linux/fs/ntfs3/lznt.c

// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
 *
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/types.h>

#include "debug.h"
#include "ntfs_fs.h"

// clang-format off
/* Src buffer is zero. */
#define LZNT_ERROR_ALL_ZEROS …
#define LZNT_CHUNK_SIZE …
// clang-format on

struct lznt_hash { … };

struct lznt { … };

static inline size_t get_match_len(const u8 *ptr, const u8 *end, const u8 *prev,
				   size_t max_len)
{ … }

static size_t longest_match_std(const u8 *src, struct lznt *ctx)
{ … }

static size_t longest_match_best(const u8 *src, struct lznt *ctx)
{ … }

static const size_t s_max_len[] = …;

static const size_t s_max_off[] = …;

static inline u16 make_pair(size_t offset, size_t len, size_t index)
{ … }

static inline size_t parse_pair(u16 pair, size_t *offset, size_t index)
{ … }

/*
 * compress_chunk
 *
 * Return:
 * * 0	- Ok, @cmpr contains @cmpr_chunk_size bytes of compressed data.
 * * 1	- Input buffer is full zero.
 * * -2 - The compressed buffer is too small to hold the compressed data.
 */
static inline int compress_chunk(size_t (*match)(const u8 *, struct lznt *),
				 const u8 *unc, const u8 *unc_end, u8 *cmpr,
				 u8 *cmpr_end, size_t *cmpr_chunk_size,
				 struct lznt *ctx)
{ … }

static inline ssize_t decompress_chunk(u8 *unc, u8 *unc_end, const u8 *cmpr,
				       const u8 *cmpr_end)
{ … }

/*
 * get_lznt_ctx
 * @level: 0 - Standard compression.
 *	   !0 - Best compression, requires a lot of cpu.
 */
struct lznt *get_lznt_ctx(int level)
{ … }

/*
 * compress_lznt - Compresses @unc into @cmpr
 *
 * Return:
 * * +x - Ok, @cmpr contains 'final_compressed_size' bytes of compressed data.
 * * 0 - Input buffer is full zero.
 */
size_t compress_lznt(const void *unc, size_t unc_size, void *cmpr,
		     size_t cmpr_size, struct lznt *ctx)
{ … }

/*
 * decompress_lznt - Decompress @cmpr into @unc.
 */
ssize_t decompress_lznt(const void *cmpr, size_t cmpr_size, void *unc,
			size_t unc_size)
{ … }