/* This file is part of libmspack.
* (C) 2003-2013 Stuart Caie.
*
* The LZX method was created by Jonathan Forbes and Tomi Poutanen, adapted
* by Microsoft Corporation.
*
* libmspack is free software; you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License (LGPL) version 2.1
*
* For further details, see the file COPYING.LIB distributed with libmspack
*/
/* LZX decompression implementation */
#include <system.h>
#include <lzx.h>
/* Microsoft's LZX document (in cab-sdk.exe) 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_LENGTHS used in the decompression pseudocode
* is not defined in the specification.
*
* The LZX document does not state the uncompressed block has an
* uncompressed length field. Where does this length field come from, so
* we can know how large the block is? The implementation has it as the 24
* bits following after the 3 blocktype bits, before the alignment
* padding.
*
* 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.
*
* The errors in LZX documentation appear have been corrected in the
* new documentation for the LZX DELTA format.
*
* http://msdn.microsoft.com/en-us/library/cc483133.aspx
*
* However, this is a different format, an extension of regular LZX.
* I have noticed the following differences, there may be more:
*
* The maximum window size has increased from 2MB to 32MB. This also
* increases the maximum number of position slots, etc.
*
* If the match length is 257 (the maximum possible), this signals
* a further length decoding step, that allows for matches up to
* 33024 bytes long.
*
* The format now allows for "reference data", supplied by the caller.
* If match offsets go further back than the number of bytes
* decompressed so far, that is them accessing the reference data.
*/
/* import bit-reading macros and code */
#define BITS_TYPE struct lzxd_stream
#define BITS_VAR lzx
#define BITS_ORDER_MSB
#define READ_BYTES do { \
unsigned char b0, b1; \
READ_IF_NEEDED; b0 = *i_ptr++; \
READ_IF_NEEDED; b1 = *i_ptr++; \
INJECT_BITS((b1 << 8) | b0, 16); \
} while (0)
#include <readbits.h>
/* import huffman-reading macros and code */
#define TABLEBITS(tbl) LZX_##tbl##_TABLEBITS
#define MAXSYMBOLS(tbl) LZX_##tbl##_MAXSYMBOLS
#define HUFF_TABLE(tbl,idx) lzx->tbl##_table[idx]
#define HUFF_LEN(tbl,idx) lzx->tbl##_len[idx]
#define HUFF_ERROR return lzx->error = MSPACK_ERR_DECRUNCH
#include <readhuff.h>
/* BUILD_TABLE(tbl) builds a huffman lookup table from code lengths */
#define BUILD_TABLE(tbl) \
if (make_decode_table(MAXSYMBOLS(tbl), TABLEBITS(tbl), \
&HUFF_LEN(tbl,0), &HUFF_TABLE(tbl,0))) \
{ \
D(("failed to build %s table", #tbl)) \
return lzx->error = MSPACK_ERR_DECRUNCH; \
}
#define BUILD_TABLE_MAYBE_EMPTY(tbl) do { \
lzx->tbl##_empty = 0; \
if (make_decode_table(MAXSYMBOLS(tbl), TABLEBITS(tbl), \
&HUFF_LEN(tbl,0), &HUFF_TABLE(tbl,0))) \
{ \
for (i = 0; i < MAXSYMBOLS(tbl); i++) { \
if (HUFF_LEN(tbl, i) > 0) { \
D(("failed to build %s table", #tbl)) \
return lzx->error = MSPACK_ERR_DECRUNCH; \
} \
} \
/* empty tree - allow it, but don't decode symbols with it */ \
lzx->tbl##_empty = 1; \
} \
} while (0)
/* READ_LENGTHS(tablename, first, last) reads in code lengths for symbols
* first to last in the given table. The code lengths are stored in their
* own special LZX way.
*/
#define READ_LENGTHS(tbl, first, last) do { \
STORE_BITS; \
if (lzxd_read_lens(lzx, &HUFF_LEN(tbl, 0), (first), \
(unsigned int)(last))) return lzx->error; \
RESTORE_BITS; \
} while (0)
static int lzxd_read_lens(struct lzxd_stream *lzx, unsigned char *lens,
unsigned int first, unsigned int last)
{
/* bit buffer and huffman symbol decode variables */
register unsigned int bit_buffer;
register int bits_left, i;
register unsigned short sym;
unsigned char *i_ptr, *i_end;
unsigned int x, y;
int z;
RESTORE_BITS;
/* read lengths for pretree (20 symbols, lengths stored in fixed 4 bits) */
for (x = 0; x < 20; x++) {
READ_BITS(y, 4);
lzx->PRETREE_len[x] = y;
}
BUILD_TABLE(PRETREE);
for (x = first; x < last; ) {
READ_HUFFSYM(PRETREE, z);
if (z == 17) {
/* code = 17, run of ([read 4 bits]+4) zeros */
READ_BITS(y, 4); y += 4;
while (y--) lens[x++] = 0;
}
else if (z == 18) {
/* code = 18, run of ([read 5 bits]+20) zeros */
READ_BITS(y, 5); y += 20;
while (y--) lens[x++] = 0;
}
else if (z == 19) {
/* code = 19, run of ([read 1 bit]+4) [read huffman symbol] */
READ_BITS(y, 1); y += 4;
READ_HUFFSYM(PRETREE, z);
z = lens[x] - z; if (z < 0) z += 17;
while (y--) lens[x++] = z;
}
else {
/* code = 0 to 16, delta current length entry */
z = lens[x] - z; if (z < 0) z += 17;
lens[x++] = z;
}
}
STORE_BITS;
return MSPACK_ERR_OK;
}
/* LZX static data tables:
*
* LZX uses 'position slots' to represent match offsets. For every match,
* a small 'position slot' number and a small offset from that slot are
* encoded instead of one large offset.
*
* The number of slots is decided by how many are needed to encode the
* largest offset for a given window size. This is easy when the gap between
* slots is less than 128Kb, it's a linear relationship. But when extra_bits
* reaches its limit of 17 (because LZX can only ensure reading 17 bits of
* data at a time), we can only jump 128Kb at a time and have to start
* using more and more position slots as each window size doubles.
*
* position_base[] is an index to the position slot bases
*
* extra_bits[] states how many bits of offset-from-base data is needed.
*
* They are calculated as follows:
* extra_bits[i] = 0 where i < 4
* extra_bits[i] = floor(i/2)-1 where i >= 4 && i < 36
* extra_bits[i] = 17 where i >= 36
* position_base[0] = 0
* position_base[i] = position_base[i-1] + (1 << extra_bits[i-1])
*/
static const unsigned int position_slots[11] = {
30, 32, 34, 36, 38, 42, 50, 66, 98, 162, 290
};
static const unsigned char extra_bits[36] = {
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16, 16
};
static const unsigned int position_base[290] = {
0, 1, 2, 3, 4, 6, 8, 12, 16, 24, 32, 48, 64, 96, 128, 192, 256, 384, 512,
768, 1024, 1536, 2048, 3072, 4096, 6144, 8192, 12288, 16384, 24576, 32768,
49152, 65536, 98304, 131072, 196608, 262144, 393216, 524288, 655360,
786432, 917504, 1048576, 1179648, 1310720, 1441792, 1572864, 1703936,
1835008, 1966080, 2097152, 2228224, 2359296, 2490368, 2621440, 2752512,
2883584, 3014656, 3145728, 3276800, 3407872, 3538944, 3670016, 3801088,
3932160, 4063232, 4194304, 4325376, 4456448, 4587520, 4718592, 4849664,
4980736, 5111808, 5242880, 5373952, 5505024, 5636096, 5767168, 5898240,
6029312, 6160384, 6291456, 6422528, 6553600, 6684672, 6815744, 6946816,
7077888, 7208960, 7340032, 7471104, 7602176, 7733248, 7864320, 7995392,
8126464, 8257536, 8388608, 8519680, 8650752, 8781824, 8912896, 9043968,
9175040, 9306112, 9437184, 9568256, 9699328, 9830400, 9961472, 10092544,
10223616, 10354688, 10485760, 10616832, 10747904, 10878976, 11010048,
11141120, 11272192, 11403264, 11534336, 11665408, 11796480, 11927552,
12058624, 12189696, 12320768, 12451840, 12582912, 12713984, 12845056,
12976128, 13107200, 13238272, 13369344, 13500416, 13631488, 13762560,
13893632, 14024704, 14155776, 14286848, 14417920, 14548992, 14680064,
14811136, 14942208, 15073280, 15204352, 15335424, 15466496, 15597568,
15728640, 15859712, 15990784, 16121856, 16252928, 16384000, 16515072,
16646144, 16777216, 16908288, 17039360, 17170432, 17301504, 17432576,
17563648, 17694720, 17825792, 17956864, 18087936, 18219008, 18350080,
18481152, 18612224, 18743296, 18874368, 19005440, 19136512, 19267584,
19398656, 19529728, 19660800, 19791872, 19922944, 20054016, 20185088,
20316160, 20447232, 20578304, 20709376, 20840448, 20971520, 21102592,
21233664, 21364736, 21495808, 21626880, 21757952, 21889024, 22020096,
22151168, 22282240, 22413312, 22544384, 22675456, 22806528, 22937600,
23068672, 23199744, 23330816, 23461888, 23592960, 23724032, 23855104,
23986176, 24117248, 24248320, 24379392, 24510464, 24641536, 24772608,
24903680, 25034752, 25165824, 25296896, 25427968, 25559040, 25690112,
25821184, 25952256, 26083328, 26214400, 26345472, 26476544, 26607616,
26738688, 26869760, 27000832, 27131904, 27262976, 27394048, 27525120,
27656192, 27787264, 27918336, 28049408, 28180480, 28311552, 28442624,
28573696, 28704768, 28835840, 28966912, 29097984, 29229056, 29360128,
29491200, 29622272, 29753344, 29884416, 30015488, 30146560, 30277632,
30408704, 30539776, 30670848, 30801920, 30932992, 31064064, 31195136,
31326208, 31457280, 31588352, 31719424, 31850496, 31981568, 32112640,
32243712, 32374784, 32505856, 32636928, 32768000, 32899072, 33030144,
33161216, 33292288, 33423360
};
static void lzxd_reset_state(struct lzxd_stream *lzx) {
int i;
lzx->R0 = 1;
lzx->R1 = 1;
lzx->R2 = 1;
lzx->header_read = 0;
lzx->block_remaining = 0;
lzx->block_type = LZX_BLOCKTYPE_INVALID;
/* initialise tables to 0 (because deltas will be applied to them) */
for (i = 0; i < LZX_MAINTREE_MAXSYMBOLS; i++) lzx->MAINTREE_len[i] = 0;
for (i = 0; i < LZX_LENGTH_MAXSYMBOLS; i++) lzx->LENGTH_len[i] = 0;
}
/*-------- main LZX code --------*/
struct lzxd_stream *lzxd_init(struct mspack_system *system,
struct mspack_file *input,
struct mspack_file *output,
int window_bits,
int reset_interval,
int input_buffer_size,
off_t output_length,
char is_delta)
{
unsigned int window_size = 1 << window_bits;
struct lzxd_stream *lzx;
if (!system) return NULL;
/* LZX DELTA window sizes are between 2^17 (128KiB) and 2^25 (32MiB),
* regular LZX windows are between 2^15 (32KiB) and 2^21 (2MiB)
*/
if (is_delta) {
if (window_bits < 17 || window_bits > 25) return NULL;
}
else {
if (window_bits < 15 || window_bits > 21) return NULL;
}
if (reset_interval < 0 || output_length < 0) {
D(("reset interval or output length < 0"))
return NULL;
}
/* round up input buffer size to multiple of two */
input_buffer_size = (input_buffer_size + 1) & -2;
if (input_buffer_size < 2) return NULL;
/* allocate decompression state */
if (!(lzx = (struct lzxd_stream *) system->alloc(system, sizeof(struct lzxd_stream)))) {
return NULL;
}
/* allocate decompression window and input buffer */
lzx->window = (unsigned char *) system->alloc(system, (size_t) window_size);
lzx->inbuf = (unsigned char *) system->alloc(system, (size_t) input_buffer_size);
if (!lzx->window || !lzx->inbuf) {
system->free(lzx->window);
system->free(lzx->inbuf);
system->free(lzx);
return NULL;
}
/* initialise decompression state */
lzx->sys = system;
lzx->input = input;
lzx->output = output;
lzx->offset = 0;
lzx->length = output_length;
lzx->inbuf_size = input_buffer_size;
lzx->window_size = 1 << window_bits;
lzx->ref_data_size = 0;
lzx->window_posn = 0;
lzx->frame_posn = 0;
lzx->frame = 0;
lzx->reset_interval = reset_interval;
lzx->intel_filesize = 0;
lzx->intel_curpos = 0;
lzx->intel_started = 0;
lzx->error = MSPACK_ERR_OK;
lzx->num_offsets = position_slots[window_bits - 15] << 3;
lzx->is_delta = is_delta;
lzx->o_ptr = lzx->o_end = &lzx->e8_buf[0];
lzxd_reset_state(lzx);
INIT_BITS;
return lzx;
}
int lzxd_set_reference_data(struct lzxd_stream *lzx,
struct mspack_system *system,
struct mspack_file *input,
unsigned int length)
{
if (!lzx) return MSPACK_ERR_ARGS;
if (!lzx->is_delta) {
D(("only LZX DELTA streams support reference data"))
return MSPACK_ERR_ARGS;
}
if (lzx->offset) {
D(("too late to set reference data after decoding starts"))
return MSPACK_ERR_ARGS;
}
if (length > lzx->window_size) {
D(("reference length (%u) is longer than the window", length))
return MSPACK_ERR_ARGS;
}
if (length > 0 && (!system || !input)) {
D(("length > 0 but no system or input"))
return MSPACK_ERR_ARGS;
}
lzx->ref_data_size = length;
if (length > 0) {
/* copy reference data */
unsigned char *pos = &lzx->window[lzx->window_size - length];
int bytes = system->read(input, pos, length);
/* length can't be more than 2^25, so no signedness problem */
if (bytes < (int)length) return MSPACK_ERR_READ;
}
lzx->ref_data_size = length;
return MSPACK_ERR_OK;
}
void lzxd_set_output_length(struct lzxd_stream *lzx, off_t out_bytes) {
if (lzx && out_bytes > 0) lzx->length = out_bytes;
}
int lzxd_decompress(struct lzxd_stream *lzx, off_t out_bytes) {
/* bitstream and huffman reading variables */
register unsigned int bit_buffer;
register int bits_left, i=0;
unsigned char *i_ptr, *i_end;
register unsigned short sym;
int match_length, length_footer, extra, verbatim_bits, bytes_todo;
int this_run, main_element, aligned_bits, j, warned = 0;
unsigned char *window, *runsrc, *rundest, buf[12];
unsigned int frame_size=0, end_frame, match_offset, window_posn;
unsigned int R0, R1, R2;
/* easy answers */
if (!lzx || (out_bytes < 0)) return MSPACK_ERR_ARGS;
if (lzx->error) return lzx->error;
/* flush out any stored-up bytes before we begin */
i = lzx->o_end - lzx->o_ptr;
if ((off_t) i > out_bytes) i = (int) out_bytes;
if (i) {
if (lzx->sys->write(lzx->output, lzx->o_ptr, i) != i) {
return lzx->error = MSPACK_ERR_WRITE;
}
lzx->o_ptr += i;
lzx->offset += i;
out_bytes -= i;
}
if (out_bytes == 0) return MSPACK_ERR_OK;
/* restore local state */
RESTORE_BITS;
window = lzx->window;
window_posn = lzx->window_posn;
R0 = lzx->R0;
R1 = lzx->R1;
R2 = lzx->R2;
end_frame = (unsigned int)((lzx->offset + out_bytes) / LZX_FRAME_SIZE) + 1;
while (lzx->frame < end_frame) {
/* have we reached the reset interval? (if there is one?) */
if (lzx->reset_interval && ((lzx->frame % lzx->reset_interval) == 0)) {
if (lzx->block_remaining) {
/* this is a file format error, we can make a best effort to extract what we can */
D(("%d bytes remaining at reset interval", lzx->block_remaining))
if (!warned) {
lzx->sys->message(NULL, "WARNING; invalid reset interval detected during LZX decompression");
warned++;
}
}
/* re-read the intel header and reset the huffman lengths */
lzxd_reset_state(lzx);
R0 = lzx->R0;
R1 = lzx->R1;
R2 = lzx->R2;
}
/* LZX DELTA format has chunk_size, not present in LZX format */
if (lzx->is_delta) {
ENSURE_BITS(16);
REMOVE_BITS(16);
}
/* read header if necessary */
if (!lzx->header_read) {
/* read 1 bit. if bit=0, intel filesize = 0.
* if bit=1, read intel filesize (32 bits) */
j = 0; READ_BITS(i, 1); if (i) { READ_BITS(i, 16); READ_BITS(j, 16); }
lzx->intel_filesize = (i << 16) | j;
lzx->header_read = 1;
}
/* calculate size of frame: all frames are 32k except the final frame
* which is 32kb or less. this can only be calculated when lzx->length
* has been filled in. */
frame_size = LZX_FRAME_SIZE;
if (lzx->length && (lzx->length - lzx->offset) < (off_t)frame_size) {
frame_size = lzx->length - lzx->offset;
}
/* decode until one more frame is available */
bytes_todo = lzx->frame_posn + frame_size - window_posn;
while (bytes_todo > 0) {
/* initialise new block, if one is needed */
if (lzx->block_remaining == 0) {
/* realign if previous block was an odd-sized UNCOMPRESSED block */
if ((lzx->block_type == LZX_BLOCKTYPE_UNCOMPRESSED) &&
(lzx->block_length & 1))
{
READ_IF_NEEDED;
i_ptr++;
}
/* read block type (3 bits) and block length (24 bits) */
READ_BITS(lzx->block_type, 3);
READ_BITS(i, 16); READ_BITS(j, 8);
lzx->block_remaining = lzx->block_length = (i << 8) | j;
/*D(("new block t%d len %u", lzx->block_type, lzx->block_length))*/
/* read individual block headers */
switch (lzx->block_type) {
case LZX_BLOCKTYPE_ALIGNED:
/* read lengths of and build aligned huffman decoding tree */
for (i = 0; i < 8; i++) { READ_BITS(j, 3); lzx->ALIGNED_len[i] = j; }
BUILD_TABLE(ALIGNED);
/* rest of aligned header is same as verbatim */ /*@fallthrough@*/
case LZX_BLOCKTYPE_VERBATIM:
/* read lengths of and build main huffman decoding tree */
READ_LENGTHS(MAINTREE, 0, 256);
READ_LENGTHS(MAINTREE, 256, LZX_NUM_CHARS + lzx->num_offsets);
BUILD_TABLE(MAINTREE);
/* if the literal 0xE8 is anywhere in the block... */
if (lzx->MAINTREE_len[0xE8] != 0) lzx->intel_started = 1;
/* read lengths of and build lengths huffman decoding tree */
READ_LENGTHS(LENGTH, 0, LZX_NUM_SECONDARY_LENGTHS);
BUILD_TABLE_MAYBE_EMPTY(LENGTH);
break;
case LZX_BLOCKTYPE_UNCOMPRESSED:
/* because we can't assume otherwise */
lzx->intel_started = 1;
/* read 1-16 (not 0-15) bits to align to bytes */
if (bits_left == 0) ENSURE_BITS(16);
bits_left = 0; bit_buffer = 0;
/* read 12 bytes of stored R0 / R1 / R2 values */
for (rundest = &buf[0], i = 0; i < 12; i++) {
READ_IF_NEEDED;
*rundest++ = *i_ptr++;
}
R0 = buf[0] | (buf[1] << 8) | (buf[2] << 16) | (buf[3] << 24);
R1 = buf[4] | (buf[5] << 8) | (buf[6] << 16) | (buf[7] << 24);
R2 = buf[8] | (buf[9] << 8) | (buf[10] << 16) | (buf[11] << 24);
break;
default:
D(("bad block type"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
}
/* decode more of the block:
* run = min(what's available, what's needed) */
this_run = lzx->block_remaining;
if (this_run > bytes_todo) this_run = bytes_todo;
/* assume we decode exactly this_run bytes, for now */
bytes_todo -= this_run;
lzx->block_remaining -= this_run;
/* decode at least this_run bytes */
switch (lzx->block_type) {
case LZX_BLOCKTYPE_VERBATIM:
while (this_run > 0) {
READ_HUFFSYM(MAINTREE, main_element);
if (main_element < LZX_NUM_CHARS) {
/* literal: 0 to LZX_NUM_CHARS-1 */
window[window_posn++] = main_element;
this_run--;
}
else {
/* match: LZX_NUM_CHARS + ((slot<<3) | length_header (3 bits)) */
main_element -= LZX_NUM_CHARS;
/* get match length */
match_length = main_element & LZX_NUM_PRIMARY_LENGTHS;
if (match_length == LZX_NUM_PRIMARY_LENGTHS) {
if (lzx->LENGTH_empty) {
D(("LENGTH symbol needed but tree is empty"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
READ_HUFFSYM(LENGTH, length_footer);
match_length += length_footer;
}
match_length += LZX_MIN_MATCH;
/* get match offset */
switch ((match_offset = (main_element >> 3))) {
case 0: match_offset = R0; break;
case 1: match_offset = R1; R1=R0; R0 = match_offset; break;
case 2: match_offset = R2; R2=R0; R0 = match_offset; break;
case 3: match_offset = 1; R2=R1; R1=R0; R0 = match_offset; break;
default:
extra = (match_offset >= 36) ? 17 : extra_bits[match_offset];
READ_BITS(verbatim_bits, extra);
match_offset = position_base[match_offset] - 2 + verbatim_bits;
R2 = R1; R1 = R0; R0 = match_offset;
}
/* LZX DELTA uses max match length to signal even longer match */
if (match_length == LZX_MAX_MATCH && lzx->is_delta) {
int extra_len = 0;
ENSURE_BITS(3); /* 4 entry huffman tree */
if (PEEK_BITS(1) == 0) {
REMOVE_BITS(1); /* '0' -> 8 extra length bits */
READ_BITS(extra_len, 8);
}
else if (PEEK_BITS(2) == 2) {
REMOVE_BITS(2); /* '10' -> 10 extra length bits + 0x100 */
READ_BITS(extra_len, 10);
extra_len += 0x100;
}
else if (PEEK_BITS(3) == 6) {
REMOVE_BITS(3); /* '110' -> 12 extra length bits + 0x500 */
READ_BITS(extra_len, 12);
extra_len += 0x500;
}
else {
REMOVE_BITS(3); /* '111' -> 15 extra length bits */
READ_BITS(extra_len, 15);
}
match_length += extra_len;
}
if ((window_posn + match_length) > lzx->window_size) {
D(("match ran over window wrap"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
/* copy match */
rundest = &window[window_posn];
i = match_length;
/* does match offset wrap the window? */
if (match_offset > window_posn) {
if (match_offset > lzx->offset &&
(match_offset - window_posn) > lzx->ref_data_size)
{
D(("match offset beyond LZX stream"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
/* j = length from match offset to end of window */
j = match_offset - window_posn;
if (j > (int) lzx->window_size) {
D(("match offset beyond window boundaries"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
runsrc = &window[lzx->window_size - j];
if (j < i) {
/* if match goes over the window edge, do two copy runs */
i -= j; while (j-- > 0) *rundest++ = *runsrc++;
runsrc = window;
}
while (i-- > 0) *rundest++ = *runsrc++;
}
else {
runsrc = rundest - match_offset;
while (i-- > 0) *rundest++ = *runsrc++;
}
this_run -= match_length;
window_posn += match_length;
}
} /* while (this_run > 0) */
break;
case LZX_BLOCKTYPE_ALIGNED:
while (this_run > 0) {
READ_HUFFSYM(MAINTREE, main_element);
if (main_element < LZX_NUM_CHARS) {
/* literal: 0 to LZX_NUM_CHARS-1 */
window[window_posn++] = main_element;
this_run--;
}
else {
/* match: LZX_NUM_CHARS + ((slot<<3) | length_header (3 bits)) */
main_element -= LZX_NUM_CHARS;
/* get match length */
match_length = main_element & LZX_NUM_PRIMARY_LENGTHS;
if (match_length == LZX_NUM_PRIMARY_LENGTHS) {
if (lzx->LENGTH_empty) {
D(("LENGTH symbol needed but tree is empty"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
READ_HUFFSYM(LENGTH, length_footer);
match_length += length_footer;
}
match_length += LZX_MIN_MATCH;
/* get match offset */
switch ((match_offset = (main_element >> 3))) {
case 0: match_offset = R0; break;
case 1: match_offset = R1; R1 = R0; R0 = match_offset; break;
case 2: match_offset = R2; R2 = R0; R0 = match_offset; break;
default:
extra = (match_offset >= 36) ? 17 : extra_bits[match_offset];
match_offset = position_base[match_offset] - 2;
if (extra > 3) {
/* verbatim and aligned bits */
extra -= 3;
READ_BITS(verbatim_bits, extra);
match_offset += (verbatim_bits << 3);
READ_HUFFSYM(ALIGNED, aligned_bits);
match_offset += aligned_bits;
}
else if (extra == 3) {
/* aligned bits only */
READ_HUFFSYM(ALIGNED, aligned_bits);
match_offset += aligned_bits;
}
else if (extra > 0) { /* extra==1, extra==2 */
/* verbatim bits only */
READ_BITS(verbatim_bits, extra);
match_offset += verbatim_bits;
}
else /* extra == 0 */ {
/* ??? not defined in LZX specification! */
match_offset = 1;
}
/* update repeated offset LRU queue */
R2 = R1; R1 = R0; R0 = match_offset;
}
/* LZX DELTA uses max match length to signal even longer match */
if (match_length == LZX_MAX_MATCH && lzx->is_delta) {
int extra_len = 0;
ENSURE_BITS(3); /* 4 entry huffman tree */
if (PEEK_BITS(1) == 0) {
REMOVE_BITS(1); /* '0' -> 8 extra length bits */
READ_BITS(extra_len, 8);
}
else if (PEEK_BITS(2) == 2) {
REMOVE_BITS(2); /* '10' -> 10 extra length bits + 0x100 */
READ_BITS(extra_len, 10);
extra_len += 0x100;
}
else if (PEEK_BITS(3) == 6) {
REMOVE_BITS(3); /* '110' -> 12 extra length bits + 0x500 */
READ_BITS(extra_len, 12);
extra_len += 0x500;
}
else {
REMOVE_BITS(3); /* '111' -> 15 extra length bits */
READ_BITS(extra_len, 15);
}
match_length += extra_len;
}
if ((window_posn + match_length) > lzx->window_size) {
D(("match ran over window wrap"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
/* copy match */
rundest = &window[window_posn];
i = match_length;
/* does match offset wrap the window? */
if (match_offset > window_posn) {
if (match_offset > lzx->offset &&
(match_offset - window_posn) > lzx->ref_data_size)
{
D(("match offset beyond LZX stream"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
/* j = length from match offset to end of window */
j = match_offset - window_posn;
if (j > (int) lzx->window_size) {
D(("match offset beyond window boundaries"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
runsrc = &window[lzx->window_size - j];
if (j < i) {
/* if match goes over the window edge, do two copy runs */
i -= j; while (j-- > 0) *rundest++ = *runsrc++;
runsrc = window;
}
while (i-- > 0) *rundest++ = *runsrc++;
}
else {
runsrc = rundest - match_offset;
while (i-- > 0) *rundest++ = *runsrc++;
}
this_run -= match_length;
window_posn += match_length;
}
} /* while (this_run > 0) */
break;
case LZX_BLOCKTYPE_UNCOMPRESSED:
/* as this_run is limited not to wrap a frame, this also means it
* won't wrap the window (as the window is a multiple of 32k) */
rundest = &window[window_posn];
window_posn += this_run;
while (this_run > 0) {
if ((i = i_end - i_ptr) == 0) {
READ_IF_NEEDED;
}
else {
if (i > this_run) i = this_run;
lzx->sys->copy(i_ptr, rundest, (size_t) i);
rundest += i;
i_ptr += i;
this_run -= i;
}
}
break;
default:
return lzx->error = MSPACK_ERR_DECRUNCH; /* might as well */
}
/* did the final match overrun our desired this_run length? */
if (this_run < 0) {
if ((unsigned int)(-this_run) > lzx->block_remaining) {
D(("overrun went past end of block by %d (%d remaining)",
-this_run, lzx->block_remaining ))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
lzx->block_remaining -= -this_run;
}
} /* while (bytes_todo > 0) */
/* streams don't extend over frame boundaries */
if ((window_posn - lzx->frame_posn) != frame_size) {
D(("decode beyond output frame limits! %d != %d",
window_posn - lzx->frame_posn, frame_size))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
/* re-align input bitstream */
if (bits_left > 0) ENSURE_BITS(16);
if (bits_left & 15) REMOVE_BITS(bits_left & 15);
/* check that we've used all of the previous frame first */
if (lzx->o_ptr != lzx->o_end) {
D(("%ld avail bytes, new %d frame",
(long)(lzx->o_end - lzx->o_ptr), frame_size))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
/* does this intel block _really_ need decoding? */
if (lzx->intel_started && lzx->intel_filesize &&
(lzx->frame <= 32768) && (frame_size > 10))
{
unsigned char *data = &lzx->e8_buf[0];
unsigned char *dataend = &lzx->e8_buf[frame_size - 10];
signed int curpos = lzx->intel_curpos;
signed int filesize = lzx->intel_filesize;
signed int abs_off, rel_off;
/* copy e8 block to the e8 buffer and tweak if needed */
lzx->o_ptr = data;
lzx->sys->copy(&lzx->window[lzx->frame_posn], data, frame_size);
while (data < dataend) {
if (*data++ != 0xE8) { curpos++; continue; }
abs_off = data[0] | (data[1]<<8) | (data[2]<<16) | (data[3]<<24);
if ((abs_off >= -curpos) && (abs_off < filesize)) {
rel_off = (abs_off >= 0) ? abs_off - curpos : abs_off + filesize;
data[0] = (unsigned char) rel_off;
data[1] = (unsigned char) (rel_off >> 8);
data[2] = (unsigned char) (rel_off >> 16);
data[3] = (unsigned char) (rel_off >> 24);
}
data += 4;
curpos += 5;
}
lzx->intel_curpos += frame_size;
}
else {
lzx->o_ptr = &lzx->window[lzx->frame_posn];
if (lzx->intel_filesize) lzx->intel_curpos += frame_size;
}
lzx->o_end = &lzx->o_ptr[frame_size];
/* write a frame */
i = (out_bytes < (off_t)frame_size) ? (unsigned int)out_bytes : frame_size;
if (lzx->sys->write(lzx->output, lzx->o_ptr, i) != i) {
return lzx->error = MSPACK_ERR_WRITE;
}
lzx->o_ptr += i;
lzx->offset += i;
out_bytes -= i;
/* advance frame start position */
lzx->frame_posn += frame_size;
lzx->frame++;
/* wrap window / frame position pointers */
if (window_posn == lzx->window_size) window_posn = 0;
if (lzx->frame_posn == lzx->window_size) lzx->frame_posn = 0;
} /* while (lzx->frame < end_frame) */
if (out_bytes) {
D(("bytes left to output"))
return lzx->error = MSPACK_ERR_DECRUNCH;
}
/* store local state */
STORE_BITS;
lzx->window_posn = window_posn;
lzx->R0 = R0;
lzx->R1 = R1;
lzx->R2 = R2;
return MSPACK_ERR_OK;
}
void lzxd_free(struct lzxd_stream *lzx) {
struct mspack_system *sys;
if (lzx) {
sys = lzx->sys;
sys->free(lzx->inbuf);
sys->free(lzx->window);
sys->free(lzx);
}
}