/*
* lzx-decomp.c
*
- * Routines for LZX decompression. The LZX format has many similarities to the
- * DEFLATE format used in zlib and gzip, but it's not quite the same.
- *
+ * 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.
*/
/*
*/
/*
- * This file has been modified from code taken from cabextract v0.5, which was,
- * itself, a modified version of the lzx decompression code from unlzx. The
- * code has been customized for wimlib.
+ * 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 file resource consists of a table of chunk offsets followed
- * by compressed chunks. All compressed chunks except 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 (at least based on M$'s
- * documentation). According to the documentation, in the cabinet format, the
- * LZX block size is independent from the CFDATA blocks and may span several
- * CFDATA blocks. However, for WIM file resources, I have seen no case of a LZX
- * block spanning multiple WIM chunks. This is probably done to make it easier
- * to randomly access the compressed file resources. WIMLIB in fact makes use
- * of this feature to allow semi-random access to file resources in the
- * read_resource() function.
+ * 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.
*
- * Usually a WIM chunk will contain only one LZX block, but on rare occasions it
- * may contain multiple LZX block. The LZX block are usually the aligned block
- * type or verbatim block type, but can (very rarely) be the uncompressed block
- * type. The size of a LZX block is specified by 1 or 17 bits following the 3
- * bits that specify the block type. A '1' means to use the default block size
- * (equal to 32768), while a '0' means that the block size is given by the next
- * 16 bits.
+ * 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 CFDATA
- * chunk is up to 6144 bytes larger than the uncompressed data. In the WIM
- * format, however, it appears that every chunk that would be 32768 bytes or
- * more when compressed, is actually stored uncompressed. This is not
- * documented by M$.
+ * 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.
* 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 documentation:
+ * 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.
#include "util.h"
#include "lzx.h"
-
#include "decomp.h"
-
#include <string.h>
/* Huffman decoding tables and maps from symbols to code lengths. */
*/
static inline int read_huffsym_using_pretree(struct input_bitstream *istream,
const u16 pretree_decode_table[],
- const u8 pretree_lens[], uint *n)
+ const u8 pretree_lens[], unsigned *n)
{
return read_huffsym(istream, pretree_decode_table, pretree_lens,
LZX_PRETREE_NUM_SYMBOLS, LZX_PRETREE_TABLEBITS, n,
/* 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,
- uint *n)
+ unsigned *n)
{
return read_huffsym(istream, tables->maintree_decode_table,
tables->maintree_lens, LZX_MAINTREE_NUM_SYMBOLS,
/* 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,
- uint *n)
+ unsigned *n)
{
return read_huffsym(istream, tables->lentree_decode_table,
tables->lentree_lens, LZX_LENTREE_NUM_SYMBOLS,
/* 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,
- uint *n)
+ unsigned *n)
{
return read_huffsym(istream, tables->alignedtree_decode_table,
tables->alignedtree_lens,
*
*/
static int lzx_read_code_lens(struct input_bitstream *istream, u8 lens[],
- uint num_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];
- uint i;
- uint len;
+ unsigned i;
+ unsigned len;
int ret;
/* Read the code lengths of the pretree codes. There are 20 lengths of
* 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. */
- uint tree_code;
- uint num_zeroes;
- uint code;
- uint num_same;
+ unsigned tree_code;
+ unsigned num_zeroes;
+ unsigned code;
+ unsigned num_same;
char value;
ret = read_huffsym_using_pretree(istream, pretree_decode_table,
* blocks, which contain this information in the header)
*/
static int lzx_read_block_header(struct input_bitstream *istream,
- int *block_size_ret, int *block_type_ret,
+ unsigned *block_size_ret,
+ unsigned *block_type_ret,
struct lzx_tables *tables,
struct lru_queue *queue)
{
int ret;
int block_type;
- uint block_size;
+ unsigned block_size;
int s;
int i;
- uint len;
+ unsigned len;
int32_t R[3];
ret = bitstream_ensure_bits(istream, 4);
struct lru_queue *queue,
struct input_bitstream *istream)
{
- uint length_header;
- uint position_slot;
- uint match_len;
- uint match_offset;
- uint additional_len;
- uint num_extra_bits;
- uint verbatim_bits;
- uint aligned_bits;
+ 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;
* format as used in other file formats, where a bit is reserved for that
* purpose. */
static void undo_call_insn_preprocessing(u8 uncompressed_data[],
- uint uncompressed_data_len)
+ unsigned uncompressed_data_len)
{
int i = 0;
int file_size = LZX_MAGIC_FILESIZE;
struct lru_queue *queue,
struct input_bitstream *istream)
{
- uint bytes_remaining;
- uint main_element;
+ unsigned bytes_remaining;
+ unsigned main_element;
int match_len;
int ret;
*
* Return non-zero on failure.
*/
-int lzx_decompress(const void *compressed_data, uint compressed_len,
- void *uncompressed_data, uint uncompressed_len)
+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;
- uint bytes_remaining;
+ struct lzx_tables tables;
+ struct input_bitstream istream;
+ struct lru_queue queue;
+ unsigned bytes_remaining;
+ unsigned block_size;
+ unsigned block_type;
int ret;
- int block_size;
- int block_type;
LZX_DEBUG("lzx_decompress (compressed_data = %p, compressed_len = %d, "
"uncompressed_data = %p, uncompressed_len = %d).",
while (bytes_remaining != 0) {
LZX_DEBUG("Reading block header.");
- ret = lzx_read_block_header(&istream, &block_size, &block_type,
- &tables, &queue);
+ ret = lzx_read_block_header(&istream, &block_size,
+ &block_type, &tables, &queue);
if (ret != 0)
return ret;
- LZX_DEBUG("block_size = %d, bytes_remaining = %d.",
+ 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 %d bytes (found %d bytes)",
+ "most %u bytes (found %u bytes)",
bytes_remaining, block_size);
return 1;
}
if (bytes_remaining != 0)
LZX_DEBUG("%d bytes remaining.", bytes_remaining);
-
}
if (uncompressed_len >= 10)
git://wimlib.net / wimlib / blobdiff