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>

fs/ntfs3/lib/lib.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Adapted for linux kernel by Alexander Mamaev:
+ * - remove implementations of get_unaligned_
+ * - assume GCC is always defined
+ * - ISO C90
+ * - linux kernel code style
+ */
+
+
+/* globals from xpress_decompress.c */
+struct xpress_decompressor *xpress_allocate_decompressor(void);
+void xpress_free_decompressor(struct xpress_decompressor *d);
+int xpress_decompress(struct xpress_decompressor *__restrict d,
+		      const void *__restrict compressed_data,
+		      size_t compressed_size,
+		      void *__restrict uncompressed_data,
+		      size_t uncompressed_size);
+
+/* globals from lzx_decompress.c */
+struct lzx_decompressor *lzx_allocate_decompressor(void);
+void lzx_free_decompressor(struct lzx_decompressor *d);
+int lzx_decompress(struct lzx_decompressor *__restrict d,
+		   const void *__restrict compressed_data,
+		   size_t compressed_size, void *__restrict uncompressed_data,
+		   size_t uncompressed_size);

fs/ntfs3/lib/xpress_decompress.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * xpress_decompress.c - A decompressor for the XPRESS compression format
+ * (Huffman variant), which can be used in "System Compressed" files.  This is
+ * based on the code from wimlib.
+ *
+ * Copyright (C) 2015 Eric Biggers
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 2 of the License, or (at your option) any later
+ * version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "decompress_common.h"
+#include "lib.h"
+
+#define XPRESS_NUM_SYMBOLS	512
+#define XPRESS_MAX_CODEWORD_LEN	15
+#define XPRESS_MIN_MATCH_LEN	3
+
+/* This value is chosen for fast decompression.  */
+#define XPRESS_TABLEBITS 12
+
+/* Reusable heap-allocated memory for XPRESS decompression  */
+struct xpress_decompressor {
+
+	/* The Huffman decoding table  */
+	u16 decode_table[(1 << XPRESS_TABLEBITS) + 2 * XPRESS_NUM_SYMBOLS];
+
+	/* An array that maps symbols to codeword lengths  */
+	u8 lens[XPRESS_NUM_SYMBOLS];
+
+	/* Temporary space for make_huffman_decode_table()  */
+	u16 working_space[2 * (1 + XPRESS_MAX_CODEWORD_LEN) +
+			  XPRESS_NUM_SYMBOLS];
+};
+
+/*
+ * xpress_allocate_decompressor - Allocate an XPRESS decompressor
+ *
+ * Return the pointer to the decompressor on success, or return NULL and set
+ * errno on failure.
+ */
+struct xpress_decompressor *xpress_allocate_decompressor(void)
+{
+	return kmalloc(sizeof(struct xpress_decompressor), GFP_NOFS);
+}
+
+/*
+ * xpress_decompress - Decompress a buffer of XPRESS-compressed data
+ *
+ * @decompressor:       A decompressor that was allocated with
+ *			xpress_allocate_decompressor()
+ * @compressed_data:	The buffer of data to decompress
+ * @compressed_size:	Number of bytes of compressed data
+ * @uncompressed_data:	The buffer in which to store the decompressed data
+ * @uncompressed_size:	The number of bytes the data decompresses into
+ *
+ * Return 0 on success, or return -1 and set errno on failure.
+ */
+int xpress_decompress(struct xpress_decompressor *decompressor,
+		      const void *compressed_data, size_t compressed_size,
+		      void *uncompressed_data, size_t uncompressed_size)
+{
+	struct xpress_decompressor *d = decompressor;
+	const u8 * const in_begin = compressed_data;
+	u8 * const out_begin = uncompressed_data;
+	u8 *out_next = out_begin;
+	u8 * const out_end = out_begin + uncompressed_size;
+	struct input_bitstream is;
+	u32 i;
+
+	/* Read the Huffman codeword lengths.  */
+	if (compressed_size < XPRESS_NUM_SYMBOLS / 2)
+		goto invalid;
+	for (i = 0; i < XPRESS_NUM_SYMBOLS / 2; i++) {
+		d->lens[i*2 + 0] = in_begin[i] & 0xF;
+		d->lens[i*2 + 1] = in_begin[i] >> 4;
+	}
+
+	/* Build a decoding table for the Huffman code.  */
+	if (make_huffman_decode_table(d->decode_table, XPRESS_NUM_SYMBOLS,
+				      XPRESS_TABLEBITS, d->lens,
+				      XPRESS_MAX_CODEWORD_LEN,
+				      d->working_space))
+		goto invalid;
+
+	/* Decode the matches and literals.  */
+
+	init_input_bitstream(&is, in_begin + XPRESS_NUM_SYMBOLS / 2,
+			     compressed_size - XPRESS_NUM_SYMBOLS / 2);
+
+	while (out_next != out_end) {
+		u32 sym;
+		u32 log2_offset;
+		u32 length;
+		u32 offset;
+
+		sym = read_huffsym(&is, d->decode_table,
+				   XPRESS_TABLEBITS, XPRESS_MAX_CODEWORD_LEN);
+		if (sym < 256) {
+			/* Literal  */
+			*out_next++ = sym;
+		} else {
+			/* Match  */
+			length = sym & 0xf;
+			log2_offset = (sym >> 4) & 0xf;
+
+			bitstream_ensure_bits(&is, 16);
+
+			offset = ((u32)1 << log2_offset) |
+				 bitstream_pop_bits(&is, log2_offset);
+
+			if (length == 0xf) {
+				length += bitstream_read_byte(&is);
+				if (length == 0xf + 0xff)
+					length = bitstream_read_u16(&is);
+			}
+			length += XPRESS_MIN_MATCH_LEN;
+
+			if (offset > (size_t)(out_next - out_begin))
+				goto invalid;
+
+			if (length > (size_t)(out_end - out_next))
+				goto invalid;
+
+			out_next = lz_copy(out_next, length, offset, out_end,
+					   XPRESS_MIN_MATCH_LEN);
+		}
+	}
+	return 0;
+
+invalid:
+	return -1;
+}
+
+/*
+ * xpress_free_decompressor - Free an XPRESS decompressor
+ *
+ * @decompressor:       A decompressor that was allocated with
+ *			xpress_allocate_decompressor(), or NULL.
+ */
+void xpress_free_decompressor(struct xpress_decompressor *decompressor)
+{
+	kfree(decompressor);
+}

fs/ntfs3/lznt.c

+// 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);
+}