inflate.c

/**
 *  Copyright 2010 by Benjamin J. Land (a.k.a. BenLand100)
 *
 *  This file is part of SJVM the Simple Java Virtual Machine.
 *
 *  SJVM 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  SJVM 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 SJVM. If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Mark Adler's INFLATE algorithm, heavily modified by Benjamin Land
 */

#define	IDBG(s) /* XXX */

#include "Inflate.h"

#define	WSIZE	0x8000

typedef struct _huft {
    unsigned char e; /* number of extra bits or operation */
    unsigned char b;

    /* number of bits in this code or subcode */
    union {
        unsigned short int n; /* literal, length base, or distance base */
        struct _huft* t; /* pointer to next level of table */
    } v;
} huft;

static int inflate_codes(inflateInfo*, huft*, huft*, int, int);
static int inflate_stored(inflateInfo*);
static int inflate_fixed(inflateInfo*);
static int inflate_dynamic(inflateInfo*);
static int inflate_block(inflateInfo*, int*);
static int huft_free(huft*);
static int inflate(inflateInfo*);
static int huft_build(inflateInfo* pG, unsigned* b, unsigned n, unsigned s, unsigned short int* d, unsigned short int* e, huft** t, int* m);

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

static unsigned short int cplens[] = {/* Copy lengths for literal codes 257..285 */
    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. */

static unsigned short int cplext[] = {/* Extra bits for literal codes 257..285 */
    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 */

static unsigned short int cpdist[] = {/* Copy offsets for distance codes 0..29 */
    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};

static unsigned short int cpdext[] = {/* Extra bits for distance codes */
    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};

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

#define	LBITS	9		/* bits in base literal/length lookup table */
#define	DBITS	6		/* bits in base distance lookup table */

#define NEEDBITS(G, N)						\
	{							\
		unsigned long int c;					\
		while (k < (N)) {				\
			if ((G)->insz <= 0) {			\
				return (1);			\
			}					\
			c = (G)->inbuf[0];			\
			(G)->inbuf++;				\
			b |= c << k;				\
			k += 8;					\
		}						\
	}

#define DUMPBITS(G, N)						\
	{							\
		b >>= (N);					\
		k -= (N);					\
	}

#define	FLUSH(G, N)						\
	{							\
		int c;						\
		int p;						\
		c = ((N) < (G)->outsz ? (N) : (G)->outsz);	\
		for (p = 0; c > 0; p++, c--) {			\
			(G)->outbuf[p] = (G)->slide[p];		\
		}						\
		(G)->outbuf += p;				\
		(G)->outsz -= p;				\
	}

static int inflate_codes(inflateInfo* pG, huft* tl, huft* td, int bl, int bd) {
    register unsigned e; /* table entry flag/number of extra bits */
    unsigned n, d; /* length and index for copy */
    unsigned w; /* current window position */
    huft *t; /* pointer to table entry */
    unsigned ml, md; /* masks for bl and bd bits */
    register unsigned long int b; /* bit buffer */
    register unsigned k; /* number of bits in bit buffer */


    /* make local copies of globals */
    b = pG->bb; /* initialize bit buffer */
    k = pG->bk;
    w = pG->wp; /* initialize 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 */ {
        NEEDBITS(pG, (unsigned) bl)
        if ((e = (t = tl + ((unsigned) b & ml))->e) > 16)
            do {
                if (e == 99)
                    return 1;
                DUMPBITS(pG, t->b)
                e -= 16;
                NEEDBITS(pG, e)
            } while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
        DUMPBITS(pG, t->b)
        if (e == 16) /* then it's a literal */ {
            pG->slide[w++] = (unsigned char) t->v.n;
            if (w == WSIZE) {
                FLUSH(pG, w);
                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 */
            NEEDBITS(pG, e)
            n = t->v.n + ((unsigned) b & mask_bits[e]);
            DUMPBITS(pG, e);

            /* decode distance of block to copy */
            NEEDBITS(pG, (unsigned) bd)
            if ((e = (t = td + ((unsigned) b & md))->e) > 16)
                do {
                    if (e == 99)
                        return 1;
                    DUMPBITS(pG, t->b)
                    e -= 16;
                    NEEDBITS(pG, e)
                } while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
            DUMPBITS(pG, t->b)
            NEEDBITS(pG, e)
            d = w - t->v.n - ((unsigned) b & mask_bits[e]);
            DUMPBITS(pG, e)

                    /* do the copy */
            do {
                n -= (e = (e = WSIZE - ((d &= WSIZE - 1) > w ? d : w)) > n ? n : e);
                if (w - d >= e) /* (this test assumes unsigned comparison) */ {
                    memcpy(pG->slide + w, pG->slide + d, e);
                    w += e;
                    d += e;
                } else /* do it slowly to avoid memcpy() overlap */
                    do {
                        pG->slide[w++] = pG->slide[d++];
                    } while (--e);
                if (w == WSIZE) {
                    FLUSH(pG, w);
                    w = 0;
                }
            } while (n);
        }
    }


    /* restore the globals from the locals */
    pG->wp = w; /* restore global window pointer */
    pG->bb = b; /* restore global bit buffer */
    pG->bk = k;


    /* done */
    return 0;
}

static int inflate_stored(inflateInfo* pG) {
    unsigned n; /* number of bytes in block */
    unsigned w; /* current window position */
    register unsigned long int b; /* bit buffer */
    register unsigned k; /* number of bits in bit buffer */


    /* make local copies of globals */
    IDBG(dprintf("\nstored block"));
    b = pG->bb; /* initialize bit buffer */
    k = pG->bk;
    w = pG->wp; /* initialize window position */


    /* go to byte boundary */
    n = k & 7;
    DUMPBITS(pG, n);


    /* get the length and its complement */
    NEEDBITS(pG, 16)
    n = ((unsigned) b & 0xffff);
    DUMPBITS(pG, 16)
    NEEDBITS(pG, 16)
    if (n != (unsigned) ((~b) & 0xffff))
        return 1; /* error in compressed data */
    DUMPBITS(pG, 16)


            /* read and output the compressed data */
    while (n--) {
        NEEDBITS(pG, 8)
        pG->slide[w++] = (unsigned char) b;
        if (w == WSIZE) {
            FLUSH(pG, w);
            w = 0;
        }
        DUMPBITS(pG, 8)
    }


    /* restore the globals from the locals */
    pG->wp = w; /* restore global window pointer */
    pG->bb = b; /* restore global bit buffer */
    pG->bk = k;
    return 0;
}

static int inflate_fixed(inflateInfo* pG) {
    /* if first time, set up tables for fixed blocks */
    IDBG(dprintf("\nliteral block"));
    if (pG->fixed_tl == 0) {
        int i; /* temporary variable */
        unsigned l[288]; /* length list for huft_build */

        /* 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;
        pG->fixed_bl = 7;
        if ((i = huft_build(pG, l, 288, 257, cplens, cplext,
                &pG->fixed_tl, &pG->fixed_bl)) != 0) {
            pG->fixed_tl = 0;
            return i;
        }

        /* distance table */
        for (i = 0; i < 30; i++) /* make an incomplete code set */
            l[i] = 5;
        pG->fixed_bd = 5;
        if ((i = huft_build(pG, l, 30, 0, cpdist, cpdext,
                &pG->fixed_td, &pG->fixed_bd)) > 1) {
            huft_free(pG->fixed_tl);
            pG->fixed_tl = 0;
            return i;
        }
    }

    /* decompress until an end-of-block code */
    return inflate_codes(pG, pG->fixed_tl, pG->fixed_td,
            pG->fixed_bl, pG->fixed_bd) != 0;
}

static int inflate_dynamic(inflateInfo* pG) {
    int i; /* temporary variables */
    unsigned j;
    unsigned l; /* last length */
    unsigned m; /* mask for bit lengths table */
    unsigned n; /* number of lengths to get */
    huft *tl; /* literal/length code table */
    huft *td; /* distance code table */
    int bl; /* lookup bits for tl */
    int bd; /* lookup bits for td */
    unsigned nb; /* number of bit length codes */
    unsigned nl; /* number of literal/length codes */
    unsigned nd; /* number of distance codes */
    unsigned ll[288 + 32]; /* literal/length and distance code lengths */
    register unsigned long int b; /* bit buffer */
    register unsigned k; /* number of bits in bit buffer */


    /* make local bit buffer */
    IDBG(dprintf("\ndynamic block"));
    b = pG->bb;
    k = pG->bk;


    /* read in table lengths */
    NEEDBITS(pG, 5)
    nl = 257 + ((unsigned) b & 0x1f); /* number of literal/length codes */
    DUMPBITS(pG, 5)
    NEEDBITS(pG, 5)
    nd = 1 + ((unsigned) b & 0x1f); /* number of distance codes */
    DUMPBITS(pG, 5)
    NEEDBITS(pG, 4)
    nb = 4 + ((unsigned) b & 0xf); /* number of bit length codes */
    DUMPBITS(pG, 4)
    if (nl > 288 || nd > 32)
        return 1; /* bad lengths */


    /* read in bit-length-code lengths */
    for (j = 0; j < nb; j++) {
        NEEDBITS(pG, 3)
        ll[border[j]] = (unsigned) b & 7;
        DUMPBITS(pG, 3)
    }
    for (; j < 19; j++)
        ll[border[j]] = 0;


    /* build decoding table for trees--single level, 7 bit lookup */
    bl = 7;
    i = huft_build(pG, ll, 19, 19, 0, 0, &tl, &bl);
    if (bl == 0) /* no bit lengths */
        i = 1;
    if (i) {
        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) i < n) {
        NEEDBITS(pG, (unsigned) bl)
        j = (td = tl + ((unsigned) b & m))->b;
        DUMPBITS(pG, 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 */ {
            NEEDBITS(pG, 2)
            j = 3 + ((unsigned) b & 3);
            DUMPBITS(pG, 2)
            if ((unsigned) i + j > n)
                return 1;
            while (j--)
                ll[i++] = l;
        } else if (j == 17) /* 3 to 10 zero length codes */ {
            NEEDBITS(pG, 3)
            j = 3 + ((unsigned) b & 7);
            DUMPBITS(pG, 3)
            if ((unsigned) i + j > n)
                return 1;
            while (j--)
                ll[i++] = 0;
            l = 0;
        } else /* j == 18: 11 to 138 zero length codes */ {
            NEEDBITS(pG, 7)
            j = 11 + ((unsigned) b & 0x7f);
            DUMPBITS(pG, 7)
            if ((unsigned) 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 */
    pG->bb = b;
    pG->bk = k;


    /* build the decoding tables for literal/length and distance codes */
    bl = LBITS;
    i = huft_build(pG, ll, nl, 257, cplens, cplext, &tl, &bl);
    if (bl == 0) /* no literals or lengths */
        i = 1;
    if (i) {
        if (i == 1) {
            huft_free(tl);
        }
        return i; /* incomplete code set */
    }
    bd = DBITS;
    i = huft_build(pG, ll + nl, nd, 0, cpdist, cpdext, &td, &bd);
    if (bd == 0 && nl > 257) /* lengths but no distances */ {
        huft_free(tl);
        return 1;
    }
    if (i == 1) {
        i = 0;
    }
    if (i) {
        huft_free(tl);
        return i;
    }


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


    /* free the decoding tables, return */
    huft_free(tl);
    huft_free(td);
    return 0;
}

static int inflate_block(inflateInfo* pG, int* e) {
    unsigned t; /* block type */
    register unsigned long int b; /* bit buffer */
    register unsigned k; /* number of bits in bit buffer */


    /* make local bit buffer */
    b = pG->bb;
    k = pG->bk;


    /* read in last block bit */
    NEEDBITS(pG, 1)
            *e = (int) b & 1;
    DUMPBITS(pG, 1)


    /* read in block type */
    NEEDBITS(pG, 2)
    t = (unsigned) b & 3;
    DUMPBITS(pG, 2)


    /* restore the global bit buffer */
    pG->bb = b;
    pG->bk = k;


    /* inflate that block type */
    if (t == 2)
        return inflate_dynamic(pG);
    if (t == 0)
        return inflate_stored(pG);
    if (t == 1)
        return inflate_fixed(pG);


    /* bad block type */
    return 2;
}

/*
 * Create a new inflater.
 */
inflateInfo* inflate_new(void) {
    inflateInfo* info;

    info = malloc(sizeof(inflateInfo));
    if (!info) {
        return 0;
    }
    info->fixed_tl = 0;
    info->fixed_td = 0;
    info->fixed_bl = 0;
    info->fixed_bd = 0;
    info->slide = malloc(WSIZE);
    if (!info->slide) {
        free(info);
        return 0;
    }

    return (info);
}

/*
 * We pass in a buffer of deflated data and a place to stored the inflated
 * result.  This does not provide continuous operation and should only be
 * use in "one shot" more.
 */
int inflate_oneshot(unsigned char* ibuf, int ilen, unsigned char* obuf, int olen) {
    int r; /* result code: 0 on success */
    inflateInfo* pG;

    pG = inflate_new();

    if (!pG) {
        return 1;
    }

    pG->inbuf = ibuf;
    pG->insz = ilen;
    pG->outbuf = obuf;
    pG->outsz = olen;

    r = inflate(pG);

    inflate_free(pG);

    return (r);
}

/*
 * Inflate the given data into the given buffer.
 */
static int inflate(inflateInfo* pG) {
    int e; /* last block flag */
    int r; /* result code */
    unsigned h; /* maximum huft's malloc'ed */

    /* initialize window, bit buffer */
    pG->wp = 0;
    pG->bk = 0;
    pG->bb = 0;

    /* decompress until the last block */
    h = 0;
    do {
        pG->hufts = 0;
        if ((r = inflate_block(pG, &e)) != 0) {
            return r;
        }
        if (pG->hufts > h) {
            h = pG->hufts;
        }
    } while (!e);


    /* flush out G.slide */
    FLUSH(pG, pG->wp);

    /* return success */
    IDBG(dprintf("\n%u bytes in Huffman tables (%d/entry)\n", h * sizeof (huft), sizeof (huft)));
    return 0;
}

int inflate_free(inflateInfo* pG) {
    if (pG != 0) {
        if (pG->fixed_tl != 0) {
            huft_free(pG->fixed_td);
            huft_free(pG->fixed_tl);
            pG->fixed_td = pG->fixed_tl = 0;
        }
        free(pG->slide);
        free(pG);
    }

    return 0;
}


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

static int huft_build(inflateInfo* pG, unsigned* b, unsigned n, unsigned s, unsigned short int* d, unsigned short int* e, huft** t, int* m) {
    unsigned a; /* counter for codes of length k */
    unsigned c[BMAX + 1]; /* bit length count table */
    unsigned el; /* length of EOB code (value 256) */
    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 lx[BMAX + 1]; /* memory for l[-1..BMAX-1] */
    int *l = lx + 1; /* stack of bits per table */
    register unsigned *p; /* pointer into c[], b[], or v[] */
    register huft *q; /* points to current table */
    huft r; /* table entry for structure assignment */
    huft * 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 */
    el = n > 256 ? b[256] : BMAX; /* set length of EOB code, if any */
    memset(c, 0, sizeof (c));
    p = b;
    i = n;
    do {
        c[*p]++;
        p++; /* assume all entries <= BMAX */
    } while (--i);
    if (c[0] == n) /* null input--all zero length codes */ {
        *t = 0;
        *m = 0;
        return 0;
    }


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


    /* 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 */
    memset(v, 0, sizeof (v));
    p = b;
    i = 0;
    do {
        if ((j = *p++) != 0)
            v[x[j]++] = i;
    } while (++i < n);
    n = x[g]; /* set n to length of v */


    /* 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[-1] = 0; /* no bits decoded yet */
    u[0] = 0; /* just to keep compilers happy */
    q = 0; /* 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[h++]; /* add bits already decoded */

                /* compute minimum size table less than or equal to *m bits */
                z = (z = g - w) > (unsigned) * m ? *m : z; /* upper limit */
                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 */
                    }
                }
                if ((unsigned) w + j > el && (unsigned) w < el)
                    j = el - w; /* make EOB code end at table */
                z = 1 << j; /* table entries for j-bit table */
                l[h] = j; /* set table size in stack */

                /* allocate and link in new table */
                if ((q = (huft *) malloc((z + 1) * sizeof (huft))) ==
                        0) {
                    if (h)
                        huft_free(u[0]);
                    return 3; /* not enough memory */
                }
                pG->hufts += z + 1; /* track memory usage */
                *t = q + 1; /* link to list for huft_free() */
                *(t = &(q->v.t)) = 0;
                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[h - 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)) >> (w - l[h - 1]);
                    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 int) * 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[h])
                w -= l[--h]; /* don't need to update q */
        }
    }


    /* return actual size of base table */
    *m = l[0];


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

static int huft_free(huft* t) {
    huft *p, *q;

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