inflate.c

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/*
 * inflate.c
 * JAR inflater.
 *
 * This is a heavily hacked version of Mark Adler's inflater taken from the
 * public domina UNZIP sources, version c15c, 28 March 1997.
 *
 * Copyright (c) 1996, 1997
 *      Transvirtual Technologies, Inc.  All rights reserved.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file.
 */

#define	IDBG(s) /* XXX */

#include "config.h"
#include "config-std.h"
#include "config-mem.h"
#include "debug.h"
#include "gtypes.h"
#include "gc.h"
#include "inflate.h"

#define	WSIZE	0x8000

typedef struct _huft {
	uint8	e;		/* number of extra bits or operation */
	uint8	b;		/* number of bits in this code or subcode */
	union {
		uint16	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, uint16* d, uint16* 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 uint16 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 uint16 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 uint16 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 uint16 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 uint16 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)						\
	{							\
		uint32 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 uint32 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++] = (uint8)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 uint32 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++] = (uint8)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 uint32 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;