 1 : Prefix buffer is referenced. It must outlive compression. Its content must remain unmodified during compression. Note 2 : If the intention is to diff some large src data blob with some prior version of itself, ensure that the window size is large enough to contain the entire source. See ZSTD_c_windowLog. Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters. It's a CPU consuming operation, with non-negligible impact on latency. If there is a need to use the same prefix multiple times, consider loadDictionary instead. Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dct_rawContent). Use experimental ZSTD_CCtx_refPrefix_advanced() to alter dictionary interpretation.
ZSTD_CCtx_reset
ZSTD_CCtx_reset() : There are 2 different things that can be reset, independently or jointly :
- The session : will stop compressing current frame, and make CCtx ready to start a new one. Useful after an error, or to interrupt any ongoing compression. Any internal data not yet flushed is cancelled. Compression parameters and dictionary remain unchanged. They will be used to compress next frame. Resetting session never fails.
- The parameters : changes all parameters back to "default". This also removes any reference to any dictionary or external sequence producer. Parameters can only be changed between 2 sessions (i.e. no compression is currently ongoing) otherwise the reset fails, and function returns an error value (which can be tested using ZSTD_isError())
- Both : similar to resetting the session, followed by resetting parameters.
ZSTD_CCtx_setParameter ZSTD_CCtx_setParameter() : Set one compression parameter, selected by enum ZSTD_cParameter. All parameters have valid bounds. Bounds can be queried using ZSTD_cParam_getBounds(). Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter). Setting a parameter is generally only possible during frame initialization (before starting compression). Exception : when using multi-threading mode (nbWorkers >= 1), the following parameters can be updated during compression (within same frame): => compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy. new parameters will be active for next job only (after a flush()). @return : an error code (which can be tested using ZSTD_isError()).
ZSTD_CCtx_setPledgedSrcSize ZSTD_CCtx_setPledgedSrcSize() : Total input data size to be compressed as a single frame. Value will be written in frame header, unless if explicitly forbidden using ZSTD_c_contentSizeFlag. This value will also be controlled at end of frame, and trigger an error if not respected. @result : 0, or an error code (which can be tested with ZSTD_isError()). Note 1 : pledgedSrcSize==0 actually means zero, aka an empty frame. In order to mean "unknown content size", pass constant ZSTD_CONTENTSIZE_UNKNOWN. ZSTD_CONTENTSIZE_UNKNOWN is default value for any new frame. Note 2 : pledgedSrcSize is only valid once, for the next frame. It's discarded at the end of the frame, and replaced by ZSTD_CONTENTSIZE_UNKNOWN. Note 3 : Whenever all input data is provided and consumed in a single round, for example with ZSTD_compress2(), or invoking immediately ZSTD_compressStream2(,,,ZSTD_e_end), this value is automatically overridden by srcSize instead.
ZSTD_CStreamInSize
ZSTD_CStreamOutSize
ZSTD_DCtx_loadDictionary ZSTD_DCtx_loadDictionary() : Requires v1.4.0+ Create an internal DDict from dict buffer, to be used to decompress all future frames. The dictionary remains valid for all future frames, until explicitly invalidated, or a new dictionary is loaded. @result : 0, or an error code (which can be tested with ZSTD_isError()). Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary, meaning "return to no-dictionary mode". Note 1 : Loading a dictionary involves building tables, which has a non-negligible impact on CPU usage and latency. It's recommended to "load once, use many times", to amortize the cost Note 2 :dict content will be copied internally, so dict can be released after loading. Use ZSTD_DCtx_loadDictionary_byReference() to reference dictionary content instead. Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to take control of how dictionary content is loaded and interpreted.
ZSTD_DCtx_refDDict ZSTD_DCtx_refDDict() : Requires v1.4.0+ Reference a prepared dictionary, to be used to decompress next frames. The dictionary remains active for decompression of future frames using same DCtx.
ZSTD_DCtx_refPrefix ZSTD_DCtx_refPrefix() : Requires v1.4.0+ Reference a prefix (single-usage dictionary) to decompress next frame. This is the reverse operation of ZSTD_CCtx_refPrefix(), and must use the same prefix as the one used during compression. Prefix is only used once. Reference is discarded at end of frame. End of frame is reached when ZSTD_decompressStream() returns 0. @result : 0, or an error code (which can be tested with ZSTD_isError()). Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary Note 2 : Prefix buffer is referenced. It must outlive decompression. Prefix buffer must remain unmodified up to the end of frame, reached when ZSTD_decompressStream() returns 0. Note 3 : By default, the prefix is treated as raw content (ZSTD_dct_rawContent). Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode (Experimental section) Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost. A full dictionary is more costly, as it requires building tables.
ZSTD_DCtx_reset ZSTD_DCtx_reset() : Return a DCtx to clean state. Session and parameters can be reset jointly or separately. Parameters can only be reset when no active frame is being decompressed. @return : 0, or an error code, which can be tested with ZSTD_isError()
ZSTD_DCtx_setParameter ZSTD_DCtx_setParameter() : Set one compression parameter, selected by enum ZSTD_dParameter. All parameters have valid bounds. Bounds can be queried using ZSTD_dParam_getBounds(). Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter). Setting a parameter is only possible during frame initialization (before starting decompression). @return : 0, or an error code (which can be tested using ZSTD_isError()).
ZSTD_DStreamInSize
ZSTD_DStreamOutSize
ZSTD_cParam_getBounds ZSTD_cParam_getBounds() : All parameters must belong to an interval with lower and upper bounds, otherwise they will either trigger an error or be automatically clamped. @return : a structure, ZSTD_bounds, which contains - an error status field, which must be tested using ZSTD_isError() - lower and upper bounds, both inclusive
ZSTD_compress Simple Core API / /*! ZSTD_compress() : Compresses src content as a single zstd compressed frame into already allocated dst. NOTE: Providing dstCapacity >= ZSTD_compressBound(srcSize) guarantees that zstd will have enough space to successfully compress the data. @return : compressed size written into dst (<= `dstCapacity), or an error code if it fails (which can be tested using ZSTD_isError()).
ZSTD_compress2
ZSTD_compress2() : Behave the same as ZSTD_compressCCtx(), but compression parameters are set using the advanced API. (note that this entry point doesn't even expose a compression level parameter). ZSTD_compress2() always starts a new frame. Should cctx hold data from a previously unfinished frame, everything about it is forgotten.
- Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*()
- The function is always blocking, returns when compression is completed. NOTE: Providing dstCapacity >= ZSTD_compressBound(srcSize) guarantees that zstd will have enough space to successfully compress the data, though it is possible it fails for other reasons. @return : compressed size written into dst (<= `dstCapacity), or an error code if it fails (which can be tested using ZSTD_isError()).
ZSTD_compressBound
ZSTD_compressCCtx ZSTD_compressCCtx() : Same as ZSTD_compress(), using an explicit ZSTD_CCtx. Important : in order to mirror ZSTD_compress() behavior, this function compresses at the requested compression level, ignoring any other advanced parameter . If any advanced parameter was set using the advanced API, they will all be reset. Only @compressionLevel remains.
ZSTD_compressStream Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue). NOTE: The return value is different. ZSTD_compressStream() returns a hint for the next read size (if non-zero and not an error). ZSTD_compressStream2() returns the minimum nb of bytes left to flush (if non-zero and not an error).
ZSTD_compressStream2
ZSTD_compressStream2() : Requires v1.4.0+ Behaves about the same as ZSTD_compressStream, with additional control on end directive.
- Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*()
- Compression parameters cannot be changed once compression is started (save a list of exceptions in multi-threading mode)
- output->pos must be <= dstCapacity, input->pos must be <= srcSize
- output->pos and input->pos will be updated. They are guaranteed to remain below their respective limit.
- endOp must be a valid directive
- When nbWorkers==0 (default), function is blocking : it completes its job before returning to caller.
- When nbWorkers>=1, function is non-blocking : it copies a portion of input, distributes jobs to internal worker threads, flush to output whatever is available, and then immediately returns, just indicating that there is some data remaining to be flushed. The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte.
- Exception : if the first call requests a ZSTD_e_end directive and provides enough dstCapacity, the function delegates to ZSTD_compress2() which is always blocking.
- @return provides a minimum amount of data remaining to be flushed from internal buffers or an error code, which can be tested using ZSTD_isError(). if @return != 0, flush is not fully completed, there is still some data left within internal buffers. This is useful for ZSTD_e_flush, since in this case more flushes are necessary to empty all buffers. For ZSTD_e_end, @return == 0 when internal buffers are fully flushed and frame is completed.
- after a ZSTD_e_end directive, if internal buffer is not fully flushed (@return != 0), only ZSTD_e_end or ZSTD_e_flush operations are allowed. Before starting a new compression job, or changing compression parameters, it is required to fully flush internal buffers.
- note: if an operation ends with an error, it may leave @cctx in an undefined state. Therefore, it's UB to invoke ZSTD_compressStream2() of ZSTD_compressStream() on such a state. In order to be re-employed after an error, a state must be reset, which can be done explicitly (ZSTD_CCtx_reset()), or is sometimes implied by methods starting a new compression job (ZSTD_initCStream(), ZSTD_compressCCtx())
ZSTD_compress_usingCDict ZSTD_compress_usingCDict() : Compression using a digested Dictionary. Recommended when same dictionary is used multiple times. Note : compression level is decided at dictionary creation time, and frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no)
ZSTD_compress_usingDict Simple dictionary API / /*! ZSTD_compress_usingDict() : Compression at an explicit compression level using a Dictionary. A dictionary can be any arbitrary data segment (also called a prefix), or a buffer with specified information (see zdict.h). Note : This function loads the dictionary, resulting in significant startup delay. It's intended for a dictionary used only once. Note 2 : When dict == NULL || dictSize < 8 no dictionary is used.
ZSTD_createCCtx
ZSTD_createCDict ZSTD_createCDict() : When compressing multiple messages or blocks using the same dictionary, it's recommended to digest the dictionary only once, since it's a costly operation. ZSTD_createCDict() will create a state from digesting a dictionary. The resulting state can be used for future compression operations with very limited startup cost. ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only. @dictBuffer can be released after ZSTD_CDict creation, because its content is copied within CDict. Note 1 : Consider experimental function ZSTD_createCDict_byReference() if you prefer to not duplicate @dictBuffer content. Note 2 : A ZSTD_CDict can be created from an empty @dictBuffer, in which case the only thing that it transports is the @compressionLevel. This can be useful in a pipeline featuring ZSTD_compress_usingCDict() exclusively, expecting a ZSTD_CDict parameter with any data, including those without a known dictionary.
ZSTD_createCStream
ZSTD_createDCtx
ZSTD_createDDict ZSTD_createDDict() : Create a digested dictionary, ready to start decompression operation without startup delay. dictBuffer can be released after DDict creation, as its content is copied inside DDict.
ZSTD_createDStream
ZSTD_dParam_getBounds ZSTD_dParam_getBounds() : All parameters must belong to an interval with lower and upper bounds, otherwise they will either trigger an error or be automatically clamped. @return : a structure, ZSTD_bounds, which contains - an error status field, which must be tested using ZSTD_isError() - both lower and upper bounds, inclusive
ZSTD_decompress ZSTD_decompress() : compressedSize : must be the exact size of some number of compressed and/or skippable frames. Multiple compressed frames can be decompressed at once with this method. The result will be the concatenation of all decompressed frames, back to back. dstCapacity is an upper bound of originalSize to regenerate. First frame's decompressed size can be extracted using ZSTD_getFrameContentSize(). If maximum upper bound isn't known, prefer using streaming mode to decompress data. @return : the number of bytes decompressed into dst (<= dstCapacity), or an errorCode if it fails (which can be tested using ZSTD_isError()).
ZSTD_decompressDCtx ZSTD_decompressDCtx() : Same as ZSTD_decompress(), requires an allocated ZSTD_DCtx. Compatible with sticky parameters (see below).
ZSTD_decompressStream
ZSTD_decompressStream() : Streaming decompression function. Call repetitively to consume full input updating it as necessary. Function will update both input and output pos fields exposing current state via these fields:
- input.pos < input.size, some input remaining and caller should provide remaining input on the next call.
- output.pos < output.size, decoder flushed internal output buffer.
- output.pos == output.size, unflushed data potentially present in the internal buffers, check ZSTD_decompressStream() @return value, if > 0, invoke it again to flush remaining data to output. Note : with no additional input, amount of data flushed <= ZSTD_BLOCKSIZE_MAX.
ZSTD_decompress_usingDDict ZSTD_decompress_usingDDict() : Decompression using a digested Dictionary. Recommended when same dictionary is used multiple times.
ZSTD_decompress_usingDict ZSTD_decompress_usingDict() : Decompression using a known Dictionary. Dictionary must be identical to the one used during compression. Note : This function loads the dictionary, resulting in significant startup delay. It's intended for a dictionary used only once. Note : When dict == NULL || dictSize < 8 no dictionary is used.
ZSTD_defaultCLevel
ZSTD_endStream Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end).
ZSTD_findFrameCompressedSize ZSTD_findFrameCompressedSize() : Requires v1.4.0+ src should point to the start of a ZSTD frame or skippable frame. srcSize must be >= first frame size @return : the compressed size of the first frame starting at src, suitable to pass as srcSize to ZSTD_decompress or similar, or an error code if input is invalid Note 1: this method is called _find*() because it's not enough to read the header, it may have to scan through the frame's content, to reach its end. Note 2: this method also works with Skippable Frames. In which case, it returns the size of the complete skippable frame, which is always equal to its content size + 8 bytes for headers.
ZSTD_flushStream Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush).
ZSTD_freeCCtx
ZSTD_freeCDict ZSTD_freeCDict() : Function frees memory allocated by ZSTD_createCDict(). If a NULL pointer is passed, no operation is performed.
ZSTD_freeCStream
ZSTD_freeDCtx
ZSTD_freeDDict ZSTD_freeDDict() : Function frees memory allocated with ZSTD_createDDict() If a NULL pointer is passed, no operation is performed.
ZSTD_freeDStream
ZSTD_getDecompressedSize ZSTD_getDecompressedSize() (obsolete): This function is now obsolete, in favor of ZSTD_getFrameContentSize(). Both functions work the same way, but ZSTD_getDecompressedSize() blends "empty", "unknown" and "error" results to the same return value (0), while ZSTD_getFrameContentSize() gives them separate return values. @return : decompressed size of src frame content if known and not empty, 0 otherwise.
ZSTD_getDictID_fromCDict ZSTD_getDictID_fromCDict() : Requires v1.5.0+ Provides the dictID of the dictionary loaded into cdict. If @return == 0, the dictionary is not conformant to Zstandard specification, or empty. Non-conformant dictionaries can still be loaded, but as content-only dictionaries.
ZSTD_getDictID_fromDDict ZSTD_getDictID_fromDDict() : Requires v1.4.0+ Provides the dictID of the dictionary loaded into ddict. If @return == 0, the dictionary is not conformant to Zstandard specification, or empty. Non-conformant dictionaries can still be loaded, but as content-only dictionaries.
ZSTD_getDictID_fromDict ZSTD_getDictID_fromDict() : Requires v1.4.0+ Provides the dictID stored within dictionary. if @return == 0, the dictionary is not conformant with Zstandard specification. It can still be loaded, but as a content-only dictionary.
ZSTD_getDictID_fromFrame
ZSTD_getDictID_fromFrame() : Requires v1.4.0+ Provides the dictID required to decompressed the frame stored within src. If @return == 0, the dictID could not be decoded. This could for one of the following reasons :
- The frame does not require a dictionary to be decoded (most common case).
- The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden piece of information. Note : this use case also happens when using a non-conformant dictionary.
- srcSize is too small, and as a result, the frame header could not be decoded (only possible if srcSize < ZSTD_FRAMEHEADERSIZE_MAX).
- This is not a Zstandard frame. When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code.
ZSTD_getErrorCode
ZSTD_getErrorName
ZSTD_getErrorString
ZSTD_getFrameContentSize
ZSTD_initCStream Equivalent to:
ZSTD_initDStream ZSTD_initDStream() : Initialize/reset DStream state for new decompression operation. Call before new decompression operation using same DStream.
ZSTD_isError
ZSTD_maxCLevel
ZSTD_minCLevel
ZSTD_sizeof_CCtx ZSTD_sizeof_*() : Requires v1.4.0+ These functions give the current memory usage of selected object. Note that object memory usage can evolve (increase or decrease) over time.
ZSTD_sizeof_CDict
ZSTD_sizeof_CStream
ZSTD_sizeof_DCtx
ZSTD_sizeof_DDict
ZSTD_sizeof_DStream
ZSTD_versionNumber ZSTD_versionNumber() : Return runtime library version, the value is (MAJOR100100 + MINOR*100 + RELEASE).
ZSTD_versionString ZSTD_versionString() : Return runtime library version, like "1.4.5". Requires v1.3.0+.

Type Aliases

ZSTD_CCtx Explicit context
ZSTD_CDict Bulk processing dictionary API
ZSTD_CStream
ZSTD_DCtx
ZSTD_DDict
ZSTD_DStream
ZSTD_inBuffer Streaming
ZSTD_outBuffer

Structs

Enums

Functions

Type Aliases

Constants