diff options
author | Konstantin Komarov <almaz.alexandrovich@paragon-software.com> | 2021-08-13 16:21:30 +0200 |
---|---|---|
committer | Konstantin Komarov <almaz.alexandrovich@paragon-software.com> | 2021-08-13 16:56:00 +0200 |
commit | 522e010b58379fbe19b38fdef5016bca0c3cf405 (patch) | |
tree | c04cdf90dc773687fa32513e822f38b30dc9c3e1 /fs/ntfs3/lznt.c | |
parent | fs/ntfs3: Add attrib operations (diff) | |
download | linux-522e010b58379fbe19b38fdef5016bca0c3cf405.tar.xz linux-522e010b58379fbe19b38fdef5016bca0c3cf405.zip |
fs/ntfs3: Add compression
This patch adds different types of NTFS-applicable compressions:
- lznt
- lzx
- xpress
Latter two (lzx, xpress) implement Windows Compact OS feature and
were taken from ntfs-3g system comression plugin authored by Eric Biggers
(https://github.com/ebiggers/ntfs-3g-system-compression)
which were ported to ntfs3 and adapted to Linux Kernel environment.
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Diffstat (limited to 'fs/ntfs3/lznt.c')
-rw-r--r-- | fs/ntfs3/lznt.c | 452 |
1 files changed, 452 insertions, 0 deletions
diff --git a/fs/ntfs3/lznt.c b/fs/ntfs3/lznt.c new file mode 100644 index 000000000000..ead9ab7d69b3 --- /dev/null +++ b/fs/ntfs3/lznt.c @@ -0,0 +1,452 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * + * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved. + * + */ +#include <linux/blkdev.h> +#include <linux/buffer_head.h> +#include <linux/fs.h> +#include <linux/nls.h> + +#include "debug.h" +#include "ntfs.h" +#include "ntfs_fs.h" + +// clang-format off +/* src buffer is zero */ +#define LZNT_ERROR_ALL_ZEROS 1 +#define LZNT_CHUNK_SIZE 0x1000 +// clang-format on + +struct lznt_hash { + const u8 *p1; + const u8 *p2; +}; + +struct lznt { + const u8 *unc; + const u8 *unc_end; + const u8 *best_match; + size_t max_len; + bool std; + + struct lznt_hash hash[LZNT_CHUNK_SIZE]; +}; + +static inline size_t get_match_len(const u8 *ptr, const u8 *end, const u8 *prev, + size_t max_len) +{ + size_t len = 0; + + while (ptr + len < end && ptr[len] == prev[len] && ++len < max_len) + ; + return len; +} + +static size_t longest_match_std(const u8 *src, struct lznt *ctx) +{ + size_t hash_index; + size_t len1 = 0, len2 = 0; + const u8 **hash; + + hash_index = + ((40543U * ((((src[0] << 4) ^ src[1]) << 4) ^ src[2])) >> 4) & + (LZNT_CHUNK_SIZE - 1); + + hash = &(ctx->hash[hash_index].p1); + + if (hash[0] >= ctx->unc && hash[0] < src && hash[0][0] == src[0] && + hash[0][1] == src[1] && hash[0][2] == src[2]) { + len1 = 3; + if (ctx->max_len > 3) + len1 += get_match_len(src + 3, ctx->unc_end, + hash[0] + 3, ctx->max_len - 3); + } + + if (hash[1] >= ctx->unc && hash[1] < src && hash[1][0] == src[0] && + hash[1][1] == src[1] && hash[1][2] == src[2]) { + len2 = 3; + if (ctx->max_len > 3) + len2 += get_match_len(src + 3, ctx->unc_end, + hash[1] + 3, ctx->max_len - 3); + } + + /* Compare two matches and select the best one */ + if (len1 < len2) { + ctx->best_match = hash[1]; + len1 = len2; + } else { + ctx->best_match = hash[0]; + } + + hash[1] = hash[0]; + hash[0] = src; + return len1; +} + +static size_t longest_match_best(const u8 *src, struct lznt *ctx) +{ + size_t max_len; + const u8 *ptr; + + if (ctx->unc >= src || !ctx->max_len) + return 0; + + max_len = 0; + for (ptr = ctx->unc; ptr < src; ++ptr) { + size_t len = + get_match_len(src, ctx->unc_end, ptr, ctx->max_len); + if (len >= max_len) { + max_len = len; + ctx->best_match = ptr; + } + } + + return max_len >= 3 ? max_len : 0; +} + +static const size_t s_max_len[] = { + 0x1002, 0x802, 0x402, 0x202, 0x102, 0x82, 0x42, 0x22, 0x12, +}; + +static const size_t s_max_off[] = { + 0x10, 0x20, 0x40, 0x80, 0x100, 0x200, 0x400, 0x800, 0x1000, +}; + +static inline u16 make_pair(size_t offset, size_t len, size_t index) +{ + return ((offset - 1) << (12 - index)) | + ((len - 3) & (((1 << (12 - index)) - 1))); +} + +static inline size_t parse_pair(u16 pair, size_t *offset, size_t index) +{ + *offset = 1 + (pair >> (12 - index)); + return 3 + (pair & ((1 << (12 - index)) - 1)); +} + +/* + * compress_chunk + * + * returns one of the three values: + * 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) +{ + size_t cnt = 0; + size_t idx = 0; + const u8 *up = unc; + u8 *cp = cmpr + 3; + u8 *cp2 = cmpr + 2; + u8 not_zero = 0; + /* Control byte of 8-bit values: ( 0 - means byte as is, 1 - short pair ) */ + u8 ohdr = 0; + u8 *last; + u16 t16; + + if (unc + LZNT_CHUNK_SIZE < unc_end) + unc_end = unc + LZNT_CHUNK_SIZE; + + last = min(cmpr + LZNT_CHUNK_SIZE + sizeof(short), cmpr_end); + + ctx->unc = unc; + ctx->unc_end = unc_end; + ctx->max_len = s_max_len[0]; + + while (up < unc_end) { + size_t max_len; + + while (unc + s_max_off[idx] < up) + ctx->max_len = s_max_len[++idx]; + + // Find match + max_len = up + 3 <= unc_end ? (*match)(up, ctx) : 0; + + if (!max_len) { + if (cp >= last) + goto NotCompressed; + not_zero |= *cp++ = *up++; + } else if (cp + 1 >= last) { + goto NotCompressed; + } else { + t16 = make_pair(up - ctx->best_match, max_len, idx); + *cp++ = t16; + *cp++ = t16 >> 8; + + ohdr |= 1 << cnt; + up += max_len; + } + + cnt = (cnt + 1) & 7; + if (!cnt) { + *cp2 = ohdr; + ohdr = 0; + cp2 = cp; + cp += 1; + } + } + + if (cp2 < last) + *cp2 = ohdr; + else + cp -= 1; + + *cmpr_chunk_size = cp - cmpr; + + t16 = (*cmpr_chunk_size - 3) | 0xB000; + cmpr[0] = t16; + cmpr[1] = t16 >> 8; + + return not_zero ? 0 : LZNT_ERROR_ALL_ZEROS; + +NotCompressed: + + if ((cmpr + LZNT_CHUNK_SIZE + sizeof(short)) > last) + return -2; + + /* + * Copy non cmpr data + * 0x3FFF == ((LZNT_CHUNK_SIZE + 2 - 3) | 0x3000) + */ + cmpr[0] = 0xff; + cmpr[1] = 0x3f; + + memcpy(cmpr + sizeof(short), unc, LZNT_CHUNK_SIZE); + *cmpr_chunk_size = LZNT_CHUNK_SIZE + sizeof(short); + + return 0; +} + +static inline ssize_t decompress_chunk(u8 *unc, u8 *unc_end, const u8 *cmpr, + const u8 *cmpr_end) +{ + u8 *up = unc; + u8 ch = *cmpr++; + size_t bit = 0; + size_t index = 0; + u16 pair; + size_t offset, length; + + /* Do decompression until pointers are inside range */ + while (up < unc_end && cmpr < cmpr_end) { + /* Correct index */ + while (unc + s_max_off[index] < up) + index += 1; + + /* Check the current flag for zero */ + if (!(ch & (1 << bit))) { + /* Just copy byte */ + *up++ = *cmpr++; + goto next; + } + + /* Check for boundary */ + if (cmpr + 1 >= cmpr_end) + return -EINVAL; + + /* Read a short from little endian stream */ + pair = cmpr[1]; + pair <<= 8; + pair |= cmpr[0]; + + cmpr += 2; + + /* Translate packed information into offset and length */ + length = parse_pair(pair, &offset, index); + + /* Check offset for boundary */ + if (unc + offset > up) + return -EINVAL; + + /* Truncate the length if necessary */ + if (up + length >= unc_end) + length = unc_end - up; + + /* Now we copy bytes. This is the heart of LZ algorithm. */ + for (; length > 0; length--, up++) + *up = *(up - offset); + +next: + /* Advance flag bit value */ + bit = (bit + 1) & 7; + + if (!bit) { + if (cmpr >= cmpr_end) + break; + + ch = *cmpr++; + } + } + + /* return the size of uncompressed data */ + return up - unc; +} + +/* + * 0 - standard compression + * !0 - best compression, requires a lot of cpu + */ +struct lznt *get_lznt_ctx(int level) +{ + struct lznt *r = ntfs_zalloc(level ? offsetof(struct lznt, hash) + : sizeof(struct lznt)); + + if (r) + r->std = !level; + return r; +} + +/* + * compress_lznt + * + * Compresses "unc" into "cmpr" + * +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) +{ + int err; + size_t (*match)(const u8 *src, struct lznt *ctx); + u8 *p = cmpr; + u8 *end = p + cmpr_size; + const u8 *unc_chunk = unc; + const u8 *unc_end = unc_chunk + unc_size; + bool is_zero = true; + + if (ctx->std) { + match = &longest_match_std; + memset(ctx->hash, 0, sizeof(ctx->hash)); + } else { + match = &longest_match_best; + } + + /* compression cycle */ + for (; unc_chunk < unc_end; unc_chunk += LZNT_CHUNK_SIZE) { + cmpr_size = 0; + err = compress_chunk(match, unc_chunk, unc_end, p, end, + &cmpr_size, ctx); + if (err < 0) + return unc_size; + + if (is_zero && err != LZNT_ERROR_ALL_ZEROS) + is_zero = false; + + p += cmpr_size; + } + + if (p <= end - 2) + p[0] = p[1] = 0; + + return is_zero ? 0 : PtrOffset(cmpr, p); +} + +/* + * decompress_lznt + * + * decompresses "cmpr" into "unc" + */ +ssize_t decompress_lznt(const void *cmpr, size_t cmpr_size, void *unc, + size_t unc_size) +{ + const u8 *cmpr_chunk = cmpr; + const u8 *cmpr_end = cmpr_chunk + cmpr_size; + u8 *unc_chunk = unc; + u8 *unc_end = unc_chunk + unc_size; + u16 chunk_hdr; + + if (cmpr_size < sizeof(short)) + return -EINVAL; + + /* read chunk header */ + chunk_hdr = cmpr_chunk[1]; + chunk_hdr <<= 8; + chunk_hdr |= cmpr_chunk[0]; + + /* loop through decompressing chunks */ + for (;;) { + size_t chunk_size_saved; + size_t unc_use; + size_t cmpr_use = 3 + (chunk_hdr & (LZNT_CHUNK_SIZE - 1)); + + /* Check that the chunk actually fits the supplied buffer */ + if (cmpr_chunk + cmpr_use > cmpr_end) + return -EINVAL; + + /* First make sure the chunk contains compressed data */ + if (chunk_hdr & 0x8000) { + /* Decompress a chunk and return if we get an error */ + ssize_t err = + decompress_chunk(unc_chunk, unc_end, + cmpr_chunk + sizeof(chunk_hdr), + cmpr_chunk + cmpr_use); + if (err < 0) + return err; + unc_use = err; + } else { + /* This chunk does not contain compressed data */ + unc_use = unc_chunk + LZNT_CHUNK_SIZE > unc_end + ? unc_end - unc_chunk + : LZNT_CHUNK_SIZE; + + if (cmpr_chunk + sizeof(chunk_hdr) + unc_use > + cmpr_end) { + return -EINVAL; + } + + memcpy(unc_chunk, cmpr_chunk + sizeof(chunk_hdr), + unc_use); + } + + /* Advance pointers */ + cmpr_chunk += cmpr_use; + unc_chunk += unc_use; + + /* Check for the end of unc buffer */ + if (unc_chunk >= unc_end) + break; + + /* Proceed the next chunk */ + if (cmpr_chunk > cmpr_end - 2) + break; + + chunk_size_saved = LZNT_CHUNK_SIZE; + + /* read chunk header */ + chunk_hdr = cmpr_chunk[1]; + chunk_hdr <<= 8; + chunk_hdr |= cmpr_chunk[0]; + + if (!chunk_hdr) + break; + + /* Check the size of unc buffer */ + if (unc_use < chunk_size_saved) { + size_t t1 = chunk_size_saved - unc_use; + u8 *t2 = unc_chunk + t1; + + /* 'Zero' memory */ + if (t2 >= unc_end) + break; + + memset(unc_chunk, 0, t1); + unc_chunk = t2; + } + } + + /* Check compression boundary */ + if (cmpr_chunk > cmpr_end) + return -EINVAL; + + /* + * The unc size is just a difference between current + * pointer and original one + */ + return PtrOffset(unc, unc_chunk); +} |