| Current File : //proc/thread-self/root/usr/src/linux-headers-6.8.0-59/include/linux/zstd.h |
/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */
/*
* Copyright (c) Yann Collet, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of https://github.com/facebook/zstd) and
* the GPLv2 (found in the COPYING file in the root directory of
* https://github.com/facebook/zstd). You may select, at your option, one of the
* above-listed licenses.
*/
#ifndef LINUX_ZSTD_H
#define LINUX_ZSTD_H
/**
* This is a kernel-style API that wraps the upstream zstd API, which cannot be
* used directly because the symbols aren't exported. It exposes the minimal
* functionality which is currently required by users of zstd in the kernel.
* Expose extra functions from lib/zstd/zstd.h as needed.
*/
/* ====== Dependency ====== */
#include <linux/types.h>
#include <linux/zstd_errors.h>
#include <linux/zstd_lib.h>
/* ====== Helper Functions ====== */
/**
* zstd_compress_bound() - maximum compressed size in worst case scenario
* @src_size: The size of the data to compress.
*
* Return: The maximum compressed size in the worst case scenario.
*/
size_t zstd_compress_bound(size_t src_size);
/**
* zstd_is_error() - 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.
*/
unsigned int zstd_is_error(size_t code);
/**
* enum zstd_error_code - zstd error codes
*/
typedef ZSTD_ErrorCode zstd_error_code;
/**
* zstd_get_error_code() - translates an error function result to an error code
* @code: The function result for which zstd_is_error(code) is true.
*
* Return: A unique error code for this error.
*/
zstd_error_code zstd_get_error_code(size_t code);
/**
* zstd_get_error_name() - translates an error function result to a string
* @code: The function result for which zstd_is_error(code) is true.
*
* Return: An error string corresponding to the error code.
*/
const char *zstd_get_error_name(size_t code);
/**
* zstd_min_clevel() - minimum allowed compression level
*
* Return: The minimum allowed compression level.
*/
int zstd_min_clevel(void);
/**
* zstd_max_clevel() - maximum allowed compression level
*
* Return: The maximum allowed compression level.
*/
int zstd_max_clevel(void);
/* ====== Parameter Selection ====== */
/**
* enum zstd_strategy - zstd compression search strategy
*
* From faster to stronger. See zstd_lib.h.
*/
typedef ZSTD_strategy zstd_strategy;
/**
* struct zstd_compression_parameters - 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.
*
* See zstd_lib.h.
*/
typedef ZSTD_compressionParameters zstd_compression_parameters;
/**
* struct zstd_frame_parameters - 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. See zstd_lib.h.
*/
typedef ZSTD_frameParameters zstd_frame_parameters;
/**
* struct zstd_parameters - zstd parameters
* @cParams: The compression parameters.
* @fParams: The frame parameters.
*/
typedef ZSTD_parameters zstd_parameters;
/**
* zstd_get_params() - returns zstd_parameters for selected level
* @level: The compression level
* @estimated_src_size: The estimated source size to compress or 0
* if unknown.
*
* Return: The selected zstd_parameters.
*/
zstd_parameters zstd_get_params(int level,
unsigned long long estimated_src_size);
/* ====== Single-pass Compression ====== */
typedef ZSTD_CCtx zstd_cctx;
/**
* zstd_cctx_workspace_bound() - max memory needed to initialize a zstd_cctx
* @parameters: The compression parameters to be used.
*
* If multiple compression parameters might be used, the caller must call
* zstd_cctx_workspace_bound() 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_init_cctx().
*/
size_t zstd_cctx_workspace_bound(const zstd_compression_parameters *parameters);
/**
* zstd_init_cctx() - initialize a zstd compression context
* @workspace: The workspace to emplace the context into. It must outlive
* the returned context.
* @workspace_size: The size of workspace. Use zstd_cctx_workspace_bound() to
* determine how large the workspace must be.
*
* Return: A zstd compression context or NULL on error.
*/
zstd_cctx *zstd_init_cctx(void *workspace, size_t workspace_size);
/**
* zstd_compress_cctx() - compress src into dst with the initialized parameters
* @cctx: The context. Must have been initialized with zstd_init_cctx().
* @dst: The buffer to compress src into.
* @dst_capacity: 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.
* @src_size: The size of the data to compress.
* @parameters: The compression parameters to be used.
*
* Return: The compressed size or an error, which can be checked using
* zstd_is_error().
*/
size_t zstd_compress_cctx(zstd_cctx *cctx, void *dst, size_t dst_capacity,
const void *src, size_t src_size, const zstd_parameters *parameters);
/* ====== Single-pass Decompression ====== */
typedef ZSTD_DCtx zstd_dctx;
/**
* zstd_dctx_workspace_bound() - max memory needed to initialize a zstd_dctx
*
* Return: A lower bound on the size of the workspace that is passed to
* zstd_init_dctx().
*/
size_t zstd_dctx_workspace_bound(void);
/**
* zstd_init_dctx() - initialize a zstd decompression context
* @workspace: The workspace to emplace the context into. It must outlive
* the returned context.
* @workspace_size: The size of workspace. Use zstd_dctx_workspace_bound() to
* determine how large the workspace must be.
*
* Return: A zstd decompression context or NULL on error.
*/
zstd_dctx *zstd_init_dctx(void *workspace, size_t workspace_size);
/**
* zstd_decompress_dctx() - decompress zstd compressed src into dst
* @dctx: The decompression context.
* @dst: The buffer to decompress src into.
* @dst_capacity: 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.
* @src_size: The exact size of the data to decompress.
*
* Return: The decompressed size or an error, which can be checked using
* zstd_is_error().
*/
size_t zstd_decompress_dctx(zstd_dctx *dctx, void *dst, size_t dst_capacity,
const void *src, size_t src_size);
/* ====== Streaming Buffers ====== */
/**
* struct zstd_in_buffer - 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.
*
* See zstd_lib.h.
*/
typedef ZSTD_inBuffer zstd_in_buffer;
/**
* struct zstd_out_buffer - 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.
*
* See zstd_lib.h.
*/
typedef ZSTD_outBuffer zstd_out_buffer;
/* ====== Streaming Compression ====== */
typedef ZSTD_CStream zstd_cstream;
/**
* zstd_cstream_workspace_bound() - 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_init_cstream().
*/
size_t zstd_cstream_workspace_bound(const zstd_compression_parameters *cparams);
/**
* zstd_init_cstream() - initialize a zstd streaming compression context
* @parameters The zstd parameters to use for compression.
* @pledged_src_size: 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.
* @workspace_size: The size of workspace.
* Use zstd_cstream_workspace_bound(params->cparams) to
* determine how large the workspace must be.
*
* Return: The zstd streaming compression context or NULL on error.
*/
zstd_cstream *zstd_init_cstream(const zstd_parameters *parameters,
unsigned long long pledged_src_size, void *workspace, size_t workspace_size);
/**
* zstd_reset_cstream() - reset the context using parameters from creation
* @cstream: The zstd streaming compression context to reset.
* @pledged_src_size: 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 `pledged_src_size` 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_is_error().
*/
size_t zstd_reset_cstream(zstd_cstream *cstream,
unsigned long long pledged_src_size);
/**
* zstd_compress_stream() - streaming compress some of input into output
* @cstream: 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_is_error().
*/
size_t zstd_compress_stream(zstd_cstream *cstream, zstd_out_buffer *output,
zstd_in_buffer *input);
/**
* zstd_flush_stream() - flush internal buffers into output
* @cstream: The zstd streaming compression context.
* @output: Destination buffer. `output->pos` is updated to indicate how much
* compressed data was written.
*
* zstd_flush_stream() must be called until it returns 0, meaning all the data
* has been flushed. Since zstd_flush_stream() 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_is_error().
*/
size_t zstd_flush_stream(zstd_cstream *cstream, zstd_out_buffer *output);
/**
* zstd_end_stream() - flush internal buffers into output and end the frame
* @cstream: The zstd streaming compression context.
* @output: Destination buffer. `output->pos` is updated to indicate how much
* compressed data was written.
*
* zstd_end_stream() 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_is_error().
*/
size_t zstd_end_stream(zstd_cstream *cstream, zstd_out_buffer *output);
/* ====== Streaming Decompression ====== */
typedef ZSTD_DStream zstd_dstream;
/**
* zstd_dstream_workspace_bound() - memory needed to initialize a zstd_dstream
* @max_window_size: The maximum window size allowed for compressed frames.
*
* Return: A lower bound on the size of the workspace that is passed
* to zstd_init_dstream().
*/
size_t zstd_dstream_workspace_bound(size_t max_window_size);
/**
* zstd_init_dstream() - initialize a zstd streaming decompression context
* @max_window_size: 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_dstream_workspace_bound(max_window_size) to
* determine how large the workspace must be.
*
* Return: The zstd streaming decompression context.
*/
zstd_dstream *zstd_init_dstream(size_t max_window_size, void *workspace,
size_t workspace_size);
/**
* zstd_reset_dstream() - reset the context using parameters from creation
* @dstream: 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_is_error().
*/
size_t zstd_reset_dstream(zstd_dstream *dstream);
/**
* zstd_decompress_stream() - streaming decompress some of input into output
* @dstream: 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_decompress_stream() 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_is_error(). The size hint will never load more than the
* frame.
*/
size_t zstd_decompress_stream(zstd_dstream *dstream, zstd_out_buffer *output,
zstd_in_buffer *input);
/* ====== Frame Inspection Functions ====== */
/**
* zstd_find_frame_compressed_size() - 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.
* @src_size: 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_is_error().
* Suitable to pass to ZSTD_decompress() or similar functions.
*/
size_t zstd_find_frame_compressed_size(const void *src, size_t src_size);
/**
* struct zstd_frame_params - zstd frame parameters stored in the frame header
* @frameContentSize: The frame content size, or ZSTD_CONTENTSIZE_UNKNOWN if not
* present.
* @windowSize: The window size, or 0 if the frame is a skippable frame.
* @blockSizeMax: The maximum block size.
* @frameType: The frame type (zstd or skippable)
* @headerSize: The size of the frame header.
* @dictID: The dictionary id, or 0 if not present.
* @checksumFlag: Whether a checksum was used.
*
* See zstd_lib.h.
*/
typedef ZSTD_frameHeader zstd_frame_header;
/**
* zstd_get_frame_header() - extracts parameters from a zstd or skippable frame
* @params: On success the frame parameters are written here.
* @src: The source buffer. It must point to a zstd or skippable frame.
* @src_size: The size of the source buffer.
*
* 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_is_error().
*/
size_t zstd_get_frame_header(zstd_frame_header *params, const void *src,
size_t src_size);
#endif /* LINUX_ZSTD_H */