// SPDX-License-Identifier: 0BSD
/*
* LZMA2 decoder
*
* Authors: Lasse Collin <[email protected]>
* Igor Pavlov <https://7-zip.org/>
*/
#include "xz_private.h"
#include "xz_lzma2.h"
/*
* Range decoder initialization eats the first five bytes of each LZMA chunk.
*/
#define RC_INIT_BYTES 5
/*
* Minimum number of usable input buffer to safely decode one LZMA symbol.
* The worst case is that we decode 22 bits using probabilities and 26
* direct bits. This may decode at maximum of 20 bytes of input. However,
* lzma_main() does an extra normalization before returning, thus we
* need to put 21 here.
*/
#define LZMA_IN_REQUIRED 21
/*
* Dictionary (history buffer)
*
* These are always true:
* start <= pos <= full <= end
* pos <= limit <= end
*
* In multi-call mode, also these are true:
* end == size
* size <= size_max
* allocated <= size
*
* Most of these variables are size_t to support single-call mode,
* in which the dictionary variables address the actual output
* buffer directly.
*/
struct dictionary {
/* Beginning of the history buffer */
uint8_t *buf;
/* Old position in buf (before decoding more data) */
size_t start;
/* Position in buf */
size_t pos;
/*
* How full dictionary is. This is used to detect corrupt input that
* would read beyond the beginning of the uncompressed stream.
*/
size_t full;
/* Write limit; we don't write to buf[limit] or later bytes. */
size_t limit;
/*
* End of the dictionary buffer. In multi-call mode, this is
* the same as the dictionary size. In single-call mode, this
* indicates the size of the output buffer.
*/
size_t end;
/*
* Size of the dictionary as specified in Block Header. This is used
* together with "full" to detect corrupt input that would make us
* read beyond the beginning of the uncompressed stream.
*/
uint32_t size;
/*
* Maximum allowed dictionary size in multi-call mode.
* This is ignored in single-call mode.
*/
uint32_t size_max;
/*
* Amount of memory currently allocated for the dictionary.
* This is used only with XZ_DYNALLOC. (With XZ_PREALLOC,
* size_max is always the same as the allocated size.)
*/
uint32_t allocated;
/* Operation mode */
enum xz_mode mode;
};
/* Range decoder */
struct rc_dec {
uint32_t range;
uint32_t code;
/*
* Number of initializing bytes remaining to be read
* by rc_read_init().
*/
uint32_t init_bytes_left;
/*
* Buffer from which we read our input. It can be either
* temp.buf or the caller-provided input buffer.
*/
const uint8_t *in;
size_t in_pos;
size_t in_limit;
};
/* Probabilities for a length decoder. */
struct lzma_len_dec {
/* Probability of match length being at least 10 */
uint16_t choice;
/* Probability of match length being at least 18 */
uint16_t choice2;
/* Probabilities for match lengths 2-9 */
uint16_t low[POS_STATES_MAX][LEN_LOW_SYMBOLS];
/* Probabilities for match lengths 10-17 */
uint16_t mid[POS_STATES_MAX][LEN_MID_SYMBOLS];
/* Probabilities for match lengths 18-273 */
uint16_t high[LEN_HIGH_SYMBOLS];
};
struct lzma_dec {
/* Distances of latest four matches */
uint32_t rep0;
uint32_t rep1;
uint32_t rep2;
uint32_t rep3;
/* Types of the most recently seen LZMA symbols */
enum lzma_state state;
/*
* Length of a match. This is updated so that dict_repeat can
* be called again to finish repeating the whole match.
*/
uint32_t len;
/*
* LZMA properties or related bit masks (number of literal
* context bits, a mask derived from the number of literal
* position bits, and a mask derived from the number
* position bits)
*/
uint32_t lc;
uint32_t literal_pos_mask; /* (1 << lp) - 1 */
uint32_t pos_mask; /* (1 << pb) - 1 */
/* If 1, it's a match. Otherwise it's a single 8-bit literal. */
uint16_t is_match[STATES][POS_STATES_MAX];
/* If 1, it's a repeated match. The distance is one of rep0 .. rep3. */
uint16_t is_rep[STATES];
/*
* If 0, distance of a repeated match is rep0.
* Otherwise check is_rep1.
*/
uint16_t is_rep0[STATES];
/*
* If 0, distance of a repeated match is rep1.
* Otherwise check is_rep2.
*/
uint16_t is_rep1[STATES];
/* If 0, distance of a repeated match is rep2. Otherwise it is rep3. */
uint16_t is_rep2[STATES];
/*
* If 1, the repeated match has length of one byte. Otherwise
* the length is decoded from rep_len_decoder.
*/
uint16_t is_rep0_long[STATES][POS_STATES_MAX];
/*
* Probability tree for the highest two bits of the match
* distance. There is a separate probability tree for match
* lengths of 2 (i.e. MATCH_LEN_MIN), 3, 4, and [5, 273].
*/
uint16_t dist_slot[DIST_STATES][DIST_SLOTS];
/*
* Probility trees for additional bits for match distance
* when the distance is in the range [4, 127].
*/
uint16_t dist_special[FULL_DISTANCES - DIST_MODEL_END];
/*
* Probability tree for the lowest four bits of a match
* distance that is equal to or greater than 128.
*/
uint16_t dist_align[ALIGN_SIZE];
/* Length of a normal match */
struct lzma_len_dec match_len_dec;
/* Length of a repeated match */
struct lzma_len_dec rep_len_dec;
/* Probabilities of literals */
uint16_t literal[LITERAL_CODERS_MAX][LITERAL_CODER_SIZE];
};
struct lzma2_dec {
/* Position in xz_dec_lzma2_run(). */
enum lzma2_seq {
SEQ_CONTROL,
SEQ_UNCOMPRESSED_1,
SEQ_UNCOMPRESSED_2,
SEQ_COMPRESSED_0,
SEQ_COMPRESSED_1,
SEQ_PROPERTIES,
SEQ_LZMA_PREPARE,
SEQ_LZMA_RUN,
SEQ_COPY
} sequence;
/* Next position after decoding the compressed size of the chunk. */
enum lzma2_seq next_sequence;
/* Uncompressed size of LZMA chunk (2 MiB at maximum) */
uint32_t uncompressed;
/*
* Compressed size of LZMA chunk or compressed/uncompressed
* size of uncompressed chunk (64 KiB at maximum)
*/
uint32_t compressed;
/*
* True if dictionary reset is needed. This is false before
* the first chunk (LZMA or uncompressed).
*/
bool need_dict_reset;
/*
* True if new LZMA properties are needed. This is false
* before the first LZMA chunk.
*/
bool need_props;
#ifdef XZ_DEC_MICROLZMA
bool pedantic_microlzma;
#endif
};
struct xz_dec_lzma2 {
/*
* The order below is important on x86 to reduce code size and
* it shouldn't hurt on other platforms. Everything up to and
* including lzma.pos_mask are in the first 128 bytes on x86-32,
* which allows using smaller instructions to access those
* variables. On x86-64, fewer variables fit into the first 128
* bytes, but this is still the best order without sacrificing
* the readability by splitting the structures.
*/
struct rc_dec rc;
struct dictionary dict;
struct lzma2_dec lzma2;
struct lzma_dec lzma;
/*
* Temporary buffer which holds small number of input bytes between
* decoder calls. See lzma2_lzma() for details.
*/
struct {
uint32_t size;
uint8_t buf[3 * LZMA_IN_REQUIRED];
} temp;
};
/**************
* Dictionary *
**************/
/*
* Reset the dictionary state. When in single-call mode, set up the beginning
* of the dictionary to point to the actual output buffer.
*/
static void dict_reset(struct dictionary *dict, struct xz_buf *b)
{
if (DEC_IS_SINGLE(dict->mode)) {
dict->buf = b->out + b->out_pos;
dict->end = b->out_size - b->out_pos;
}
dict->start = 0;
dict->pos = 0;
dict->limit = 0;
dict->full = 0;
}
/* Set dictionary write limit */
static void dict_limit(struct dictionary *dict, size_t out_max)
{
if (dict->end - dict->pos <= out_max)
dict->limit = dict->end;
else
dict->limit = dict->pos + out_max;
}
/* Return true if at least one byte can be written into the dictionary. */
static inline bool dict_has_space(const struct dictionary *dict)
{
return dict->pos < dict->limit;
}
/*
* Get a byte from the dictionary at the given distance. The distance is
* assumed to valid, or as a special case, zero when the dictionary is
* still empty. This special case is needed for single-call decoding to
* avoid writing a '\0' to the end of the destination buffer.
*/
static inline uint32_t dict_get(const struct dictionary *dict, uint32_t dist)
{
size_t offset = dict->pos - dist - 1;
if (dist >= dict->pos)
offset += dict->end;
return dict->full > 0 ? dict->buf[offset] : 0;
}
/*
* Put one byte into the dictionary. It is assumed that there is space for it.
*/
static inline void dict_put(struct dictionary *dict, uint8_t byte)
{
dict->buf[dict->pos++] = byte;
if (dict->full < dict->pos)
dict->full = dict->pos;
}
/*
* Repeat given number of bytes from the given distance. If the distance is
* invalid, false is returned. On success, true is returned and *len is
* updated to indicate how many bytes were left to be repeated.
*/
static bool dict_repeat(struct dictionary *dict, uint32_t *len, uint32_t dist)
{
size_t back;
uint32_t left;
if (dist >= dict->full || dist >= dict->size)
return false;
left = min_t(size_t, dict->limit - dict->pos, *len);
*len -= left;
back = dict->pos - dist - 1;
if (dist >= dict->pos)
back += dict->end;
do {
dict->buf[dict->pos++] = dict->buf[back++];
if (back == dict->end)
back = 0;
} while (--left > 0);
if (dict->full < dict->pos)
dict->full = dict->pos;
return true;
}
/* Copy uncompressed data as is from input to dictionary and output buffers. */
static void dict_uncompressed(struct dictionary *dict, struct xz_buf *b,
uint32_t *left)
{
size_t copy_size;
while (*left > 0 && b->in_pos < b->in_size
&& b->out_pos < b->out_size) {
copy_size = min(b->in_size - b->in_pos,
b->out_size - b->out_pos);
if (copy_size > dict->end - dict->pos)
copy_size = dict->end - dict->pos;
if (copy_size > *left)
copy_size = *left;
*left -= copy_size;
/*
* If doing in-place decompression in single-call mode and the
* uncompressed size of the file is larger than the caller
* thought (i.e. it is invalid input!), the buffers below may
* overlap and cause undefined behavior with memcpy().
* With valid inputs memcpy() would be fine here.
*/
memmove(dict->buf + dict->pos, b->in + b->in_pos, copy_size);
dict->pos += copy_size;
if (dict->full < dict->pos)
dict->full = dict->pos;
if (DEC_IS_MULTI(dict->mode)) {
if (dict->pos == dict->end)
dict->pos = 0;
/*
* Like above but for multi-call mode: use memmove()
* to avoid undefined behavior with invalid input.
*/
memmove(b->out + b->out_pos, b->in + b->in_pos,
copy_size);
}
dict->start = dict->pos;
b->out_pos += copy_size;
b->in_pos += copy_size;
}
}
#ifdef XZ_DEC_MICROLZMA
# define DICT_FLUSH_SUPPORTS_SKIPPING true
#else
# define DICT_FLUSH_SUPPORTS_SKIPPING false
#endif
/*
* Flush pending data from dictionary to b->out. It is assumed that there is
* enough space in b->out. This is guaranteed because caller uses dict_limit()
* before decoding data into the dictionary.
*/
static uint32_t dict_flush(struct dictionary *dict, struct xz_buf *b)
{
size_t copy_size = dict->pos - dict->start;
if (DEC_IS_MULTI(dict->mode)) {
if (dict->pos == dict->end)
dict->pos = 0;
/*
* These buffers cannot overlap even if doing in-place
* decompression because in multi-call mode dict->buf
* has been allocated by us in this file; it's not
* provided by the caller like in single-call mode.
*
* With MicroLZMA, b->out can be NULL to skip bytes that
* the caller doesn't need. This cannot be done with XZ
* because it would break BCJ filters.
*/
if (!DICT_FLUSH_SUPPORTS_SKIPPING || b->out != NULL)
memcpy(b->out + b->out_pos, dict->buf + dict->start,
copy_size);
}
dict->start = dict->pos;
b->out_pos += copy_size;
return copy_size;
}
/*****************
* Range decoder *
*****************/
/* Reset the range decoder. */
static void rc_reset(struct rc_dec *rc)
{
rc->range = (uint32_t)-1;
rc->code = 0;
rc->init_bytes_left = RC_INIT_BYTES;
}
/*
* Read the first five initial bytes into rc->code if they haven't been
* read already. (Yes, the first byte gets completely ignored.)
*/
static bool rc_read_init(struct rc_dec *rc, struct xz_buf *b)
{
while (rc->init_bytes_left > 0) {
if (b->in_pos == b->in_size)
return false;
rc->code = (rc->code << 8) + b->in[b->in_pos++];
--rc->init_bytes_left;
}
return true;
}
/* Return true if there may not be enough input for the next decoding loop. */
static inline bool rc_limit_exceeded(const struct rc_dec *rc)
{
return rc->in_pos > rc->in_limit;
}
/*
* Return true if it is possible (from point of view of range decoder) that
* we have reached the end of the LZMA chunk.
*/
static inline bool rc_is_finished(const struct rc_dec *rc)
{
return rc->code == 0;
}
/* Read the next input byte if needed. */
static __always_inline void rc_normalize(struct rc_dec *rc)
{
if (rc->range < RC_TOP_VALUE) {
rc->range <<= RC_SHIFT_BITS;
rc->code = (rc->code << RC_SHIFT_BITS) + rc->in[rc->in_pos++];
}
}
/*
* Decode one bit. In some versions, this function has been split in three
* functions so that the compiler is supposed to be able to more easily avoid
* an extra branch. In this particular version of the LZMA decoder, this
* doesn't seem to be a good idea (tested with GCC 3.3.6, 3.4.6, and 4.3.3
* on x86). Using a non-split version results in nicer looking code too.
*
* NOTE: This must return an int. Do not make it return a bool or the speed
* of the code generated by GCC 3.x decreases 10-15 %. (GCC 4.3 doesn't care,
* and it generates 10-20 % faster code than GCC 3.x from this file anyway.)
*/
static __always_inline int rc_bit(struct rc_dec *rc, uint16_t *prob)
{
uint32_t bound;
int bit;
rc_normalize(rc);
bound = (rc->range >> RC_BIT_MODEL_TOTAL_BITS) * *prob;
if (rc->code < bound) {
rc->range = bound;
*prob += (RC_BIT_MODEL_TOTAL - *prob) >> RC_MOVE_BITS;
bit = 0;
} else {
rc->range -= bound;
rc->code -= bound;
*prob -= *prob >> RC_MOVE_BITS;
bit = 1;
}
return bit;
}
/* Decode a bittree starting from the most significant bit. */
static __always_inline uint32_t rc_bittree(struct rc_dec *rc,
uint16_t *probs, uint32_t limit)
{
uint32_t symbol = 1;
do {
if (rc_bit(rc, &probs[symbol]))
symbol = (symbol << 1) + 1;
else
symbol <<= 1;
} while (symbol < limit);
return symbol;
}
/* Decode a bittree starting from the least significant bit. */
static __always_inline void rc_bittree_reverse(struct rc_dec *rc,
uint16_t *probs,
uint32_t *dest, uint32_t limit)
{
uint32_t symbol = 1;
uint32_t i = 0;
do {
if (rc_bit(rc, &probs[symbol])) {
symbol = (symbol << 1) + 1;
*dest += 1 << i;
} else {
symbol <<= 1;
}
} while (++i < limit);
}
/* Decode direct bits (fixed fifty-fifty probability) */
static inline void rc_direct(struct rc_dec *rc, uint32_t *dest, uint32_t limit)
{
uint32_t mask;
do {
rc_normalize(rc);
rc->range >>= 1;
rc->code -= rc->range;
mask = (uint32_t)0 - (rc->code >> 31);
rc->code += rc->range & mask;
*dest = (*dest << 1) + (mask + 1);
} while (--limit > 0);
}
/********
* LZMA *
********/
/* Get pointer to literal coder probability array. */
static uint16_t *lzma_literal_probs(struct xz_dec_lzma2 *s)
{
uint32_t prev_byte = dict_get(&s->dict, 0);
uint32_t low = prev_byte >> (8 - s->lzma.lc);
uint32_t high = (s->dict.pos & s->lzma.literal_pos_mask) << s->lzma.lc;
return s->lzma.literal[low + high];
}
/* Decode a literal (one 8-bit byte) */
static void lzma_literal(struct xz_dec_lzma2 *s)
{
uint16_t *probs;
uint32_t symbol;
uint32_t match_byte;
uint32_t match_bit;
uint32_t offset;
uint32_t i;
probs = lzma_literal_probs(s);
if (lzma_state_is_literal(s->lzma.state)) {
symbol = rc_bittree(&s->rc, probs, 0x100);
} else {
symbol = 1;
match_byte = dict_get(&s->dict, s->lzma.rep0) << 1;
offset = 0x100;
do {
match_bit = match_byte & offset;
match_byte <<= 1;
i = offset + match_bit + symbol;
if (rc_bit(&s->rc, &probs[i])) {
symbol = (symbol << 1) + 1;
offset &= match_bit;
} else {
symbol <<= 1;
offset &= ~match_bit;
}
} while (symbol < 0x100);
}
dict_put(&s->dict, (uint8_t)symbol);
lzma_state_literal(&s->lzma.state);
}
/* Decode the length of the match into s->lzma.len. */
static void lzma_len(struct xz_dec_lzma2 *s, struct lzma_len_dec *l,
uint32_t pos_state)
{
uint16_t *probs;
uint32_t limit;
if (!rc_bit(&s->rc, &l->choice)) {
probs = l->low[pos_state];
limit = LEN_LOW_SYMBOLS;
s->lzma.len = MATCH_LEN_MIN;
} else {
if (!rc_bit(&s->rc, &l->choice2)) {
probs = l->mid[pos_state];
limit = LEN_MID_SYMBOLS;
s->lzma.len = MATCH_LEN_MIN + LEN_LOW_SYMBOLS;
} else {
probs = l->high;
limit = LEN_HIGH_SYMBOLS;
s->lzma.len = MATCH_LEN_MIN + LEN_LOW_SYMBOLS
+ LEN_MID_SYMBOLS;
}
}
s->lzma.len += rc_bittree(&s->rc, probs, limit) - limit;
}
/* Decode a match. The distance will be stored in s->lzma.rep0. */
static void lzma_match(struct xz_dec_lzma2 *s, uint32_t pos_state)
{
uint16_t *probs;
uint32_t dist_slot;
uint32_t limit;
lzma_state_match(&s->lzma.state);
s->lzma.rep3 = s->lzma.rep2;
s->lzma.rep2 = s->lzma.rep1;
s->lzma.rep1 = s->lzma.rep0;
lzma_len(s, &s->lzma.match_len_dec, pos_state);
probs = s->lzma.dist_slot[lzma_get_dist_state(s->lzma.len)];
dist_slot = rc_bittree(&s->rc, probs, DIST_SLOTS) - DIST_SLOTS;
if (dist_slot < DIST_MODEL_START) {
s->lzma.rep0 = dist_slot;
} else {
limit = (dist_slot >> 1) - 1;
s->lzma.rep0 = 2 + (dist_slot & 1);
if (dist_slot < DIST_MODEL_END) {
s->lzma.rep0 <<= limit;
probs = s->lzma.dist_special + s->lzma.rep0
- dist_slot - 1;
rc_bittree_reverse(&s->rc, probs,
&s->lzma.rep0, limit);
} else {
rc_direct(&s->rc, &s->lzma.rep0, limit - ALIGN_BITS);
s->lzma.rep0 <<= ALIGN_BITS;
rc_bittree_reverse(&s->rc, s->lzma.dist_align,
&s->lzma.rep0, ALIGN_BITS);
}
}
}
/*
* Decode a repeated match. The distance is one of the four most recently
* seen matches. The distance will be stored in s->lzma.rep0.
*/
static void lzma_rep_match(struct xz_dec_lzma2 *s, uint32_t pos_state)
{
uint32_t tmp;
if (!rc_bit(&s->rc, &s->lzma.is_rep0[s->lzma.state])) {
if (!rc_bit(&s->rc, &s->lzma.is_rep0_long[
s->lzma.state][pos_state])) {
lzma_state_short_rep(&s->lzma.state);
s->lzma.len = 1;
return;
}
} else {
if (!rc_bit(&s->rc, &s->lzma.is_rep1[s->lzma.state])) {
tmp = s->lzma.rep1;
} else {
if (!rc_bit(&s->rc, &s->lzma.is_rep2[s->lzma.state])) {
tmp = s->lzma.rep2;
} else {
tmp = s->lzma.rep3;
s->lzma.rep3 = s->lzma.rep2;
}
s->lzma.rep2 = s->lzma.rep1;
}
s->lzma.rep1 = s->lzma.rep0;
s->lzma.rep0 = tmp;
}
lzma_state_long_rep(&s->lzma.state);
lzma_len(s, &s->lzma.rep_len_dec, pos_state);
}
/* LZMA decoder core */
static bool lzma_main(struct xz_dec_lzma2 *s)
{
uint32_t pos_state;
/*
* If the dictionary was reached during the previous call, try to
* finish the possibly pending repeat in the dictionary.
*/
if (dict_has_space(&s->dict) && s->lzma.len > 0)
dict_repeat(&s->dict, &s->lzma.len, s->lzma.rep0);
/*
* Decode more LZMA symbols. One iteration may consume up to
* LZMA_IN_REQUIRED - 1 bytes.
*/
while (dict_has_space(&s->dict) && !rc_limit_exceeded(&s->rc)) {
pos_state = s->dict.pos & s->lzma.pos_mask;
if (!rc_bit(&s->rc, &s->lzma.is_match[
s->lzma.state][pos_state])) {
lzma_literal(s);
} else {
if (rc_bit(&s->rc, &s->lzma.is_rep[s->lzma.state]))
lzma_rep_match(s, pos_state);
else
lzma_match(s, pos_state);
if (!dict_repeat(&s->dict, &s->lzma.len, s->lzma.rep0))
return false;
}
}
/*
* Having the range decoder always normalized when we are outside
* this function makes it easier to correctly handle end of the chunk.
*/
rc_normalize(&s->rc);
return true;
}
/*
* Reset the LZMA decoder and range decoder state. Dictionary is not reset
* here, because LZMA state may be reset without resetting the dictionary.
*/
static void lzma_reset(struct xz_dec_lzma2 *s)
{
uint16_t *probs;
size_t i;
s->lzma.state = STATE_LIT_LIT;
s->lzma.rep0 = 0;
s->lzma.rep1 = 0;
s->lzma.rep2 = 0;
s->lzma.rep3 = 0;
s->lzma.len = 0;
/*
* All probabilities are initialized to the same value. This hack
* makes the code smaller by avoiding a separate loop for each
* probability array.
*
* This could be optimized so that only that part of literal
* probabilities that are actually required. In the common case
* we would write 12 KiB less.
*/
probs = s->lzma.is_match[0];
for (i = 0; i < PROBS_TOTAL; ++i)
probs[i] = RC_BIT_MODEL_TOTAL / 2;
rc_reset(&s->rc);
}
/*
* Decode and validate LZMA properties (lc/lp/pb) and calculate the bit masks
* from the decoded lp and pb values. On success, the LZMA decoder state is
* reset and true is returned.
*/
static bool lzma_props(struct xz_dec_lzma2 *s, uint8_t props)
{
if (props > (4 * 5 + 4) * 9 + 8)
return false;
s->lzma.pos_mask = 0;
while (props >= 9 * 5) {
props -= 9 * 5;
++s->lzma.pos_mask;
}
s->lzma.pos_mask = (1 << s->lzma.pos_mask) - 1;
s->lzma.literal_pos_mask = 0;
while (props >= 9) {
props -= 9;
++s->lzma.literal_pos_mask;
}
s->lzma.lc = props;
if (s->lzma.lc + s->lzma.literal_pos_mask > 4)
return false;
s->lzma.literal_pos_mask = (1 << s->lzma.literal_pos_mask) - 1;
lzma_reset(s);
return true;
}
/*********
* LZMA2 *
*********/
/*
* The LZMA decoder assumes that if the input limit (s->rc.in_limit) hasn't
* been exceeded, it is safe to read up to LZMA_IN_REQUIRED bytes. This
* wrapper function takes care of making the LZMA decoder's assumption safe.
*
* As long as there is plenty of input left to be decoded in the current LZMA
* chunk, we decode directly from the caller-supplied input buffer until
* there's LZMA_IN_REQUIRED bytes left. Those remaining bytes are copied into
* s->temp.buf, which (hopefully) gets filled on the next call to this
* function. We decode a few bytes from the temporary buffer so that we can
* continue decoding from the caller-supplied input buffer again.
*/
static bool lzma2_lzma(struct xz_dec_lzma2 *s, struct xz_buf *b)
{
size_t in_avail;
uint32_t tmp;
in_avail = b->in_size - b->in_pos;
if (s->temp.size > 0 || s->lzma2.compressed == 0) {
tmp = 2 * LZMA_IN_REQUIRED - s->temp.size;
if (tmp > s->lzma2.compressed - s->temp.size)
tmp = s->lzma2.compressed - s->temp.size;
if (tmp > in_avail)
tmp = in_avail;
memcpy(s->temp.buf + s->temp.size, b->in + b->in_pos, tmp);
if (s->temp.size + tmp == s->lzma2.compressed) {
memzero(s->temp.buf + s->temp.size + tmp,
sizeof(s->temp.buf)
- s->temp.size - tmp);
s->rc.in_limit = s->temp.size + tmp;
} else if (s->temp.size + tmp < LZMA_IN_REQUIRED) {
s->temp.size += tmp;
b->in_pos += tmp;
return true;
} else {
s->rc.in_limit = s->temp.size + tmp - LZMA_IN_REQUIRED;
}
s->rc.in = s->temp.buf;
s->rc.in_pos = 0;
if (!lzma_main(s) || s->rc.in_pos > s->temp.size + tmp)
return false;
s->lzma2.compressed -= s->rc.in_pos;
if (s->rc.in_pos < s->temp.size) {
s->temp.size -= s->rc.in_pos;
memmove(s->temp.buf, s->temp.buf + s->rc.in_pos,
s->temp.size);
return true;
}
b->in_pos += s->rc.in_pos - s->temp.size;
s->temp.size = 0;
}
in_avail = b->in_size - b->in_pos;
if (in_avail >= LZMA_IN_REQUIRED) {
s->rc.in = b->in;
s->rc.in_pos = b->in_pos;
if (in_avail >= s->lzma2.compressed + LZMA_IN_REQUIRED)
s->rc.in_limit = b->in_pos + s->lzma2.compressed;
else
s->rc.in_limit = b->in_size - LZMA_IN_REQUIRED;
if (!lzma_main(s))
return false;
in_avail = s->rc.in_pos - b->in_pos;
if (in_avail > s->lzma2.compressed)
return false;
s->lzma2.compressed -= in_avail;
b->in_pos = s->rc.in_pos;
}
in_avail = b->in_size - b->in_pos;
if (in_avail < LZMA_IN_REQUIRED) {
if (in_avail > s->lzma2.compressed)
in_avail = s->lzma2.compressed;
memcpy(s->temp.buf, b->in + b->in_pos, in_avail);
s->temp.size = in_avail;
b->in_pos += in_avail;
}
return true;
}
/*
* Take care of the LZMA2 control layer, and forward the job of actual LZMA
* decoding or copying of uncompressed chunks to other functions.
*/
enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s, struct xz_buf *b)
{
uint32_t tmp;
while (b->in_pos < b->in_size || s->lzma2.sequence == SEQ_LZMA_RUN) {
switch (s->lzma2.sequence) {
case SEQ_CONTROL:
/*
* LZMA2 control byte
*
* Exact values:
* 0x00 End marker
* 0x01 Dictionary reset followed by
* an uncompressed chunk
* 0x02 Uncompressed chunk (no dictionary reset)
*
* Highest three bits (s->control & 0xE0):
* 0xE0 Dictionary reset, new properties and state
* reset, followed by LZMA compressed chunk
* 0xC0 New properties and state reset, followed
* by LZMA compressed chunk (no dictionary
* reset)
* 0xA0 State reset using old properties,
* followed by LZMA compressed chunk (no
* dictionary reset)
* 0x80 LZMA chunk (no dictionary or state reset)
*
* For LZMA compressed chunks, the lowest five bits
* (s->control & 1F) are the highest bits of the
* uncompressed size (bits 16-20).
*
* A new LZMA2 stream must begin with a dictionary
* reset. The first LZMA chunk must set new
* properties and reset the LZMA state.
*
* Values that don't match anything described above
* are invalid and we return XZ_DATA_ERROR.
*/
tmp = b->in[b->in_pos++];
if (tmp == 0x00)
return XZ_STREAM_END;
if (tmp >= 0xE0 || tmp == 0x01) {
s->lzma2.need_props = true;
s->lzma2.need_dict_reset = false;
dict_reset(&s->dict, b);
} else if (s->lzma2.need_dict_reset) {
return XZ_DATA_ERROR;
}
if (tmp >= 0x80) {
s->lzma2.uncompressed = (tmp & 0x1F) << 16;
s->lzma2.sequence = SEQ_UNCOMPRESSED_1;
if (tmp >= 0xC0) {
/*
* When there are new properties,
* state reset is done at
* SEQ_PROPERTIES.
*/
s->lzma2.need_props = false;
s->lzma2.next_sequence
= SEQ_PROPERTIES;
} else if (s->lzma2.need_props) {
return XZ_DATA_ERROR;
} else {
s->lzma2.next_sequence
= SEQ_LZMA_PREPARE;
if (tmp >= 0xA0)
lzma_reset(s);
}
} else {
if (tmp > 0x02)
return XZ_DATA_ERROR;
s->lzma2.sequence = SEQ_COMPRESSED_0;
s->lzma2.next_sequence = SEQ_COPY;
}
break;
case SEQ_UNCOMPRESSED_1:
s->lzma2.uncompressed
+= (uint32_t)b->in[b->in_pos++] << 8;
s->lzma2.sequence = SEQ_UNCOMPRESSED_2;
break;
case SEQ_UNCOMPRESSED_2:
s->lzma2.uncompressed
+= (uint32_t)b->in[b->in_pos++] + 1;
s->lzma2.sequence = SEQ_COMPRESSED_0;
break;
case SEQ_COMPRESSED_0:
s->lzma2.compressed
= (uint32_t)b->in[b->in_pos++] << 8;
s->lzma2.sequence = SEQ_COMPRESSED_1;
break;
case SEQ_COMPRESSED_1:
s->lzma2.compressed
+= (uint32_t)b->in[b->in_pos++] + 1;
s->lzma2.sequence = s->lzma2.next_sequence;
break;
case SEQ_PROPERTIES:
if (!lzma_props(s, b->in[b->in_pos++]))
return XZ_DATA_ERROR;
s->lzma2.sequence = SEQ_LZMA_PREPARE;
fallthrough;
case SEQ_LZMA_PREPARE:
if (s->lzma2.compressed < RC_INIT_BYTES)
return XZ_DATA_ERROR;
if (!rc_read_init(&s->rc, b))
return XZ_OK;
s->lzma2.compressed -= RC_INIT_BYTES;
s->lzma2.sequence = SEQ_LZMA_RUN;
fallthrough;
case SEQ_LZMA_RUN:
/*
* Set dictionary limit to indicate how much we want
* to be encoded at maximum. Decode new data into the
* dictionary. Flush the new data from dictionary to
* b->out. Check if we finished decoding this chunk.
* In case the dictionary got full but we didn't fill
* the output buffer yet, we may run this loop
* multiple times without changing s->lzma2.sequence.
*/
dict_limit(&s->dict, min_t(size_t,
b->out_size - b->out_pos,
s->lzma2.uncompressed));
if (!lzma2_lzma(s, b))
return XZ_DATA_ERROR;
s->lzma2.uncompressed -= dict_flush(&s->dict, b);
if (s->lzma2.uncompressed == 0) {
if (s->lzma2.compressed > 0 || s->lzma.len > 0
|| !rc_is_finished(&s->rc))
return XZ_DATA_ERROR;
rc_reset(&s->rc);
s->lzma2.sequence = SEQ_CONTROL;
} else if (b->out_pos == b->out_size
|| (b->in_pos == b->in_size
&& s->temp.size
< s->lzma2.compressed)) {
return XZ_OK;
}
break;
case SEQ_COPY:
dict_uncompressed(&s->dict, b, &s->lzma2.compressed);
if (s->lzma2.compressed > 0)
return XZ_OK;
s->lzma2.sequence = SEQ_CONTROL;
break;
}
}
return XZ_OK;
}
struct xz_dec_lzma2 *xz_dec_lzma2_create(enum xz_mode mode, uint32_t dict_max)
{
struct xz_dec_lzma2 *s = kmalloc(sizeof(*s), GFP_KERNEL);
if (s == NULL)
return NULL;
s->dict.mode = mode;
s->dict.size_max = dict_max;
if (DEC_IS_PREALLOC(mode)) {
s->dict.buf = vmalloc(dict_max);
if (s->dict.buf == NULL) {
kfree(s);
return NULL;
}
} else if (DEC_IS_DYNALLOC(mode)) {
s->dict.buf = NULL;
s->dict.allocated = 0;
}
return s;
}
enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s, uint8_t props)
{
/* This limits dictionary size to 3 GiB to keep parsing simpler. */
if (props > 39)
return XZ_OPTIONS_ERROR;
s->dict.size = 2 + (props & 1);
s->dict.size <<= (props >> 1) + 11;
if (DEC_IS_MULTI(s->dict.mode)) {
if (s->dict.size > s->dict.size_max)
return XZ_MEMLIMIT_ERROR;
s->dict.end = s->dict.size;
if (DEC_IS_DYNALLOC(s->dict.mode)) {
if (s->dict.allocated < s->dict.size) {
s->dict.allocated = s->dict.size;
vfree(s->dict.buf);
s->dict.buf = vmalloc(s->dict.size);
if (s->dict.buf == NULL) {
s->dict.allocated = 0;
return XZ_MEM_ERROR;
}
}
}
}
s->lzma2.sequence = SEQ_CONTROL;
s->lzma2.need_dict_reset = true;
s->temp.size = 0;
return XZ_OK;
}
void xz_dec_lzma2_end(struct xz_dec_lzma2 *s)
{
if (DEC_IS_MULTI(s->dict.mode))
vfree(s->dict.buf);
kfree(s);
}
#ifdef XZ_DEC_MICROLZMA
/* This is a wrapper struct to have a nice struct name in the public API. */
struct xz_dec_microlzma {
struct xz_dec_lzma2 s;
};
enum xz_ret xz_dec_microlzma_run(struct xz_dec_microlzma *s_ptr,
struct xz_buf *b)
{
struct xz_dec_lzma2 *s = &s_ptr->s;
/*
* sequence is SEQ_PROPERTIES before the first input byte,
* SEQ_LZMA_PREPARE until a total of five bytes have been read,
* and SEQ_LZMA_RUN for the rest of the input stream.
*/
if (s->lzma2.sequence != SEQ_LZMA_RUN) {
if (s->lzma2.sequence == SEQ_PROPERTIES) {
/* One byte is needed for the props. */
if (b->in_pos >= b->in_size)
return XZ_OK;
/*
* Don't increment b->in_pos here. The same byte is
* also passed to rc_read_init() which will ignore it.
*/
if (!lzma_props(s, ~b->in[b->in_pos]))
return XZ_DATA_ERROR;
s->lzma2.sequence = SEQ_LZMA_PREPARE;
}
/*
* xz_dec_microlzma_reset() doesn't validate the compressed
* size so we do it here. We have to limit the maximum size
* to avoid integer overflows in lzma2_lzma(). 3 GiB is a nice
* round number and much more than users of this code should
* ever need.
*/
if (s->lzma2.compressed < RC_INIT_BYTES
|| s->lzma2.compressed > (3U << 30))
return XZ_DATA_ERROR;
if (!rc_read_init(&s->rc, b))
return XZ_OK;
s->lzma2.compressed -= RC_INIT_BYTES;
s->lzma2.sequence = SEQ_LZMA_RUN;
dict_reset(&s->dict, b);
}
/* This is to allow increasing b->out_size between calls. */
if (DEC_IS_SINGLE(s->dict.mode))
s->dict.end = b->out_size - b->out_pos;
while (true) {
dict_limit(&s->dict, min_t(size_t, b->out_size - b->out_pos,
s->lzma2.uncompressed));
if (!lzma2_lzma(s, b))
return XZ_DATA_ERROR;
s->lzma2.uncompressed -= dict_flush(&s->dict, b);
if (s->lzma2.uncompressed == 0) {
if (s->lzma2.pedantic_microlzma) {
if (s->lzma2.compressed > 0 || s->lzma.len > 0
|| !rc_is_finished(&s->rc))
return XZ_DATA_ERROR;
}
return XZ_STREAM_END;
}
if (b->out_pos == b->out_size)
return XZ_OK;
if (b->in_pos == b->in_size
&& s->temp.size < s->lzma2.compressed)
return XZ_OK;
}
}
struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode,
uint32_t dict_size)
{
struct xz_dec_microlzma *s;
/* Restrict dict_size to the same range as in the LZMA2 code. */
if (dict_size < 4096 || dict_size > (3U << 30))
return NULL;
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (s == NULL)
return NULL;
s->s.dict.mode = mode;
s->s.dict.size = dict_size;
if (DEC_IS_MULTI(mode)) {
s->s.dict.end = dict_size;
s->s.dict.buf = vmalloc(dict_size);
if (s->s.dict.buf == NULL) {
kfree(s);
return NULL;
}
}
return s;
}
void xz_dec_microlzma_reset(struct xz_dec_microlzma *s, uint32_t comp_size,
uint32_t uncomp_size, int uncomp_size_is_exact)
{
/*
* comp_size is validated in xz_dec_microlzma_run().
* uncomp_size can safely be anything.
*/
s->s.lzma2.compressed = comp_size;
s->s.lzma2.uncompressed = uncomp_size;
s->s.lzma2.pedantic_microlzma = uncomp_size_is_exact;
s->s.lzma2.sequence = SEQ_PROPERTIES;
s->s.temp.size = 0;
}
void xz_dec_microlzma_end(struct xz_dec_microlzma *s)
{
if (DEC_IS_MULTI(s->s.dict.mode))
vfree(s->s.dict.buf);
kfree(s);
}
#endif
Codebase Browser
linux