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zstd/contrib/linux-kernel/include/linux/zstd.h
Nick Terrell d1a5790f8e [linux-kernel] Dual license with GPLv2
2017-05-17 12:08:15 -07:00

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/*
* Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of https://github.com/facebook/zstd.
* An additional grant of patent rights can be found in the PATENTS file in the
* same directory.
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License version 2 as published by the
* Free Software Foundation. This program is dual-licensed; you may select
* either version 2 of the GNU General Public License ("GPL") or BSD license
* ("BSD").
*/
#ifndef ZSTD_H
#define ZSTD_H
/* ====== Dependency ======*/
#include <linux/types.h> /* size_t */
/*-*****************************************************************************
* Introduction
*
* zstd, short for Zstandard, is a fast lossless compression algorithm,
* targeting real-time compression scenarios at zlib-level and better
* compression ratios. The zstd compression library provides in-memory
* compression and decompression functions. The library supports compression
* levels from 1 up to ZSTD_maxCLevel() which is 22. Levels >= 20, labeled
* ultra, should be used with caution, as they require more memory.
* Compression can be done in:
* - a single step, reusing a context (described as Explicit memory management)
* - unbounded multiple steps (described as Streaming compression)
* The compression ratio achievable on small data can be highly improved using
* compression with a dictionary in:
* - a single step (described as Simple dictionary API)
* - a single step, reusing a dictionary (described as Fast dictionary API)
******************************************************************************/
/*====== Helper functions ======*/
/**
* enum ZSTD_ErrorCode - zstd error codes
*
* Functions that return size_t can be checked for errors using ZSTD_isError()
* and the ZSTD_ErrorCode can be extracted using ZSTD_getErrorCode().
*/
typedef enum {
ZSTD_error_no_error,
ZSTD_error_GENERIC,
ZSTD_error_prefix_unknown,
ZSTD_error_version_unsupported,
ZSTD_error_parameter_unknown,
ZSTD_error_frameParameter_unsupported,
ZSTD_error_frameParameter_unsupportedBy32bits,
ZSTD_error_frameParameter_windowTooLarge,
ZSTD_error_compressionParameter_unsupported,
ZSTD_error_init_missing,
ZSTD_error_memory_allocation,
ZSTD_error_stage_wrong,
ZSTD_error_dstSize_tooSmall,
ZSTD_error_srcSize_wrong,
ZSTD_error_corruption_detected,
ZSTD_error_checksum_wrong,
ZSTD_error_tableLog_tooLarge,
ZSTD_error_maxSymbolValue_tooLarge,
ZSTD_error_maxSymbolValue_tooSmall,
ZSTD_error_dictionary_corrupted,
ZSTD_error_dictionary_wrong,
ZSTD_error_dictionaryCreation_failed,
ZSTD_error_maxCode
} ZSTD_ErrorCode;
/**
* ZSTD_maxCLevel() - maximum compression level available
*
* Return: Maximum compression level available.
*/
int ZSTD_maxCLevel(void);
/**
* ZSTD_compressBound() - maximum compressed size in worst case scenario
* @srcSize: The size of the data to compress.
*
* Return: The maximum compressed size in the worst case scenario.
*/
size_t ZSTD_compressBound(size_t srcSize);
/**
* ZSTD_isError() - tells if a size_t function result is an error code
* @code: The function result to check for error.
*
* Return: Non-zero iff the code is an error.
*/
static __attribute__((unused)) unsigned int ZSTD_isError(size_t code)
{
return code > (size_t)-ZSTD_error_maxCode;
}
/**
* ZSTD_getErrorCode() - translates an error function result to a ZSTD_ErrorCode
* @functionResult: The result of a function for which ZSTD_isError() is true.
*
* Return: The ZSTD_ErrorCode corresponding to the functionResult or 0
* if the functionResult isn't an error.
*/
static __attribute__((unused)) ZSTD_ErrorCode ZSTD_getErrorCode(
size_t functionResult)
{
if (!ZSTD_isError(functionResult))
return (ZSTD_ErrorCode)0;
return (ZSTD_ErrorCode)(0 - functionResult);
}
/**
* enum ZSTD_strategy - zstd compression search strategy
*
* From faster to stronger.
*/
typedef enum {
ZSTD_fast,
ZSTD_dfast,
ZSTD_greedy,
ZSTD_lazy,
ZSTD_lazy2,
ZSTD_btlazy2,
ZSTD_btopt,
ZSTD_btopt2
} ZSTD_strategy;
/**
* struct ZSTD_compressionParameters - zstd compression parameters
* @windowLog: Log of the largest match distance. Larger means more
* compression, and more memory needed during decompression.
* @chainLog: Fully searched segment. Larger means more compression, slower,
* and more memory (useless for fast).
* @hashLog: Dispatch table. Larger means more compression,
* slower, and more memory.
* @searchLog: Number of searches. Larger means more compression and slower.
* @searchLength: Match length searched. Larger means faster decompression,
* sometimes less compression.
* @targetLength: Acceptable match size for optimal parser (only). Larger means
* more compression, and slower.
* @strategy: The zstd compression strategy.
*/
typedef struct {
unsigned int windowLog;
unsigned int chainLog;
unsigned int hashLog;
unsigned int searchLog;
unsigned int searchLength;
unsigned int targetLength;
ZSTD_strategy strategy;
} ZSTD_compressionParameters;
/**
* struct ZSTD_frameParameters - zstd frame parameters
* @contentSizeFlag: Controls whether content size will be present in the frame
* header (when known).
* @checksumFlag: Controls whether a 32-bit checksum is generated at the end
* of the frame for error detection.
* @noDictIDFlag: Controls whether dictID will be saved into the frame header
* when using dictionary compression.
*
* The default value is all fields set to 0.
*/
typedef struct {
unsigned int contentSizeFlag;
unsigned int checksumFlag;
unsigned int noDictIDFlag;
} ZSTD_frameParameters;
/**
* struct ZSTD_parameters - zstd parameters
* @cParams: The compression parameters.
* @fParams: The frame parameters.
*/
typedef struct {
ZSTD_compressionParameters cParams;
ZSTD_frameParameters fParams;
} ZSTD_parameters;
/**
* ZSTD_getCParams() - returns ZSTD_compressionParameters for selected level
* @compressionLevel: The compression level from 1 to ZSTD_maxCLevel().
* @estimatedSrcSize: The estimated source size to compress or 0 if unknown.
* @dictSize: The dictionary size or 0 if a dictionary isn't being used.
*
* Return: The selected ZSTD_compressionParameters.
*/
ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel,
unsigned long long estimatedSrcSize, size_t dictSize);
/**
* ZSTD_getParams() - returns ZSTD_parameters for selected level
* @compressionLevel: The compression level from 1 to ZSTD_maxCLevel().
* @estimatedSrcSize: The estimated source size to compress or 0 if unknown.
* @dictSize: The dictionary size or 0 if a dictionary isn't being used.
*
* The same as ZSTD_getCParams() except also selects the default frame
* parameters (all zero).
*
* Return: The selected ZSTD_parameters.
*/
ZSTD_parameters ZSTD_getParams(int compressionLevel,
unsigned long long estimatedSrcSize, size_t dictSize);
/*-*************************************
* Explicit memory management
**************************************/
/**
* ZSTD_CCtxWorkspaceBound() - amount of memory needed to initialize a ZSTD_CCtx
* @cParams: The compression parameters to be used for compression.
*
* If multiple compression parameters might be used, the caller must call
* ZSTD_CCtxWorkspaceBound() for each set of parameters and use the maximum
* size.
*
* Return: A lower bound on the size of the workspace that is passed to
* ZSTD_initCCtx().
*/
size_t ZSTD_CCtxWorkspaceBound(ZSTD_compressionParameters cParams);
/**
* struct ZSTD_CCtx - the zstd compression context
*
* When compressing many times it is recommended to allocate a context just once
* and reuse it for each successive compression operation.
*/
typedef struct ZSTD_CCtx_s ZSTD_CCtx;
/**
* ZSTD_initCCtx() - initialize a zstd compression context
* @workspace: The workspace to emplace the context into. It must outlive
* the returned context.
* @workspaceSize: The size of workspace. Use ZSTD_CCtxWorkspaceBound() to
* determine how large the workspace must be.
*
* Return: A compression context emplaced into workspace.
*/
ZSTD_CCtx *ZSTD_initCCtx(void *workspace, size_t workspaceSize);
/**
* ZSTD_compressCCtx() - compress src into dst
* @ctx: The context. Must have been initialized with a workspace at
* least as large as ZSTD_CCtxWorkspaceBound(params.cParams).
* @dst: The buffer to compress src into.
* @dstCapacity: The size of the destination buffer. May be any size, but
* ZSTD_compressBound(srcSize) is guaranteed to be large enough.
* @src: The data to compress.
* @srcSize: The size of the data to compress.
* @params: The parameters to use for compression. See ZSTD_getParams().
*
* Return: The compressed size or an error, which can be checked using
* ZSTD_isError().
*/
size_t ZSTD_compressCCtx(ZSTD_CCtx *ctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize, ZSTD_parameters params);
/**
* ZSTD_DCtxWorkspaceBound() - amount of memory needed to initialize a ZSTD_DCtx
*
* Return: A lower bound on the size of the workspace that is passed to
* ZSTD_initDCtx().
*/
size_t ZSTD_DCtxWorkspaceBound(void);
/**
* struct ZSTD_DCtx - the zstd decompression context
*
* When decompressing many times it is recommended to allocate a context just
* once and reuse it for each successive decompression operation.
*/
typedef struct ZSTD_DCtx_s ZSTD_DCtx;
/**
* ZSTD_initDCtx() - initialize a zstd decompression context
* @workspace: The workspace to emplace the context into. It must outlive
* the returned context.
* @workspaceSize: The size of workspace. Use ZSTD_DCtxWorkspaceBound() to
* determine how large the workspace must be.
*
* Return: A decompression context emplaced into workspace.
*/
ZSTD_DCtx *ZSTD_initDCtx(void *workspace, size_t workspaceSize);
/**
* ZSTD_decompressDCtx() - decompress zstd compressed src into dst
* @ctx: The decompression context.
* @dst: The buffer to decompress src into.
* @dstCapacity: The size of the destination buffer. Must be at least as large
* as the decompressed size. If the caller cannot upper bound the
* decompressed size, then it's better to use the streaming API.
* @src: The zstd compressed data to decompress. Multiple concatenated
* frames and skippable frames are allowed.
* @srcSize: The exact size of the data to decompress.
*
* Return: The decompressed size or an error, which can be checked using
* ZSTD_isError().
*/
size_t ZSTD_decompressDCtx(ZSTD_DCtx *ctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize);
/*-************************
* Simple dictionary API
**************************/
/**
* ZSTD_compress_usingDict() - compress src into dst using a dictionary
* @ctx: The context. Must have been initialized with a workspace at
* least as large as ZSTD_CCtxWorkspaceBound(params.cParams).
* @dst: The buffer to compress src into.
* @dstCapacity: The size of the destination buffer. May be any size, but
* ZSTD_compressBound(srcSize) is guaranteed to be large enough.
* @src: The data to compress.
* @srcSize: The size of the data to compress.
* @dict: The dictionary to use for compression.
* @dictSize: The size of the dictionary.
* @params: The parameters to use for compression. See ZSTD_getParams().
*
* Compression using a predefined dictionary. The same dictionary must be used
* during decompression.
*
* Return: The compressed size or an error, which can be checked using
* ZSTD_isError().
*/
size_t ZSTD_compress_usingDict(ZSTD_CCtx *ctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize, const void *dict, size_t dictSize,
ZSTD_parameters params);
/**
* ZSTD_decompress_usingDict() - decompress src into dst using a dictionary
* @ctx: The decompression context.
* @dst: The buffer to decompress src into.
* @dstCapacity: The size of the destination buffer. Must be at least as large
* as the decompressed size. If the caller cannot upper bound the
* decompressed size, then it's better to use the streaming API.
* @src: The zstd compressed data to decompress. Multiple concatenated
* frames and skippable frames are allowed.
* @srcSize: The exact size of the data to decompress.
* @dict: The dictionary to use for decompression. The same dictionary
* must've been used to compress the data.
* @dictSize: The size of the dictionary.
*
* Return: The decompressed size or an error, which can be checked using
* ZSTD_isError().
*/
size_t ZSTD_decompress_usingDict(ZSTD_DCtx *ctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize, const void *dict, size_t dictSize);
/*-**************************
* Fast dictionary API
***************************/
/**
* ZSTD_CDictWorkspaceBound() - memory needed to initialize a ZSTD_CDict
* @cParams: The compression parameters to be used for compression.
*
* Return: A lower bound on the size of the workspace that is passed to
* ZSTD_initCDict().
*/
size_t ZSTD_CDictWorkspaceBound(ZSTD_compressionParameters cParams);
/**
* struct ZSTD_CDict - a digested dictionary to be used for compression
*/
typedef struct ZSTD_CDict_s ZSTD_CDict;
/**
* ZSTD_initCDict() - initialize a digested dictionary for compression
* @dictBuffer: The dictionary to digest. The buffer is referenced by the
* ZSTD_CDict so it must outlive the returned ZSTD_CDict.
* @dictSize: The size of the dictionary.
* @params: The parameters to use for compression. See ZSTD_getParams().
* @workspace: The workspace. It must outlive the returned ZSTD_CDict.
* @workspaceSize: The workspace size. Must be at least
* ZSTD_CDictWorkspaceBound(params.cParams).
*
* When compressing multiple messages / blocks with the same dictionary it is
* recommended to load it just once. The ZSTD_CDict merely references the
* dictBuffer, so it must outlive the returned ZSTD_CDict.
*
* Return: The digested dictionary emplaced into workspace.
*/
ZSTD_CDict *ZSTD_initCDict(const void *dictBuffer, size_t dictSize,
ZSTD_parameters params, void *workspace, size_t workspaceSize);
/**
* ZSTD_compress_usingCDict() - compress src into dst using a ZSTD_CDict
* @ctx: The context. Must have been initialized with a workspace at
* least as large as ZSTD_CCtxWorkspaceBound(cParams) where
* cParams are the compression parameters used to initialize the
* cdict.
* @dst: The buffer to compress src into.
* @dstCapacity: The size of the destination buffer. May be any size, but
* ZSTD_compressBound(srcSize) is guaranteed to be large enough.
* @src: The data to compress.
* @srcSize: The size of the data to compress.
* @cdict: The digested dictionary to use for compression.
* @params: The parameters to use for compression. See ZSTD_getParams().
*
* Compression using a digested dictionary. The same dictionary must be used
* during decompression.
*
* Return: The compressed size or an error, which can be checked using
* ZSTD_isError().
*/
size_t ZSTD_compress_usingCDict(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize, const ZSTD_CDict *cdict);
/**
* ZSTD_DDictWorkspaceBound() - memory needed to initialize a ZSTD_DDict
*
* Return: A lower bound on the size of the workspace that is passed to
* ZSTD_initDDict().
*/
size_t ZSTD_DDictWorkspaceBound(void);
/**
* struct ZSTD_DDict - a digested dictionary to be used for decompression
*/
typedef struct ZSTD_DDict_s ZSTD_DDict;
/**
* ZSTD_initDDict() - initialize a digested dictionary for decompression
* @dictBuffer: The dictionary to digest. The buffer is referenced by the
* ZSTD_DDict so it must outlive the returned ZSTD_DDict.
* @dictSize: The size of the dictionary.
* @workspace: The workspace. It must outlive the returned ZSTD_DDict.
* @workspaceSize: The workspace size. Must be at least
* ZSTD_DDictWorkspaceBound().
*
* When decompressing multiple messages / blocks with the same dictionary it is
* recommended to load it just once. The ZSTD_DDict merely references the
* dictBuffer, so it must outlive the returned ZSTD_DDict.
*
* Return: The digested dictionary emplaced into workspace.
*/
ZSTD_DDict *ZSTD_initDDict(const void *dictBuffer, size_t dictSize,
void *workspace, size_t workspaceSize);
/**
* ZSTD_decompress_usingDDict() - decompress src into dst using a ZSTD_DDict
* @ctx: The decompression context.
* @dst: The buffer to decompress src into.
* @dstCapacity: The size of the destination buffer. Must be at least as large
* as the decompressed size. If the caller cannot upper bound the
* decompressed size, then it's better to use the streaming API.
* @src: The zstd compressed data to decompress. Multiple concatenated
* frames and skippable frames are allowed.
* @srcSize: The exact size of the data to decompress.
* @ddict: The digested dictionary to use for decompression. The same
* dictionary must've been used to compress the data.
*
* Return: The decompressed size or an error, which can be checked using
* ZSTD_isError().
*/
size_t ZSTD_decompress_usingDDict(ZSTD_DCtx *dctx, void *dst,
size_t dstCapacity, const void *src, size_t srcSize,
const ZSTD_DDict *ddict);
/*-**************************
* Streaming
***************************/
/**
* struct ZSTD_inBuffer - input buffer for streaming
* @src: Start of the input buffer.
* @size: Size of the input buffer.
* @pos: Position where reading stopped. Will be updated.
* Necessarily 0 <= pos <= size.
*/
typedef struct ZSTD_inBuffer_s {
const void *src;
size_t size;
size_t pos;
} ZSTD_inBuffer;
/**
* struct ZSTD_outBuffer - output buffer for streaming
* @dst: Start of the output buffer.
* @size: Size of the output buffer.
* @pos: Position where writing stopped. Will be updated.
* Necessarily 0 <= pos <= size.
*/
typedef struct ZSTD_outBuffer_s {
void *dst;
size_t size;
size_t pos;
} ZSTD_outBuffer;
/*-*****************************************************************************
* Streaming compression - HowTo
*
* A ZSTD_CStream object is required to track streaming operation.
* Use ZSTD_initCStream() to initialize a ZSTD_CStream object.
* ZSTD_CStream objects can be reused multiple times on consecutive compression
* operations. It is recommended to re-use ZSTD_CStream in situations where many
* streaming operations will be achieved consecutively. Use one separate
* ZSTD_CStream per thread for parallel execution.
*
* Use ZSTD_compressStream() repetitively to consume input stream.
* The function will automatically update both `pos` fields.
* Note that it may not consume the entire input, in which case `pos < size`,
* and it's up to the caller to present again remaining data.
* It returns a hint for the preferred number of bytes to use as an input for
* the next function call.
*
* At any moment, it's possible to flush whatever data remains within internal
* buffer, using ZSTD_flushStream(). `output->pos` will be updated. There might
* still be some content left within the internal buffer if `output->size` is
* too small. It returns the number of bytes left in the internal buffer and
* must be called until it returns 0.
*
* ZSTD_endStream() instructs to finish a frame. It will perform a flush and
* write frame epilogue. The epilogue is required for decoders to consider a
* frame completed. Similar to ZSTD_flushStream(), it may not be able to flush
* the full content if `output->size` is too small. In which case, call again
* ZSTD_endStream() to complete the flush. It returns the number of bytes left
* in the internal buffer and must be called until it returns 0.
******************************************************************************/
/**
* ZSTD_CStreamWorkspaceBound() - memory needed to initialize a ZSTD_CStream
* @cParams: The compression parameters to be used for compression.
*
* Return: A lower bound on the size of the workspace that is passed to
* ZSTD_initCStream() and ZSTD_initCStream_usingCDict().
*/
size_t ZSTD_CStreamWorkspaceBound(ZSTD_compressionParameters cParams);
/**
* struct ZSTD_CStream - the zstd streaming compression context
*/
typedef struct ZSTD_CStream_s ZSTD_CStream;
/*===== ZSTD_CStream management functions =====*/
/**
* ZSTD_initCStream() - initialize a zstd streaming compression context
* @params: The zstd compression parameters.
* @pledgedSrcSize: If params.fParams.contentSizeFlag == 1 then the caller must
* pass the source size (zero means empty source). Otherwise,
* the caller may optionally pass the source size, or zero if
* unknown.
* @workspace: The workspace to emplace the context into. It must outlive
* the returned context.
* @workspaceSize: The size of workspace.
* Use ZSTD_CStreamWorkspaceBound(params.cParams) to determine
* how large the workspace must be.
*
* Return: The zstd streaming compression context.
*/
ZSTD_CStream *ZSTD_initCStream(ZSTD_parameters params,
unsigned long long pledgedSrcSize, void *workspace,
size_t workspaceSize);
/**
* ZSTD_initCStream_usingCDict() - initialize a streaming compression context
* @cdict: The digested dictionary to use for compression.
* @pledgedSrcSize: Optionally the source size, or zero if unknown.
* @workspace: The workspace to emplace the context into. It must outlive
* the returned context.
* @workspaceSize: The size of workspace. Call ZSTD_CStreamWorkspaceBound()
* with the cParams used to initialize the cdict to determine
* how large the workspace must be.
*
* Return: The zstd streaming compression context.
*/
ZSTD_CStream *ZSTD_initCStream_usingCDict(const ZSTD_CDict *cdict,
unsigned long long pledgedSrcSize, void *workspace,
size_t workspaceSize);
/*===== Streaming compression functions =====*/
/**
* ZSTD_resetCStream() - reset the context using parameters from creation
* @zcs: The zstd streaming compression context to reset.
* @pledgedSrcSize: Optionally the source size, or zero if unknown.
*
* Resets the context using the parameters from creation. Skips dictionary
* loading, since it can be reused. If `pledgedSrcSize` is non-zero the frame
* content size is always written into the frame header.
*
* Return: Zero or an error, which can be checked using ZSTD_isError().
*/
size_t ZSTD_resetCStream(ZSTD_CStream *zcs, unsigned long long pledgedSrcSize);
/**
* ZSTD_compressStream() - streaming compress some of input into output
* @zcs: The zstd streaming compression context.
* @output: Destination buffer. `output->pos` is updated to indicate how much
* compressed data was written.
* @input: Source buffer. `input->pos` is updated to indicate how much data was
* read. Note that it may not consume the entire input, in which case
* `input->pos < input->size`, and it's up to the caller to present
* remaining data again.
*
* The `input` and `output` buffers may be any size. Guaranteed to make some
* forward progress if `input` and `output` are not empty.
*
* Return: A hint for the number of bytes to use as the input for the next
* function call or an error, which can be checked using
* ZSTD_isError().
*/
size_t ZSTD_compressStream(ZSTD_CStream *zcs, ZSTD_outBuffer *output,
ZSTD_inBuffer *input);
/**
* ZSTD_flushStream() - flush internal buffers into output
* @zcs: The zstd streaming compression context.
* @output: Destination buffer. `output->pos` is updated to indicate how much
* compressed data was written.
*
* ZSTD_flushStream() must be called until it returns 0, meaning all the data
* has been flushed. Since ZSTD_flushStream() causes a block to be ended,
* calling it too often will degrade the compression ratio.
*
* Return: The number of bytes still present within internal buffers or an
* error, which can be checked using ZSTD_isError().
*/
size_t ZSTD_flushStream(ZSTD_CStream *zcs, ZSTD_outBuffer *output);
/**
* ZSTD_endStream() - flush internal buffers into output and end the frame
* @zcs: The zstd streaming compression context.
* @output: Destination buffer. `output->pos` is updated to indicate how much
* compressed data was written.
*
* ZSTD_endStream() must be called until it returns 0, meaning all the data has
* been flushed and the frame epilogue has been written.
*
* Return: The number of bytes still present within internal buffers or an
* error, which can be checked using ZSTD_isError().
*/
size_t ZSTD_endStream(ZSTD_CStream *zcs, ZSTD_outBuffer *output);
/**
* ZSTD_CStreamInSize() - recommended size for the input buffer
*
* Return: The recommended size for the input buffer.
*/
size_t ZSTD_CStreamInSize(void);
/**
* ZSTD_CStreamOutSize() - recommended size for the output buffer
*
* When the output buffer is at least this large, it is guaranteed to be large
* enough to flush at least one complete compressed block.
*
* Return: The recommended size for the output buffer.
*/
size_t ZSTD_CStreamOutSize(void);
/*-*****************************************************************************
* Streaming decompression - HowTo
*
* A ZSTD_DStream object is required to track streaming operations.
* Use ZSTD_initDStream() to initialize a ZSTD_DStream object.
* ZSTD_DStream objects can be re-used multiple times.
*
* Use ZSTD_decompressStream() repetitively to consume your input.
* The function will update both `pos` fields.
* If `input->pos < input->size`, some input has not been consumed.
* It's up to the caller to present again remaining data.
* If `output->pos < output->size`, decoder has flushed everything it could.
* Returns 0 iff a frame is completely decoded and fully flushed.
* Otherwise it returns a suggested next input size that will never load more
* than the current frame.
******************************************************************************/
/**
* ZSTD_DStreamWorkspaceBound() - memory needed to initialize a ZSTD_DStream
* @maxWindowSize: The maximum window size allowed for compressed frames.
*
* Return: A lower bound on the size of the workspace that is passed to
* ZSTD_initDStream() and ZSTD_initDStream_usingDDict().
*/
size_t ZSTD_DStreamWorkspaceBound(size_t maxWindowSize);
/**
* struct ZSTD_DStream - the zstd streaming decompression context
*/
typedef struct ZSTD_DStream_s ZSTD_DStream;
/*===== ZSTD_DStream management functions =====*/
/**
* ZSTD_initDStream() - initialize a zstd streaming decompression context
* @maxWindowSize: The maximum window size allowed for compressed frames.
* @workspace: The workspace to emplace the context into. It must outlive
* the returned context.
* @workspaceSize: The size of workspace.
* Use ZSTD_DStreamWorkspaceBound(maxWindowSize) to determine
* how large the workspace must be.
*
* Return: The zstd streaming decompression context.
*/
ZSTD_DStream *ZSTD_initDStream(size_t maxWindowSize, void *workspace,
size_t workspaceSize);
/**
* ZSTD_initDStream_usingDDict() - initialize streaming decompression context
* @maxWindowSize: The maximum window size allowed for compressed frames.
* @ddict: The digested dictionary to use for decompression.
* @workspace: The workspace to emplace the context into. It must outlive
* the returned context.
* @workspaceSize: The size of workspace.
* Use ZSTD_DStreamWorkspaceBound(maxWindowSize) to determine
* how large the workspace must be.
*
* Return: The zstd streaming decompression context.
*/
ZSTD_DStream *ZSTD_initDStream_usingDDict(size_t maxWindowSize,
const ZSTD_DDict *ddict, void *workspace, size_t workspaceSize);
/*===== Streaming decompression functions =====*/
/**
* ZSTD_resetDStream() - reset the context using parameters from creation
* @zds: The zstd streaming decompression context to reset.
*
* Resets the context using the parameters from creation. Skips dictionary
* loading, since it can be reused.
*
* Return: Zero or an error, which can be checked using ZSTD_isError().
*/
size_t ZSTD_resetDStream(ZSTD_DStream *zds);
/**
* ZSTD_decompressStream() - streaming decompress some of input into output
* @zds: The zstd streaming decompression context.
* @output: Destination buffer. `output.pos` is updated to indicate how much
* decompressed data was written.
* @input: Source buffer. `input.pos` is updated to indicate how much data was
* read. Note that it may not consume the entire input, in which case
* `input.pos < input.size`, and it's up to the caller to present
* remaining data again.
*
* The `input` and `output` buffers may be any size. Guaranteed to make some
* forward progress if `input` and `output` are not empty.
* ZSTD_decompressStream() will not consume the last byte of the frame until
* the entire frame is flushed.
*
* Return: Returns 0 iff a frame is completely decoded and fully flushed.
* Otherwise returns a hint for the number of bytes to use as the input
* for the next function call or an error, which can be checked using
* ZSTD_isError(). The size hint will never load more than the frame.
*/
size_t ZSTD_decompressStream(ZSTD_DStream *zds, ZSTD_outBuffer *output,
ZSTD_inBuffer *input);
/**
* ZSTD_DStreamInSize() - recommended size for the input buffer
*
* Return: The recommended size for the input buffer.
*/
size_t ZSTD_DStreamInSize(void);
/**
* ZSTD_DStreamOutSize() - recommended size for the output buffer
*
* When the output buffer is at least this large, it is guaranteed to be large
* enough to flush at least one complete decompressed block.
*
* Return: The recommended size for the output buffer.
*/
size_t ZSTD_DStreamOutSize(void);
/* --- Constants ---*/
#define ZSTD_MAGICNUMBER 0xFD2FB528 /* >= v0.8.0 */
#define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U
#define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1)
#define ZSTD_CONTENTSIZE_ERROR (0ULL - 2)
#define ZSTD_WINDOWLOG_MAX_32 27
#define ZSTD_WINDOWLOG_MAX_64 27
#define ZSTD_WINDOWLOG_MAX \
((unsigned int)(sizeof(size_t) == 4 \
? ZSTD_WINDOWLOG_MAX_32 \
: ZSTD_WINDOWLOG_MAX_64))
#define ZSTD_WINDOWLOG_MIN 10
#define ZSTD_HASHLOG_MAX ZSTD_WINDOWLOG_MAX
#define ZSTD_HASHLOG_MIN 6
#define ZSTD_CHAINLOG_MAX (ZSTD_WINDOWLOG_MAX+1)
#define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN
#define ZSTD_HASHLOG3_MAX 17
#define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1)
#define ZSTD_SEARCHLOG_MIN 1
/* only for ZSTD_fast, other strategies are limited to 6 */
#define ZSTD_SEARCHLENGTH_MAX 7
/* only for ZSTD_btopt, other strategies are limited to 4 */
#define ZSTD_SEARCHLENGTH_MIN 3
#define ZSTD_TARGETLENGTH_MIN 4
#define ZSTD_TARGETLENGTH_MAX 999
/* for static allocation */
#define ZSTD_FRAMEHEADERSIZE_MAX 18
#define ZSTD_FRAMEHEADERSIZE_MIN 6
static const size_t ZSTD_frameHeaderSize_prefix = 5;
static const size_t ZSTD_frameHeaderSize_min = ZSTD_FRAMEHEADERSIZE_MIN;
static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX;
/* magic number + skippable frame length */
static const size_t ZSTD_skippableHeaderSize = 8;
/*-*************************************
* Compressed size functions
**************************************/
/**
* ZSTD_findFrameCompressedSize() - returns the size of a compressed frame
* @src: Source buffer. It should point to the start of a zstd encoded frame
* or a skippable frame.
* @srcSize: The size of the source buffer. It must be at least as large as the
* size of the frame.
*
* Return: The compressed size of the frame pointed to by `src` or an error,
* which can be check with ZSTD_isError().
* Suitable to pass to ZSTD_decompress() or similar functions.
*/
size_t ZSTD_findFrameCompressedSize(const void *src, size_t srcSize);
/*-*************************************
* Decompressed size functions
**************************************/
/**
* ZSTD_getFrameContentSize() - returns the content size in a zstd frame header
* @src: It should point to the start of a zstd encoded frame.
* @srcSize: The size of the source buffer. It must be at least as large as the
* frame header. `ZSTD_frameHeaderSize_max` is always large enough.
*
* Return: The frame content size stored in the frame header if known.
* `ZSTD_CONTENTSIZE_UNKNOWN` if the content size isn't stored in the
* frame header. `ZSTD_CONTENTSIZE_ERROR` on invalid input.
*/
unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize);
/**
* ZSTD_findDecompressedSize() - returns decompressed size of a series of frames
* @src: It should point to the start of a series of zstd encoded and/or
* skippable frames.
* @srcSize: The exact size of the series of frames.
*
* If any zstd encoded frame in the series doesn't have the frame content size
* set, `ZSTD_CONTENTSIZE_UNKNOWN` is returned. But frame content size is always
* set when using ZSTD_compress(). The decompressed size can be very large.
* If the source is untrusted, the decompressed size could be wrong or
* intentionally modified. Always ensure the result fits within the
* application's authorized limits. ZSTD_findDecompressedSize() handles multiple
* frames, and so it must traverse the input to read each frame header. This is
* efficient as most of the data is skipped, however it does mean that all frame
* data must be present and valid.
*
* Return: Decompressed size of all the data contained in the frames if known.
* `ZSTD_CONTENTSIZE_UNKNOWN` if the decompressed size is unknown.
* `ZSTD_CONTENTSIZE_ERROR` if an error occurred.
*/
unsigned long long ZSTD_findDecompressedSize(const void *src, size_t srcSize);
/*-*************************************
* Advanced compression functions
**************************************/
/**
* ZSTD_checkCParams() - ensure parameter values remain within authorized range
* @cParams: The zstd compression parameters.
*
* Return: Zero or an error, which can be checked using ZSTD_isError().
*/
size_t ZSTD_checkCParams(ZSTD_compressionParameters cParams);
/**
* ZSTD_adjustCParams() - optimize parameters for a given srcSize and dictSize
* @srcSize: Optionally the estimated source size, or zero if unknown.
* @dictSize: Optionally the estimated dictionary size, or zero if unknown.
*
* Return: The optimized parameters.
*/
ZSTD_compressionParameters ZSTD_adjustCParams(
ZSTD_compressionParameters cParams, unsigned long long srcSize,
size_t dictSize);
/*--- Advanced decompression functions ---*/
/**
* ZSTD_isFrame() - returns true iff the buffer starts with a valid frame
* @buffer: The source buffer to check.
* @size: The size of the source buffer, must be at least 4 bytes.
*
* Return: True iff the buffer starts with a zstd or skippable frame identifier.
*/
unsigned int ZSTD_isFrame(const void *buffer, size_t size);
/**
* ZSTD_getDictID_fromDict() - returns the dictionary id stored in a dictionary
* @dict: The dictionary buffer.
* @dictSize: The size of the dictionary buffer.
*
* Return: The dictionary id stored within the dictionary or 0 if the
* dictionary is not a zstd dictionary. If it returns 0 the
* dictionary can still be loaded as a content-only dictionary.
*/
unsigned int ZSTD_getDictID_fromDict(const void *dict, size_t dictSize);
/**
* ZSTD_getDictID_fromDDict() - returns the dictionary id stored in a ZSTD_DDict
* @ddict: The ddict to find the id of.
*
* Return: The dictionary id stored within `ddict` or 0 if the dictionary is not
* a zstd dictionary. If it returns 0 `ddict` will be loaded as a
* content-only dictionary.
*/
unsigned int ZSTD_getDictID_fromDDict(const ZSTD_DDict *ddict);
/**
* ZSTD_getDictID_fromFrame() - returns the dictionary id stored in a zstd frame
* @src: Source buffer. It must be a zstd encoded frame.
* @srcSize: The size of the source buffer. It must be at least as large as the
* frame header. `ZSTD_frameHeaderSize_max` is always large enough.
*
* Return: The dictionary id required to decompress the frame stored within
* `src` or 0 if the dictionary id could not be decoded. It can return
* 0 if the frame does not require a dictionary, the dictionary id
* wasn't stored in the frame, `src` is not a zstd frame, or `srcSize`
* is too small.
*/
unsigned int ZSTD_getDictID_fromFrame(const void *src, size_t srcSize);
/**
* struct ZSTD_frameParams - zstd frame parameters stored in the frame header
* @frameContentSize: The frame content size, or 0 if not present.
* @windowSize: The window size, or 0 if the frame is a skippable frame.
* @dictID: The dictionary id, or 0 if not present.
* @checksumFlag: Whether a checksum was used.
*/
typedef struct {
unsigned long long frameContentSize;
unsigned int windowSize;
unsigned int dictID;
unsigned int checksumFlag;
} ZSTD_frameParams;
/**
* ZSTD_getFrameParams() - extracts parameters from a zstd or skippable frame
* @fparamsPtr: On success the frame parameters are written here.
* @src: The source buffer. It must point to a zstd or skippable frame.
* @srcSize: The size of the source buffer. `ZSTD_frameHeaderSize_max` is
* always large enough to succeed.
*
* Return: 0 on success. If more data is required it returns how many bytes
* must be provided to make forward progress. Otherwise it returns
* an error, which can be checked using ZSTD_isError().
*/
size_t ZSTD_getFrameParams(ZSTD_frameParams *fparamsPtr, const void *src,
size_t srcSize);
/*-*****************************************************************************
* Buffer-less and synchronous inner streaming functions
*
* This is an advanced API, giving full control over buffer management, for
* users which need direct control over memory.
* But it's also a complex one, with many restrictions (documented below).
* Prefer using normal streaming API for an easier experience
******************************************************************************/
/*-*****************************************************************************
* Buffer-less streaming compression (synchronous mode)
*
* A ZSTD_CCtx object is required to track streaming operations.
* Use ZSTD_initCCtx() to initialize a context.
* ZSTD_CCtx object can be re-used multiple times within successive compression
* operations.
*
* Start by initializing a context.
* Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary
* compression,
* or ZSTD_compressBegin_advanced(), for finer parameter control.
* It's also possible to duplicate a reference context which has already been
* initialized, using ZSTD_copyCCtx()
*
* Then, consume your input using ZSTD_compressContinue().
* There are some important considerations to keep in mind when using this
* advanced function :
* - ZSTD_compressContinue() has no internal buffer. It uses externally provided
* buffer only.
* - Interface is synchronous : input is consumed entirely and produce 1+
* (or more) compressed blocks.
* - Caller must ensure there is enough space in `dst` to store compressed data
* under worst case scenario. Worst case evaluation is provided by
* ZSTD_compressBound().
* ZSTD_compressContinue() doesn't guarantee recover after a failed
* compression.
* - ZSTD_compressContinue() presumes prior input ***is still accessible and
* unmodified*** (up to maximum distance size, see WindowLog).
* It remembers all previous contiguous blocks, plus one separated memory
* segment (which can itself consists of multiple contiguous blocks)
* - ZSTD_compressContinue() detects that prior input has been overwritten when
* `src` buffer overlaps. In which case, it will "discard" the relevant memory
* section from its history.
*
* Finish a frame with ZSTD_compressEnd(), which will write the last block(s)
* and optional checksum. It's possible to use srcSize==0, in which case, it
* will write a final empty block to end the frame. Without last block mark,
* frames will be considered unfinished (corrupted) by decoders.
*
* `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress some new
* frame.
******************************************************************************/
/*===== Buffer-less streaming compression functions =====*/
size_t ZSTD_compressBegin(ZSTD_CCtx *cctx, int compressionLevel);
size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx *cctx, const void *dict,
size_t dictSize, int compressionLevel);
size_t ZSTD_compressBegin_advanced(ZSTD_CCtx *cctx, const void *dict,
size_t dictSize, ZSTD_parameters params,
unsigned long long pledgedSrcSize);
size_t ZSTD_copyCCtx(ZSTD_CCtx *cctx, const ZSTD_CCtx *preparedCCtx,
unsigned long long pledgedSrcSize);
size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx *cctx, const ZSTD_CDict *cdict,
unsigned long long pledgedSrcSize);
size_t ZSTD_compressContinue(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize);
size_t ZSTD_compressEnd(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize);
/*-*****************************************************************************
* Buffer-less streaming decompression (synchronous mode)
*
* A ZSTD_DCtx object is required to track streaming operations.
* Use ZSTD_initDCtx() to initialize a context.
* A ZSTD_DCtx object can be re-used multiple times.
*
* First typical operation is to retrieve frame parameters, using
* ZSTD_getFrameParams(). It fills a ZSTD_frameParams structure which provide
* important information to correctly decode the frame, such as the minimum
* rolling buffer size to allocate to decompress data (`windowSize`), and the
* dictionary ID used.
* Note: content size is optional, it may not be present. 0 means unknown.
* Note that these values could be wrong, either because of data malformation,
* or because an attacker is spoofing deliberate false information. As a
* consequence, check that values remain within valid application range,
* especially `windowSize`, before allocation. Each application can set its own
* limit, depending on local restrictions. For extended interoperability, it is
* recommended to support at least 8 MB.
* Frame parameters are extracted from the beginning of the compressed frame.
* Data fragment must be large enough to ensure successful decoding, typically
* `ZSTD_frameHeaderSize_max` bytes.
* Result: 0: successful decoding, the `ZSTD_frameParams` structure is filled.
* >0: `srcSize` is too small, provide at least this many bytes.
* errorCode, which can be tested using ZSTD_isError().
*
* Start decompression, with ZSTD_decompressBegin() or
* ZSTD_decompressBegin_usingDict(). Alternatively, you can copy a prepared
* context, using ZSTD_copyDCtx().
*
* Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue()
* alternatively.
* ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize'
* to ZSTD_decompressContinue().
* ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will
* fail.
*
* The result of ZSTD_decompressContinue() is the number of bytes regenerated
* within 'dst' (necessarily <= dstCapacity). It can be zero, which is not an
* error; it just means ZSTD_decompressContinue() has decoded some metadata
* item. It can also be an error code, which can be tested with ZSTD_isError().
*
* ZSTD_decompressContinue() needs previous data blocks during decompression, up
* to `windowSize`. They should preferably be located contiguously, prior to
* current block. Alternatively, a round buffer of sufficient size is also
* possible. Sufficient size is determined by frame parameters.
* ZSTD_decompressContinue() is very sensitive to contiguity, if 2 blocks don't
* follow each other, make sure that either the compressor breaks contiguity at
* the same place, or that previous contiguous segment is large enough to
* properly handle maximum back-reference.
*
* A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero.
* Context can then be reset to start a new decompression.
*
* Note: it's possible to know if next input to present is a header or a block,
* using ZSTD_nextInputType(). This information is not required to properly
* decode a frame.
*
* == Special case: skippable frames ==
*
* Skippable frames allow integration of user-defined data into a flow of
* concatenated frames. Skippable frames will be ignored (skipped) by a
* decompressor. The format of skippable frames is as follows:
* a) Skippable frame ID - 4 Bytes, Little endian format, any value from
* 0x184D2A50 to 0x184D2A5F
* b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits
* c) Frame Content - any content (User Data) of length equal to Frame Size
* For skippable frames ZSTD_decompressContinue() always returns 0.
* For skippable frames ZSTD_getFrameParams() returns fparamsPtr->windowLog==0
* what means that a frame is skippable.
* Note: If fparamsPtr->frameContentSize==0, it is ambiguous: the frame might
* actually be a zstd encoded frame with no content. For purposes of
* decompression, it is valid in both cases to skip the frame using
* ZSTD_findFrameCompressedSize() to find its size in bytes.
* It also returns frame size as fparamsPtr->frameContentSize.
******************************************************************************/
/*===== Buffer-less streaming decompression functions =====*/
size_t ZSTD_decompressBegin(ZSTD_DCtx *dctx);
size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx *dctx, const void *dict,
size_t dictSize);
void ZSTD_copyDCtx(ZSTD_DCtx *dctx, const ZSTD_DCtx *preparedDCtx);
size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx *dctx);
size_t ZSTD_decompressContinue(ZSTD_DCtx *dctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize);
typedef enum {
ZSTDnit_frameHeader,
ZSTDnit_blockHeader,
ZSTDnit_block,
ZSTDnit_lastBlock,
ZSTDnit_checksum,
ZSTDnit_skippableFrame
} ZSTD_nextInputType_e;
ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx *dctx);
/*-*****************************************************************************
* Block functions
*
* Block functions produce and decode raw zstd blocks, without frame metadata.
* Frame metadata cost is typically ~18 bytes, which can be non-negligible for
* very small blocks (< 100 bytes). User will have to take in charge required
* information to regenerate data, such as compressed and content sizes.
*
* A few rules to respect:
* - Compressing and decompressing require a context structure
* + Use ZSTD_initCCtx() and ZSTD_initDCtx()
* - It is necessary to init context before starting
* + compression : ZSTD_compressBegin()
* + decompression : ZSTD_decompressBegin()
* + variants _usingDict() are also allowed
* + copyCCtx() and copyDCtx() work too
* - Block size is limited, it must be <= ZSTD_getBlockSizeMax()
* + If you need to compress more, cut data into multiple blocks
* + Consider using the regular ZSTD_compress() instead, as frame metadata
* costs become negligible when source size is large.
* - When a block is considered not compressible enough, ZSTD_compressBlock()
* result will be zero. In which case, nothing is produced into `dst`.
* + User must test for such outcome and deal directly with uncompressed data
* + ZSTD_decompressBlock() doesn't accept uncompressed data as input!!!
* + In case of multiple successive blocks, decoder must be informed of
* uncompressed block existence to follow proper history. Use
* ZSTD_insertBlock() in such a case.
******************************************************************************/
/* Define for static allocation */
#define ZSTD_BLOCKSIZE_ABSOLUTEMAX (128 * 1024)
/*===== Raw zstd block functions =====*/
size_t ZSTD_getBlockSizeMax(ZSTD_CCtx *cctx);
size_t ZSTD_compressBlock(ZSTD_CCtx *cctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize);
size_t ZSTD_decompressBlock(ZSTD_DCtx *dctx, void *dst, size_t dstCapacity,
const void *src, size_t srcSize);
size_t ZSTD_insertBlock(ZSTD_DCtx *dctx, const void *blockStart,
size_t blockSize);
#endif /* ZSTD_H */
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