[oweals/busybox.git] / archival / libunarchive / decompress_unzip.c

/* 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 <andersee@debian.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@optushome.com.au>
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 *
 * 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 license_msg below and the file COPYING for the software license.
 * See the file algorithm.doc for the compression algorithms and file formats.
 */

#if 0
static char *license_msg[] = {
        "   Copyright (C) 1992-1993 Jean-loup Gailly",
        "   This program is free software; you can redistribute it and/or modify",
        "   it under the terms of the GNU General Public License as published by",
        "   the Free Software Foundation; either version 2, 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 General Public License for more details.",
        "",
        "   You should have received a copy of the GNU General Public License",
        "   along with this program; if not, write to the Free Software",
        "   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.",
        0
};
#endif

#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include "config.h"
#include "busybox.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 */

/* This is used to sanify any unused bits from the bitbuffer 
 * so they arent skipped when reading trailers (trailing headers) */
unsigned char gunzip_in_buffer_count;
unsigned char *gunzip_in_buffer;

/* gunzip_window size--must be a power of two, and
 *  at least 32K for zip's deflate method */
static const int gunzip_wsize = 0x8000;
static int output_buffer_size = 0x8000; // gunzip_wsize initially

static unsigned char *gunzip_window;
static unsigned int *gunzip_crc_table;
unsigned int gunzip_crc;

static unsigned char *output_buffer;
static unsigned int output_buffer_len;

/* 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 */

static unsigned int gunzip_hufts;       /* track memory usage */
static unsigned int gunzip_bb;  /* bit buffer */
static unsigned char gunzip_bk; /* bits in bit buffer */

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) {
                bitbuffer |= ((unsigned int) xread_char(gunzip_src_fd)) << *current;
                *current += 8;
        }

        return(bitbuffer);
}

static void abort_gzip(void)
{
        error_msg("gzip aborted\n");
        exit(-1);
}

static void make_gunzip_crc_table(void)
{
        const unsigned int poly = 0xedb88320;   /* polynomial exclusive-or pattern */
        unsigned short i;       /* counter for all possible eight bit values */

        /* initial shift register value */
        gunzip_crc = 0xffffffffL;
        gunzip_crc_table = (unsigned int *) malloc(256 * sizeof(unsigned int));

        /* Compute and print table of CRC's, five per line */
        for (i = 0; i < 256; i++) {
                unsigned int table_entry;       /* crc shift register */
                unsigned char k;        /* byte being shifted into crc apparatus */

                table_entry = i;
                /* The idea to initialize the register with the byte instead of
                   * zero was stolen from Haruhiko Okumura's ar002
                 */
                for (k = 8; k; k--) {
                        if (table_entry & 1) {
                                table_entry = (table_entry >> 1) ^ poly;
                        } else {
                                table_entry >>= 1;
        }
        }
                gunzip_crc_table[i] = table_entry;
        }
}

/*
 * 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, int *m)
{
        unsigned a;                     /* counter for codes of length k */
        unsigned c[BMAX + 1];   /* bit length count table */
        unsigned f;                     /* i repeats in table every f entries */
        int g;                          /* maximum code length */
        int h;                          /* table level */
        register unsigned i;    /* counter, current code */
        register unsigned j;    /* counter */
        register int k;         /* number of bits in current code */
        int l;                          /* bits per table (returned in m) */
        register unsigned *p;   /* pointer into c[], b[], or v[] */
        register 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 */
        register int w;         /* bits before this table == (l * h) */
        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 */

        /* 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 0;
        }

        /* Find minimum and maximum length, bound *m by those */
        l = *m;
        for (j = 1; j <= BMAX; j++) {
                if (c[j]) {
                        break;
                }
        }
        k = j;                          /* minimum code length */
        if ((unsigned) l < j) {
                l = j;
        }
        for (i = BMAX; i; i--) {
                if (c[i]) {
                        break;
                }
        }
        g = i;                          /* maximum code length */
        if ((unsigned) l > i) {
                l = i;
        }
        *m = l;

        /* 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 */
        h = -1;                         /* no tables yet--level -1 */
        w = -l;                         /* bits decoded == (l * h) */
        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 > w + l) {
                                h++;
                                w += l; /* previous table always l bits */

                                /* compute minimum size table less than or equal to l bits */
                                z = (z = g - w) > (unsigned) l ? l : 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 */
                                        }
                                }
                                z = 1 << j;     /* table entries for j-bit table */

                                /* allocate and link in new table */
                                q = (huft_t *) xmalloc((z + 1) * sizeof(huft_t));

                                gunzip_hufts += z + 1;  /* track memory usage */
                                *t = q + 1;     /* link to list for huft_free() */
                                *(t = &(q->v.t)) = NULL;
                                u[h] = ++q;     /* table starts after link */

                                /* connect to last table, if there is one */
                                if (h) {
                                        x[h] = i;       /* save pattern for backing up */
                                        r.b = (unsigned char) l;        /* 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 >> (w - l);       /* (get around Turbo C bug) */
                                        u[h - 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 end-of-block code */
                                r.v.n = (unsigned short) (*p);  /* simple code is just the value */
                                p++;    /* one compiler does not like *p++ */
                        } 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[h]) {
                                h--;    /* don't need to update q */
                                w -= l;
                        }
                }
        }
        /* Return true (1) if we were given an incomplete table */
        return y != 0 && g != 1;
}

/* ===========================================================================
 * Write the output gunzip_window gunzip_window[0..gunzip_outbuf_count-1] and update crc and gunzip_bytes_out.
 * (Used for the decompressed data only.)
 */
static void flush_gunzip_window(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);
        }

        if (output_buffer_len == 0) { // Our buffer is empty -> straight memcpy
                memcpy(output_buffer, gunzip_window, gunzip_outbuf_count);
                output_buffer_len = gunzip_outbuf_count;
        } else { // Bit more complicated, append to end of output_buffer, realloc as necessary
                int newlen = output_buffer_len + gunzip_outbuf_count;
                if (newlen > output_buffer_size) {
                        output_buffer = xrealloc(output_buffer, newlen); // Could free later, but as we now have the memory...
                        //printf("Using %d byte output buffer\n", newlen);
                        output_buffer_size = newlen;
                }
                memcpy(output_buffer + output_buffer_len, gunzip_window, gunzip_outbuf_count);
                output_buffer_len += gunzip_outbuf_count;
        }
        
        gunzip_bytes_out += gunzip_outbuf_count;
        gunzip_outbuf_count = 0;
}

/*
 * 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 * tl, huft_t * td, const unsigned int bl, const unsigned int bd)
{
        unsigned int e; /* table entry flag/number of extra bits */
        unsigned int n, d;      /* length and index for copy */
        unsigned int w; /* current gunzip_window position */
        huft_t *t;                      /* pointer to table entry */
        unsigned int ml, md;    /* masks for bl and bd bits */
        unsigned int b; /* bit buffer */
        unsigned int k;                 /* number of bits in bit buffer */

        /* 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];
        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) {
                                        return 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;
                        }
                } 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)
                                                return 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;
                        b = fill_bitbuffer(b, &k, e);
                        d = w - t->v.n - ((unsigned) b & mask_bits[e]);
                        b >>= e;
                        k -= e;

                        /* do the 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);
                                        flush_gunzip_window();
                                        w = 0;
                                }

                        } while (n);
                }
        }

        /* 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;

        /* done */
        return 0;
}

/*
 * decompress an inflated block
 * e: last block flag
 *
 * GLOBAL VARIABLES: bb, kk,
 */
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 w; /* current gunzip_window position */
                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;
                w = gunzip_outbuf_count;                /* initialize gunzip_window position */

                /* 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;

                /* 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 == (unsigned int) gunzip_wsize) {
                                gunzip_outbuf_count = (w);
                                flush_gunzip_window();
                                w = 0;
                        }
                        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;
        }
        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 */
                if (inflate_codes(tl, td, bl, bd)) {
                        return 1;
                }

                /* free the decoding tables, return */
                huft_free(tl);
                huft_free(td);
                return 0;
        }
        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) {
                                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) {
                                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 */
                if (inflate_codes(tl, td, bl, bd)) {
                        return 1;
                }

                /* free the decoding tables, return */
                huft_free(tl);
                huft_free(td);
                return 0;
        }
        default:
                /* bad block type */
                error_msg("bad block type %d\n", t);
                return 2;
        }
}

/*
 * decompress an inflated entry
 *
 * GLOBAL VARIABLES: gunzip_outbuf_count, bk, gunzip_bb, hufts, inptr
 */

extern ssize_t read_gz(int fd, void *buf, size_t count)
{
        static int e = 0;                               /* last block flag */
        int r;                          /* result code */
        unsigned h = 0;         /* maximum struct huft's malloc'ed */
        ssize_t written = count;
        static char *output_buffer_ptr = 0;

        while (output_buffer_len == 0) { // We need more data
                if (e) return 0; // No more data here!
                gunzip_hufts = 0;
                r = inflate_block(&e);
                if (r != 0) {
                        error_msg_and_die("inflate error %d", r);
                        return -1;
                }
                if (gunzip_hufts > h) {
                        h = gunzip_hufts;
                }
                if (e) { // Ok finished uncompressing, get any buffered uncompressed data
                        flush_gunzip_window();
                }
                output_buffer_ptr = output_buffer;
        }
        if (count > output_buffer_len) written = output_buffer_len; // We're only giving them as much as we have!
        memcpy(buf, output_buffer_ptr, written);
        output_buffer_ptr += written;
        output_buffer_len -= written;

        return written;
}

extern void GZ_gzReadOpen(int fd, void *unused, int nUnused)
{
        typedef void (*sig_type) (int);

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

        gunzip_in_buffer = malloc(8);

        if (signal(SIGINT, SIG_IGN) != SIG_IGN) {
                (void) signal(SIGINT, (sig_type) abort_gzip);
        }
#ifdef SIGHUP
        if (signal(SIGHUP, SIG_IGN) != SIG_IGN) {
                (void) signal(SIGHUP, (sig_type) abort_gzip);
        }
#endif

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

        /* Create the crc table */
        make_gunzip_crc_table();
}

extern void GZ_gzReadClose(void)
{
        /* Cleanup */
        free(gunzip_window);
        free(output_buffer);
        free(gunzip_crc_table);

        /* Store unused bytes in a global buffer so calling applets can access it */
        gunzip_in_buffer_count = 0;
        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. */
                gunzip_in_buffer[gunzip_in_buffer_count] = gunzip_bb & 0xff;
                gunzip_in_buffer_count++;
                gunzip_bb >>= 8;
                gunzip_bk -= 8;
        }
}

extern int inflate(int in, int out)
{
        char buf[8192];
        ssize_t nread, nwrote;
        ssize_t total = 0;

        GZ_gzReadOpen(in, 0, 0);
        while(1) { // Robbed from copyfd.c
                nread = read_gz(in, buf, sizeof(buf));
                if (nread == 0) break; // no data to write
                else if (nread == -1) {
                        perror_msg("read");
                        return -1;
                }
                nwrote = full_write(out, buf, nread);
                if (nwrote == -1) {
                        perror_msg("write");
                        return -1;
                }
                total += nwrote;
        }
        GZ_gzReadClose();
        return 0;
}