decompress_unlzma.c

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/* Lzma decompressor for Linux kernel. Shamelessly snarfed
 *from busybox 1.1.1
 *
 *Linux kernel adaptation
 *Copyright (C) 2006  Alain < [email protected] >
 *
 *Based on small lzma deflate implementation/Small range coder
 *implementation for lzma.
 *Copyright (C) 2006  Aurelien Jacobs < [email protected] >
 *
 *Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
 *Copyright (C) 1999-2005  Igor Pavlov
 *
 *Copyrights of the parts, see headers below.
 *
 *
 *This program is free software; you can redistribute it and/or
 *modify it under the terms of the GNU Lesser General Public
 *License as published by the Free Software Foundation; either
 *version 2.1 of the License, or (at your option) any later version.
 *
 *This program is distributed in the hope that it will be useful,
 *but WITHOUT ANY WARRANTY; without even the implied warranty of
 *MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *Lesser General Public License for more details.
 *
 *You should have received a copy of the GNU Lesser General Public
 *License along with this library; if not, write to the Free Software
 *Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifdef STATIC
#define PREBOOT
#else
#include <linux/decompress/unlzma.h>
#endif /* STATIC */

#include <linux/decompress/mm.h>

#define MIN(a, b) (((a) < (b)) ? (a) : (b))

static long long INIT read_int(unsigned char *ptr, int size)
{
    int i;
    long long ret = 0;

    for (i = 0; i < size; i++)
        ret = (ret << 8) | ptr[size-i-1];
    return ret;
}

#define ENDIAN_CONVERT(x) \
  x = (typeof(x))read_int((unsigned char *)&x, sizeof(x))


/* Small range coder implementation for lzma.
 *Copyright (C) 2006  Aurelien Jacobs < [email protected] >
 *
 *Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
 *Copyright (c) 1999-2005  Igor Pavlov
 */

#include <linux/compiler.h>

#define LZMA_IOBUF_SIZE 0x10000

struct rc {
    int (*fill)(void*, unsigned int);
    uint8_t *ptr;
    uint8_t *buffer;
    uint8_t *buffer_end;
    int buffer_size;
    uint32_t code;
    uint32_t range;
    uint32_t bound;
    void (*error)(char *);
};


#define RC_TOP_BITS 24
#define RC_MOVE_BITS 5
#define RC_MODEL_TOTAL_BITS 11


static int INIT nofill(void *buffer, unsigned int len)
{
    return -1;
}

/* Called twice: once at startup and once in rc_normalize() */
static void INIT rc_read(struct rc *rc)
{
    rc->buffer_size = rc->fill((char *)rc->buffer, LZMA_IOBUF_SIZE);
    if (rc->buffer_size <= 0)
        rc->error("unexpected EOF");
    rc->ptr = rc->buffer;
    rc->buffer_end = rc->buffer + rc->buffer_size;
}

/* Called once */
static inline void INIT rc_init(struct rc *rc,
                       int (*fill)(void*, unsigned int),
                       char *buffer, int buffer_size)
{
    if (fill)
        rc->fill = fill;
    else
        rc->fill = nofill;
    rc->buffer = (uint8_t *)buffer;
    rc->buffer_size = buffer_size;
    rc->buffer_end = rc->buffer + rc->buffer_size;
    rc->ptr = rc->buffer;

    rc->code = 0;
    rc->range = 0xFFFFFFFF;
}

static inline void INIT rc_init_code(struct rc *rc)
{
    int i;

    for (i = 0; i < 5; i++) {
        if (rc->ptr >= rc->buffer_end)
            rc_read(rc);
        rc->code = (rc->code << 8) | *rc->ptr++;
    }
}


/* Called twice, but one callsite is in inline'd rc_is_bit_0_helper() */
static void INIT rc_do_normalize(struct rc *rc)
{
    if (rc->ptr >= rc->buffer_end)
        rc_read(rc);
    rc->range <<= 8;
    rc->code = (rc->code << 8) | *rc->ptr++;
}
static inline void INIT rc_normalize(struct rc *rc)
{
    if (rc->range < (1 << RC_TOP_BITS))
        rc_do_normalize(rc);
}

/* Called 9 times */
/* Why rc_is_bit_0_helper exists?
 *Because we want to always expose (rc->code < rc->bound) to optimizer
 */
static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p)
{
    rc_normalize(rc);
    rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
    return rc->bound;
}
static inline int INIT rc_is_bit_0(struct rc *rc, uint16_t *p)
{
    uint32_t t = rc_is_bit_0_helper(rc, p);
    return rc->code < t;
}

/* Called ~10 times, but very small, thus inlined */
static inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p)
{
    rc->range = rc->bound;
    *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
}
static inline void INIT rc_update_bit_1(struct rc *rc, uint16_t *p)
{
    rc->range -= rc->bound;
    rc->code -= rc->bound;
    *p -= *p >> RC_MOVE_BITS;
}

/* Called 4 times in unlzma loop */
static int INIT rc_get_bit(struct rc *rc, uint16_t *p, int *symbol)
{
    if (rc_is_bit_0(rc, p)) {
        rc_update_bit_0(rc, p);
        *symbol *= 2;
        return 0;
    } else {
        rc_update_bit_1(rc, p);
        *symbol = *symbol * 2 + 1;
        return 1;
    }
}

/* Called once */
static inline int INIT rc_direct_bit(struct rc *rc)
{
    rc_normalize(rc);
    rc->range >>= 1;
    if (rc->code >= rc->range) {
        rc->code -= rc->range;
        return 1;
    }
    return 0;
}

/* Called twice */
static inline void INIT
rc_bit_tree_decode(struct rc *rc, uint16_t *p, int num_levels, int *symbol)
{
    int i = num_levels;

    *symbol = 1;
    while (i--)
        rc_get_bit(rc, p + *symbol, symbol);
    *symbol -= 1 << num_levels;
}


/*
 * Small lzma deflate implementation.
 * Copyright (C) 2006  Aurelien Jacobs < [email protected] >
 *
 * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
 * Copyright (C) 1999-2005  Igor Pavlov
 */


struct lzma_header {
    uint8_t pos;
    uint32_t dict_size;
    uint64_t dst_size;
} __attribute__ ((packed)) ;


#define LZMA_BASE_SIZE 1846
#define LZMA_LIT_SIZE 768

#define LZMA_NUM_POS_BITS_MAX 4

#define LZMA_LEN_NUM_LOW_BITS 3
#define LZMA_LEN_NUM_MID_BITS 3
#define LZMA_LEN_NUM_HIGH_BITS 8

#define LZMA_LEN_CHOICE 0
#define LZMA_LEN_CHOICE_2 (LZMA_LEN_CHOICE + 1)
#define LZMA_LEN_LOW (LZMA_LEN_CHOICE_2 + 1)
#define LZMA_LEN_MID (LZMA_LEN_LOW \
              + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS)))
#define LZMA_LEN_HIGH (LZMA_LEN_MID \
               +(1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS)))
#define LZMA_NUM_LEN_PROBS (LZMA_LEN_HIGH + (1 << LZMA_LEN_NUM_HIGH_BITS))

#define LZMA_NUM_STATES 12
#define LZMA_NUM_LIT_STATES 7

#define LZMA_START_POS_MODEL_INDEX 4
#define LZMA_END_POS_MODEL_INDEX 14
#define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX >> 1))

#define LZMA_NUM_POS_SLOT_BITS 6
#define LZMA_NUM_LEN_TO_POS_STATES 4

#define LZMA_NUM_ALIGN_BITS 4

#define LZMA_MATCH_MIN_LEN 2

#define LZMA_IS_MATCH 0
#define LZMA_IS_REP (LZMA_IS_MATCH + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
#define LZMA_IS_REP_G0 (LZMA_IS_REP + LZMA_NUM_STATES)
#define LZMA_IS_REP_G1 (LZMA_IS_REP_G0 + LZMA_NUM_STATES)
#define LZMA_IS_REP_G2 (LZMA_IS_REP_G1 + LZMA_NUM_STATES)
#define LZMA_IS_REP_0_LONG (LZMA_IS_REP_G2 + LZMA_NUM_STATES)
#define LZMA_POS_SLOT (LZMA_IS_REP_0_LONG \
               + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
#define LZMA_SPEC_POS (LZMA_POS_SLOT \
               +(LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS))
#define LZMA_ALIGN (LZMA_SPEC_POS \
            + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX)
#define LZMA_LEN_CODER (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS))
#define LZMA_REP_LEN_CODER (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS)
#define LZMA_LITERAL (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS)


struct writer {
    uint8_t *buffer;
    uint8_t previous_byte;
    size_t buffer_pos;
    int bufsize;
    size_t global_pos;
    int(*flush)(void*, unsigned int);
    struct lzma_header *header;
};

struct cstate {
    int state;
    uint32_t rep0, rep1, rep2, rep3;
};

static inline size_t INIT get_pos(struct writer *wr)
{
    return
        wr->global_pos + wr->buffer_pos;
}

static inline uint8_t INIT peek_old_byte(struct writer *wr,
                        uint32_t offs)
{
    if (!wr->flush) {
        int32_t pos;
        while (offs > wr->header->dict_size)
            offs -= wr->header->dict_size;
        pos = wr->buffer_pos - offs;
        return wr->buffer[pos];
    } else {
        uint32_t pos = wr->buffer_pos - offs;
        while (pos >= wr->header->dict_size)
            pos += wr->header->dict_size;
        return wr->buffer[pos];
    }

}

static inline int INIT write_byte(struct writer *wr, uint8_t byte)
{
    wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte;
    if (wr->flush && wr->buffer_pos == wr->header->dict_size) {
        wr->buffer_pos = 0;
        wr->global_pos += wr->header->dict_size;
        if (wr->flush((char *)wr->buffer, wr->header->dict_size)
                != wr->header->dict_size)
            return -1;
    }
    return 0;
}


static inline int INIT copy_byte(struct writer *wr, uint32_t offs)
{
    return write_byte(wr, peek_old_byte(wr, offs));
}

static inline int INIT copy_bytes(struct writer *wr,
                     uint32_t rep0, int len)
{
    do {
        if (copy_byte(wr, rep0))
            return -1;
        len--;
    } while (len != 0 && wr->buffer_pos < wr->header->dst_size);

    return len;
}

static inline int INIT process_bit0(struct writer *wr, struct rc *rc,
                     struct cstate *cst, uint16_t *p,
                     int pos_state, uint16_t *prob,
                     int lc, uint32_t literal_pos_mask) {
    int mi = 1;
    rc_update_bit_0(rc, prob);
    prob = (p + LZMA_LITERAL +
        (LZMA_LIT_SIZE
         * (((get_pos(wr) & literal_pos_mask) << lc)
            + (wr->previous_byte >> (8 - lc))))
        );

    if (cst->state >= LZMA_NUM_LIT_STATES) {
        int match_byte = peek_old_byte(wr, cst->rep0);
        do {
            int bit;
            uint16_t *prob_lit;

            match_byte <<= 1;
            bit = match_byte & 0x100;
            prob_lit = prob + 0x100 + bit + mi;
            if (rc_get_bit(rc, prob_lit, &mi)) {
                if (!bit)
                    break;
            } else {
                if (bit)
                    break;
            }
        } while (mi < 0x100);
    }
    while (mi < 0x100) {
        uint16_t *prob_lit = prob + mi;
        rc_get_bit(rc, prob_lit, &mi);
    }
    if (cst->state < 4)
        cst->state = 0;
    else if (cst->state < 10)
        cst->state -= 3;
    else
        cst->state -= 6;

    return write_byte(wr, mi);
}

static inline int INIT process_bit1(struct writer *wr, struct rc *rc,
                        struct cstate *cst, uint16_t *p,
                        int pos_state, uint16_t *prob) {
  int offset;
    uint16_t *prob_len;
    int num_bits;
    int len;

    rc_update_bit_1(rc, prob);
    prob = p + LZMA_IS_REP + cst->state;
    if (rc_is_bit_0(rc, prob)) {
        rc_update_bit_0(rc, prob);
        cst->rep3 = cst->rep2;
        cst->rep2 = cst->rep1;
        cst->rep1 = cst->rep0;
        cst->state = cst->state < LZMA_NUM_LIT_STATES ? 0 : 3;
        prob = p + LZMA_LEN_CODER;
    } else {
        rc_update_bit_1(rc, prob);
        prob = p + LZMA_IS_REP_G0 + cst->state;
        if (rc_is_bit_0(rc, prob)) {
            rc_update_bit_0(rc, prob);
            prob = (p + LZMA_IS_REP_0_LONG
                + (cst->state <<
                   LZMA_NUM_POS_BITS_MAX) +
                pos_state);
            if (rc_is_bit_0(rc, prob)) {
                rc_update_bit_0(rc, prob);

                cst->state = cst->state < LZMA_NUM_LIT_STATES ?
                    9 : 11;
                return copy_byte(wr, cst->rep0);
            } else {
                rc_update_bit_1(rc, prob);
            }
        } else {
            uint32_t distance;

            rc_update_bit_1(rc, prob);
            prob = p + LZMA_IS_REP_G1 + cst->state;
            if (rc_is_bit_0(rc, prob)) {
                rc_update_bit_0(rc, prob);
                distance = cst->rep1;
            } else {
                rc_update_bit_1(rc, prob);
                prob = p + LZMA_IS_REP_G2 + cst->state;
                if (rc_is_bit_0(rc, prob)) {
                    rc_update_bit_0(rc, prob);
                    distance = cst->rep2;
                } else {
                    rc_update_bit_1(rc, prob);
                    distance = cst->rep3;
                    cst->rep3 = cst->rep2;
                }
                cst->rep2 = cst->rep1;
            }
            cst->rep1 = cst->rep0;
            cst->rep0 = distance;
        }
        cst->state = cst->state < LZMA_NUM_LIT_STATES ? 8 : 11;
        prob = p + LZMA_REP_LEN_CODER;
    }

    prob_len = prob + LZMA_LEN_CHOICE;
    if (rc_is_bit_0(rc, prob_len)) {
        rc_update_bit_0(rc, prob_len);
        prob_len = (prob + LZMA_LEN_LOW
                + (pos_state <<
                   LZMA_LEN_NUM_LOW_BITS));
        offset = 0;
        num_bits = LZMA_LEN_NUM_LOW_BITS;
    } else {
        rc_update_bit_1(rc, prob_len);
        prob_len = prob + LZMA_LEN_CHOICE_2;
        if (rc_is_bit_0(rc, prob_len)) {
            rc_update_bit_0(rc, prob_len);
            prob_len = (prob + LZMA_LEN_MID
                    + (pos_state <<
                       LZMA_LEN_NUM_MID_BITS));
            offset = 1 << LZMA_LEN_NUM_LOW_BITS;
            num_bits = LZMA_LEN_NUM_MID_BITS;
        } else {
            rc_update_bit_1(rc, prob_len);
            prob_len = prob + LZMA_LEN_HIGH;
            offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
                  + (1 << LZMA_LEN_NUM_MID_BITS));
            num_bits = LZMA_LEN_NUM_HIGH_BITS;
        }
    }

    rc_bit_tree_decode(rc, prob_len, num_bits, &len);
    len += offset;

    if (cst->state < 4) {
        int pos_slot;

        cst->state += LZMA_NUM_LIT_STATES;
        prob =
            p + LZMA_POS_SLOT +
            ((len <
              LZMA_NUM_LEN_TO_POS_STATES ? len :
              LZMA_NUM_LEN_TO_POS_STATES - 1)
             << LZMA_NUM_POS_SLOT_BITS);
        rc_bit_tree_decode(rc, prob,
                   LZMA_NUM_POS_SLOT_BITS,
                   &pos_slot);
        if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
            int i, mi;
            num_bits = (pos_slot >> 1) - 1;
            cst->rep0 = 2 | (pos_slot & 1);
            if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
                cst->rep0 <<= num_bits;
                prob = p + LZMA_SPEC_POS +
                    cst->rep0 - pos_slot - 1;
            } else {
                num_bits -= LZMA_NUM_ALIGN_BITS;
                while (num_bits--)
                    cst->rep0 = (cst->rep0 << 1) |
                        rc_direct_bit(rc);
                prob = p + LZMA_ALIGN;
                cst->rep0 <<= LZMA_NUM_ALIGN_BITS;
                num_bits = LZMA_NUM_ALIGN_BITS;
            }
            i = 1;
            mi = 1;
            while (num_bits--) {
                if (rc_get_bit(rc, prob + mi, &mi))
                    cst->rep0 |= i;
                i <<= 1;
            }
        } else
            cst->rep0 = pos_slot;
        if (++(cst->rep0) == 0)
            return 0;
        if (cst->rep0 > wr->header->dict_size
                || cst->rep0 > get_pos(wr))
            return -1;
    }

    len += LZMA_MATCH_MIN_LEN;

    return copy_bytes(wr, cst->rep0, len);
}



STATIC inline int INIT unlzma(unsigned char *buf, int in_len,
                  int(*fill)(void*, unsigned int),
                  int(*flush)(void*, unsigned int),
                  unsigned char *output,
                  int *posp,
                  void(*error)(char *x)
    )
{
    struct lzma_header header;
    int lc, pb, lp;
    uint32_t pos_state_mask;
    uint32_t literal_pos_mask;
    uint16_t *p;
    int num_probs;
    struct rc rc;
    int i, mi;
    struct writer wr;
    struct cstate cst;
    unsigned char *inbuf;
    int ret = -1;

    rc.error = error;

    if (buf)
        inbuf = buf;
    else
        inbuf = malloc(LZMA_IOBUF_SIZE);
    if (!inbuf) {
        error("Could not allocate input buffer");
        goto exit_0;
    }

    cst.state = 0;
    cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1;

    wr.header = &header;
    wr.flush = flush;
    wr.global_pos = 0;
    wr.previous_byte = 0;
    wr.buffer_pos = 0;

    rc_init(&rc, fill, inbuf, in_len);

    for (i = 0; i < sizeof(header); i++) {
        if (rc.ptr >= rc.buffer_end)
            rc_read(&rc);
        ((unsigned char *)&header)[i] = *rc.ptr++;
    }

    if (header.pos >= (9 * 5 * 5)) {
        error("bad header");
        goto exit_1;
    }

    mi = 0;
    lc = header.pos;
    while (lc >= 9) {
        mi++;
        lc -= 9;
    }
    pb = 0;
    lp = mi;
    while (lp >= 5) {
        pb++;
        lp -= 5;
    }
    pos_state_mask = (1 << pb) - 1;
    literal_pos_mask = (1 << lp) - 1;

    ENDIAN_CONVERT(header.dict_size);
    ENDIAN_CONVERT(header.dst_size);

    if (header.dict_size == 0)
        header.dict_size = 1;

    if (output)
        wr.buffer = output;
    else {
        wr.bufsize = MIN(header.dst_size, header.dict_size);
        wr.buffer = large_malloc(wr.bufsize);
    }
    if (wr.buffer == NULL)
        goto exit_1;

    num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
    p = (uint16_t *) large_malloc(num_probs * sizeof(*p));
    if (p == 0)
        goto exit_2;
    num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
    for (i = 0; i < num_probs; i++)
        p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;

    rc_init_code(&rc);

    while (get_pos(&wr) < header.dst_size) {
        int pos_state = get_pos(&wr) & pos_state_mask;
        uint16_t *prob = p + LZMA_IS_MATCH +
            (cst.state << LZMA_NUM_POS_BITS_MAX) + pos_state;
        if (rc_is_bit_0(&rc, prob)) {
            if (process_bit0(&wr, &rc, &cst, p, pos_state, prob,
                    lc, literal_pos_mask)) {
                error("LZMA data is corrupt");
                goto exit_3;
            }
        } else {
            if (process_bit1(&wr, &rc, &cst, p, pos_state, prob)) {
                error("LZMA data is corrupt");
                goto exit_3;
            }
            if (cst.rep0 == 0)
                break;
        }
        if (rc.buffer_size <= 0)
            goto exit_3;
    }

    if (posp)
        *posp = rc.ptr-rc.buffer;
    if (!wr.flush || wr.flush(wr.buffer, wr.buffer_pos) == wr.buffer_pos)
        ret = 0;
exit_3:
    large_free(p);
exit_2:
    if (!output)
        large_free(wr.buffer);
exit_1:
    if (!buf)
        free(inbuf);
exit_0:
    return ret;
}

#ifdef PREBOOT
STATIC int INIT decompress(unsigned char *buf, int in_len,
                  int(*fill)(void*, unsigned int),
                  int(*flush)(void*, unsigned int),
                  unsigned char *output,
                  int *posp,
                  void(*error)(char *x)
    )
{
    return unlzma(buf, in_len - 4, fill, flush, output, posp, error);
}
#endif