/*
* lzms-decompress.c
*
- * LZMS decompression routines.
+ * A decompressor for the LZMS compression format.
*/
/*
* along with wimlib; if not, see http://www.gnu.org/licenses/.
*/
-#include "wimlib/win32_common.h"
-#include "wimlib/lzms.h"
+/*
+ * This is a decompressor for the LZMS compression format used by Microsoft.
+ * This format is not documented, but it is one of the formats supported by the
+ * compression API available in Windows 8, and as of Windows 8 it is one of the
+ * formats that can be used in WIM files.
+ *
+ * This decompressor only implements "raw" decompression, which decompresses a
+ * single LZMS-compressed block. This behavior is the same as that of
+ * Decompress() in the Windows 8 compression API when using a compression handle
+ * created with CreateDecompressor() with the Algorithm parameter specified as
+ * COMPRESS_ALGORITHM_LZMS | COMPRESS_RAW. Presumably, non-raw LZMS data
+ * is a container format from which the locations and sizes (both compressed and
+ * uncompressed) of the constituent blocks can be determined.
+ *
+ * A LZMS-compressed block must be read in 16-bit little endian units from both
+ * directions. One logical bitstream starts at the front of the block and
+ * proceeds forwards. Another logical bitstream starts at the end of the block
+ * and proceeds backwards. Bits read from the forwards bitstream constitute
+ * range-encoded data, whereas bits read from the backwards bitstream constitute
+ * Huffman-encoded symbols or verbatim bits. For both bitstreams, the ordering
+ * of the bits within the 16-bit coding units is such that the first bit is the
+ * high-order bit and the last bit is the low-order bit.
+ *
+ * From these two logical bitstreams, a LZMS decompressor can reconstitute the
+ * series of items that make up the LZMS data representation. Each such item
+ * may be a literal byte or a match. Matches may be either traditional LZ77
+ * matches or "delta" matches, either of which can have its offset encoded
+ * explicitly or encoded via a reference to a recently used (repeat) offset.
+ *
+ * A traditional LZ match consists of a length and offset; it asserts that the
+ * sequence of bytes beginning at the current position and extending for the
+ * length is exactly equal to the equal-length sequence of bytes at the offset
+ * back in the window. On the other hand, a delta match consists of a length,
+ * raw offset, and power. It asserts that the sequence of bytes of beginning at
+ * the current position and extending for the length is equal to the bytewise
+ * sum of the two equal-length sequences of bytes (2**power) and (raw_offset *
+ * 2**power) bytes before the current position, minus bytewise the sequence of
+ * bytes beginning at (2**power + raw_offset * 2**power) bytes before the
+ * current position. Although not generally as useful as traditional LZ
+ * matches, delta matches can be helpful on some types of data. Both LZ and
+ * delta matches may overlap with the current position; in fact, the minimum
+ * offset is 1, regardless of match length.
+ *
+ * For LZ matches, up to 3 repeat offsets are allowed, similar to some other
+ * LZ-based formats such as LZX and LZMA. They must updated in a LRU fashion,
+ * except for a quirk: updates to the queue must be delayed by one LZMS item,
+ * except for the removal of a repeat match. As a result, 4 entries are
+ * actually needed in the queue, even though it is only possible to decode
+ * references to the first 3 at any given time. The queue must be initialized
+ * to the offsets {1, 2, 3, 4}.
+ *
+ * Repeat delta matches are handled similarly, but for them there are two queues
+ * updated in lock-step: one for powers and one for raw offsets. The power
+ * queue must be initialized to {0, 0, 0, 0}, and the raw offset queue must be
+ * initialized to {1, 2, 3, 4}.
+ *
+ * Bits from the range decoder must be used to disambiguate item types. The
+ * range decoder must hold two state variables: the range, which must initially
+ * be set to 0xffffffff, and the current code, which must initially be set to
+ * the first 32 bits read from the forwards bitstream. The range must be
+ * maintained above 0xffff; when it falls below 0xffff, both the range and code
+ * must be left-shifted by 16 bits and the low 16 bits of the code must be
+ * filled in with the next 16 bits from the forwards bitstream.
+ *
+ * To decode each bit, the range decoder requires a probability that is
+ * logically a real number between 0 and 1. Multiplying this
+ * probability by the current range and taking the floor gives the bound between
+ * the 0-bit region of the range and the 1-bit region of the range. However, in
+ * LZMS, probabilities are restricted to values of n/64 where n is an integer is
+ * between 1 and 63 inclusively, so the implementation may use integer
+ * operations instead. Following calculation of the bound, if the current code
+ * is in the 0-bit region, the new range becomes the current code and the
+ * decoded bit is 0; otherwise, the bound must be subtracted from both the range
+ * and the code, and the decoded bit is 1. More information about range coding
+ * can be found https://en.wikipedia.org/wiki/Range_encoding. Furthermore, note
+ * that the LZMA format also uses range coding and has public domain code
+ * available for it.
+ *
+ * The probability used to range-decode each bit must be taken from a table, of
+ * which one instance must exist for each distinct context in which a
+ * range-decoded bit is needed. At each call of the range decoder, the
+ * appropriate probability must be obtained by indexing the appropriate
+ * probability table with the last 4 (in the context disambiguating literals
+ * from matches), 5 (in the context disambiguating LZ matches from delta
+ * matches), or 6 (in all other contexts) bits recently range-decoded in that
+ * context, ordered such that the most recently decoded bit is the low-order bit
+ * of the index.
+ *
+ * Furthermore, each probability entry itself is variable, as its value must be
+ * maintained as n/64 where n is the number of 0 bits in the most recently
+ * decoded 64 bits with that same entry. This allows the compressed
+ * representation to adapt to the input and use fewer bits to represent the most
+ * likely data; note that LZMA uses a similar scheme. Initially, the most
+ * recently 64 decoded bits for each probability entry are assumed to be
+ * 0x0000000055555555 (high order to low order); therefore, all probabilities
+ * are initially 48/64. During the course of decoding, each probability may be
+ * updated to as low as 0/64 (as a result of reading many consecutive 1 bits
+ * with that entry) or as high as 64/64 (as a result of reading many consecutive
+ * 0 bits with that entry); however, probabilities of 0/64 and 64/64 cannot be
+ * used as-is but rather must be adjusted to 1/64 and 63/64, respectively,
+ * before being used for range decoding.
+ *
+ * Representations of the LZMS items themselves must be read from the backwards
+ * bitstream. For this, there are 5 different Huffman codes used:
+ *
+ * - The literal code, used for decoding literal bytes. Each of the 256
+ * symbols represents literal byte. This code must be rebuilt whenever 1024
+ * symbols have been decoded with it.
+ *
+ * - The LZ offset code, used for decoding the offsets of standard LZ77
+ * matches. Each symbol represents a position slot, which corresponds to a
+ * base value and some number of extra bits which must be read and added to
+ * the base value to reconstitute the full offset. The number of symbols in
+ * this code is the number of position slots needed to represent all possible
+ * offsets in the uncompressed block. This code must be rebuilt whenever
+ * 1024 symbols have been decoded with it.
+ *
+ * - The length code, used for decoding length symbols. Each of the 54 symbols
+ * represents a length slot, which corresponds to a base value and some
+ * number of extra bits which must be read and added to the base value to
+ * reconstitute the full length. This code must be rebuilt whenever 512
+ * symbols have been decoded with it.
+ *
+ * - The delta offset code, used for decoding the offsets of delta matches.
+ * Each symbol corresponds to a position slot, which corresponds to a base
+ * value and some number of extra bits which must be read and added to the
+ * base value to reconstitute the full offset. The number of symbols in this
+ * code is equal to the number of symbols in the LZ offset code. This code
+ * must be rebuilt whenever 1024 symbols have been decoded with it.
+ *
+ * - The delta power code, used for decoding the powers of delta matches. Each
+ * of the 8 symbols corresponds to a power. This code must be rebuilt
+ * whenever 512 symbols have been decoded with it.
+ *
+ * All the LZMS Huffman codes must be built adaptively based on symbol
+ * frequencies. Initially, each code must be built assuming that all symbols
+ * have equal frequency. Following that, each code must be rebuilt whenever a
+ * certain number of symbols has been decoded with it.
+ *
+ * In general, multiple valid Huffman codes can be constructed from a set of
+ * symbol frequencies. Like other compression formats such as XPRESS, LZX, and
+ * DEFLATE, the LZMS format solves this ambiguity by requiring that all Huffman
+ * codes be constructed in canonical form. This form requires that same-length
+ * codewords be lexicographically ordered the same way as the corresponding
+ * symbols and that all shorter codewords lexicographically precede longer
+ * codewords.
+ *
+ * Codewords in all the LZMS Huffman codes are limited to 15 bits. If the
+ * canonical code for a given set of symbol frequencies has any codewords longer
+ * than 15 bits, all frequencies must be divided by 2, rounding up, and the code
+ * construction must be attempted again.
+ *
+ * A LZMS-compressed block seemingly cannot have a size greater than or equal to
+ * the original uncompressed size. In such cases the block must be stored
+ * uncompressed.
+ *
+ * After all LZMS items have been decoded, the data must be postprocessed to
+ * translate absolute address encoded in x86 instructions into their original
+ * relative addresses.
+ *
+ * Details omitted above can be found in the code. Note that in the absence of
+ * an official specification there is no guarantee that this decompressor
+ * handles all possible cases.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include "wimlib.h"
+#include "wimlib/compress.h"
+#include "wimlib/decompress.h"
#include "wimlib/error.h"
+#include "wimlib/lzms.h"
+#include "wimlib/util.h"
+
+#include <limits.h>
#include <pthread.h>
-typedef HANDLE DECOMPRESSOR_HANDLE;
-typedef PVOID PCOMPRESS_ALLOCATION_ROUTINES;
-typedef DECOMPRESSOR_HANDLE *PDECOMPRESSOR_HANDLE;
+#define LZMS_DECODE_TABLE_BITS 10
+
+/* Structure used for range decoding, reading bits forwards. This is the first
+ * logical bitstream mentioned above. */
+struct lzms_range_decoder_raw {
+ /* The relevant part of the current range. Although the logical range
+ * for range decoding is a very large integer, only a small portion
+ * matters at any given time, and it can be normalized (shifted left)
+ * whenever it gets too small. */
+ u32 range;
+
+ /* The current position in the range encoded by the portion of the input
+ * read so far. */
+ u32 code;
+
+ /* Pointer to the next little-endian 16-bit integer in the compressed
+ * input data (reading forwards). */
+ const le16 *in;
+
+ /* Number of 16-bit integers remaining in the compressed input data
+ * (reading forwards). */
+ size_t num_le16_remaining;
+};
+
+/* Structure used for reading raw bits backwards. This is the second logical
+ * bitstream mentioned above. */
+struct lzms_input_bitstream {
+ /* Holding variable for bits that have been read from the compressed
+ * data. The bits are ordered from high-order to low-order. */
+ /* XXX: Without special-case code to handle reading more than 17 bits
+ * at a time, this needs to be 64 bits rather than 32 bits. */
+ u64 bitbuf;
+
+ /* Number of bits in @bitbuf that are are used. */
+ unsigned num_filled_bits;
+
+ /* Pointer to the one past the next little-endian 16-bit integer in the
+ * compressed input data (reading backwards). */
+ const le16 *in;
+
+ /* Number of 16-bit integers remaining in the compressed input data
+ * (reading backwards). */
+ size_t num_le16_remaining;
+};
+
+/* Probability entry for use by the range decoder when in a specific state. */
+struct lzms_probability_entry {
+
+ /* Number of zeroes in the most recent LZMS_PROBABILITY_MAX bits that
+ * have been decoded using this probability entry. This is a cached
+ * value because it can be computed as LZMS_PROBABILITY_MAX minus the
+ * Hamming weight of the low-order LZMS_PROBABILITY_MAX bits of
+ * @recent_bits. */
+ u32 num_recent_zero_bits;
+
+ /* The most recent LZMS_PROBABILITY_MAX bits that have been decoded
+ * using this probability entry. The size of this variable, in bits,
+ * must be at least LZMS_PROBABILITY_MAX. */
+ u64 recent_bits;
+};
+
+/* Structure used for range decoding. This wraps around `struct
+ * lzms_range_decoder_raw' to use and maintain probability entries. */
+struct lzms_range_decoder {
+ /* Pointer to the raw range decoder, which has no persistent knowledge
+ * of probabilities. Multiple lzms_range_decoder's share the same
+ * lzms_range_decoder_raw. */
+ struct lzms_range_decoder_raw *rd;
+
+ /* Bits recently decoded by this range decoder. This are used as in
+ * index into @prob_entries. */
+ u32 state;
+
+ /* Bitmask for @state to prevent its value from exceeding the number of
+ * probability entries. */
+ u32 mask;
+
+ /* Probability entries being used for this range decoder. */
+ struct lzms_probability_entry prob_entries[LZMS_MAX_NUM_STATES];
+};
+
+/* Structure used for Huffman decoding, optionally using the decoded symbols as
+ * slots into a base table to determine how many extra bits need to be read to
+ * reconstitute the full value. */
+struct lzms_huffman_decoder {
+
+ /* Bitstream to read Huffman-encoded symbols and verbatim bits from.
+ * Multiple lzms_huffman_decoder's share the same lzms_input_bitstream.
+ */
+ struct lzms_input_bitstream *is;
+
+ /* Pointer to the slot base table to use. It is indexed by the decoded
+ * Huffman symbol that specifies the slot. The entry specifies the base
+ * value to use, and the position of its high bit is the number of
+ * additional bits that must be read to reconstitute the full value.
+ *
+ * This member need not be set if only raw Huffman symbols are being
+ * read using this decoder. */
+ const u32 *slot_base_tab;
+
+ /* Number of symbols that have been read using this code far. Reset to
+ * 0 whenever the code is rebuilt. */
+ u32 num_syms_read;
+
+ /* When @num_syms_read reaches this number, the Huffman code must be
+ * rebuilt. */
+ u32 rebuild_freq;
+
+ /* Number of symbols in the represented Huffman code. */
+ unsigned num_syms;
+
+ /* Running totals of symbol frequencies. These are diluted slightly
+ * whenever the code is rebuilt. */
+ u32 sym_freqs[LZMS_MAX_NUM_SYMS];
+
+ /* The length, in bits, of each symbol in the Huffman code. */
+ u8 lens[LZMS_MAX_NUM_SYMS];
+
+ /* The codeword of each symbol in the Huffman code. */
+ u16 codewords[LZMS_MAX_NUM_SYMS];
+
+ /* A table for quickly decoding symbols encoded using the Huffman code.
+ */
+ u16 decode_table[(1U << LZMS_DECODE_TABLE_BITS) + 2 * LZMS_MAX_NUM_SYMS]
+ _aligned_attribute(DECODE_TABLE_ALIGNMENT);
+};
+
+/* State of the LZMS decompressor. */
+struct lzms_decompressor {
+
+ /* Pointer to the beginning of the uncompressed data buffer. */
+ u8 *out_begin;
+
+ /* Pointer to the next position in the uncompressed data buffer. */
+ u8 *out_next;
+
+ /* Pointer to one past the end of the uncompressed data buffer. */
+ u8 *out_end;
+
+ /* Range decoder, which reads bits from the beginning of the compressed
+ * block, going forwards. */
+ struct lzms_range_decoder_raw rd;
+
+ /* Input bitstream, which reads from the end of the compressed block,
+ * going backwards. */
+ struct lzms_input_bitstream is;
+
+ /* Range decoders. */
+ struct lzms_range_decoder main_range_decoder;
+ struct lzms_range_decoder match_range_decoder;
+ struct lzms_range_decoder lz_match_range_decoder;
+ struct lzms_range_decoder lz_repeat_match_range_decoders[LZMS_NUM_RECENT_OFFSETS - 1];
+ struct lzms_range_decoder delta_match_range_decoder;
+ struct lzms_range_decoder delta_repeat_match_range_decoders[LZMS_NUM_RECENT_OFFSETS - 1];
+
+ /* Huffman decoders. */
+ struct lzms_huffman_decoder literal_decoder;
+ struct lzms_huffman_decoder lz_offset_decoder;
+ struct lzms_huffman_decoder length_decoder;
+ struct lzms_huffman_decoder delta_power_decoder;
+ struct lzms_huffman_decoder delta_offset_decoder;
+
+ /* LRU (least-recently-used) queue of LZ match offsets. */
+ u64 recent_lz_offsets[LZMS_NUM_RECENT_OFFSETS + 1];
+
+ /* LRU (least-recently-used) queue of delta match powers. */
+ u32 recent_delta_powers[LZMS_NUM_RECENT_OFFSETS + 1];
+
+ /* LRU (least-recently-used) queue of delta match offsets. */
+ u32 recent_delta_offsets[LZMS_NUM_RECENT_OFFSETS + 1];
+
+ /* These variables are used to delay updates to the LRU queues by one
+ * decoded item. */
+ u32 prev_lz_offset;
+ u32 prev_delta_power;
+ u32 prev_delta_offset;
+ u32 upcoming_lz_offset;
+ u32 upcoming_delta_power;
+ u32 upcoming_delta_offset;
+};
+
+/* A table that maps position slots to their base values. These are constants
+ * computed at runtime by lzms_compute_slot_bases(). */
+static u32 lzms_position_slot_base[LZMS_MAX_NUM_OFFSET_SYMS + 1];
+
+/* A table that maps length slots to their base values. These are constants
+ * computed at runtime by lzms_compute_slot_bases(). */
+static u32 lzms_length_slot_base[LZMS_NUM_LEN_SYMS + 1];
+
+static void
+lzms_decode_delta_rle_slot_bases(u32 slot_bases[],
+ const u8 delta_run_lens[], size_t num_run_lens)
+{
+ u32 delta = 1;
+ u32 base = 0;
+ size_t slot = 0;
+ for (size_t i = 0; i < num_run_lens; i++) {
+ u8 run_len = delta_run_lens[i];
+ while (run_len--) {
+ base += delta;
+ slot_bases[slot++] = base;
+ }
+ delta <<= 1;
+ }
+}
+
+/* Initialize the global position and length slot tables. */
+static void
+lzms_compute_slot_bases(void)
+{
+ /* If an explicit formula that maps LZMS position and length slots to
+ * slot bases exists, then it could be used here. But until one is
+ * found, the following code fills in the slots using the observation
+ * that the increase from one slot base to the next is an increasing
+ * power of 2. Therefore, run-length encoding of the delta of adjacent
+ * entries can be used. */
+ static const u8 position_slot_delta_run_lens[] = {
+ 9, 0, 9, 7, 10, 15, 15, 20,
+ 20, 30, 33, 40, 42, 45, 60, 73,
+ 80, 85, 95, 105, 6,
+ };
+
+ static const u8 length_slot_delta_run_lens[] = {
+ 27, 4, 6, 4, 5, 2, 1, 1,
+ 1, 1, 1, 0, 0, 0, 0, 0,
+ 1,
+ };
+
+ lzms_decode_delta_rle_slot_bases(lzms_position_slot_base,
+ position_slot_delta_run_lens,
+ ARRAY_LEN(position_slot_delta_run_lens));
+
+ lzms_position_slot_base[LZMS_MAX_NUM_OFFSET_SYMS] = 0x7fffffff;
+
+ lzms_decode_delta_rle_slot_bases(lzms_length_slot_base,
+ length_slot_delta_run_lens,
+ ARRAY_LEN(length_slot_delta_run_lens));
+
+ lzms_length_slot_base[LZMS_NUM_LEN_SYMS] = 0x400108ab;
+}
+
+/* Initialize the global position length slot tables if not done so already. */
+static void
+lzms_init_slot_bases(void)
+{
+ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+ static bool already_computed = false;
+
+ if (unlikely(!already_computed)) {
+ pthread_mutex_lock(&mutex);
+ if (!already_computed) {
+ lzms_compute_slot_bases();
+ already_computed = true;
+ }
+ pthread_mutex_unlock(&mutex);
+ }
+}
+
+/* Return the position slot for the specified offset. */
+static u32
+lzms_get_position_slot_raw(u32 offset)
+{
+ u32 position_slot = 0;
+ while (lzms_position_slot_base[position_slot + 1] <= offset)
+ position_slot++;
+ return position_slot;
+}
+
+/* Initialize the input bitstream @is to read forwards from the specified
+ * compressed data buffer @in that is @in_limit 16-bit integers long. */
+static void
+lzms_input_bitstream_init(struct lzms_input_bitstream *is,
+ const le16 *in, size_t in_limit)
+{
+ is->bitbuf = 0;
+ is->num_filled_bits = 0;
+ is->in = in + in_limit;
+ is->num_le16_remaining = in_limit;
+}
+
+/* Ensures that @num_bits bits are buffered in the input bitstream. */
+static int
+lzms_input_bitstream_ensure_bits(struct lzms_input_bitstream *is,
+ unsigned num_bits)
+{
+ while (is->num_filled_bits < num_bits) {
+ u64 next;
+
+ LZMS_ASSERT(is->num_filled_bits + 16 <= sizeof(is->bitbuf) * 8);
+
+ if (unlikely(is->num_le16_remaining == 0))
+ return -1;
+
+ next = le16_to_cpu(*--is->in);
+ is->num_le16_remaining--;
+
+ is->bitbuf |= next << (sizeof(is->bitbuf) * 8 - is->num_filled_bits - 16);
+ is->num_filled_bits += 16;
+ }
+ return 0;
+
+}
+
+/* Returns the next @num_bits bits that are buffered in the input bitstream. */
+static u32
+lzms_input_bitstream_peek_bits(struct lzms_input_bitstream *is,
+ unsigned num_bits)
+{
+ LZMS_ASSERT(is->num_filled_bits >= num_bits);
+ return is->bitbuf >> (sizeof(is->bitbuf) * 8 - num_bits);
+}
+
+/* Removes the next @num_bits bits that are buffered in the input bitstream. */
+static void
+lzms_input_bitstream_remove_bits(struct lzms_input_bitstream *is,
+ unsigned num_bits)
+{
+ LZMS_ASSERT(is->num_filled_bits >= num_bits);
+ is->bitbuf <<= num_bits;
+ is->num_filled_bits -= num_bits;
+}
+
+/* Removes and returns the next @num_bits bits that are buffered in the input
+ * bitstream. */
+static u32
+lzms_input_bitstream_pop_bits(struct lzms_input_bitstream *is,
+ unsigned num_bits)
+{
+ u32 bits = lzms_input_bitstream_peek_bits(is, num_bits);
+ lzms_input_bitstream_remove_bits(is, num_bits);
+ return bits;
+}
+
+/* Reads the next @num_bits from the input bitstream. */
+static u32
+lzms_input_bitstream_read_bits(struct lzms_input_bitstream *is,
+ unsigned num_bits)
+{
+ if (unlikely(lzms_input_bitstream_ensure_bits(is, num_bits)))
+ return 0;
+ return lzms_input_bitstream_pop_bits(is, num_bits);
+}
+
+/* Initialize the range decoder @rd to read forwards from the specified
+ * compressed data buffer @in that is @in_limit 16-bit integers long. */
+static void
+lzms_range_decoder_raw_init(struct lzms_range_decoder_raw *rd,
+ const le16 *in, size_t in_limit)
+{
+ rd->range = 0xffffffff;
+ rd->code = ((u32)le16_to_cpu(in[0]) << 16) |
+ ((u32)le16_to_cpu(in[1]) << 0);
+ rd->in = in + 2;
+ rd->num_le16_remaining = in_limit - 2;
+}
+
+/* Ensures the current range of the range decoder has at least 16 bits of
+ * precision. */
+static int
+lzms_range_decoder_raw_normalize(struct lzms_range_decoder_raw *rd)
+{
+ if (rd->range <= 0xffff) {
+ rd->range <<= 16;
+ if (unlikely(rd->num_le16_remaining == 0))
+ return -1;
+ rd->code = (rd->code << 16) | le16_to_cpu(*rd->in++);
+ rd->num_le16_remaining--;
+ }
+ return 0;
+}
+
+/* Decode and return the next bit from the range decoder (raw version).
+ *
+ * @prob is the chance out of LZMS_PROBABILITY_MAX that the next bit is 0.
+ */
+static int
+lzms_range_decoder_raw_decode_bit(struct lzms_range_decoder_raw *rd, u32 prob)
+{
+ u32 bound;
+
+ /* Ensure the range has at least 16 bits of precision. */
+ lzms_range_decoder_raw_normalize(rd);
+
+ /* Based on the probability, calculate the bound between the 0-bit
+ * region and the 1-bit region of the range. */
+ bound = (rd->range >> LZMS_PROBABILITY_BITS) * prob;
+
+ if (rd->code < bound) {
+ /* Current code is in the 0-bit region of the range. */
+ rd->range = bound;
+ return 0;
+ } else {
+ /* Current code is in the 1-bit region of the range. */
+ rd->range -= bound;
+ rd->code -= bound;
+ return 1;
+ }
+}
+
+/* Decode and return the next bit from the range decoder. This wraps around
+ * lzms_range_decoder_raw_decode_bit() to handle using and updating the
+ * appropriate probability table. */
+static int
+lzms_range_decode_bit(struct lzms_range_decoder *dec)
+{
+ struct lzms_probability_entry *prob_entry;
+ u32 prob;
+ int bit;
+
+ /* Load the probability entry corresponding to the current state. */
+ prob_entry = &dec->prob_entries[dec->state];
+
+ /* Treat the number of zero bits in the most recently decoded
+ * LZMS_PROBABILITY_MAX bits with this probability entry as the chance,
+ * out of LZMS_PROBABILITY_MAX, that the next bit will be a 0. However,
+ * don't allow 0% or 100% probabilities. */
+ prob = prob_entry->num_recent_zero_bits;
+ if (prob == LZMS_PROBABILITY_MAX)
+ prob = LZMS_PROBABILITY_MAX - 1;
+ else if (prob == 0)
+ prob = 1;
+
+ /* Decode the next bit. */
+ bit = lzms_range_decoder_raw_decode_bit(dec->rd, prob);
+
+ /* Update the state based on the newly decoded bit. */
+ dec->state = (((dec->state << 1) | bit) & dec->mask);
+
+ /* Update the recent bits, including the cached count of 0's. */
+ BUILD_BUG_ON(LZMS_PROBABILITY_MAX > sizeof(prob_entry->recent_bits) * 8);
+ if (bit == 0) {
+ if (prob_entry->recent_bits & (1ULL << (LZMS_PROBABILITY_MAX - 1))) {
+ /* Replacing 1 bit with 0 bit; increment the zero count.
+ */
+ prob_entry->num_recent_zero_bits++;
+ }
+ } else {
+ if (!(prob_entry->recent_bits & (1ULL << (LZMS_PROBABILITY_MAX - 1)))) {
+ /* Replacing 0 bit with 1 bit; decrement the zero count.
+ */
+ prob_entry->num_recent_zero_bits--;
+ }
+ }
+ prob_entry->recent_bits = (prob_entry->recent_bits << 1) | bit;
+
+ /* Return the decoded bit. */
+ return bit;
+}
+
+
+/* Build the decoding table for a new adaptive Huffman code using the alphabet
+ * used in the specified Huffman decoder, with the symbol frequencies
+ * dec->sym_freqs. */
+static void
+lzms_rebuild_adaptive_huffman_code(struct lzms_huffman_decoder *dec)
+{
+ int ret;
+
+ /* XXX: This implementation that makes use of code already implemented
+ * for the XPRESS and LZX compression formats. However, since for the
+ * adaptive codes used in LZMS we don't actually need the explicit codes
+ * themselves, only the decode tables, it may be possible to optimize
+ * this by somehow directly building or updating the Huffman decode
+ * table. This may be a worthwhile optimization because the adaptive
+ * codes change many times throughout a decompression run. */
+ LZMS_DEBUG("Rebuilding adaptive Huffman code (num_syms=%u)",
+ dec->num_syms);
+ make_canonical_huffman_code(dec->num_syms, LZMS_MAX_CODEWORD_LEN,
+ dec->sym_freqs, dec->lens, dec->codewords);
+ ret = make_huffman_decode_table(dec->decode_table, dec->num_syms,
+ LZMS_DECODE_TABLE_BITS, dec->lens,
+ LZMS_MAX_CODEWORD_LEN);
+ LZMS_ASSERT(ret == 0);
+}
+
+/* Decode and return the next Huffman-encoded symbol from the LZMS-compressed
+ * block using the specified Huffman decoder. */
+static u32
+lzms_decode_huffman_symbol(struct lzms_huffman_decoder *dec)
+{
+ const u8 *lens = dec->lens;
+ const u16 *decode_table = dec->decode_table;
+ struct lzms_input_bitstream *is = dec->is;
+
+ /* The Huffman codes used in LZMS are adaptive and must be rebuilt
+ * whenever a certain number of symbols have been read. Each such
+ * rebuild uses the current symbol frequencies, but the format also
+ * requires that the symbol frequencies be halved after each code
+ * rebuild. This diminishes the effect of old symbols on the current
+ * Huffman codes, thereby causing the Huffman codes to be more locally
+ * adaptable. */
+ if (dec->num_syms_read == dec->rebuild_freq) {
+ lzms_rebuild_adaptive_huffman_code(dec);
+ for (unsigned i = 0; i < dec->num_syms; i++) {
+ dec->sym_freqs[i] >>= 1;
+ dec->sym_freqs[i] += 1;
+ }
+ dec->num_syms_read = 0;
+ }
+
+ /* In the following Huffman decoding implementation, the first
+ * LZMS_DECODE_TABLE_BITS of the input are used as an offset into a
+ * decode table. The entry will either provide the decoded symbol
+ * directly, or else a "real" Huffman binary tree will be searched to
+ * decode the symbol. */
+
+ lzms_input_bitstream_ensure_bits(is, LZMS_MAX_CODEWORD_LEN);
+
+ u16 key_bits = lzms_input_bitstream_peek_bits(is, LZMS_DECODE_TABLE_BITS);
+ u16 sym = decode_table[key_bits];
+
+ if (sym < dec->num_syms) {
+ /* Fast case: The decode table directly provided the symbol. */
+ lzms_input_bitstream_remove_bits(is, lens[sym]);
+ } else {
+ /* Slow case: The symbol took too many bits to include directly
+ * in the decode table, so search for it in a binary tree at the
+ * end of the decode table. */
+ lzms_input_bitstream_remove_bits(is, LZMS_DECODE_TABLE_BITS);
+ do {
+ key_bits = sym + lzms_input_bitstream_pop_bits(is, 1);
+ } while ((sym = decode_table[key_bits]) >= dec->num_syms);
+ }
+
+ /* Tally and return the decoded symbol. */
+ ++dec->sym_freqs[sym];
+ ++dec->num_syms_read;
+ return sym;
+}
+
+/* Decode a number from the LZMS bitstream, encoded as a Huffman-encoded symbol
+ * specifying a "slot" (whose corresponding value is looked up in a static
+ * table) plus the number specified by a number of extra bits depending on the
+ * slot. */
+static u32
+lzms_decode_value(struct lzms_huffman_decoder *dec)
+{
+ unsigned slot;
+ unsigned num_extra_bits;
+ u32 extra_bits;
+
+ /* Read the slot (position slot, length slot, etc.), which is encoded as
+ * a Huffman symbol. */
+ slot = lzms_decode_huffman_symbol(dec);
+
+ LZMS_ASSERT(dec->slot_base_tab != NULL);
+
+ /* Get the number of extra bits needed to represent the range of values
+ * that share the slot. */
+ num_extra_bits = bsr32(dec->slot_base_tab[slot + 1] -
+ dec->slot_base_tab[slot]);
+
+ /* Read the number of extra bits and add them to the slot to form the
+ * final decoded value. */
+ extra_bits = lzms_input_bitstream_read_bits(dec->is, num_extra_bits);
+ return dec->slot_base_tab[slot] + extra_bits;
+}
-typedef enum {
- COMPRESS_INFORMATION_CLASS_INVALID = 0,
- COMPRESS_INFORMATION_CLASS_LEVEL,
- COMPRESS_INFORMATION_CLASS_BLOCK_SIZE
-} COMPRESS_INFORMATION_CLASS;
+/* Copy a literal to the output buffer. */
+static int
+lzms_copy_literal(struct lzms_decompressor *ctx, u8 literal)
+{
+ *ctx->out_next++ = literal;
+ return 0;
+}
-#define COMPRESS_ALGORITHM_LZMS 0x00000005
-#define COMPRESS_RAW 0x20000000 /* Not documented */
+/* Validate a LZ match and copy it to the output buffer. */
+static int
+lzms_copy_lz_match(struct lzms_decompressor *ctx, u32 length, u32 offset)
+{
+ u8 *out_next;
+ u8 *matchptr;
-static HMODULE hCabinetDll;
-static pthread_mutex_t cabinetDllMutex = PTHREAD_MUTEX_INITIALIZER;
+ if (length > ctx->out_end - ctx->out_next) {
+ LZMS_DEBUG("Match overrun!");
+ return -1;
+ }
+ if (offset > ctx->out_next - ctx->out_begin) {
+ LZMS_DEBUG("Match underrun!");
+ return -1;
+ }
-static BOOL (WINAPI *CreateDecompressor)
- (DWORD Algorithm,
- PCOMPRESS_ALLOCATION_ROUTINES AllocationRoutines,
- PDECOMPRESSOR_HANDLE DecompressorHandle);
+ out_next = ctx->out_next;
+ matchptr = out_next - offset;
+ while (length--)
+ *out_next++ = *matchptr++;
-static BOOL (WINAPI *CloseDecompressor)
- (DECOMPRESSOR_HANDLE DecompressorHandle);
+ ctx->out_next = out_next;
+ return 0;
+}
-static BOOL (WINAPI *Decompress)
- (DECOMPRESSOR_HANDLE DecompressorHandle,
- PVOID CompressedData,
- SIZE_T CompressedDataSize,
- PVOID UncompressedBuffer,
- SIZE_T UncompressedBufferSize,
- PSIZE_T UncompressedDataSize);
+/* Validate a delta match and copy it to the output buffer. */
+static int
+lzms_copy_delta_match(struct lzms_decompressor *ctx, u32 length,
+ u32 power, u32 raw_offset)
+{
+ u32 offset1 = 1U << power;
+ u32 offset2 = raw_offset << power;
+ u32 offset = offset1 + offset2;
+ u8 *out_next;
+ u8 *matchptr1;
+ u8 *matchptr2;
+ u8 *matchptr;
-int
-lzms_decompress(const void *cbuf, unsigned clen, void *ubuf, unsigned ulen,
- unsigned window_size)
+ if (length > ctx->out_end - ctx->out_next) {
+ LZMS_DEBUG("Match overrun!");
+ return -1;
+ }
+ if (offset > ctx->out_next - ctx->out_begin) {
+ LZMS_DEBUG("Match underrun!");
+ return -1;
+ }
+
+ out_next = ctx->out_next;
+ matchptr1 = out_next - offset1;
+ matchptr2 = out_next - offset2;
+ matchptr = out_next - offset;
+
+ while (length--)
+ *out_next++ = *matchptr1++ + *matchptr2++ - *matchptr++;
+
+ ctx->out_next = out_next;
+ return 0;
+}
+
+/* Decode a (length, offset) pair from the input. */
+static int
+lzms_decode_lz_match(struct lzms_decompressor *ctx)
+{
+ int bit;
+ u32 length, offset;
+
+ /* Decode the match offset. The next range-encoded bit indicates
+ * whether it's a repeat offset or an explicit offset. */
+
+ bit = lzms_range_decode_bit(&ctx->lz_match_range_decoder);
+ if (bit == 0) {
+ /* Explicit offset. */
+ offset = lzms_decode_value(&ctx->lz_offset_decoder);
+ } else {
+ /* Repeat offset. */
+ int i;
+
+ for (i = 0; i < LZMS_NUM_RECENT_OFFSETS - 1; i++)
+ if (!lzms_range_decode_bit(&ctx->lz_repeat_match_range_decoders[i]))
+ break;
+
+ offset = ctx->recent_lz_offsets[i];
+
+ for (; i < LZMS_NUM_RECENT_OFFSETS; i++)
+ ctx->recent_lz_offsets[i] = ctx->recent_lz_offsets[i + 1];
+ }
+
+ /* Decode match length, which is always given explicitly (there is no
+ * LRU queue for repeat lengths). */
+ length = lzms_decode_value(&ctx->length_decoder);
+
+ ctx->upcoming_lz_offset = offset;
+
+ LZMS_DEBUG("Decoded %s LZ match: length=%u, offset=%u",
+ (bit ? "repeat" : "explicit"), length, offset);
+
+ /* Validate the match and copy it to the output. */
+ return lzms_copy_lz_match(ctx, length, offset);
+}
+
+/* Decodes a "delta" match from the input. */
+static int
+lzms_decode_delta_match(struct lzms_decompressor *ctx)
+{
+ int bit;
+ u32 length, power, raw_offset;
+
+ /* Decode the match power and raw offset. The next range-encoded bit
+ * indicates whether these data are a repeat, or given explicitly. */
+
+ bit = lzms_range_decode_bit(&ctx->delta_match_range_decoder);
+ if (bit == 0) {
+ power = lzms_decode_huffman_symbol(&ctx->delta_power_decoder);
+ raw_offset = lzms_decode_value(&ctx->delta_offset_decoder);
+ } else {
+ int i;
+
+ for (i = 0; i < LZMS_NUM_RECENT_OFFSETS - 1; i++)
+ if (!lzms_range_decode_bit(&ctx->delta_repeat_match_range_decoders[i]))
+ break;
+
+ power = ctx->recent_delta_powers[i];
+ raw_offset = ctx->recent_delta_offsets[i];
+
+ for (; i < LZMS_NUM_RECENT_OFFSETS; i++) {
+ ctx->recent_delta_powers[i] = ctx->recent_delta_powers[i + 1];
+ ctx->recent_delta_offsets[i] = ctx->recent_delta_offsets[i + 1];
+ }
+ }
+
+ length = lzms_decode_value(&ctx->length_decoder);
+
+ ctx->upcoming_delta_power = power;
+ ctx->upcoming_delta_offset = raw_offset;
+
+ LZMS_DEBUG("Decoded %s delta match: length=%u, power=%u, raw_offset=%u",
+ (bit ? "repeat" : "explicit"), length, power, raw_offset);
+
+ /* Validate the match and copy it to the output. */
+ return lzms_copy_delta_match(ctx, length, power, raw_offset);
+}
+
+static int
+lzms_decode_match(struct lzms_decompressor *ctx)
+{
+ if (!lzms_range_decode_bit(&ctx->match_range_decoder))
+ return lzms_decode_lz_match(ctx);
+ else
+ return lzms_decode_delta_match(ctx);
+}
+
+/* Decode a literal byte encoded using the literal Huffman code. */
+static int
+lzms_decode_literal(struct lzms_decompressor *ctx)
+{
+ u8 literal = lzms_decode_huffman_symbol(&ctx->literal_decoder);
+ LZMS_DEBUG("Decoded literal: 0x%02x", literal);
+ return lzms_copy_literal(ctx, literal);
+}
+
+/* Decode the next LZMS match or literal. */
+static int
+lzms_decode_item(struct lzms_decompressor *ctx)
{
int ret;
- DECOMPRESSOR_HANDLE h;
- ERROR("clen=%u, ulen=%u, window_size=%u", clen, ulen, window_size);
+ ctx->upcoming_delta_offset = 0;
+ ctx->upcoming_lz_offset = 0;
+ ctx->upcoming_delta_power = 0;
+
+ if (lzms_range_decode_bit(&ctx->main_range_decoder))
+ ret = lzms_decode_match(ctx);
+ else
+ ret = lzms_decode_literal(ctx);
+
+ if (ret)
+ return ret;
+
+ /* Update LRU queues */
+ if (ctx->prev_lz_offset != 0) {
+ for (int i = LZMS_NUM_RECENT_OFFSETS - 1; i >= 0; i--)
+ ctx->recent_lz_offsets[i + 1] = ctx->recent_lz_offsets[i];
+ ctx->recent_lz_offsets[0] = ctx->prev_lz_offset;
+
+ }
+
+ if (ctx->prev_delta_offset != 0) {
+ for (int i = LZMS_NUM_RECENT_OFFSETS - 1; i >= 0; i--) {
+ ctx->recent_delta_powers[i + 1] = ctx->recent_delta_powers[i];
+ ctx->recent_delta_offsets[i + 1] = ctx->recent_delta_offsets[i];
+ }
+ ctx->recent_delta_powers[0] = ctx->prev_delta_power;
+ ctx->recent_delta_offsets[0] = ctx->prev_delta_offset;
+ }
+
+ ctx->prev_lz_offset = ctx->upcoming_lz_offset;
+ ctx->prev_delta_offset = ctx->upcoming_delta_offset;
+ ctx->prev_delta_power = ctx->upcoming_delta_power;
+ return 0;
+}
+
+static void
+lzms_init_range_decoder(struct lzms_range_decoder *dec,
+ struct lzms_range_decoder_raw *rd, u32 num_states)
+{
+ dec->rd = rd;
+ dec->state = 0;
+ dec->mask = num_states - 1;
+ for (u32 i = 0; i < num_states; i++) {
+ dec->prob_entries[i].num_recent_zero_bits = LZMS_INITIAL_PROBABILITY;
+ dec->prob_entries[i].recent_bits = LZMS_INITIAL_RECENT_BITS;
+ }
+}
+
+static void
+lzms_init_huffman_decoder(struct lzms_huffman_decoder *dec,
+ struct lzms_input_bitstream *is,
+ const u32 *slot_base_tab, unsigned num_syms,
+ unsigned rebuild_freq)
+{
+ dec->is = is;
+ dec->slot_base_tab = slot_base_tab;
+ dec->num_syms = num_syms;
+ dec->num_syms_read = rebuild_freq;
+ dec->rebuild_freq = rebuild_freq;
+ for (unsigned i = 0; i < num_syms; i++)
+ dec->sym_freqs[i] = 1;
+}
+
+/* Prepare to decode items from a LZMS-compressed block. */
+static void
+lzms_init_decompressor(struct lzms_decompressor *ctx,
+ const void *cdata, unsigned clen,
+ void *ubuf, unsigned ulen)
+{
+ unsigned num_position_slots;
+
+ LZMS_DEBUG("Initializing decompressor (clen=%u, ulen=%u)", clen, ulen);
+
+ /* Initialize output pointers. */
+ ctx->out_begin = ubuf;
+ ctx->out_next = ubuf;
+ ctx->out_end = (u8*)ubuf + ulen;
+
+ /* Initialize the raw range decoder (reading forwards). */
+ lzms_range_decoder_raw_init(&ctx->rd, cdata, clen / 2);
+
+ /* Initialize the input bitstream for Huffman symbols (reading
+ * backwards) */
+ lzms_input_bitstream_init(&ctx->is, cdata, clen / 2);
+
+ /* Initialize position and length slot bases if not done already. */
+ lzms_init_slot_bases();
+
+ /* Like in other compression formats such as LZX and DEFLATE, match
+ * offsets in LZMS are represented as a position slot, which corresponds
+ * to a fixed lesser or equal match offset, followed by a
+ * position-slot-dependent number of extra bits that gives an additional
+ * offset from that position slot. Because the full number of position
+ * slots may exceed the length of the compressed block, here we
+ * calculate the number of position slots that will actually be used in
+ * the compressed representation. */
+ num_position_slots = lzms_get_position_slot_raw(ulen - 1) + 1;
- if (hCabinetDll == NULL) {
- pthread_mutex_lock(&cabinetDllMutex);
+ LZMS_DEBUG("Using %u position slots", num_position_slots);
- if (hCabinetDll == NULL) {
- hCabinetDll = LoadLibrary(L"Cabinet.dll");
+ /* Initialize Huffman decoders for each alphabet used in the compressed
+ * representation. */
+ lzms_init_huffman_decoder(&ctx->literal_decoder, &ctx->is,
+ NULL, LZMS_NUM_LITERAL_SYMS,
+ LZMS_LITERAL_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_decoder(&ctx->lz_offset_decoder, &ctx->is,
+ lzms_position_slot_base, num_position_slots,
+ LZMS_LZ_OFFSET_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_decoder(&ctx->length_decoder, &ctx->is,
+ lzms_length_slot_base, LZMS_NUM_LEN_SYMS,
+ LZMS_LENGTH_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_decoder(&ctx->delta_offset_decoder, &ctx->is,
+ lzms_position_slot_base, num_position_slots,
+ LZMS_DELTA_OFFSET_CODE_REBUILD_FREQ);
+
+ lzms_init_huffman_decoder(&ctx->delta_power_decoder, &ctx->is,
+ NULL, LZMS_NUM_DELTA_POWER_SYMS,
+ LZMS_DELTA_POWER_CODE_REBUILD_FREQ);
+
+
+ /* Initialize range decoders (all of which wrap around the same
+ * lzms_range_decoder_raw). */
+ lzms_init_range_decoder(&ctx->main_range_decoder,
+ &ctx->rd, LZMS_NUM_MAIN_STATES);
+
+ lzms_init_range_decoder(&ctx->match_range_decoder,
+ &ctx->rd, LZMS_NUM_MATCH_STATES);
+
+ lzms_init_range_decoder(&ctx->lz_match_range_decoder,
+ &ctx->rd, LZMS_NUM_LZ_MATCH_STATES);
+
+ for (size_t i = 0; i < ARRAY_LEN(ctx->lz_repeat_match_range_decoders); i++)
+ lzms_init_range_decoder(&ctx->lz_repeat_match_range_decoders[i],
+ &ctx->rd, LZMS_NUM_LZ_REPEAT_MATCH_STATES);
+
+ lzms_init_range_decoder(&ctx->delta_match_range_decoder,
+ &ctx->rd, LZMS_NUM_DELTA_MATCH_STATES);
+
+ for (size_t i = 0; i < ARRAY_LEN(ctx->delta_repeat_match_range_decoders); i++)
+ lzms_init_range_decoder(&ctx->delta_repeat_match_range_decoders[i],
+ &ctx->rd, LZMS_NUM_DELTA_REPEAT_MATCH_STATES);
+
+
+ /* Initialize the LRU queue for recent match offsets. */
+ for (size_t i = 0; i < LZMS_NUM_RECENT_OFFSETS + 1; i++)
+ ctx->recent_lz_offsets[i] = i + 1;
+
+ for (size_t i = 0; i < LZMS_NUM_RECENT_OFFSETS + 1; i++) {
+ ctx->recent_delta_powers[i] = 0;
+ ctx->recent_delta_offsets[i] = i + 1;
+ }
+ ctx->prev_lz_offset = 0;
+ ctx->prev_delta_offset = 0;
+ ctx->prev_delta_power = 0;
+ ctx->upcoming_lz_offset = 0;
+ ctx->upcoming_delta_offset = 0;
+ ctx->upcoming_delta_power = 0;
+
+ LZMS_DEBUG("Decompressor successfully initialized");
+}
+
+/* Decode the series of literals and matches from the LZMS-compressed data.
+ * Returns 0 on success; nonzero if the compressed data is invalid. */
+static int
+lzms_decode_items(const u8 *cdata, size_t clen, u8 *ubuf, size_t ulen)
+{
+ /* XXX: The context could be allocated on the heap. */
+ struct lzms_decompressor ctx;
- if (hCabinetDll == NULL) {
- ERROR("Can't load Cabinet.dll");
- ret = -1;
- goto unlock;
+ /* Initialize the LZMS decompressor. */
+ lzms_init_decompressor(&ctx, cdata, clen, ubuf, ulen);
+
+ /* Decode the sequence of items. */
+ while (ctx.out_next != ctx.out_end) {
+ LZMS_DEBUG("Position %u", ctx.out_next - ctx.out_begin);
+ if (lzms_decode_item(&ctx))
+ return -1;
+ }
+ return 0;
+}
+
+static s32
+lzms_try_x86_translation(u8 *ubuf, s32 i, s32 num_op_bytes,
+ s32 *closest_target_usage_p, s32 last_target_usages[],
+ s32 max_trans_offset)
+{
+ u16 pos;
+
+ if (i - *closest_target_usage_p <= max_trans_offset) {
+ LZMS_DEBUG("Performed x86 translation at position %d "
+ "(opcode 0x%02x)", i, ubuf[i]);
+ le32 *p32 = (le32*)&ubuf[i + num_op_bytes];
+ u32 n = le32_to_cpu(*p32);
+ *p32 = cpu_to_le32(n - i);
+ }
+
+ pos = i + le16_to_cpu(*(const le16*)&ubuf[i + num_op_bytes]);
+
+ i += num_op_bytes + sizeof(le32) - 1;
+
+ if (i - last_target_usages[pos] <= LZMS_X86_MAX_GOOD_TARGET_OFFSET)
+ *closest_target_usage_p = i;
+
+ last_target_usages[pos] = i;
+
+ return i + 1;
+}
+
+static s32
+lzms_process_x86_translation(u8 *ubuf, s32 i, s32 *closest_target_usage_p,
+ s32 last_target_usages[])
+{
+ /* Switch on first byte of the opcode, assuming it is really an x86
+ * instruction. */
+ switch (ubuf[i]) {
+ case 0x48:
+ if (ubuf[i + 1] == 0x8b) {
+ if (ubuf[i + 2] == 0x5 || ubuf[i + 2] == 0xd) {
+ /* Load relative (x86_64) */
+ return lzms_try_x86_translation(ubuf, i, 3,
+ closest_target_usage_p,
+ last_target_usages,
+ LZMS_X86_MAX_TRANSLATION_OFFSET);
}
+ } else if (ubuf[i + 1] == 0x8d) {
+ if ((ubuf[i + 2] & 0x7) == 0x5) {
+ /* Load effective address relative (x86_64) */
+ return lzms_try_x86_translation(ubuf, i, 3,
+ closest_target_usage_p,
+ last_target_usages,
+ LZMS_X86_MAX_TRANSLATION_OFFSET);
+ }
+ }
+ break;
- CreateDecompressor = (void*)GetProcAddress(hCabinetDll, "CreateDecompressor");
- Decompress = (void*)GetProcAddress(hCabinetDll, "Decompress");
- CloseDecompressor = (void*)GetProcAddress(hCabinetDll, "CloseDecompressor");
-
- if (CreateDecompressor == NULL ||
- Decompress == NULL ||
- CloseDecompressor == NULL)
- {
- ERROR("Can't find LZMS compression routines in Cabinet.dll");
- ret = -1;
- goto unlock;
+ case 0x4c:
+ if (ubuf[i + 1] == 0x8d) {
+ if ((ubuf[i + 2] & 0x7) == 0x5) {
+ /* Load effective address relative (x86_64) */
+ return lzms_try_x86_translation(ubuf, i, 3,
+ closest_target_usage_p,
+ last_target_usages,
+ LZMS_X86_MAX_TRANSLATION_OFFSET);
}
}
- ret = 0;
- unlock:
- pthread_mutex_unlock(&cabinetDllMutex);
- if (ret)
- goto out;
+ break;
+
+ case 0xe8:
+ /* Call relative */
+ return lzms_try_x86_translation(ubuf, i, 1, closest_target_usage_p,
+ last_target_usages,
+ LZMS_X86_MAX_TRANSLATION_OFFSET / 2);
+
+ case 0xe9:
+ /* Jump relative */
+ return i + 5;
+
+ case 0xf0:
+ if (ubuf[i + 1] == 0x83 && ubuf[i + 2] == 0x05) {
+ /* Lock add relative */
+ return lzms_try_x86_translation(ubuf, i, 3,
+ closest_target_usage_p,
+ last_target_usages,
+ LZMS_X86_MAX_TRANSLATION_OFFSET);
+ }
+ break;
+
+ case 0xff:
+ if (ubuf[i + 1] == 0x15) {
+ /* Call indirect */
+ return lzms_try_x86_translation(ubuf, i, 2,
+ closest_target_usage_p,
+ last_target_usages,
+ LZMS_X86_MAX_TRANSLATION_OFFSET);
+ }
+ break;
+ }
+ return i + 1;
+}
+
+/* Postprocess the uncompressed data by undoing the translation of relative
+ * addresses embedded in x86 instructions into absolute addresses.
+ *
+ * There does not appear to be any way to check to see if this postprocessing
+ * actually needs to be done (or to plug in alternate filters, like in LZMA),
+ * and the corresponding preprocessing seems to be done unconditionally. */
+static void
+lzms_postprocess_data(u8 *ubuf, s32 ulen)
+{
+ /* Offset (from beginning of buffer) of the most recent reference to a
+ * seemingly valid target address. */
+ s32 closest_target_usage = -LZMS_X86_MAX_TRANSLATION_OFFSET - 1;
+
+ /* Offset (from beginning of buffer) of the most recently used target
+ * address beginning with two bytes equal to the array index.
+ *
+ * XXX: This array could be allocated on the heap. */
+ s32 last_target_usages[65536];
+ for (s32 i = 0; i < 65536; i++)
+ last_target_usages[i] = -LZMS_X86_MAX_GOOD_TARGET_OFFSET - 1;
+
+ /* Check each byte in the buffer for an x86 opcode for which a
+ * translation may be possible. No translations are done on any
+ * instructions starting in the last 11 bytes of the buffer. */
+ for (s32 i = 0; i < ulen - 11; )
+ i = lzms_process_x86_translation(ubuf, i, &closest_target_usage,
+ last_target_usages);
+}
+
+/* API function documented in wimlib.h */
+WIMLIBAPI int
+wimlib_lzms_decompress(const void *cdata, unsigned clen,
+ void *ubuf, unsigned ulen)
+{
+ /* The range decoder requires that a minimum of 4 bytes of compressed
+ * data be initially available. */
+ if (clen < 4) {
+ LZMS_DEBUG("Compressed length too small (got %u, expected >= 4)",
+ clen);
+ return -1;
}
+ /* A LZMS-compressed data block should be evenly divisible into 16-bit
+ * integers. */
+ if (clen % 2 != 0) {
+ LZMS_DEBUG("Compressed length not divisible by 2 (got %u)", clen);
+ return -1;
+ }
+
+ /* Handle the trivial case where nothing needs to be decompressed.
+ * (Necessary because a window of size 0 does not have a valid position
+ * slot.) */
+ if (ulen == 0)
+ return 0;
- if (!CreateDecompressor(COMPRESS_ALGORITHM_LZMS | COMPRESS_RAW, NULL, &h)) {
- ERROR("Failed to create LZMS decompressor (err %d)!", GetLastError());
- ret = -1;
- goto out;
+ /* The x86 post-processor requires that the uncompressed length fit into
+ * a signed 32-bit integer. Also, the position slot table cannot be
+ * searched for a position of INT32_MAX or greater. */
+ if (ulen >= INT32_MAX) {
+ LZMS_DEBUG("Uncompressed length too large "
+ "(got %u, expected < INT32_MAX)", ulen);
+ return -1;
}
+ /* Decode the literals and matches. */
+ if (lzms_decode_items(cdata, clen, ubuf, ulen))
+ return -1;
- /* TODO: Some sort of chunk header? */
- unsigned offset;
- if (clen <= window_size) {
- offset = 0;
- } else {
- const unsigned *p = cbuf;
- ERROR("%08x(%u) %08x %08x %08x %08x(%u)",
- p[0], p[0], p[1], p[2], p[3], p[4], p[4]);
- offset = 20;
- }
- SIZE_T actual_ulen = -1;
- if (!Decompress(h, (void*)cbuf + offset, clen - offset, ubuf, ulen, &actual_ulen)) {
- ERROR("Failed to decompress LZMS-compressed data (err %d)!", GetLastError());
- ret = -1;
- goto out_close_decompressor;
- }
-
- if (actual_ulen != ulen) {
- ERROR("Unexpected actual uncompressed length (got %u, expected %u)",
- actual_ulen, ulen);
- ret = -1;
- goto out_close_decompressor;
- }
-
- ERROR("Successfully decompressed data.");
- ret = 0;
-out_close_decompressor:
- CloseDecompressor(h);
-out:
- return ret;
+ /* Postprocess the data. */
+ lzms_postprocess_data(ubuf, ulen);
+
+ LZMS_DEBUG("Decompression successful.");
+ return 0;
}
git://wimlib.net / wimlib / blobdiff