+++ /dev/null
-/*
- * lzx-decomp.c
- *
- * LZX decompression routines, originally based on code taken from cabextract
- * v0.5, which was, itself, a modified version of the lzx decompression code
- * from unlzx.
- */
-
-/*
- * Copyright (C) 2012 Eric Biggers
- *
- * This file is part of wimlib, a library for working with WIM files.
- *
- * wimlib 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 3 of the License, or (at your option)
- * any later version.
- *
- * wimlib 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 wimlib; if not, see http://www.gnu.org/licenses/.
- */
-
-/*
- * LZX is a LZ77 and Huffman-code based compression format that has many
- * similarities to the DEFLATE format used in zlib. The compression ratio is as
- * good or better than DEFLATE. However, in WIM files only up to 32768 bytes of
- * data can ever compressed be in the same LZX block, so a .tar.gz file could
- * potentially be smaller than a WIM file that uses LZX compression because it
- * can use a larger LZ77 window size.
- *
- * Some notes on the LZX compression format as used in Windows Imaging (WIM)
- * files:
- *
- * A compressed WIM resource consists of a table of chunk offsets followed by
- * the compressed chunks themselves. All compressed chunks except possibly the
- * last decompress to WIM_CHUNK_SIZE (= 32768) bytes. This is quite similar to
- * the cabinet (.cab) file format, but they are not the same. According to the
- * cabinet format documentation, the LZX block size is independent from the
- * CFDATA blocks, and a LZX block may span several CFDATA blocks. However, in
- * WIMs, LZX blocks do not appear to ever span multiple WIM chunks. Note that
- * this means any WIM chunk may be decompressed or compressed independently from
- * any other chunk, which is convenient.
- *
- * A LZX compressed WIM chunk contains one or more LZX blocks of the aligned,
- * verbatim, or uncompressed block types. For aligned and verbatim blocks, the
- * size of the block in uncompressed bytes is specified by a bit following the 3
- * bits that specify the block type, possibly followed by an additional 16 bits.
- * '1' means to use the default block size (equal to 32768, the size of a WIM
- * chunk--- and this seems to only be valid for the first LZX block in a WIM
- * chunk), while '0' means that the block size is provided by the next 16 bits.
- *
- * The cabinet format, as documented, allows for the possibility that a
- * compressed CFDATA chunk is up to 6144 bytes larger than the data it
- * uncompresses to. However, in the WIM format it appears that every chunk that
- * would be 32768 bytes or more when compressed is actually stored fully
- * uncompressed.
- *
- * The 'e8' preprocessing step that changes x86 call instructions to use
- * absolute offsets instead of relative offsets relies on a filesize parameter.
- * There is no such parameter for this in the WIM files (even though the size of
- * the file resource could be used for this purpose), and instead a magic file
- * size of 12000000 is used. The 'e8' preprocessing is always done, and there
- * is no bit to indicate whether it is done or not.
- */
-
-/*
- * Some more notes about errors in Microsoft's LZX documentation:
- *
- * Microsoft's LZX document and their implementation of the com.ms.util.cab Java
- * package do not concur.
- *
- * In the LZX document, there is a table showing the correlation between window
- * size and the number of position slots. It states that the 1MB window = 40
- * slots and the 2MB window = 42 slots. In the implementation, 1MB = 42 slots,
- * 2MB = 50 slots. The actual calculation is 'find the first slot whose position
- * base is equal to or more than the required window size'. This would explain
- * why other tables in the document refer to 50 slots rather than 42.
- *
- * The constant NUM_PRIMARY_LENS used in the decompression pseudocode is not
- * defined in the specification.
- *
- * The LZX document states that aligned offset blocks have their aligned offset
- * huffman tree AFTER the main and length trees. The implementation suggests
- * that the aligned offset tree is BEFORE the main and length trees.
- *
- * The LZX document decoding algorithm states that, in an aligned offset block,
- * if an extra_bits value is 1, 2 or 3, then that number of bits should be read
- * and the result added to the match offset. This is correct for 1 and 2, but
- * not 3, where just a huffman symbol (using the aligned tree) should be read.
- *
- * Regarding the E8 preprocessing, the LZX document states 'No translation may
- * be performed on the last 6 bytes of the input block'. This is correct.
- * However, the pseudocode provided checks for the *E8 leader* up to the last 6
- * bytes. If the leader appears between -10 and -7 bytes from the end, this
- * would cause the next four bytes to be modified, at least one of which would
- * be in the last 6 bytes, which is not allowed according to the spec.
- *
- * The specification states that the huffman trees must always contain at least
- * one element. However, many CAB files contain blocks where the length tree is
- * completely empty (because there are no matches), and this is expected to
- * succeed.
- */
-
-#include "util.h"
-#include "lzx.h"
-#include "decomp.h"
-#include <string.h>
-
-/* Huffman decoding tables and maps from symbols to code lengths. */
-struct lzx_tables {
-
- u16 maintree_decode_table[(1 << LZX_MAINTREE_TABLEBITS) +
- (LZX_MAINTREE_NUM_SYMBOLS * 2)];
- u8 maintree_lens[LZX_MAINTREE_NUM_SYMBOLS];
-
-
- u16 lentree_decode_table[(1 << LZX_LENTREE_TABLEBITS) +
- (LZX_LENTREE_NUM_SYMBOLS * 2)];
- u8 lentree_lens[LZX_LENTREE_NUM_SYMBOLS];
-
-
- u16 alignedtree_decode_table[(1 << LZX_ALIGNEDTREE_TABLEBITS) +
- (LZX_ALIGNEDTREE_NUM_SYMBOLS * 2)];
- u8 alignedtree_lens[LZX_ALIGNEDTREE_NUM_SYMBOLS];
-};
-
-
-/*
- * Reads a Huffman-encoded symbol using the pre-tree.
- */
-static inline int read_huffsym_using_pretree(struct input_bitstream *istream,
- const u16 pretree_decode_table[],
- const u8 pretree_lens[], unsigned *n)
-{
- return read_huffsym(istream, pretree_decode_table, pretree_lens,
- LZX_PRETREE_NUM_SYMBOLS, LZX_PRETREE_TABLEBITS, n,
- LZX_MAX_CODEWORD_LEN);
-}
-
-/* Reads a Huffman-encoded symbol using the main tree. */
-static inline int read_huffsym_using_maintree(struct input_bitstream *istream,
- const struct lzx_tables *tables,
- unsigned *n)
-{
- return read_huffsym(istream, tables->maintree_decode_table,
- tables->maintree_lens, LZX_MAINTREE_NUM_SYMBOLS,
- LZX_MAINTREE_TABLEBITS, n, LZX_MAX_CODEWORD_LEN);
-}
-
-/* Reads a Huffman-encoded symbol using the length tree. */
-static inline int read_huffsym_using_lentree(struct input_bitstream *istream,
- const struct lzx_tables *tables,
- unsigned *n)
-{
- return read_huffsym(istream, tables->lentree_decode_table,
- tables->lentree_lens, LZX_LENTREE_NUM_SYMBOLS,
- LZX_LENTREE_TABLEBITS, n, LZX_MAX_CODEWORD_LEN);
-}
-
-/* Reads a Huffman-encoded symbol using the aligned offset tree. */
-static inline int read_huffsym_using_alignedtree(struct input_bitstream *istream,
- const struct lzx_tables *tables,
- unsigned *n)
-{
- return read_huffsym(istream, tables->alignedtree_decode_table,
- tables->alignedtree_lens,
- LZX_ALIGNEDTREE_NUM_SYMBOLS,
- LZX_ALIGNEDTREE_TABLEBITS, n, 8);
-}
-
-/*
- * Reads the pretree from the input, then uses the pretree to decode @num_lens
- * code length values from the input.
- *
- * @istream: The bit stream for the input. It is positioned on the beginning
- * of the pretree for the code length values.
- * @lens: An array that contains the length values from the previous time
- * the code lengths for this Huffman tree were read, or all
- * 0's if this is the first time.
- * @num_lens: Number of length values to decode and return.
- *
- */
-static int lzx_read_code_lens(struct input_bitstream *istream, u8 lens[],
- unsigned num_lens)
-{
- /* Declare the decoding table and length table for the pretree. */
- u16 pretree_decode_table[(1 << LZX_PRETREE_TABLEBITS) +
- (LZX_PRETREE_NUM_SYMBOLS * 2)];
- u8 pretree_lens[LZX_PRETREE_NUM_SYMBOLS];
- unsigned i;
- unsigned len;
- int ret;
-
- /* Read the code lengths of the pretree codes. There are 20 lengths of
- * 4 bits each. */
- for (i = 0; i < LZX_PRETREE_NUM_SYMBOLS; i++) {
- ret = bitstream_read_bits(istream, LZX_PRETREE_ELEMENT_SIZE,
- &len);
- if (ret != 0)
- return ret;
- pretree_lens[i] = len;
- }
-
- /* Make the decoding table for the pretree. */
- ret = make_huffman_decode_table(pretree_decode_table,
- LZX_PRETREE_NUM_SYMBOLS,
- LZX_PRETREE_TABLEBITS,
- pretree_lens,
- LZX_MAX_CODEWORD_LEN);
- if (ret != 0)
- return ret;
-
- /* Pointer past the last length value that needs to be filled in. */
- u8 *lens_end = lens + num_lens;
-
- while (1) {
-
- /* Decode a symbol from the input. If the symbol is between 0
- * and 16, it is the difference from the old length. If it is
- * between 17 and 19, it is a special code that indicates that
- * some number of the next lengths are all 0, or some number of
- * the next lengths are all equal to the next symbol in the
- * input. */
- unsigned tree_code;
- unsigned num_zeroes;
- unsigned code;
- unsigned num_same;
- char value;
-
- ret = read_huffsym_using_pretree(istream, pretree_decode_table,
- pretree_lens, &tree_code);
- if (ret != 0)
- return ret;
- switch (tree_code) {
- case 17: /* Run of 0's */
- ret = bitstream_read_bits(istream, 4, &num_zeroes);
- if (ret != 0)
- return ret;
- num_zeroes += 4;
- while (num_zeroes--) {
- *lens = 0;
- if (++lens == lens_end)
- return 0;
- }
- break;
- case 18: /* Longer run of 0's */
- ret = bitstream_read_bits(istream, 5, &num_zeroes);
- if (ret != 0)
- return ret;
- num_zeroes += 20;
- while (num_zeroes--) {
- *lens = 0;
- if (++lens == lens_end)
- return 0;
- }
- break;
- case 19: /* Run of identical lengths */
- ret = bitstream_read_bits(istream, 1, &num_same);
- if (ret != 0)
- return ret;
- num_same += 4;
-
- ret = read_huffsym_using_pretree(istream,
- pretree_decode_table,
- pretree_lens, &code);
- if (ret != 0)
- return ret;
- value = (char)*lens - (char)code;
- if (value < 0)
- value += 17;
- while (num_same--) {
- *lens = value;
- if (++lens == lens_end)
- return 0;
- }
- break;
- default: /* Difference from old length. */
- value = (char)*lens - (char)tree_code;
- if (value < 0)
- value += 17;
- *lens = value;
- if (++lens == lens_end)
- return 0;
- break;
- }
- }
-}
-
-/*
- * Reads the header for an LZX-compressed block.
- *
- * @istream: The input bitstream.
- * @block_size_ret: A pointer to an int into which the size of the block,
- * in bytes, will be returned.
- * @block_type_ret: A pointer to an int into which the type of the block
- * (LZX_BLOCKTYPE_*) will be returned.
- * @tables: A pointer to a lzx_tables structure in which the
- * main tree, the length tree, and possibly the
- * aligned offset tree will be constructed.
- * @queue: A pointer to the least-recently-used queue into which
- * R0, R1, and R2 will be written (only for uncompressed
- * blocks, which contain this information in the header)
- */
-static int lzx_read_block_header(struct input_bitstream *istream,
- unsigned *block_size_ret,
- unsigned *block_type_ret,
- struct lzx_tables *tables,
- struct lru_queue *queue)
-{
- int ret;
- int block_type;
- unsigned block_size;
- int s;
- int i;
- unsigned len;
- int32_t R[3];
-
- ret = bitstream_ensure_bits(istream, 4);
- if (ret != 0) {
- ERROR("LZX input stream overrun");
- return ret;
- }
-
- /* The first three bits tell us what kind of block it is, and are one
- * of the LZX_BLOCKTYPE_* values. */
- block_type = bitstream_read_bits_nocheck(istream, 3);
-
- /* The next bit indicates whether the block size is the default (32768),
- * indicated by a 1 bit, or whether the block size is given by the next
- * 16 bits, indicated by a 0 bit. */
- s = bitstream_read_bits_nocheck(istream, 1);
-
- if (s == 1) {
- block_size = 1 << 15;
- } else {
- ret = bitstream_read_bits(istream, 16, &block_size);
- if (ret != 0)
- return ret;
- block_size = le16_to_cpu(block_size);
- }
-
- switch (block_type) {
- case LZX_BLOCKTYPE_ALIGNED:
- /* Read the path lengths for the elements of the aligned tree,
- * then build it. */
-
- for (i = 0; i < LZX_ALIGNEDTREE_NUM_SYMBOLS; i++) {
- ret = bitstream_read_bits(istream,
- LZX_ALIGNEDTREE_ELEMENT_SIZE,
- &len);
- if (ret != 0)
- return ret;
- tables->alignedtree_lens[i] = len;
- }
-
- LZX_DEBUG("Building the aligned tree.");
- ret = make_huffman_decode_table(tables->alignedtree_decode_table,
- LZX_ALIGNEDTREE_NUM_SYMBOLS,
- LZX_ALIGNEDTREE_TABLEBITS,
- tables->alignedtree_lens,
- 8);
- if (ret != 0) {
- ERROR("lzx_decompress(): Failed to make the decode "
- "table for the aligned offset tree");
- return ret;
- }
-
- /* Fall though, since the rest of the header for aligned offset
- * blocks is the same as that for verbatim blocks */
-
- case LZX_BLOCKTYPE_VERBATIM:
- if (block_type == LZX_BLOCKTYPE_VERBATIM)
- LZX_DEBUG("Found verbatim block.");
-
- LZX_DEBUG("Reading path lengths for main tree.");
- /* Read the path lengths for the first 256 elements of the main
- * tree. */
- ret = lzx_read_code_lens(istream, tables->maintree_lens,
- LZX_NUM_CHARS);
- if (ret != 0) {
- ERROR("lzx_decompress(): Failed to read the code "
- "lengths for the first 256 elements of the "
- "main tree");
- return ret;
- }
-
- /* Read the path lengths for the remaining elements of the main
- * tree. */
- LZX_DEBUG("Reading path lengths for remaining elements of "
- "main tree (%d elements).",
- LZX_MAINTREE_NUM_SYMBOLS - LZX_NUM_CHARS);
- ret = lzx_read_code_lens(istream,
- tables->maintree_lens + LZX_NUM_CHARS,
- LZX_MAINTREE_NUM_SYMBOLS - LZX_NUM_CHARS);
- if (ret != 0) {
- ERROR("lzx_decompress(): Failed to read the path "
- "lengths for the remaining elements of the main "
- "tree");
- return ret;
- }
-
- LZX_DEBUG("Building the Huffman decoding "
- "table for the main tree.");
-
- ret = make_huffman_decode_table(tables->maintree_decode_table,
- LZX_MAINTREE_NUM_SYMBOLS,
- LZX_MAINTREE_TABLEBITS,
- tables->maintree_lens,
- LZX_MAX_CODEWORD_LEN);
- if (ret != 0) {
- ERROR("lzx_decompress(): Failed to make the decode "
- "table for the main tree");
- return ret;
- }
-
- LZX_DEBUG("Reading path lengths for the length tree.");
- ret = lzx_read_code_lens(istream, tables->lentree_lens,
- LZX_LENTREE_NUM_SYMBOLS);
- if (ret != 0) {
- ERROR("lzx_decompress(): Failed to read the path "
- "lengths for the length tree");
- return ret;
- }
-
- LZX_DEBUG("Building the length tree.");
- ret = make_huffman_decode_table(tables->lentree_decode_table,
- LZX_LENTREE_NUM_SYMBOLS,
- LZX_LENTREE_TABLEBITS,
- tables->lentree_lens,
- LZX_MAX_CODEWORD_LEN);
- if (ret != 0) {
- ERROR("lzx_decompress(): Failed to build the length "
- "Huffman tree");
- return ret;
- }
-
- break;
-
- case LZX_BLOCKTYPE_UNCOMPRESSED:
- LZX_DEBUG("Found uncompressed block.");
- ret = align_input_bitstream(istream, true);
- if (ret != 0)
- return ret;
- ret = bitstream_read_bytes(istream, sizeof(R), R);
- if (ret != 0)
- return ret;
- queue->R0 = le32_to_cpu(R[0]);
- queue->R1 = le32_to_cpu(R[1]);
- queue->R2 = le32_to_cpu(R[2]);
- break;
- default:
- LZX_DEBUG("Found invalid block.");
- return 1;
- }
- *block_type_ret = block_type;
- *block_size_ret = block_size;
- return 0;
-}
-
-/*
- * Decodes a compressed literal match value. It refers to some match_offset to
- * a point earlier in the window, and some match_len, for which the data is to
- * be copied to the current position in the window.
- *
- * @main_element: The start of the match data, as decoded using the main
- * tree.
- * @block_type: The type of the block (LZX_BLOCKTYPE_ALIGNED or
- * LZX_BLOCKTYPE_VERBATIM)
- * @bytes_remaining: The amount of uncompressed data remaining to be
- * uncompressed. It is an error if the match
- * is longer than @bytes_remaining.
- * @window: A pointer to the window into which the uncompressed
- * data is being written.
- * @window_pos: The current position in the window.
- * @tables: Contains the Huffman tables for the block (main,
- * length, and also aligned offset only for
- * LZX_BLOCKTYPE_ALIGNED)
- * @queue: The least-recently used queue for match offsets.
- * @istream: The input bitstream.
- *
- * Returns the length of the match, or -1 on error (match would exceed
- * the amount of data needing to be uncompressed, or match refers to data before
- * the window, or the input bitstream ended unexpectedly).
- */
-static int lzx_decode_match(int main_element, int block_type,
- int bytes_remaining, u8 *window, int window_pos,
- const struct lzx_tables *tables,
- struct lru_queue *queue,
- struct input_bitstream *istream)
-{
- unsigned length_header;
- unsigned position_slot;
- unsigned match_len;
- unsigned match_offset;
- unsigned additional_len;
- unsigned num_extra_bits;
- unsigned verbatim_bits;
- unsigned aligned_bits;
- int ret;
- int i;
- u8 *match_dest;
- u8 *match_src;
-
- /* The main element is offset by 256 because values under 256 indicate a
- * literal value. */
- main_element -= LZX_NUM_CHARS;
-
- /* The length header consists of the lower 3 bits of the main element.
- * The position slot is the rest of it. */
- length_header = main_element & LZX_NUM_PRIMARY_LENS;
- position_slot = main_element >> 3;
-
- /* If the length_header is less than LZX_NUM_PRIMARY_LENS (= 7), it
- * gives the match length as the offset from LZX_MIN_MATCH. Otherwise,
- * the length is given by an additional symbol encoded using the length
- * tree, offset by 9 (LZX_MIN_MATCH + LZX_NUM_PRIMARY_LENS) */
- match_len = LZX_MIN_MATCH + length_header;
- if (length_header == LZX_NUM_PRIMARY_LENS) {
- ret = read_huffsym_using_lentree(istream, tables,
- &additional_len);
- if (ret != 0)
- return -1;
- match_len += additional_len;
- }
-
-
- /* If the position_slot is 0, 1, or 2, the match offset is retrieved
- * from the LRU queue. Otherwise, the match offset is not in the LRU
- * queue. */
- switch (position_slot) {
- case 0:
- match_offset = queue->R0;
- break;
- case 1:
- match_offset = queue->R1;
- swap(queue->R0, queue->R1);
- break;
- case 2:
- /* The queue doesn't work quite the same as a real LRU queue,
- * since using the R2 offset doesn't bump the R1 offset down to
- * R2. */
- match_offset = queue->R2;
- swap(queue->R0, queue->R2);
- break;
- default:
- /* Otherwise, the offset was not encoded as one the offsets in
- * the queue. Depending on the position slot, there is a
- * certain number of extra bits that need to be read to fully
- * decode the match offset. */
-
- /* Look up the number of extra bits that need to be read. */
- num_extra_bits = lzx_extra_bits[position_slot];
-
- /* For aligned blocks, if there are at least 3 extra bits, the
- * actual number of extra bits is 3 less, and they encode a
- * number of 8-byte words that are added to the offset; there
- * is then an additional symbol read using the aligned tree that
- * specifies the actual byte alignment. */
- if (block_type == LZX_BLOCKTYPE_ALIGNED && num_extra_bits >= 3) {
-
- /* There is an error in the LZX "specification" at this
- * point; it indicates that a Huffman symbol is to be
- * read only if num_extra_bits is greater than 3, but
- * actually it is if num_extra_bits is greater than or
- * equal to 3. (Note that in the case with
- * num_extra_bits == 3, the assignment to verbatim_bits
- * will just set it to 0. ) */
- ret = bitstream_read_bits(istream, num_extra_bits - 3,
- &verbatim_bits);
- if (ret != 0)
- return -1;
-
- verbatim_bits <<= 3;
-
- ret = read_huffsym_using_alignedtree(istream, tables,
- &aligned_bits);
- if (ret != 0)
- return -1;
- } else {
- /* For non-aligned blocks, or for aligned blocks with
- * less than 3 extra bits, the extra bits are added
- * directly to the match offset, and the correction for
- * the alignment is taken to be 0. */
- ret = bitstream_read_bits(istream, num_extra_bits,
- &verbatim_bits);
- if (ret != 0)
- return -1;
-
- aligned_bits = 0;
- }
-
- /* Calculate the match offset. */
- match_offset = lzx_position_base[position_slot] + verbatim_bits +
- aligned_bits - 2;
-
- /* Update the LRU queue. */
- queue->R2 = queue->R1;
- queue->R1 = queue->R0;
- queue->R0 = match_offset;
- break;
- }
-
- /* Verify that the match is in the bounds of the part of the window
- * currently in use, then copy the source of the match to the current
- * position. */
- match_dest = window + window_pos;
- match_src = match_dest - match_offset;
-
- if (match_len > bytes_remaining) {
- ERROR("lzx_decode_match(): Match of length %d bytes overflows "
- "uncompressed block size", match_len);
- return -1;
- }
-
- if (match_src < window) {
- ERROR("lzx_decode_match(): Match of length %d bytes references "
- "data before window (match_offset = %d, window_pos = %d)",
- match_len, match_offset, window_pos);
- return -1;
- }
-
-#if 0
- printf("Match: src %u, dst %u, len %u\n", match_src - window,
- match_dest - window,
- match_len);
- putchar('|');
- for (i = 0; i < match_len; i++) {
- match_dest[i] = match_src[i];
- putchar(match_src[i]);
- }
- putchar('|');
- putchar('\n');
-#else
- for (i = 0; i < match_len; i++)
- match_dest[i] = match_src[i];
-#endif
-
- return match_len;
-}
-
-
-
-/* Undo the 'E8' preprocessing, where the targets of x86 CALL instructions were
- * changed from relative offsets to absolute offsets. This type of
- * preprocessing can be used on any binary data even if it is not actually
- * machine code. It seems to always be used in WIM files, even though there is
- * no bit to indicate that it actually is used, unlike in the LZX compressed
- * format as used in other file formats, where a bit is reserved for that
- * purpose. */
-static void undo_call_insn_preprocessing(u8 uncompressed_data[],
- unsigned uncompressed_data_len)
-{
- int i = 0;
- int file_size = LZX_MAGIC_FILESIZE;
- int32_t abs_offset;
- int32_t rel_offset;
-
- /* Not enabled in the last 6 bytes, which means the 5-byte call
- * instruction cannot start in the last *10* bytes. */
- while (i < uncompressed_data_len - 10) {
- if (uncompressed_data[i] != 0xe8) {
- i++;
- continue;
- }
- abs_offset = le32_to_cpu(*(int32_t*)(uncompressed_data + i + 1));
-
- if (abs_offset >= -i && abs_offset < file_size) {
- if (abs_offset >= 0) {
- /* "good translation" */
- rel_offset = abs_offset - i;
- } else {
- /* "compensating translation" */
- rel_offset = abs_offset + file_size;
- }
- *(int32_t*)(uncompressed_data + i + 1) =
- cpu_to_le32(rel_offset);
- }
- i += 5;
- }
-}
-
-/*
- * Decompresses a compressed block of data from which the header has already
- * been read.
- *
- * @block_type: The type of the block (LZX_BLOCKTYPE_VERBATIM or
- * LZX_BLOCKTYPE_ALIGNED)
- * @block_size: The size of the block, in bytes.
- * @window: Pointer to the decompression window.
- * @window_pos: The current position in the window. Will be 0 for the first
- * block.
- * @tables: The Huffman decoding tables for the block (main, length, and
- * aligned offset, the latter only for LZX_BLOCKTYPE_ALIGNED)
- * @queue: The least-recently-used queue for match offsets.
- * @istream: The input bitstream for the compressed literals.
- */
-static int lzx_decompress_block(int block_type, int block_size, u8 *window,
- int window_pos,
- const struct lzx_tables *tables,
- struct lru_queue *queue,
- struct input_bitstream *istream)
-{
- unsigned bytes_remaining;
- unsigned main_element;
- int match_len;
- int ret;
-
- bytes_remaining = block_size;
- while (bytes_remaining > 0) {
-
- ret = read_huffsym_using_maintree(istream, tables,
- &main_element);
- if (ret != 0)
- return ret;
-
- if (main_element < LZX_NUM_CHARS) {
- /* literal: 0 to LZX_NUM_CHARS - 1 */
- window[window_pos + block_size - bytes_remaining] =
- main_element;
- bytes_remaining--;
- } else {
- /* match: LZX_NUM_CHARS to LZX_MAINTREE_NUM_SYMBOLS - 1 */
- match_len = lzx_decode_match(main_element,
- block_type, bytes_remaining, window,
- block_size + window_pos -
- bytes_remaining,
- tables, queue, istream);
- if (match_len == -1)
- return 1;
-
- bytes_remaining -= match_len;
- }
- }
- return 0;
-}
-
-/*
- * Decompresses a block of LZX-compressed data using a window size of 32768.
- *
- * @compressed_data: A pointer to the compressed data.
- * @compressed_len: The length of the compressed data, in bytes.
- * @uncompressed_data: A pointer to the buffer into which to write the
- * uncompressed data.
- * @uncompressed_len: The length of the uncompressed data.
- *
- * Return non-zero on failure.
- */
-int lzx_decompress(const void *compressed_data, unsigned compressed_len,
- void *uncompressed_data, unsigned uncompressed_len)
-{
- struct lzx_tables tables;
- struct input_bitstream istream;
- struct lru_queue queue;
- unsigned bytes_remaining;
- unsigned block_size;
- unsigned block_type;
- int ret;
-
- LZX_DEBUG("lzx_decompress (compressed_data = %p, compressed_len = %d, "
- "uncompressed_data = %p, uncompressed_len = %d).",
- compressed_data, compressed_len,
- uncompressed_data, uncompressed_len);
-
- wimlib_assert(uncompressed_len <= 32768);
-
- memset(tables.maintree_lens, 0, sizeof(tables.maintree_lens));
- memset(tables.lentree_lens, 0, sizeof(tables.lentree_lens));
- queue.R0 = 1;
- queue.R1 = 1;
- queue.R2 = 1;
- bytes_remaining = uncompressed_len;
-
- init_input_bitstream(&istream, compressed_data, compressed_len);
-
- /* The compressed data will consist of one or more blocks. The
- * following loop decompresses one block, and it runs until there all
- * the compressed data has been decompressed, so there are no more
- * blocks. */
-
- while (bytes_remaining != 0) {
-
- LZX_DEBUG("Reading block header.");
- ret = lzx_read_block_header(&istream, &block_size,
- &block_type, &tables, &queue);
- if (ret != 0)
- return ret;
-
- LZX_DEBUG("block_size = %u, bytes_remaining = %u",
- block_size, bytes_remaining);
-
- if (block_size > bytes_remaining) {
- ERROR("lzx_decompress(): Expected a block size of at "
- "most %u bytes (found %u bytes)",
- bytes_remaining, block_size);
- return 1;
- }
-
- switch (block_type) {
- case LZX_BLOCKTYPE_VERBATIM:
- case LZX_BLOCKTYPE_ALIGNED:
- if (block_type == LZX_BLOCKTYPE_VERBATIM)
- LZX_DEBUG("LZX_BLOCKTYPE_VERBATIM");
- else
- LZX_DEBUG("LZX_BLOCKTYPE_ALIGNED");
-
- ret = lzx_decompress_block(block_type,
- block_size,
- uncompressed_data,
- uncompressed_len -
- bytes_remaining,
- &tables, &queue, &istream);
- if (ret != 0)
- return ret;
- break;
- case LZX_BLOCKTYPE_UNCOMPRESSED:
- LZX_DEBUG("LZX_BLOCKTYPE_UNCOMPRESSED");
- ret = bitstream_read_bytes(&istream, block_size,
- uncompressed_data +
- uncompressed_len -
- bytes_remaining);
- if (ret != 0)
- return ret;
- if (block_size & 1)
- align_input_bitstream(&istream, false);
- break;
- default:
- wimlib_assert(0);
- break;
- }
-
- bytes_remaining -= block_size;
-
- if (bytes_remaining != 0)
- LZX_DEBUG("%d bytes remaining.", bytes_remaining);
- }
-
- if (uncompressed_len >= 10)
- undo_call_insn_preprocessing(uncompressed_data,
- uncompressed_len);
-
- return 0;
-}
projects / wimlib / blobdiff