unzip.cpp

来自「zip解压源码.」· C++ 代码 · 共 969 行 · 第 1/2 页

      /* set up table entry in r */
      r.b = (uch)(k - w);
      if (p >= v + n)
        r.e = 99;               /* out of values--invalid code */
      else if (*p < s)
      {
        r.e = (uch)(*p < 256 ? 16 : 15);    /* 256 is end-of-block code */
        r.v.n = (ush)(*p);             /* simple code is just the value */
	p++;                           /* one compiler does not like *p++ */
      }
      else
      {
        r.e = (uch)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;
}

int huft_free(UnZipDate* unzipdate,struct huft *t)         /* table to free */
/* 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. */
{
  register struct huft *p, *q;

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

int inflate_codes(UnZipDate* unzipdate,	struct huft *tl, 
					struct huft *td,   /* literal/length and distance decoder tables */
					int			 bl, 
					int			 bd)             /* number of bits decoded by tl[] and td[] */
/* inflate (decompress) the codes in a deflated (compressed) block.
   Return an error code or zero if it all goes ok. */
{
  register unsigned e;  /* table entry flag/number of extra bits */
  unsigned n, d;        /* length and index for copy */
  unsigned w;           /* current window position */
  struct huft *t;       /* pointer to table entry */
  unsigned ml, md;      /* masks for bl and bd bits */
  register ulg b;       /* bit buffer */
  register unsigned k;  /* number of bits in bit buffer */

  /* make local copies of globals */
  b = bb;                       /* initialize bit buffer */
  k = bk;
  w = wp;                       /* initialize window position */

  /* inflate the coded data */
  ml = mask_bits[bl];           /* precompute masks for speed */
  md = mask_bits[bd];
  for (;;)                      /* do until end of block */
  {
    NEEDBITS((unsigned)bl)
    if ((e = (t = tl + ((unsigned)b & ml))->e) > 16)
      do {
        if (e == 99)
          return 1;
        DUMPBITS(t->b)
        e -= 16;
        NEEDBITS(e)
      } while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16);
    DUMPBITS(t->b)
    if (e == 16)                /* then it's a literal */
    {
      slide[w++] = (uch)t->v.n;
      Tracevv((stderr, "%c", slide[w-1]));
      if (w == WSIZE)
      {
        flush_output(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(e)
      n = t->v.n + ((unsigned)b & mask_bits[e]);
      DUMPBITS(e);

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

      /* do the copy */
      do {
        n -= (e = (e = WSIZE - ((d &= WSIZE-1) > w ? d : w)) > n ? n : e);
#if !defined(NOMEMCPY) && !defined(DEBUG)
        if (w - d >= e)         /* (this test assumes unsigned comparison) */
        {
          memcpy(slide + w, slide + d, e);
          w += e;
          d += e;
        }
        else                      /* do it slow to avoid memcpy() overlap */
#endif /* !NOMEMCPY */
          do {
            slide[w++] = slide[d++];
	    Tracevv((stderr, "%c", slide[w-1]));
          } while (--e);
        if (w == WSIZE)
        {
          flush_output(w);
          w = 0;
        }
      } while (n);
    }
  }

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

  /* done */
  return 0;
}

int inflate_stored(UnZipDate* unzipdate)
/* "decompress" an inflated type 0 (stored) block. */
{
  unsigned n;           /* number of bytes in block */
  unsigned w;           /* current window position */
  register ulg b;       /* bit buffer */
  register unsigned k;  /* number of bits in bit buffer */

  /* make local copies of globals */
  b = bb;                       /* initialize bit buffer */
  k = bk;
  w = wp;                       /* initialize window position */

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

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

  /* read and output the compressed data */
  while (n--)
  {
    NEEDBITS(8)
    slide[w++] = (uch)b;
    if (w == WSIZE)
    {
      flush_output(w);
      w = 0;
    }
    DUMPBITS(8)
  }
  /* restore the globals from the locals */
  wp = w;                       /* restore global window pointer */
  bb = b;                       /* restore global bit buffer */
  bk = k;
  return 0;
}

int inflate_fixed(UnZipDate* unzipdate)
/* 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 */
  struct huft *tl;      /* literal/length code table */
  struct huft *td;      /* distance code table */
  int bl;               /* lookup bits for tl */
  int bd;               /* lookup bits for td */
  unsigned 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(unzipdate,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(unzipdate,l, 30, 0, cpdist, cpdext, &td, &bd)) > 1)
  {
    huft_free(unzipdate,tl);
    return i;
  }

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

  if(errorNumber!=0) return 0;

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

int inflate_dynamic(UnZipDate* unzipdate)
/* decompress an inflated type 2 (dynamic Huffman codes) block. */
{
  int i;                /* temporary variables */
  unsigned j;
  unsigned l;           /* last length */
  unsigned m;           /* mask for bit lengths table */
  unsigned n;           /* number of lengths to get */
  struct huft *tl;      /* literal/length code table */
  struct 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 */
#ifdef PKZIP_BUG_WORKAROUND
  unsigned ll[288+32];  /* literal/length and distance code lengths */
#else
  unsigned ll[286+30];  /* literal/length and distance code lengths */
#endif
  register ulg b;       /* bit buffer */
  register unsigned k;  /* number of bits in bit buffer */

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

  /* read in table lengths */
  NEEDBITS(5)
  nl = 257 + ((unsigned)b & 0x1f);      /* number of literal/length codes */
  DUMPBITS(5)
  NEEDBITS(5)
  nd = 1 + ((unsigned)b & 0x1f);        /* number of distance codes */
  DUMPBITS(5)
  NEEDBITS(4)
  nb = 4 + ((unsigned)b & 0xf);         /* number of bit length codes */
  DUMPBITS(4)
#ifdef PKZIP_BUG_WORKAROUND
  if (nl > 288 || nd > 32)
#else
  if (nl > 286 || nd > 30)
#endif
    return 1;                   /* bad lengths */

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

  /* build decoding table for trees--single level, 7 bit lookup */
  bl = 7;
  if ((i = huft_build(unzipdate,ll, 19, 19, NULL, NULL, &tl, &bl)) != 0)
  {
    if (i == 1)
      huft_free(unzipdate,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((unsigned)bl)
    j = (td = tl + ((unsigned)b & m))->b;
    DUMPBITS(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(2)
      j = 3 + ((unsigned)b & 3);
      DUMPBITS(2)
      if ((unsigned)i + j > n)
        return 1;
      while (j--)
        ll[i++] = l;
    }
    else if (j == 17)           /* 3 to 10 zero length codes */
    {
      NEEDBITS(3)
      j = 3 + ((unsigned)b & 7);
      DUMPBITS(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(7)
      j = 11 + ((unsigned)b & 0x7f);
      DUMPBITS(7)
      if ((unsigned)i + j > n)
        return 1;
      while (j--)
        ll[i++] = 0;
      l = 0;
    }
  }

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

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

  /* build the decoding tables for literal/length and distance codes */
  bl = lbits;
  if ((i = huft_build(unzipdate,ll, nl, 257, cplens, cplext, &tl, &bl)) != 0)
  {
    if (i == 1) {
//      fprintf(stderr, " incomplete literal tree\n");
      huft_free(unzipdate,tl);
    }
    return i;                   /* incomplete code set */
  }
  bd = dbits;
  if ((i = huft_build(unzipdate,ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0)
  {
    if (i == 1) {
//      fprintf(stderr, " incomplete distance tree\n");
#ifdef PKZIP_BUG_WORKAROUND
      i = 0;
    }
#else
      huft_free(unzipdate,td);
    }
    huft_free(unzipdate,tl);
    return i;                   /* incomplete code set */
#endif
  }

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

  if(errorNumber!=0) return 0;

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

int inflate_block(UnZipDate* unzipdate,int *e)                 /* last block flag */
/* decompress an inflated block */
{
  unsigned t;           /* block type */
  register ulg b;       /* bit buffer */
  register unsigned k;  /* number of bits in bit buffer */

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

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

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

  /* restore the global bit buffer */
  bb = b;
  bk = k;
	if(errorNumber!=0) return 0;

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

  return 2;
}

int inflate(UnZipDate* unzipdate)
/* decompress an inflated entry */
{
  int e;                /* last block flag */
  int r;                /* result code */
  unsigned h;           /* maximum struct huft's malloc'ed */


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


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

  /* Undo too much lookahead. The next read will be byte aligned so we
   * can discard unused bits in the last meaningful byte.
   */
  while (bk >= 8) {
    bk -= 8;
    inptr--;
  }

  /* flush out slide */
  flush_output(wp);


  /* return success */
  return 0;
}
////////////////////////////////////////////////////////