/* 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 */ 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. */ 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. */ 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. */ zstd_frame_parameters; /** * struct zstd_parameters - zstd parameters * @cParams: The compression parameters. * @fParams: The frame 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 ====== */ 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 ====== */ 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. */ 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. */ zstd_out_buffer; /* ====== Streaming Compression ====== */ 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 ====== */ 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. */ 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 */
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