From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- fs/ntfs3/lib/xpress_decompress.c | 142 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 142 insertions(+) create mode 100644 fs/ntfs3/lib/xpress_decompress.c (limited to 'fs/ntfs3/lib/xpress_decompress.c') diff --git a/fs/ntfs3/lib/xpress_decompress.c b/fs/ntfs3/lib/xpress_decompress.c new file mode 100644 index 0000000000..769c6d3dde --- /dev/null +++ b/fs/ntfs3/lib/xpress_decompress.c @@ -0,0 +1,142 @@ +// 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 + */ + +#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); +} -- cgit v1.2.3