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xz_crc32.c
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xz_dec_lzma2.c
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xz_lzma2.h
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Editing: xz_dec_lzma2.c
/* * LZMA2 decoder * * Authors: Lasse Collin <lasse.collin@tukaani.org> * Igor Pavlov <http://7-zip.org/> * * This file has been put into the public domain. * You can do whatever you want with this file. */ #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 dervied from the number of literal * position bits, and a mask dervied 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; }; 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; memcpy(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; memcpy(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; } } /* * 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; 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 splitted 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-splitted 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 nore 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; /* * 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. */ XZ_EXTERN 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; 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; 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; } XZ_EXTERN 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; } XZ_EXTERN 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) { 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->lzma.len = 0; s->lzma2.sequence = SEQ_CONTROL; s->lzma2.need_dict_reset = true; s->temp.size = 0; return XZ_OK; } XZ_EXTERN void xz_dec_lzma2_end(struct xz_dec_lzma2 *s) { if (DEC_IS_MULTI(s->dict.mode)) vfree(s->dict.buf); kfree(s); }
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