diff options
Diffstat (limited to 'contrib/linux-kernel/linux_zstd.h')
| -rw-r--r-- | contrib/linux-kernel/linux_zstd.h | 459 |
1 files changed, 459 insertions, 0 deletions
diff --git a/contrib/linux-kernel/linux_zstd.h b/contrib/linux-kernel/linux_zstd.h new file mode 100644 index 00000000..dcd1ec18 --- /dev/null +++ b/contrib/linux-kernel/linux_zstd.h @@ -0,0 +1,459 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * 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 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> + +/* ====== 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); + +/** + * 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. + */ +int 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); + +/* ====== Parameter Selection ====== */ + +/** + * enum zstd_strategy - zstd compression search strategy + * + * From faster to stronger. + */ +enum zstd_strategy { + zstd_fast = 1, + zstd_dfast = 2, + zstd_greedy = 3, + zstd_lazy = 4, + zstd_lazy2 = 5, + zstd_btlazy2 = 6, + zstd_btopt = 7, + zstd_btultra = 8, + zstd_btultra2 = 9 +}; + +/** + * struct zstd_compression_parameters - zstd compression parameters + * @window_log: Log of the largest match distance. Larger means more + * compression, and more memory needed during decompression. + * @chain_log: Fully searched segment. Larger means more compression, + * slower, and more memory (useless for fast). + * @hash_log: Dispatch table. Larger means more compression, + * slower, and more memory. + * @search_log: Number of searches. Larger means more compression and slower. + * @search_length: Match length searched. Larger means faster decompression, + * sometimes less compression. + * @target_length: Acceptable match size for optimal parser (only). Larger means + * more compression, and slower. + * @strategy: The zstd compression strategy. + */ +struct zstd_compression_parameters { + unsigned int window_log; + unsigned int chain_log; + unsigned int hash_log; + unsigned int search_log; + unsigned int search_length; + unsigned int target_length; + enum zstd_strategy strategy; +}; + +/** + * struct zstd_frame_parameters - zstd frame parameters + * @content_size_flag: Controls whether content size will be present in the + * frame header (when known). + * @checksum_flag: Controls whether a 32-bit checksum is generated at the + * end of the frame for error detection. + * @no_dict_id_flag: Controls whether dictID will be saved into the frame + * header when using dictionary compression. + * + * The default value is all fields set to 0. + */ +struct zstd_frame_parameters { + unsigned int content_size_flag; + unsigned int checksum_flag; + unsigned int no_dict_id_flag; +}; + +/** + * struct zstd_parameters - zstd parameters + * @cparams: The compression parameters. + * @fparams: The frame parameters. + */ +struct zstd_parameters { + struct zstd_compression_parameters cparams; + struct zstd_frame_parameters fparams; +}; + +/** + * 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. + */ +struct zstd_parameters zstd_get_params(int level, + unsigned long long estimated_src_size); + +/* ====== Single-pass Compression ====== */ + +typedef struct ZSTD_CCtx_s 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 struct 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 struct zstd_parameters *parameters); + +/* ====== Single-pass Decompression ====== */ + +typedef struct ZSTD_DCtx_s 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. + */ +struct zstd_in_buffer { + const void *src; + size_t size; + size_t pos; +}; + +/** + * 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. + */ +struct zstd_out_buffer { + void *dst; + size_t size; + size_t pos; +}; + +/* ====== Streaming Compression ====== */ + +typedef struct ZSTD_CCtx_s 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 struct 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 struct 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, + struct zstd_out_buffer *output, struct 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, struct 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, struct zstd_out_buffer *output); + +/* ====== Streaming Decompression ====== */ + +typedef struct ZSTD_DCtx_s 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, + struct zstd_out_buffer *output, struct 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 + * @frame_content_size: The frame content size, or 0 if not present. + * @window_size: The window size, or 0 if the frame is a skippable frame. + * @dict_id: The dictionary id, or 0 if not present. + * @checksum_flag: Whether a checksum was used. + */ +struct zstd_frame_params { + unsigned long long frame_content_size; + unsigned int window_size; + unsigned int dict_id; + unsigned int checksum_flag; +}; + +/** + * zstd_get_frame_params() - 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_params(struct zstd_frame_params *params, const void *src, + size_t src_size); + +#endif /* LINUX_ZSTD_H */ |