source: MondoRescue/branches/stable/mindi-busybox/archival/libunarchive/decompress_unzip.c@ 821

/* vi: set sw=4 ts=4: */
/*
 * gunzip implementation for busybox
 *
 * Based on GNU gzip v1.2.4 Copyright (C) 1992-1993 Jean-loup Gailly.
 *
 * Originally adjusted for busybox by Sven Rudolph <sr1@inf.tu-dresden.de>
 * based on gzip sources
 *
 * Adjusted further by Erik Andersen <andersen@codepoet.org> to support
 * files as well as stdin/stdout, and to generally behave itself wrt
 * command line handling.
 *
 * General cleanup to better adhere to the style guide and make use of standard
 * busybox functions by Glenn McGrath <bug1@iinet.net.au>
 *
 * read_gz interface + associated hacking by Laurence Anderson
 *
 * Fixed huft_build() so decoding end-of-block code does not grab more bits
 * than necessary (this is required by unzip applet), added inflate_cleanup()
 * to free leaked bytebuffer memory (used in unzip.c), and some minor style
 * guide cleanups by Ed Clark
 *
 * gzip (GNU zip) -- compress files with zip algorithm and 'compress' interface
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * The unzip code was written and put in the public domain by Mark Adler.
 * Portions of the lzw code are derived from the public domain 'compress'
 * written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
 * Ken Turkowski, Dave Mack and Peter Jannesen.
 *
 * See the file algorithm.doc for the compression algorithms and file formats.
 * 
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"
#include <sys/wait.h>
#include <signal.h>
#include "unarchive.h"

typedef struct huft_s {
    unsigned char e;    /* number of extra bits or operation */
    unsigned char b;    /* number of bits in this code or subcode */
    union {
        unsigned short n;   /* literal, length base, or distance base */
        struct huft_s *t;   /* pointer to next level of table */
    } v;
} huft_t;

static int gunzip_src_fd;
unsigned int gunzip_bytes_out;  /* number of output bytes */
static unsigned int gunzip_outbuf_count;    /* bytes in output buffer */

/* gunzip_window size--must be a power of two, and
 *  at least 32K for zip's deflate method */
enum { gunzip_wsize = 0x8000 };
static unsigned char *gunzip_window;

static uint32_t *gunzip_crc_table;
uint32_t gunzip_crc;

/* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
#define BMAX 16 /* maximum bit length of any code (16 for explode) */
#define N_MAX 288   /* maximum number of codes in any set */

/* bitbuffer */
static unsigned int gunzip_bb;  /* bit buffer */
static unsigned char gunzip_bk; /* bits in bit buffer */

/* These control the size of the bytebuffer */
static unsigned int bytebuffer_max = 0x8000;
static unsigned char *bytebuffer = NULL;
static unsigned int bytebuffer_offset = 0;
static unsigned int bytebuffer_size = 0;

static const unsigned short mask_bits[] = {
    0x0000, 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
    0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
};

/* Copy lengths for literal codes 257..285 */
static const unsigned short cplens[] = {
    3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59,
    67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0
};

/* note: see note #13 above about the 258 in this list. */
/* Extra bits for literal codes 257..285 */
static const unsigned char cplext[] = {
    0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5,
    5, 5, 5, 0, 99, 99
};                      /* 99==invalid */

/* Copy offsets for distance codes 0..29 */
static const unsigned short cpdist[] = {
    1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513,
    769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577
};

/* Extra bits for distance codes */
static const unsigned char cpdext[] = {
    0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10,
    11, 11, 12, 12, 13, 13
};

/* Tables for deflate from PKZIP's appnote.txt. */
/* Order of the bit length code lengths */
static const unsigned char border[] = {
    16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
};

static unsigned int fill_bitbuffer(unsigned int bitbuffer, unsigned int *current, const unsigned int required)
{
    while (*current < required) {
        if (bytebuffer_offset >= bytebuffer_size) {
            /* Leave the first 4 bytes empty so we can always unwind the bitbuffer
             * to the front of the bytebuffer, leave 4 bytes free at end of tail
             * so we can easily top up buffer in check_trailer_gzip() */
            if (!(bytebuffer_size = bb_xread(gunzip_src_fd, &bytebuffer[4], bytebuffer_max - 8))) {
                bb_error_msg_and_die("unexpected end of file");
            }
            bytebuffer_size += 4;
            bytebuffer_offset = 4;
        }
        bitbuffer |= ((unsigned int) bytebuffer[bytebuffer_offset]) << *current;
        bytebuffer_offset++;
        *current += 8;
    }
    return(bitbuffer);
}

/*
 * Free the malloc'ed tables built by huft_build(), which makes a linked
 * list of the tables it made, with the links in a dummy first entry of
 * each table.
 * t: table to free
 */
static int huft_free(huft_t * t)
{
    huft_t *p;
    huft_t *q;

    /* Go through linked list, freeing from the malloced (t[-1]) address. */
    p = t;
    while (p != (huft_t *) NULL) {
        q = (--p)->v.t;
        free((char *) p);
        p = q;
    }
    return 0;
}

/* Given a list of code lengths and a maximum table size, make a set of
 * tables to decode that set of codes.  Return zero on success, one if
 * the given code set is incomplete (the tables are still built in this
 * case), two if the input is invalid (all zero length codes or an
 * oversubscribed set of lengths), and three if not enough memory.
 *
 * b:   code lengths in bits (all assumed <= BMAX)
 * n:   number of codes (assumed <= N_MAX)
 * s:   number of simple-valued codes (0..s-1)
 * d:   list of base values for non-simple codes
 * e:   list of extra bits for non-simple codes
 * t:   result: starting table
 * m:   maximum lookup bits, returns actual
 */
static
int huft_build(unsigned int *b, const unsigned int n,
               const unsigned int s, const unsigned short *d,
               const unsigned char *e, huft_t ** t, unsigned int *m)
{
    unsigned a;             /* counter for codes of length k */
    unsigned c[BMAX + 1];   /* bit length count table */
    unsigned eob_len;       /* length of end-of-block code (value 256) */
    unsigned f;             /* i repeats in table every f entries */
    int g;                  /* maximum code length */
    int htl;                /* table level */
    unsigned i;             /* counter, current code */
    unsigned j;             /* counter */
    int k;                  /* number of bits in current code */
    unsigned *p;            /* pointer into c[], b[], or v[] */
    huft_t *q;              /* points to current table */
    huft_t r;               /* table entry for structure assignment */
    huft_t *u[BMAX];        /* table stack */
    unsigned v[N_MAX];      /* values in order of bit length */
    int ws[BMAX+1];         /* bits decoded stack */
    int w;                  /* bits decoded */
    unsigned x[BMAX + 1];   /* bit offsets, then code stack */
    unsigned *xp;           /* pointer into x */
    int y;                  /* number of dummy codes added */
    unsigned z;             /* number of entries in current table */

    /* Length of EOB code, if any */
    eob_len = n > 256 ? b[256] : BMAX;

    /* Generate counts for each bit length */
    memset((void *)c, 0, sizeof(c));
    p = b;
    i = n;
    do {
        c[*p]++; /* assume all entries <= BMAX */
        p++; /* Can't combine with above line (Solaris bug) */
    } while (--i);
    if (c[0] == n) { /* null input--all zero length codes */
        *t = (huft_t *) NULL;
        *m = 0;
        return 2;
    }

    /* Find minimum and maximum length, bound *m by those */
    for (j = 1; (c[j] == 0) && (j <= BMAX); j++);
    k = j; /* minimum code length */
    for (i = BMAX; (c[i] == 0) && i; i--);
    g = i; /* maximum code length */
    *m = (*m < j) ? j : ((*m > i) ? i : *m);

    /* Adjust last length count to fill out codes, if needed */
    for (y = 1 << j; j < i; j++, y <<= 1) {
        if ((y -= c[j]) < 0) {
            return 2; /* bad input: more codes than bits */
        }
    }
    if ((y -= c[i]) < 0) {
        return 2;
    }
    c[i] += y;

    /* Generate starting offsets into the value table for each length */
    x[1] = j = 0;
    p = c + 1;
    xp = x + 2;
    while (--i) { /* note that i == g from above */
        *xp++ = (j += *p++);
    }

    /* Make a table of values in order of bit lengths */
    p = b;
    i = 0;
    do {
        if ((j = *p++) != 0) {
            v[x[j]++] = i;
        }
    } while (++i < n);

    /* Generate the Huffman codes and for each, make the table entries */
    x[0] = i = 0;           /* first Huffman code is zero */
    p = v;                  /* grab values in bit order */
    htl = -1;               /* no tables yet--level -1 */
    w = ws[0] = 0;          /* bits decoded */
    u[0] = (huft_t *) NULL; /* just to keep compilers happy */
    q = (huft_t *) NULL;    /* ditto */
    z = 0;                  /* ditto */

    /* go through the bit lengths (k already is bits in shortest code) */
    for (; k <= g; k++) {
        a = c[k];
        while (a--) {
            /* here i is the Huffman code of length k bits for value *p */
            /* make tables up to required level */
            while (k > ws[htl + 1]) {
                w = ws[++htl];

                /* compute minimum size table less than or equal to *m bits */
                z = (z = g - w) > *m ? *m : z; /* upper limit on table size */
                if ((f = 1 << (j = k - w)) > a + 1) { /* try a k-w bit table */
                    /* too few codes for k-w bit table */
                    f -= a + 1; /* deduct codes from patterns left */
                    xp = c + k;
                    while (++j < z) { /* try smaller tables up to z bits */
                        if ((f <<= 1) <= *++xp) {
                            break; /* enough codes to use up j bits */
                        }
                        f -= *xp; /* else deduct codes from patterns */
                    }
                }
                j = (w + j > eob_len && w < eob_len) ? eob_len - w : j; /* make EOB code end at table */
                z = 1 << j; /* table entries for j-bit table */
                ws[htl+1] = w + j;  /* set bits decoded in stack */

                /* allocate and link in new table */
                q = (huft_t *) xzalloc((z + 1) * sizeof(huft_t));
                *t = q + 1; /* link to list for huft_free() */
                t = &(q->v.t);
                u[htl] = ++q;   /* table starts after link */

                /* connect to last table, if there is one */
                if (htl) {
                    x[htl] = i; /* save pattern for backing up */
                    r.b = (unsigned char) (w - ws[htl - 1]); /* bits to dump before this table */
                    r.e = (unsigned char) (16 + j); /* bits in this table */
                    r.v.t = q; /* pointer to this table */
                    j = (i & ((1 << w) - 1)) >> ws[htl - 1];
                    u[htl - 1][j] = r; /* connect to last table */
                }
            }

            /* set up table entry in r */
            r.b = (unsigned char) (k - w);
            if (p >= v + n) {
                r.e = 99; /* out of values--invalid code */
            } else if (*p < s) {
                r.e = (unsigned char) (*p < 256 ? 16 : 15); /* 256 is EOB code */
                r.v.n = (unsigned short) (*p++); /* simple code is just the value */
            } else {
                r.e = (unsigned char) e[*p - s]; /* non-simple--look up in lists */
                r.v.n = d[*p++ - s];
            }

            /* fill code-like entries with r */
            f = 1 << (k - w);
            for (j = i >> w; j < z; j += f) {
                q[j] = r;
            }

            /* backwards increment the k-bit code i */
            for (j = 1 << (k - 1); i & j; j >>= 1) {
                i ^= j;
            }
            i ^= j;

            /* backup over finished tables */
            while ((i & ((1 << w) - 1)) != x[htl]) {
                w = ws[--htl];
            }
        }
    }

    /* return actual size of base table */
    *m = ws[1];

    /* Return true (1) if we were given an incomplete table */
    return y != 0 && g != 1;
}

/*
 * inflate (decompress) the codes in a deflated (compressed) block.
 * Return an error code or zero if it all goes ok.
 *
 * tl, td: literal/length and distance decoder tables
 * bl, bd: number of bits decoded by tl[] and td[]
 */
static int inflate_codes(huft_t * my_tl, huft_t * my_td, const unsigned int my_bl, const unsigned int my_bd, int setup)
{
    static unsigned int e;  /* table entry flag/number of extra bits */
    static unsigned int n, d;   /* length and index for copy */
    static unsigned int w;  /* current gunzip_window position */
    static huft_t *t;           /* pointer to table entry */
    static unsigned int ml, md; /* masks for bl and bd bits */
    static unsigned int b;  /* bit buffer */
    static unsigned int k;          /* number of bits in bit buffer */
    static huft_t *tl, *td;
    static unsigned int bl, bd;
    static int resumeCopy = 0;

    if (setup) { // 1st time we are called, copy in variables
        tl = my_tl;
        td = my_td;
        bl = my_bl;
        bd = my_bd;
        /* make local copies of globals */
        b = gunzip_bb;              /* initialize bit buffer */
        k = gunzip_bk;
        w = gunzip_outbuf_count;            /* initialize gunzip_window position */

        /* inflate the coded data */
        ml = mask_bits[bl]; /* precompute masks for speed */
        md = mask_bits[bd];
        return 0; // Don't actually do anything the first time
    }

    if (resumeCopy) goto do_copy;

    while (1) {         /* do until end of block */
        b = fill_bitbuffer(b, &k, bl);
        if ((e = (t = tl + ((unsigned) b & ml))->e) > 16)
            do {
                if (e == 99) {
                    bb_error_msg_and_die("inflate_codes error 1");
                }
                b >>= t->b;
                k -= t->b;
                e -= 16;
                b = fill_bitbuffer(b, &k, e);
            } while ((e =
                      (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
        b >>= t->b;
        k -= t->b;
        if (e == 16) {  /* then it's a literal */
            gunzip_window[w++] = (unsigned char) t->v.n;
            if (w == gunzip_wsize) {
                gunzip_outbuf_count = (w);
                //flush_gunzip_window();
                w = 0;
                return 1; // We have a block to read
            }
        } else {        /* it's an EOB or a length */

            /* exit if end of block */
            if (e == 15) {
                break;
            }

            /* get length of block to copy */
            b = fill_bitbuffer(b, &k, e);
            n = t->v.n + ((unsigned) b & mask_bits[e]);
            b >>= e;
            k -= e;

            /* decode distance of block to copy */
            b = fill_bitbuffer(b, &k, bd);
            if ((e = (t = td + ((unsigned) b & md))->e) > 16)
                do {
                    if (e == 99)
                        bb_error_msg_and_die("inflate_codes error 2");
                    b >>= t->b;
                    k -= t->b;
                    e -= 16;
                    b = fill_bitbuffer(b, &k, e);
                } while ((e =
                          (t =
                           t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
            b >>= t->b;
            k -= t->b;
            b = fill_bitbuffer(b, &k, e);
            d = w - t->v.n - ((unsigned) b & mask_bits[e]);
            b >>= e;
            k -= e;

            /* do the copy */
do_copy:        do {
                n -= (e =
                      (e =
                       gunzip_wsize - ((d &= gunzip_wsize - 1) > w ? d : w)) > n ? n : e);
               /* copy to new buffer to prevent possible overwrite */
                if (w - d >= e) {   /* (this test assumes unsigned comparison) */
                    memcpy(gunzip_window + w, gunzip_window + d, e);
                    w += e;
                    d += e;
                } else {
                   /* do it slow to avoid memcpy() overlap */
                   /* !NOMEMCPY */
                    do {
                        gunzip_window[w++] = gunzip_window[d++];
                    } while (--e);
                }
                if (w == gunzip_wsize) {
                    gunzip_outbuf_count = (w);
                    if (n) resumeCopy = 1;
                    else resumeCopy = 0;
                    //flush_gunzip_window();
                    w = 0;
                    return 1;
                }
            } while (n);
            resumeCopy = 0;
        }
    }

    /* restore the globals from the locals */
    gunzip_outbuf_count = w;            /* restore global gunzip_window pointer */
    gunzip_bb = b;              /* restore global bit buffer */
    gunzip_bk = k;

    /* normally just after call to inflate_codes, but save code by putting it here */
    /* free the decoding tables, return */
    huft_free(tl);
    huft_free(td);

    /* done */
    return 0;
}

static int inflate_stored(int my_n, int my_b_stored, int my_k_stored, int setup)
{
    static unsigned int n, b_stored, k_stored, w;
    if (setup) {
        n = my_n;
        b_stored = my_b_stored;
        k_stored = my_k_stored;
        w = gunzip_outbuf_count;        /* initialize gunzip_window position */
        return 0; // Don't do anything first time
    }

    /* read and output the compressed data */
    while (n--) {
        b_stored = fill_bitbuffer(b_stored, &k_stored, 8);
        gunzip_window[w++] = (unsigned char) b_stored;
        if (w == gunzip_wsize) {
            gunzip_outbuf_count = (w);
            //flush_gunzip_window();
            w = 0;
            b_stored >>= 8;
            k_stored -= 8;
            return 1; // We have a block
        }
        b_stored >>= 8;
        k_stored -= 8;
    }

    /* restore the globals from the locals */
    gunzip_outbuf_count = w;        /* restore global gunzip_window pointer */
    gunzip_bb = b_stored;   /* restore global bit buffer */
    gunzip_bk = k_stored;
    return 0; // Finished
}

/*
 * decompress an inflated block
 * e: last block flag
 *
 * GLOBAL VARIABLES: bb, kk,
 */
 // Return values: -1 = inflate_stored, -2 = inflate_codes
static int inflate_block(int *e)
{
    unsigned t;         /* block type */
    register unsigned int b;    /* bit buffer */
    unsigned int k; /* number of bits in bit buffer */

    /* make local bit buffer */

    b = gunzip_bb;
    k = gunzip_bk;

    /* read in last block bit */
    b = fill_bitbuffer(b, &k, 1);
    *e = (int) b & 1;
    b >>= 1;
    k -= 1;

    /* read in block type */
    b = fill_bitbuffer(b, &k, 2);
    t = (unsigned) b & 3;
    b >>= 2;
    k -= 2;

    /* restore the global bit buffer */
    gunzip_bb = b;
    gunzip_bk = k;

    /* inflate that block type */
    switch (t) {
    case 0:         /* Inflate stored */
    {
        unsigned int n; /* number of bytes in block */
        unsigned int b_stored;  /* bit buffer */
        unsigned int k_stored;  /* number of bits in bit buffer */

        /* make local copies of globals */
        b_stored = gunzip_bb;   /* initialize bit buffer */
        k_stored = gunzip_bk;

        /* go to byte boundary */
        n = k_stored & 7;
        b_stored >>= n;
        k_stored -= n;

        /* get the length and its complement */
        b_stored = fill_bitbuffer(b_stored, &k_stored, 16);
        n = ((unsigned) b_stored & 0xffff);
        b_stored >>= 16;
        k_stored -= 16;

        b_stored = fill_bitbuffer(b_stored, &k_stored, 16);
        if (n != (unsigned) ((~b_stored) & 0xffff)) {
            return 1;   /* error in compressed data */
        }
        b_stored >>= 16;
        k_stored -= 16;

        inflate_stored(n, b_stored, k_stored, 1); // Setup inflate_stored
        return -1;
    }
    case 1:         /* Inflate fixed
                           * decompress an inflated type 1 (fixed Huffman codes) block.  We should
                           * either replace this with a custom decoder, or at least precompute the
                           * Huffman tables.
                         */
    {
        int i;          /* temporary variable */
        huft_t *tl;     /* literal/length code table */
        huft_t *td;     /* distance code table */
        unsigned int bl;            /* lookup bits for tl */
        unsigned int bd;            /* lookup bits for td */
        unsigned int l[288];    /* length list for huft_build */

        /* set up literal table */
        for (i = 0; i < 144; i++) {
            l[i] = 8;
        }
        for (; i < 256; i++) {
            l[i] = 9;
        }
        for (; i < 280; i++) {
            l[i] = 7;
        }
        for (; i < 288; i++) {  /* make a complete, but wrong code set */
            l[i] = 8;
        }
        bl = 7;
        if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) {
            return i;
        }

        /* set up distance table */
        for (i = 0; i < 30; i++) {  /* make an incomplete code set */
            l[i] = 5;
        }
        bd = 5;
        if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1) {
            huft_free(tl);
            return i;
        }

        /* decompress until an end-of-block code */
        inflate_codes(tl, td, bl, bd, 1); // Setup inflate_codes

        /* huft_free code moved into inflate_codes */

        return -2;
    }
    case 2:         /* Inflate dynamic */
    {
        const int dbits = 6;    /* bits in base distance lookup table */
        const int lbits = 9;    /* bits in base literal/length lookup table */

        huft_t *tl;     /* literal/length code table */
        huft_t *td;     /* distance code table */
        unsigned int i;         /* temporary variables */
        unsigned int j;
        unsigned int l;     /* last length */
        unsigned int m;     /* mask for bit lengths table */
        unsigned int n;     /* number of lengths to get */
        unsigned int bl;            /* lookup bits for tl */
        unsigned int bd;            /* lookup bits for td */
        unsigned int nb;    /* number of bit length codes */
        unsigned int nl;    /* number of literal/length codes */
        unsigned int nd;    /* number of distance codes */

        unsigned int ll[286 + 30];  /* literal/length and distance code lengths */
        unsigned int b_dynamic; /* bit buffer */
        unsigned int k_dynamic; /* number of bits in bit buffer */

        /* make local bit buffer */
        b_dynamic = gunzip_bb;
        k_dynamic = gunzip_bk;

        /* read in table lengths */
        b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 5);
        nl = 257 + ((unsigned int) b_dynamic & 0x1f);   /* number of literal/length codes */

        b_dynamic >>= 5;
        k_dynamic -= 5;
        b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 5);
        nd = 1 + ((unsigned int) b_dynamic & 0x1f); /* number of distance codes */

        b_dynamic >>= 5;
        k_dynamic -= 5;
        b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 4);
        nb = 4 + ((unsigned int) b_dynamic & 0xf);  /* number of bit length codes */

        b_dynamic >>= 4;
        k_dynamic -= 4;
        if (nl > 286 || nd > 30) {
            return 1;   /* bad lengths */
        }

        /* read in bit-length-code lengths */
        for (j = 0; j < nb; j++) {
            b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 3);
            ll[border[j]] = (unsigned int) b_dynamic & 7;
            b_dynamic >>= 3;
            k_dynamic -= 3;
        }
        for (; j < 19; j++) {
            ll[border[j]] = 0;
        }

        /* build decoding table for trees--single level, 7 bit lookup */
        bl = 7;
        i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl);
        if (i != 0) {
            if (i == 1) {
                huft_free(tl);
            }
            return i;   /* incomplete code set */
        }

        /* read in literal and distance code lengths */
        n = nl + nd;
        m = mask_bits[bl];
        i = l = 0;
        while ((unsigned int) i < n) {
            b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, (unsigned int)bl);
            j = (td = tl + ((unsigned int) b_dynamic & m))->b;
            b_dynamic >>= j;
            k_dynamic -= j;
            j = td->v.n;
            if (j < 16) {   /* length of code in bits (0..15) */
                ll[i++] = l = j;    /* save last length in l */
            } else if (j == 16) {   /* repeat last length 3 to 6 times */
                b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 2);
                j = 3 + ((unsigned int) b_dynamic & 3);
                b_dynamic >>= 2;
                k_dynamic -= 2;
                if ((unsigned int) i + j > n) {
                    return 1;
                }
                while (j--) {
                    ll[i++] = l;
                }
            } else if (j == 17) {   /* 3 to 10 zero length codes */
                b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 3);
                j = 3 + ((unsigned int) b_dynamic & 7);
                b_dynamic >>= 3;
                k_dynamic -= 3;
                if ((unsigned int) i + j > n) {
                    return 1;
                }
                while (j--) {
                    ll[i++] = 0;
                }
                l = 0;
            } else {    /* j == 18: 11 to 138 zero length codes */
                b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 7);
                j = 11 + ((unsigned int) b_dynamic & 0x7f);
                b_dynamic >>= 7;
                k_dynamic -= 7;
                if ((unsigned int) i + j > n) {
                    return 1;
                }
                while (j--) {
                    ll[i++] = 0;
                }
                l = 0;
            }
        }

        /* free decoding table for trees */
        huft_free(tl);

        /* restore the global bit buffer */
        gunzip_bb = b_dynamic;
        gunzip_bk = k_dynamic;

        /* build the decoding tables for literal/length and distance codes */
        bl = lbits;

        if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) {
            if (i == 1) {
                bb_error_msg_and_die("Incomplete literal tree");
                huft_free(tl);
            }
            return i;   /* incomplete code set */
        }

        bd = dbits;
        if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) {
            if (i == 1) {
                bb_error_msg_and_die("incomplete distance tree");
                huft_free(td);
            }
            huft_free(tl);
            return i;   /* incomplete code set */
        }

        /* decompress until an end-of-block code */
        inflate_codes(tl, td, bl, bd, 1); // Setup inflate_codes

        /* huft_free code moved into inflate_codes */

        return -2;
    }
    default:
        /* bad block type */
        bb_error_msg_and_die("bad block type %d\n", t);
    }
}

static void calculate_gunzip_crc(void)
{
    int n;
    for (n = 0; n < gunzip_outbuf_count; n++) {
        gunzip_crc = gunzip_crc_table[((int) gunzip_crc ^ (gunzip_window[n])) & 0xff] ^ (gunzip_crc >> 8);
    }
    gunzip_bytes_out += gunzip_outbuf_count;
}

static int inflate_get_next_window(void)
{
    static int method = -1; // Method == -1 for stored, -2 for codes
    static int e = 0;
    static int needAnotherBlock = 1;

    gunzip_outbuf_count = 0;

    while(1) {
        int ret;

        if (needAnotherBlock) {
            if(e) {
                calculate_gunzip_crc();
                e = 0;
                needAnotherBlock = 1;
                return 0;
            } // Last block
            method = inflate_block(&e);
            needAnotherBlock = 0;
        }

        switch (method) {
            case -1:    ret = inflate_stored(0,0,0,0);
                    break;
            case -2:    ret = inflate_codes(0,0,0,0,0);
                    break;
            default:    bb_error_msg_and_die("inflate error %d", method);
        }

        if (ret == 1) {
            calculate_gunzip_crc();
            return 1; // More data left
        } else needAnotherBlock = 1; // End of that block
    }
    /* Doesnt get here */
}

/* Initialise bytebuffer, be careful not to overfill the buffer */
void inflate_init(unsigned int bufsize)
{
    /* Set the bytebuffer size, default is same as gunzip_wsize */
    bytebuffer_max = bufsize + 8;
    bytebuffer_offset = 4;
    bytebuffer_size = 0;
}

void inflate_cleanup(void)
{
    free(bytebuffer);
}

int inflate_unzip(int in, int out)
{
    ssize_t nwrote;
    typedef void (*sig_type) (int);

    /* Allocate all global buffers (for DYN_ALLOC option) */
    gunzip_window = xmalloc(gunzip_wsize);
    gunzip_outbuf_count = 0;
    gunzip_bytes_out = 0;
    gunzip_src_fd = in;

    /* initialize gunzip_window, bit buffer */
    gunzip_bk = 0;
    gunzip_bb = 0;

    /* Create the crc table */
    gunzip_crc_table = bb_crc32_filltable(0);
    gunzip_crc = ~0;
    
    /* Allocate space for buffer */
    bytebuffer = xmalloc(bytebuffer_max);

    while(1) {
        int ret = inflate_get_next_window();
        nwrote = bb_full_write(out, gunzip_window, gunzip_outbuf_count);
        if (nwrote == -1) {
            bb_perror_msg("write");
            return -1;
        }
        if (ret == 0) break;
    }

    /* Cleanup */
    free(gunzip_window);
    free(gunzip_crc_table);

    /* Store unused bytes in a global buffer so calling applets can access it */
    if (gunzip_bk >= 8) {
        /* Undo too much lookahead. The next read will be byte aligned
         * so we can discard unused bits in the last meaningful byte. */
        bytebuffer_offset--;
        bytebuffer[bytebuffer_offset] = gunzip_bb & 0xff;
        gunzip_bb >>= 8;
        gunzip_bk -= 8;
    }
    return 0;
}

int inflate_gunzip(int in, int out)
{
    uint32_t stored_crc = 0;
    unsigned int count;

    inflate_unzip(in, out);

    /* top up the input buffer with the rest of the trailer */
    count = bytebuffer_size - bytebuffer_offset;
    if (count < 8) {
        bb_xread_all(in, &bytebuffer[bytebuffer_size], 8 - count);
        bytebuffer_size += 8 - count;
    }
    for (count = 0; count != 4; count++) {
        stored_crc |= (bytebuffer[bytebuffer_offset] << (count * 8));
        bytebuffer_offset++;
    }

    /* Validate decompression - crc */
    if (stored_crc != (~gunzip_crc)) {
        bb_error_msg("crc error");
        return -1;
    }

    /* Validate decompression - size */
    if (gunzip_bytes_out !=
        (bytebuffer[bytebuffer_offset] | (bytebuffer[bytebuffer_offset+1] << 8) |
        (bytebuffer[bytebuffer_offset+2] << 16) | (bytebuffer[bytebuffer_offset+3] << 24))) {
        bb_error_msg("Incorrect length");
        return -1;
    }

    return 0;
}