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-rw-r--r--fs/ntfs3/lib/lzx_decompress.c670
1 files changed, 670 insertions, 0 deletions
diff --git a/fs/ntfs3/lib/lzx_decompress.c b/fs/ntfs3/lib/lzx_decompress.c
new file mode 100644
index 000000000..6b16f0707
--- /dev/null
+++ b/fs/ntfs3/lib/lzx_decompress.c
@@ -0,0 +1,670 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * lzx_decompress.c - A decompressor for the LZX compression format, which can
+ * be used in "System Compressed" files. This is based on the code from wimlib.
+ * This code only supports a window size (dictionary size) of 32768 bytes, since
+ * this is the only size used in System Compression.
+ *
+ * Copyright (C) 2015 Eric Biggers
+ */
+
+#include "decompress_common.h"
+#include "lib.h"
+
+/* Number of literal byte values */
+#define LZX_NUM_CHARS 256
+
+/* The smallest and largest allowed match lengths */
+#define LZX_MIN_MATCH_LEN 2
+#define LZX_MAX_MATCH_LEN 257
+
+/* Number of distinct match lengths that can be represented */
+#define LZX_NUM_LENS (LZX_MAX_MATCH_LEN - LZX_MIN_MATCH_LEN + 1)
+
+/* Number of match lengths for which no length symbol is required */
+#define LZX_NUM_PRIMARY_LENS 7
+#define LZX_NUM_LEN_HEADERS (LZX_NUM_PRIMARY_LENS + 1)
+
+/* Valid values of the 3-bit block type field */
+#define LZX_BLOCKTYPE_VERBATIM 1
+#define LZX_BLOCKTYPE_ALIGNED 2
+#define LZX_BLOCKTYPE_UNCOMPRESSED 3
+
+/* Number of offset slots for a window size of 32768 */
+#define LZX_NUM_OFFSET_SLOTS 30
+
+/* Number of symbols in the main code for a window size of 32768 */
+#define LZX_MAINCODE_NUM_SYMBOLS \
+ (LZX_NUM_CHARS + (LZX_NUM_OFFSET_SLOTS * LZX_NUM_LEN_HEADERS))
+
+/* Number of symbols in the length code */
+#define LZX_LENCODE_NUM_SYMBOLS (LZX_NUM_LENS - LZX_NUM_PRIMARY_LENS)
+
+/* Number of symbols in the precode */
+#define LZX_PRECODE_NUM_SYMBOLS 20
+
+/* Number of bits in which each precode codeword length is represented */
+#define LZX_PRECODE_ELEMENT_SIZE 4
+
+/* Number of low-order bits of each match offset that are entropy-encoded in
+ * aligned offset blocks
+ */
+#define LZX_NUM_ALIGNED_OFFSET_BITS 3
+
+/* Number of symbols in the aligned offset code */
+#define LZX_ALIGNEDCODE_NUM_SYMBOLS (1 << LZX_NUM_ALIGNED_OFFSET_BITS)
+
+/* Mask for the match offset bits that are entropy-encoded in aligned offset
+ * blocks
+ */
+#define LZX_ALIGNED_OFFSET_BITMASK ((1 << LZX_NUM_ALIGNED_OFFSET_BITS) - 1)
+
+/* Number of bits in which each aligned offset codeword length is represented */
+#define LZX_ALIGNEDCODE_ELEMENT_SIZE 3
+
+/* Maximum lengths (in bits) of the codewords in each Huffman code */
+#define LZX_MAX_MAIN_CODEWORD_LEN 16
+#define LZX_MAX_LEN_CODEWORD_LEN 16
+#define LZX_MAX_PRE_CODEWORD_LEN ((1 << LZX_PRECODE_ELEMENT_SIZE) - 1)
+#define LZX_MAX_ALIGNED_CODEWORD_LEN ((1 << LZX_ALIGNEDCODE_ELEMENT_SIZE) - 1)
+
+/* The default "filesize" value used in pre/post-processing. In the LZX format
+ * used in cabinet files this value must be given to the decompressor, whereas
+ * in the LZX format used in WIM files and system-compressed files this value is
+ * fixed at 12000000.
+ */
+#define LZX_DEFAULT_FILESIZE 12000000
+
+/* Assumed block size when the encoded block size begins with a 0 bit. */
+#define LZX_DEFAULT_BLOCK_SIZE 32768
+
+/* Number of offsets in the recent (or "repeat") offsets queue. */
+#define LZX_NUM_RECENT_OFFSETS 3
+
+/* These values are chosen for fast decompression. */
+#define LZX_MAINCODE_TABLEBITS 11
+#define LZX_LENCODE_TABLEBITS 10
+#define LZX_PRECODE_TABLEBITS 6
+#define LZX_ALIGNEDCODE_TABLEBITS 7
+
+#define LZX_READ_LENS_MAX_OVERRUN 50
+
+/* Mapping: offset slot => first match offset that uses that offset slot.
+ */
+static const u32 lzx_offset_slot_base[LZX_NUM_OFFSET_SLOTS + 1] = {
+ 0, 1, 2, 3, 4, /* 0 --- 4 */
+ 6, 8, 12, 16, 24, /* 5 --- 9 */
+ 32, 48, 64, 96, 128, /* 10 --- 14 */
+ 192, 256, 384, 512, 768, /* 15 --- 19 */
+ 1024, 1536, 2048, 3072, 4096, /* 20 --- 24 */
+ 6144, 8192, 12288, 16384, 24576, /* 25 --- 29 */
+ 32768, /* extra */
+};
+
+/* Mapping: offset slot => how many extra bits must be read and added to the
+ * corresponding offset slot base to decode the match offset.
+ */
+static const u8 lzx_extra_offset_bits[LZX_NUM_OFFSET_SLOTS] = {
+ 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,
+};
+
+/* Reusable heap-allocated memory for LZX decompression */
+struct lzx_decompressor {
+
+ /* Huffman decoding tables, and arrays that map symbols to codeword
+ * lengths
+ */
+
+ u16 maincode_decode_table[(1 << LZX_MAINCODE_TABLEBITS) +
+ (LZX_MAINCODE_NUM_SYMBOLS * 2)];
+ u8 maincode_lens[LZX_MAINCODE_NUM_SYMBOLS + LZX_READ_LENS_MAX_OVERRUN];
+
+
+ u16 lencode_decode_table[(1 << LZX_LENCODE_TABLEBITS) +
+ (LZX_LENCODE_NUM_SYMBOLS * 2)];
+ u8 lencode_lens[LZX_LENCODE_NUM_SYMBOLS + LZX_READ_LENS_MAX_OVERRUN];
+
+
+ u16 alignedcode_decode_table[(1 << LZX_ALIGNEDCODE_TABLEBITS) +
+ (LZX_ALIGNEDCODE_NUM_SYMBOLS * 2)];
+ u8 alignedcode_lens[LZX_ALIGNEDCODE_NUM_SYMBOLS];
+
+ u16 precode_decode_table[(1 << LZX_PRECODE_TABLEBITS) +
+ (LZX_PRECODE_NUM_SYMBOLS * 2)];
+ u8 precode_lens[LZX_PRECODE_NUM_SYMBOLS];
+
+ /* Temporary space for make_huffman_decode_table() */
+ u16 working_space[2 * (1 + LZX_MAX_MAIN_CODEWORD_LEN) +
+ LZX_MAINCODE_NUM_SYMBOLS];
+};
+
+static void undo_e8_translation(void *target, s32 input_pos)
+{
+ s32 abs_offset, rel_offset;
+
+ abs_offset = get_unaligned_le32(target);
+ if (abs_offset >= 0) {
+ if (abs_offset < LZX_DEFAULT_FILESIZE) {
+ /* "good translation" */
+ rel_offset = abs_offset - input_pos;
+ put_unaligned_le32(rel_offset, target);
+ }
+ } else {
+ if (abs_offset >= -input_pos) {
+ /* "compensating translation" */
+ rel_offset = abs_offset + LZX_DEFAULT_FILESIZE;
+ put_unaligned_le32(rel_offset, target);
+ }
+ }
+}
+
+/*
+ * Undo the 'E8' preprocessing used in LZX. Before compression, the
+ * uncompressed data was preprocessed by changing the targets of suspected x86
+ * CALL instructions from relative offsets to absolute offsets. After
+ * match/literal decoding, the decompressor must undo the translation.
+ */
+static void lzx_postprocess(u8 *data, u32 size)
+{
+ /*
+ * A worthwhile optimization is to push the end-of-buffer check into the
+ * relatively rare E8 case. This is possible if we replace the last six
+ * bytes of data with E8 bytes; then we are guaranteed to hit an E8 byte
+ * before reaching end-of-buffer. In addition, this scheme guarantees
+ * that no translation can begin following an E8 byte in the last 10
+ * bytes because a 4-byte offset containing E8 as its high byte is a
+ * large negative number that is not valid for translation. That is
+ * exactly what we need.
+ */
+ u8 *tail;
+ u8 saved_bytes[6];
+ u8 *p;
+
+ if (size <= 10)
+ return;
+
+ tail = &data[size - 6];
+ memcpy(saved_bytes, tail, 6);
+ memset(tail, 0xE8, 6);
+ p = data;
+ for (;;) {
+ while (*p != 0xE8)
+ p++;
+ if (p >= tail)
+ break;
+ undo_e8_translation(p + 1, p - data);
+ p += 5;
+ }
+ memcpy(tail, saved_bytes, 6);
+}
+
+/* Read a Huffman-encoded symbol using the precode. */
+static forceinline u32 read_presym(const struct lzx_decompressor *d,
+ struct input_bitstream *is)
+{
+ return read_huffsym(is, d->precode_decode_table,
+ LZX_PRECODE_TABLEBITS, LZX_MAX_PRE_CODEWORD_LEN);
+}
+
+/* Read a Huffman-encoded symbol using the main code. */
+static forceinline u32 read_mainsym(const struct lzx_decompressor *d,
+ struct input_bitstream *is)
+{
+ return read_huffsym(is, d->maincode_decode_table,
+ LZX_MAINCODE_TABLEBITS, LZX_MAX_MAIN_CODEWORD_LEN);
+}
+
+/* Read a Huffman-encoded symbol using the length code. */
+static forceinline u32 read_lensym(const struct lzx_decompressor *d,
+ struct input_bitstream *is)
+{
+ return read_huffsym(is, d->lencode_decode_table,
+ LZX_LENCODE_TABLEBITS, LZX_MAX_LEN_CODEWORD_LEN);
+}
+
+/* Read a Huffman-encoded symbol using the aligned offset code. */
+static forceinline u32 read_alignedsym(const struct lzx_decompressor *d,
+ struct input_bitstream *is)
+{
+ return read_huffsym(is, d->alignedcode_decode_table,
+ LZX_ALIGNEDCODE_TABLEBITS,
+ LZX_MAX_ALIGNED_CODEWORD_LEN);
+}
+
+/*
+ * Read the precode from the compressed input bitstream, then use it to decode
+ * @num_lens codeword length values.
+ *
+ * @is: The input bitstream.
+ *
+ * @lens: An array that contains the length values from the previous time
+ * the codeword lengths for this Huffman code were read, or all 0's
+ * if this is the first time. This array must have at least
+ * (@num_lens + LZX_READ_LENS_MAX_OVERRUN) entries.
+ *
+ * @num_lens: Number of length values to decode.
+ *
+ * Returns 0 on success, or -1 if the data was invalid.
+ */
+static int lzx_read_codeword_lens(struct lzx_decompressor *d,
+ struct input_bitstream *is,
+ u8 *lens, u32 num_lens)
+{
+ u8 *len_ptr = lens;
+ u8 *lens_end = lens + num_lens;
+ int i;
+
+ /* Read the lengths of the precode codewords. These are given
+ * explicitly.
+ */
+ for (i = 0; i < LZX_PRECODE_NUM_SYMBOLS; i++) {
+ d->precode_lens[i] =
+ bitstream_read_bits(is, LZX_PRECODE_ELEMENT_SIZE);
+ }
+
+ /* Make the decoding table for the precode. */
+ if (make_huffman_decode_table(d->precode_decode_table,
+ LZX_PRECODE_NUM_SYMBOLS,
+ LZX_PRECODE_TABLEBITS,
+ d->precode_lens,
+ LZX_MAX_PRE_CODEWORD_LEN,
+ d->working_space))
+ return -1;
+
+ /* Decode the codeword lengths. */
+ do {
+ u32 presym;
+ u8 len;
+
+ /* Read the next precode symbol. */
+ presym = read_presym(d, is);
+ if (presym < 17) {
+ /* Difference from old length */
+ len = *len_ptr - presym;
+ if ((s8)len < 0)
+ len += 17;
+ *len_ptr++ = len;
+ } else {
+ /* Special RLE values */
+
+ u32 run_len;
+
+ if (presym == 17) {
+ /* Run of 0's */
+ run_len = 4 + bitstream_read_bits(is, 4);
+ len = 0;
+ } else if (presym == 18) {
+ /* Longer run of 0's */
+ run_len = 20 + bitstream_read_bits(is, 5);
+ len = 0;
+ } else {
+ /* Run of identical lengths */
+ run_len = 4 + bitstream_read_bits(is, 1);
+ presym = read_presym(d, is);
+ if (presym > 17)
+ return -1;
+ len = *len_ptr - presym;
+ if ((s8)len < 0)
+ len += 17;
+ }
+
+ do {
+ *len_ptr++ = len;
+ } while (--run_len);
+ /* Worst case overrun is when presym == 18,
+ * run_len == 20 + 31, and only 1 length was remaining.
+ * So LZX_READ_LENS_MAX_OVERRUN == 50.
+ *
+ * Overrun while reading the first half of maincode_lens
+ * can corrupt the previous values in the second half.
+ * This doesn't really matter because the resulting
+ * lengths will still be in range, and data that
+ * generates overruns is invalid anyway.
+ */
+ }
+ } while (len_ptr < lens_end);
+
+ return 0;
+}
+
+/*
+ * Read the header of an LZX block and save the block type and (uncompressed)
+ * size in *block_type_ret and *block_size_ret, respectively.
+ *
+ * If the block is compressed, also update the Huffman decode @tables with the
+ * new Huffman codes. If the block is uncompressed, also update the match
+ * offset @queue with the new match offsets.
+ *
+ * Return 0 on success, or -1 if the data was invalid.
+ */
+static int lzx_read_block_header(struct lzx_decompressor *d,
+ struct input_bitstream *is,
+ int *block_type_ret,
+ u32 *block_size_ret,
+ u32 recent_offsets[])
+{
+ int block_type;
+ u32 block_size;
+ int i;
+
+ bitstream_ensure_bits(is, 4);
+
+ /* The first three bits tell us what kind of block it is, and should be
+ * one of the LZX_BLOCKTYPE_* values.
+ */
+ block_type = bitstream_pop_bits(is, 3);
+
+ /* Read the block size. */
+ if (bitstream_pop_bits(is, 1)) {
+ block_size = LZX_DEFAULT_BLOCK_SIZE;
+ } else {
+ block_size = 0;
+ block_size |= bitstream_read_bits(is, 8);
+ block_size <<= 8;
+ block_size |= bitstream_read_bits(is, 8);
+ }
+
+ switch (block_type) {
+
+ case LZX_BLOCKTYPE_ALIGNED:
+
+ /* Read the aligned offset code and prepare its decode table.
+ */
+
+ for (i = 0; i < LZX_ALIGNEDCODE_NUM_SYMBOLS; i++) {
+ d->alignedcode_lens[i] =
+ bitstream_read_bits(is,
+ LZX_ALIGNEDCODE_ELEMENT_SIZE);
+ }
+
+ if (make_huffman_decode_table(d->alignedcode_decode_table,
+ LZX_ALIGNEDCODE_NUM_SYMBOLS,
+ LZX_ALIGNEDCODE_TABLEBITS,
+ d->alignedcode_lens,
+ LZX_MAX_ALIGNED_CODEWORD_LEN,
+ d->working_space))
+ return -1;
+
+ /* Fall though, since the rest of the header for aligned offset
+ * blocks is the same as that for verbatim blocks.
+ */
+ fallthrough;
+
+ case LZX_BLOCKTYPE_VERBATIM:
+
+ /* Read the main code and prepare its decode table.
+ *
+ * Note that the codeword lengths in the main code are encoded
+ * in two parts: one part for literal symbols, and one part for
+ * match symbols.
+ */
+
+ if (lzx_read_codeword_lens(d, is, d->maincode_lens,
+ LZX_NUM_CHARS))
+ return -1;
+
+ if (lzx_read_codeword_lens(d, is,
+ d->maincode_lens + LZX_NUM_CHARS,
+ LZX_MAINCODE_NUM_SYMBOLS - LZX_NUM_CHARS))
+ return -1;
+
+ if (make_huffman_decode_table(d->maincode_decode_table,
+ LZX_MAINCODE_NUM_SYMBOLS,
+ LZX_MAINCODE_TABLEBITS,
+ d->maincode_lens,
+ LZX_MAX_MAIN_CODEWORD_LEN,
+ d->working_space))
+ return -1;
+
+ /* Read the length code and prepare its decode table. */
+
+ if (lzx_read_codeword_lens(d, is, d->lencode_lens,
+ LZX_LENCODE_NUM_SYMBOLS))
+ return -1;
+
+ if (make_huffman_decode_table(d->lencode_decode_table,
+ LZX_LENCODE_NUM_SYMBOLS,
+ LZX_LENCODE_TABLEBITS,
+ d->lencode_lens,
+ LZX_MAX_LEN_CODEWORD_LEN,
+ d->working_space))
+ return -1;
+
+ break;
+
+ case LZX_BLOCKTYPE_UNCOMPRESSED:
+
+ /* Before reading the three recent offsets from the uncompressed
+ * block header, the stream must be aligned on a 16-bit
+ * boundary. But if the stream is *already* aligned, then the
+ * next 16 bits must be discarded.
+ */
+ bitstream_ensure_bits(is, 1);
+ bitstream_align(is);
+
+ recent_offsets[0] = bitstream_read_u32(is);
+ recent_offsets[1] = bitstream_read_u32(is);
+ recent_offsets[2] = bitstream_read_u32(is);
+
+ /* Offsets of 0 are invalid. */
+ if (recent_offsets[0] == 0 || recent_offsets[1] == 0 ||
+ recent_offsets[2] == 0)
+ return -1;
+ break;
+
+ default:
+ /* Unrecognized block type. */
+ return -1;
+ }
+
+ *block_type_ret = block_type;
+ *block_size_ret = block_size;
+ return 0;
+}
+
+/* Decompress a block of LZX-compressed data. */
+static int lzx_decompress_block(const struct lzx_decompressor *d,
+ struct input_bitstream *is,
+ int block_type, u32 block_size,
+ u8 * const out_begin, u8 *out_next,
+ u32 recent_offsets[])
+{
+ u8 * const block_end = out_next + block_size;
+ u32 ones_if_aligned = 0U - (block_type == LZX_BLOCKTYPE_ALIGNED);
+
+ do {
+ u32 mainsym;
+ u32 match_len;
+ u32 match_offset;
+ u32 offset_slot;
+ u32 num_extra_bits;
+
+ mainsym = read_mainsym(d, is);
+ if (mainsym < LZX_NUM_CHARS) {
+ /* Literal */
+ *out_next++ = mainsym;
+ continue;
+ }
+
+ /* Match */
+
+ /* Decode the length header and offset slot. */
+ mainsym -= LZX_NUM_CHARS;
+ match_len = mainsym % LZX_NUM_LEN_HEADERS;
+ offset_slot = mainsym / LZX_NUM_LEN_HEADERS;
+
+ /* If needed, read a length symbol to decode the full length. */
+ if (match_len == LZX_NUM_PRIMARY_LENS)
+ match_len += read_lensym(d, is);
+ match_len += LZX_MIN_MATCH_LEN;
+
+ if (offset_slot < LZX_NUM_RECENT_OFFSETS) {
+ /* Repeat offset */
+
+ /* Note: This isn't a real LRU queue, since using the R2
+ * offset doesn't bump the R1 offset down to R2. This
+ * quirk allows all 3 recent offsets to be handled by
+ * the same code. (For R0, the swap is a no-op.)
+ */
+ match_offset = recent_offsets[offset_slot];
+ recent_offsets[offset_slot] = recent_offsets[0];
+ recent_offsets[0] = match_offset;
+ } else {
+ /* Explicit offset */
+
+ /* Look up the number of extra bits that need to be read
+ * to decode offsets with this offset slot.
+ */
+ num_extra_bits = lzx_extra_offset_bits[offset_slot];
+
+ /* Start with the offset slot base value. */
+ match_offset = lzx_offset_slot_base[offset_slot];
+
+ /* In aligned offset blocks, the low-order 3 bits of
+ * each offset are encoded using the aligned offset
+ * code. Otherwise, all the extra bits are literal.
+ */
+
+ if ((num_extra_bits & ones_if_aligned) >= LZX_NUM_ALIGNED_OFFSET_BITS) {
+ match_offset +=
+ bitstream_read_bits(is, num_extra_bits -
+ LZX_NUM_ALIGNED_OFFSET_BITS)
+ << LZX_NUM_ALIGNED_OFFSET_BITS;
+ match_offset += read_alignedsym(d, is);
+ } else {
+ match_offset += bitstream_read_bits(is, num_extra_bits);
+ }
+
+ /* Adjust the offset. */
+ match_offset -= (LZX_NUM_RECENT_OFFSETS - 1);
+
+ /* Update the recent offsets. */
+ recent_offsets[2] = recent_offsets[1];
+ recent_offsets[1] = recent_offsets[0];
+ recent_offsets[0] = match_offset;
+ }
+
+ /* Validate the match, then copy it to the current position. */
+
+ if (match_len > (size_t)(block_end - out_next))
+ return -1;
+
+ if (match_offset > (size_t)(out_next - out_begin))
+ return -1;
+
+ out_next = lz_copy(out_next, match_len, match_offset,
+ block_end, LZX_MIN_MATCH_LEN);
+
+ } while (out_next != block_end);
+
+ return 0;
+}
+
+/*
+ * lzx_allocate_decompressor - Allocate an LZX decompressor
+ *
+ * Return the pointer to the decompressor on success, or return NULL and set
+ * errno on failure.
+ */
+struct lzx_decompressor *lzx_allocate_decompressor(void)
+{
+ return kmalloc(sizeof(struct lzx_decompressor), GFP_NOFS);
+}
+
+/*
+ * lzx_decompress - Decompress a buffer of LZX-compressed data
+ *
+ * @decompressor: A decompressor allocated with lzx_allocate_decompressor()
+ * @compressed_data: The buffer of data to decompress
+ * @compressed_size: Number of bytes of compressed data
+ * @uncompressed_data: The buffer in which to store the decompressed data
+ * @uncompressed_size: The number of bytes the data decompresses into
+ *
+ * Return 0 on success, or return -1 and set errno on failure.
+ */
+int lzx_decompress(struct lzx_decompressor *decompressor,
+ const void *compressed_data, size_t compressed_size,
+ void *uncompressed_data, size_t uncompressed_size)
+{
+ struct lzx_decompressor *d = decompressor;
+ u8 * const out_begin = uncompressed_data;
+ u8 *out_next = out_begin;
+ u8 * const out_end = out_begin + uncompressed_size;
+ struct input_bitstream is;
+ u32 recent_offsets[LZX_NUM_RECENT_OFFSETS] = {1, 1, 1};
+ int e8_status = 0;
+
+ init_input_bitstream(&is, compressed_data, compressed_size);
+
+ /* Codeword lengths begin as all 0's for delta encoding purposes. */
+ memset(d->maincode_lens, 0, LZX_MAINCODE_NUM_SYMBOLS);
+ memset(d->lencode_lens, 0, LZX_LENCODE_NUM_SYMBOLS);
+
+ /* Decompress blocks until we have all the uncompressed data. */
+
+ while (out_next != out_end) {
+ int block_type;
+ u32 block_size;
+
+ if (lzx_read_block_header(d, &is, &block_type, &block_size,
+ recent_offsets))
+ goto invalid;
+
+ if (block_size < 1 || block_size > (size_t)(out_end - out_next))
+ goto invalid;
+
+ if (block_type != LZX_BLOCKTYPE_UNCOMPRESSED) {
+
+ /* Compressed block */
+
+ if (lzx_decompress_block(d,
+ &is,
+ block_type,
+ block_size,
+ out_begin,
+ out_next,
+ recent_offsets))
+ goto invalid;
+
+ e8_status |= d->maincode_lens[0xe8];
+ out_next += block_size;
+ } else {
+ /* Uncompressed block */
+
+ out_next = bitstream_read_bytes(&is, out_next,
+ block_size);
+ if (!out_next)
+ goto invalid;
+
+ if (block_size & 1)
+ bitstream_read_byte(&is);
+
+ e8_status = 1;
+ }
+ }
+
+ /* Postprocess the data unless it cannot possibly contain 0xe8 bytes. */
+ if (e8_status)
+ lzx_postprocess(uncompressed_data, uncompressed_size);
+
+ return 0;
+
+invalid:
+ return -1;
+}
+
+/*
+ * lzx_free_decompressor - Free an LZX decompressor
+ *
+ * @decompressor: A decompressor that was allocated with
+ * lzx_allocate_decompressor(), or NULL.
+ */
+void lzx_free_decompressor(struct lzx_decompressor *decompressor)
+{
+ kfree(decompressor);
+}