source: MondoRescue/branches/stable/mindi-busybox/archival/libunarchive/decompress_unlzma.c@ 1770

/* vi: set sw=4 ts=4: */
/*
 * Small lzma deflate implementation.
 * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>
 *
 * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
 * Copyright (C) 1999-2005  Igor Pavlov
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"
#include "unarchive.h"

#if ENABLE_FEATURE_LZMA_FAST
#  define speed_inline ALWAYS_INLINE
#else
#  define speed_inline
#endif


typedef struct {
    int fd;
    uint8_t *ptr;

/* Was keeping rc on stack in unlzma and separately allocating buffer,
 * but with "buffer 'attached to' allocated rc" code is smaller: */
    /* uint8_t *buffer; */
#define RC_BUFFER ((uint8_t*)(rc+1))

    uint8_t *buffer_end;

/* Had provisions for variable buffer, but we don't need it here */
    /* int buffer_size; */
#define RC_BUFFER_SIZE 0x10000

    uint32_t code;
    uint32_t range;
    uint32_t bound;
} rc_t;

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


/* Called twice: once at startup and once in rc_normalize() */
static void rc_read(rc_t * rc)
{
    int buffer_size = safe_read(rc->fd, RC_BUFFER, RC_BUFFER_SIZE);
    if (buffer_size <= 0)
        bb_error_msg_and_die("unexpected EOF");
    rc->ptr = RC_BUFFER;
    rc->buffer_end = RC_BUFFER + buffer_size;
}

/* Called once */
static rc_t* rc_init(int fd) /*, int buffer_size) */
{
    int i;
    rc_t* rc;

    rc = xmalloc(sizeof(rc_t) + RC_BUFFER_SIZE);

    rc->fd = fd;
    /* rc->buffer_size = buffer_size; */
    rc->buffer_end = RC_BUFFER + RC_BUFFER_SIZE;
    rc->ptr = rc->buffer_end;

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

/* Called once  */
static ALWAYS_INLINE void rc_free(rc_t * rc)
{
    if (ENABLE_FEATURE_CLEAN_UP)
        free(rc);
}

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

/* rc_is_bit_0 is called 9 times */
/* Why rc_is_bit_0_helper exists?
 * Because we want to always expose (rc->code < rc->bound) to optimizer.
 * Thus rc_is_bit_0 is always inlined, and rc_is_bit_0_helper is inlined
 * only if we compile for speed.
 */
static speed_inline uint32_t rc_is_bit_0_helper(rc_t * rc, uint16_t * p)
{
    rc_normalize(rc);
    rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
    return rc->bound;
}
static ALWAYS_INLINE int rc_is_bit_0(rc_t * 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 speed_inline void rc_update_bit_0(rc_t * rc, uint16_t * p)
{
    rc->range = rc->bound;
    *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
}
static speed_inline void rc_update_bit_1(rc_t * 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 rc_get_bit(rc_t * 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 ALWAYS_INLINE int rc_direct_bit(rc_t * rc)
{
    rc_normalize(rc);
    rc->range >>= 1;
    if (rc->code >= rc->range) {
        rc->code -= rc->range;
        return 1;
    }
    return 0;
}

/* Called twice */
static speed_inline void
rc_bit_tree_decode(rc_t * 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;
}


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


/* #defines will force compiler to compute/optimize each one with each usage.
 * Have heart and use enum instead. */
enum {
    LZMA_BASE_SIZE = 1846,
    LZMA_LIT_SIZE  = 768,

    LZMA_NUM_POS_BITS_MAX = 4,

    LZMA_LEN_NUM_LOW_BITS  = 3,
    LZMA_LEN_NUM_MID_BITS  = 3,
    LZMA_LEN_NUM_HIGH_BITS = 8,

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

    LZMA_NUM_STATES     = 12,
    LZMA_NUM_LIT_STATES = 7,

    LZMA_START_POS_MODEL_INDEX = 4,
    LZMA_END_POS_MODEL_INDEX   = 14,
    LZMA_NUM_FULL_DISTANCES    = (1 << (LZMA_END_POS_MODEL_INDEX >> 1)),

    LZMA_NUM_POS_SLOT_BITS = 6,
    LZMA_NUM_LEN_TO_POS_STATES = 4,

    LZMA_NUM_ALIGN_BITS = 4,

    LZMA_MATCH_MIN_LEN  = 2,

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


USE_DESKTOP(long long) int
unpack_lzma_stream(int src_fd, int dst_fd)
{
    USE_DESKTOP(long long total_written = 0;)
    lzma_header_t header;
    int lc, pb, lp;
    uint32_t pos_state_mask;
    uint32_t literal_pos_mask;
    uint32_t pos;
    uint16_t *p;
    uint16_t *prob;
    uint16_t *prob_lit;
    int num_bits;
    int num_probs;
    rc_t *rc;
    int i, mi;
    uint8_t *buffer;
    uint8_t previous_byte = 0;
    size_t buffer_pos = 0, global_pos = 0;
    int len = 0;
    int state = 0;
    uint32_t rep0 = 1, rep1 = 1, rep2 = 1, rep3 = 1;

    xread(src_fd, &header, sizeof(header));

    if (header.pos >= (9 * 5 * 5))
        bb_error_msg_and_die("bad header");
    mi = header.pos / 9;
    lc = header.pos % 9;
    pb = mi / 5;
    lp = mi % 5;
    pos_state_mask = (1 << pb) - 1;
    literal_pos_mask = (1 << lp) - 1;

    header.dict_size = SWAP_LE32(header.dict_size);
    header.dst_size = SWAP_LE64(header.dst_size);

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

    buffer = xmalloc(MIN(header.dst_size, header.dict_size));

    num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
    p = xmalloc(num_probs * sizeof(*p));
    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 = rc_init(src_fd); /*, RC_BUFFER_SIZE); */

    while (global_pos + buffer_pos < header.dst_size) {
        int pos_state = (buffer_pos + global_pos) & pos_state_mask;

        prob =
            p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;
        if (rc_is_bit_0(rc, prob)) {
            mi = 1;
            rc_update_bit_0(rc, prob);
            prob = (p + LZMA_LITERAL + (LZMA_LIT_SIZE
                    * ((((buffer_pos + global_pos) & literal_pos_mask) << lc)
                    + (previous_byte >> (8 - lc)))));

            if (state >= LZMA_NUM_LIT_STATES) {
                int match_byte;

                pos = buffer_pos - rep0;
                while (pos >= header.dict_size)
                    pos += header.dict_size;
                match_byte = buffer[pos];
                do {
                    int bit;

                    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) {
                prob_lit = prob + mi;
                rc_get_bit(rc, prob_lit, &mi);
            }
            previous_byte = (uint8_t) mi;

            buffer[buffer_pos++] = previous_byte;
            if (buffer_pos == header.dict_size) {
                buffer_pos = 0;
                global_pos += header.dict_size;
                if (full_write(dst_fd, buffer, header.dict_size) != header.dict_size)
                    goto bad;
                USE_DESKTOP(total_written += header.dict_size;)
            }
            if (state < 4)
                state = 0;
            else if (state < 10)
                state -= 3;
            else
                state -= 6;
        } else {
            int offset;
            uint16_t *prob_len;

            rc_update_bit_1(rc, prob);
            prob = p + LZMA_IS_REP + state;
            if (rc_is_bit_0(rc, prob)) {
                rc_update_bit_0(rc, prob);
                rep3 = rep2;
                rep2 = rep1;
                rep1 = rep0;
                state = 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 + state;
                if (rc_is_bit_0(rc, prob)) {
                    rc_update_bit_0(rc, prob);
                    prob = (p + LZMA_IS_REP_0_LONG
                            + (state << LZMA_NUM_POS_BITS_MAX) + pos_state);
                    if (rc_is_bit_0(rc, prob)) {
                        rc_update_bit_0(rc, prob);

                        state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
                        pos = buffer_pos - rep0;
                        while (pos >= header.dict_size)
                            pos += header.dict_size;
                        previous_byte = buffer[pos];
                        buffer[buffer_pos++] = previous_byte;
                        if (buffer_pos == header.dict_size) {
                            buffer_pos = 0;
                            global_pos += header.dict_size;
                            if (full_write(dst_fd, buffer, header.dict_size) != header.dict_size)
                                goto bad;
                            USE_DESKTOP(total_written += header.dict_size;)
                        }
                        continue;
                    } else {
                        rc_update_bit_1(rc, prob);
                    }
                } else {
                    uint32_t distance;

                    rc_update_bit_1(rc, prob);
                    prob = p + LZMA_IS_REP_G1 + state;
                    if (rc_is_bit_0(rc, prob)) {
                        rc_update_bit_0(rc, prob);
                        distance = rep1;
                    } else {
                        rc_update_bit_1(rc, prob);
                        prob = p + LZMA_IS_REP_G2 + state;
                        if (rc_is_bit_0(rc, prob)) {
                            rc_update_bit_0(rc, prob);
                            distance = rep2;
                        } else {
                            rc_update_bit_1(rc, prob);
                            distance = rep3;
                            rep3 = rep2;
                        }
                        rep2 = rep1;
                    }
                    rep1 = rep0;
                    rep0 = distance;
                }
                state = 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 (state < 4) {
                int pos_slot;

                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) {
                    num_bits = (pos_slot >> 1) - 1;
                    rep0 = 2 | (pos_slot & 1);
                    if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
                        rep0 <<= num_bits;
                        prob = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
                    } else {
                        num_bits -= LZMA_NUM_ALIGN_BITS;
                        while (num_bits--)
                            rep0 = (rep0 << 1) | rc_direct_bit(rc);
                        prob = p + LZMA_ALIGN;
                        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))
                            rep0 |= i;
                        i <<= 1;
                    }
                } else
                    rep0 = pos_slot;
                if (++rep0 == 0)
                    break;
            }

            len += LZMA_MATCH_MIN_LEN;

            do {
                pos = buffer_pos - rep0;
                while (pos >= header.dict_size)
                    pos += header.dict_size;
                previous_byte = buffer[pos];
                buffer[buffer_pos++] = previous_byte;
                if (buffer_pos == header.dict_size) {
                    buffer_pos = 0;
                    global_pos += header.dict_size;
                    if (full_write(dst_fd, buffer, header.dict_size) != header.dict_size)
                        goto bad;
                    USE_DESKTOP(total_written += header.dict_size;)
                }
                len--;
            } while (len != 0 && buffer_pos < header.dst_size);
        }
    }


    if (full_write(dst_fd, buffer, buffer_pos) != buffer_pos) {
 bad:
        rc_free(rc);
        return -1;
    }
    rc_free(rc);
    USE_DESKTOP(total_written += buffer_pos;)
    return USE_DESKTOP(total_written) + 0;
}