inflate.c 38.6 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9
#define DEBG(x)
#define DEBG1(x)
/* inflate.c -- Not copyrighted 1992 by Mark Adler
   version c10p1, 10 January 1993 */

/* 
 * Adapted for booting Linux by Hannu Savolainen 1993
 * based on gzip-1.0.3 
 *
10
 * Nicolas Pitre <nico@fluxnic.net>, 1999/04/14 :
Linus Torvalds's avatar
Linus Torvalds committed
11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105
 *   Little mods for all variable to reside either into rodata or bss segments
 *   by marking constant variables with 'const' and initializing all the others
 *   at run-time only.  This allows for the kernel uncompressor to run
 *   directly from Flash or ROM memory on embedded systems.
 */

/*
   Inflate deflated (PKZIP's method 8 compressed) data.  The compression
   method searches for as much of the current string of bytes (up to a
   length of 258) in the previous 32 K bytes.  If it doesn't find any
   matches (of at least length 3), it codes the next byte.  Otherwise, it
   codes the length of the matched string and its distance backwards from
   the current position.  There is a single Huffman code that codes both
   single bytes (called "literals") and match lengths.  A second Huffman
   code codes the distance information, which follows a length code.  Each
   length or distance code actually represents a base value and a number
   of "extra" (sometimes zero) bits to get to add to the base value.  At
   the end of each deflated block is a special end-of-block (EOB) literal/
   length code.  The decoding process is basically: get a literal/length
   code; if EOB then done; if a literal, emit the decoded byte; if a
   length then get the distance and emit the referred-to bytes from the
   sliding window of previously emitted data.

   There are (currently) three kinds of inflate blocks: stored, fixed, and
   dynamic.  The compressor deals with some chunk of data at a time, and
   decides which method to use on a chunk-by-chunk basis.  A chunk might
   typically be 32 K or 64 K.  If the chunk is incompressible, then the
   "stored" method is used.  In this case, the bytes are simply stored as
   is, eight bits per byte, with none of the above coding.  The bytes are
   preceded by a count, since there is no longer an EOB code.

   If the data is compressible, then either the fixed or dynamic methods
   are used.  In the dynamic method, the compressed data is preceded by
   an encoding of the literal/length and distance Huffman codes that are
   to be used to decode this block.  The representation is itself Huffman
   coded, and so is preceded by a description of that code.  These code
   descriptions take up a little space, and so for small blocks, there is
   a predefined set of codes, called the fixed codes.  The fixed method is
   used if the block codes up smaller that way (usually for quite small
   chunks), otherwise the dynamic method is used.  In the latter case, the
   codes are customized to the probabilities in the current block, and so
   can code it much better than the pre-determined fixed codes.
 
   The Huffman codes themselves are decoded using a multi-level table
   lookup, in order to maximize the speed of decoding plus the speed of
   building the decoding tables.  See the comments below that precede the
   lbits and dbits tuning parameters.
 */


/*
   Notes beyond the 1.93a appnote.txt:

   1. Distance pointers never point before the beginning of the output
      stream.
   2. Distance pointers can point back across blocks, up to 32k away.
   3. There is an implied maximum of 7 bits for the bit length table and
      15 bits for the actual data.
   4. If only one code exists, then it is encoded using one bit.  (Zero
      would be more efficient, but perhaps a little confusing.)  If two
      codes exist, they are coded using one bit each (0 and 1).
   5. There is no way of sending zero distance codes--a dummy must be
      sent if there are none.  (History: a pre 2.0 version of PKZIP would
      store blocks with no distance codes, but this was discovered to be
      too harsh a criterion.)  Valid only for 1.93a.  2.04c does allow
      zero distance codes, which is sent as one code of zero bits in
      length.
   6. There are up to 286 literal/length codes.  Code 256 represents the
      end-of-block.  Note however that the static length tree defines
      288 codes just to fill out the Huffman codes.  Codes 286 and 287
      cannot be used though, since there is no length base or extra bits
      defined for them.  Similarly, there are up to 30 distance codes.
      However, static trees define 32 codes (all 5 bits) to fill out the
      Huffman codes, but the last two had better not show up in the data.
   7. Unzip can check dynamic Huffman blocks for complete code sets.
      The exception is that a single code would not be complete (see #4).
   8. The five bits following the block type is really the number of
      literal codes sent minus 257.
   9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
      (1+6+6).  Therefore, to output three times the length, you output
      three codes (1+1+1), whereas to output four times the same length,
      you only need two codes (1+3).  Hmm.
  10. In the tree reconstruction algorithm, Code = Code + Increment
      only if BitLength(i) is not zero.  (Pretty obvious.)
  11. Correction: 4 Bits: # of Bit Length codes - 4     (4 - 19)
  12. Note: length code 284 can represent 227-258, but length code 285
      really is 258.  The last length deserves its own, short code
      since it gets used a lot in very redundant files.  The length
      258 is special since 258 - 3 (the min match length) is 255.
  13. The literal/length and distance code bit lengths are read as a
      single stream of lengths.  It is possible (and advantageous) for
      a repeat code (16, 17, or 18) to go across the boundary between
      the two sets of lengths.
 */
#include <linux/compiler.h>
106
#ifdef NO_INFLATE_MALLOC
107
#include <linux/slab.h>
108
#endif
Linus Torvalds's avatar
Linus Torvalds committed
109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235

#ifdef RCSID
static char rcsid[] = "#Id: inflate.c,v 0.14 1993/06/10 13:27:04 jloup Exp #";
#endif

#ifndef STATIC

#if defined(STDC_HEADERS) || defined(HAVE_STDLIB_H)
#  include <sys/types.h>
#  include <stdlib.h>
#endif

#include "gzip.h"
#define STATIC
#endif /* !STATIC */

#ifndef INIT
#define INIT
#endif
	
#define slide window

/* Huffman code lookup table entry--this entry is four bytes for machines
   that have 16-bit pointers (e.g. PC's in the small or medium model).
   Valid extra bits are 0..13.  e == 15 is EOB (end of block), e == 16
   means that v is a literal, 16 < e < 32 means that v is a pointer to
   the next table, which codes e - 16 bits, and lastly e == 99 indicates
   an unused code.  If a code with e == 99 is looked up, this implies an
   error in the data. */
struct huft {
  uch e;                /* number of extra bits or operation */
  uch b;                /* number of bits in this code or subcode */
  union {
    ush n;              /* literal, length base, or distance base */
    struct huft *t;     /* pointer to next level of table */
  } v;
};


/* Function prototypes */
STATIC int INIT huft_build OF((unsigned *, unsigned, unsigned, 
		const ush *, const ush *, struct huft **, int *));
STATIC int INIT huft_free OF((struct huft *));
STATIC int INIT inflate_codes OF((struct huft *, struct huft *, int, int));
STATIC int INIT inflate_stored OF((void));
STATIC int INIT inflate_fixed OF((void));
STATIC int INIT inflate_dynamic OF((void));
STATIC int INIT inflate_block OF((int *));
STATIC int INIT inflate OF((void));


/* The inflate algorithm uses a sliding 32 K byte window on the uncompressed
   stream to find repeated byte strings.  This is implemented here as a
   circular buffer.  The index is updated simply by incrementing and then
   ANDing with 0x7fff (32K-1). */
/* It is left to other modules to supply the 32 K area.  It is assumed
   to be usable as if it were declared "uch slide[32768];" or as just
   "uch *slide;" and then malloc'ed in the latter case.  The definition
   must be in unzip.h, included above. */
/* unsigned wp;             current position in slide */
#define wp outcnt
#define flush_output(w) (wp=(w),flush_window())

/* Tables for deflate from PKZIP's appnote.txt. */
static const 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 const ush 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 const ush 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 const ush 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 const ush 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};



/* Macros for inflate() bit peeking and grabbing.
   The usage is:
   
        NEEDBITS(j)
        x = b & mask_bits[j];
        DUMPBITS(j)

   where NEEDBITS makes sure that b has at least j bits in it, and
   DUMPBITS removes the bits from b.  The macros use the variable k
   for the number of bits in b.  Normally, b and k are register
   variables for speed, and are initialized at the beginning of a
   routine that uses these macros from a global bit buffer and count.

   If we assume that EOB will be the longest code, then we will never
   ask for bits with NEEDBITS that are beyond the end of the stream.
   So, NEEDBITS should not read any more bytes than are needed to
   meet the request.  Then no bytes need to be "returned" to the buffer
   at the end of the last block.

   However, this assumption is not true for fixed blocks--the EOB code
   is 7 bits, but the other literal/length codes can be 8 or 9 bits.
   (The EOB code is shorter than other codes because fixed blocks are
   generally short.  So, while a block always has an EOB, many other
   literal/length codes have a significantly lower probability of
   showing up at all.)  However, by making the first table have a
   lookup of seven bits, the EOB code will be found in that first
   lookup, and so will not require that too many bits be pulled from
   the stream.
 */

STATIC ulg bb;                         /* bit buffer */
STATIC unsigned bk;                    /* bits in bit buffer */

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

#define NEXTBYTE()  ({ int v = get_byte(); if (v < 0) goto underrun; (uch)v; })
#define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE())<<k;k+=8;}}
#define DUMPBITS(n) {b>>=(n);k-=(n);}

236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274
#ifndef NO_INFLATE_MALLOC
/* A trivial malloc implementation, adapted from
 *  malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994
 */

static unsigned long malloc_ptr;
static int malloc_count;

static void *malloc(int size)
{
       void *p;

       if (size < 0)
		error("Malloc error");
       if (!malloc_ptr)
		malloc_ptr = free_mem_ptr;

       malloc_ptr = (malloc_ptr + 3) & ~3;     /* Align */

       p = (void *)malloc_ptr;
       malloc_ptr += size;

       if (free_mem_end_ptr && malloc_ptr >= free_mem_end_ptr)
		error("Out of memory");

       malloc_count++;
       return p;
}

static void free(void *where)
{
       malloc_count--;
       if (!malloc_count)
		malloc_ptr = free_mem_ptr;
}
#else
#define malloc(a) kmalloc(a, GFP_KERNEL)
#define free(a) kfree(a)
#endif
Linus Torvalds's avatar
Linus Torvalds committed
275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350

/*
   Huffman code decoding is performed using a multi-level table lookup.
   The fastest way to decode is to simply build a lookup table whose
   size is determined by the longest code.  However, the time it takes
   to build this table can also be a factor if the data being decoded
   is not very long.  The most common codes are necessarily the
   shortest codes, so those codes dominate the decoding time, and hence
   the speed.  The idea is you can have a shorter table that decodes the
   shorter, more probable codes, and then point to subsidiary tables for
   the longer codes.  The time it costs to decode the longer codes is
   then traded against the time it takes to make longer tables.

   This results of this trade are in the variables lbits and dbits
   below.  lbits is the number of bits the first level table for literal/
   length codes can decode in one step, and dbits is the same thing for
   the distance codes.  Subsequent tables are also less than or equal to
   those sizes.  These values may be adjusted either when all of the
   codes are shorter than that, in which case the longest code length in
   bits is used, or when the shortest code is *longer* than the requested
   table size, in which case the length of the shortest code in bits is
   used.

   There are two different values for the two tables, since they code a
   different number of possibilities each.  The literal/length table
   codes 286 possible values, or in a flat code, a little over eight
   bits.  The distance table codes 30 possible values, or a little less
   than five bits, flat.  The optimum values for speed end up being
   about one bit more than those, so lbits is 8+1 and dbits is 5+1.
   The optimum values may differ though from machine to machine, and
   possibly even between compilers.  Your mileage may vary.
 */


STATIC const int lbits = 9;          /* bits in base literal/length lookup table */
STATIC const int dbits = 6;          /* bits in base distance lookup table */


/* 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 hufts;         /* track memory usage */


STATIC int INIT huft_build(
	unsigned *b,            /* code lengths in bits (all assumed <= BMAX) */
	unsigned n,             /* number of codes (assumed <= N_MAX) */
	unsigned s,             /* number of simple-valued codes (0..s-1) */
	const ush *d,           /* list of base values for non-simple codes */
	const ush *e,           /* list of extra bits for non-simple codes */
	struct huft **t,        /* result: starting table */
	int *m                  /* maximum lookup bits, returns actual */
	)
/* 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. */
{
  unsigned a;                   /* counter for codes of length k */
  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 struct huft *q;      /* points to current table */
  struct huft r;                /* table entry for structure assignment */
  register int w;               /* bits before this table == (l * h) */
  unsigned *xp;                 /* pointer into x */
  int y;                        /* number of dummy codes added */
  unsigned z;                   /* number of entries in current table */
351 352 353 354 355 356 357 358 359
  struct {
    unsigned c[BMAX+1];           /* bit length count table */
    struct huft *u[BMAX];         /* table stack */
    unsigned v[N_MAX];            /* values in order of bit length */
    unsigned x[BMAX+1];           /* bit offsets, then code stack */
  } *stk;
  unsigned *c, *v, *x;
  struct huft **u;
  int ret;
Linus Torvalds's avatar
Linus Torvalds committed
360 361 362

DEBG("huft1 ");

363 364 365 366 367 368 369 370 371
  stk = malloc(sizeof(*stk));
  if (stk == NULL)
    return 3;			/* out of memory */

  c = stk->c;
  v = stk->v;
  x = stk->x;
  u = stk->u;

Linus Torvalds's avatar
Linus Torvalds committed
372
  /* Generate counts for each bit length */
373
  memzero(stk->c, sizeof(stk->c));
Linus Torvalds's avatar
Linus Torvalds committed
374 375 376 377 378 379 380 381 382 383 384
  p = b;  i = n;
  do {
    Tracecv(*p, (stderr, (n-i >= ' ' && n-i <= '~' ? "%c %d\n" : "0x%x %d\n"), 
	    n-i, *p));
    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 = (struct huft *)NULL;
    *m = 0;
385 386
    ret = 2;
    goto out;
Linus Torvalds's avatar
Linus Torvalds committed
387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410
  }

DEBG("huft2 ");

  /* 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;

DEBG("huft3 ");

  /* Adjust last length count to fill out codes, if needed */
  for (y = 1 << j; j < i; j++, y <<= 1)
411 412 413 414 415 416 417 418
    if ((y -= c[j]) < 0) {
      ret = 2;                 /* bad input: more codes than bits */
      goto out;
    }
  if ((y -= c[i]) < 0) {
    ret = 2;
    goto out;
  }
Linus Torvalds's avatar
Linus Torvalds committed
419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437
  c[i] += y;

DEBG("huft4 ");

  /* 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++);
  }

DEBG("huft5 ");

  /* 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);
438
  n = x[g];                   /* set n to length of v */
Linus Torvalds's avatar
Linus Torvalds committed
439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474

DEBG("h6 ");

  /* 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] = (struct huft *)NULL;   /* just to keep compilers happy */
  q = (struct huft *)NULL;      /* ditto */
  z = 0;                        /* ditto */
DEBG("h6a ");

  /* go through the bit lengths (k already is bits in shortest code) */
  for (; k <= g; k++)
  {
DEBG("h6b ");
    a = c[k];
    while (a--)
    {
DEBG("h6b1 ");
      /* here i is the Huffman code of length k bits for value *p */
      /* make tables up to required level */
      while (k > w + l)
      {
DEBG1("1 ");
        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 */
DEBG1("2 ");
          f -= a + 1;           /* deduct codes from patterns left */
          xp = c + k;
475 476 477 478 479 480 481
          if (j < z)
            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 */
            }
Linus Torvalds's avatar
Linus Torvalds committed
482 483 484 485 486 487 488 489 490 491
        }
DEBG1("3 ");
        z = 1 << j;             /* table entries for j-bit table */

        /* allocate and link in new table */
        if ((q = (struct huft *)malloc((z + 1)*sizeof(struct huft))) ==
            (struct huft *)NULL)
        {
          if (h)
            huft_free(u[0]);
492 493
          ret = 3;             /* not enough memory */
	  goto out;
Linus Torvalds's avatar
Linus Torvalds committed
494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556
        }
DEBG1("4 ");
        hufts += z + 1;         /* track memory usage */
        *t = q + 1;             /* link to list for huft_free() */
        *(t = &(q->v.t)) = (struct huft *)NULL;
        u[h] = ++q;             /* table starts after link */

DEBG1("5 ");
        /* connect to last table, if there is one */
        if (h)
        {
          x[h] = i;             /* save pattern for backing up */
          r.b = (uch)l;         /* bits to dump before this table */
          r.e = (uch)(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 */
        }
DEBG1("6 ");
      }
DEBG("h6c ");

      /* 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];
      }
DEBG("h6d ");

      /* 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;
      }
DEBG("h6e ");
    }
DEBG("h6f ");
  }

DEBG("huft7 ");

  /* Return true (1) if we were given an incomplete table */
557 558 559 560 561
  ret = y != 0 && g != 1;

  out:
  free(stk);
  return ret;
Linus Torvalds's avatar
Linus Torvalds committed
562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773
}



STATIC int INIT huft_free(
	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;
}


STATIC int INIT inflate_codes(
	struct huft *tl,    /* literal/length decoder tables */
	struct huft *td,    /* distance decoder tables */
	int bl,             /* number of bits decoded by tl[] */
	int bd              /* number of bits decoded by 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;

 underrun:
  return 4;			/* Input underrun */
}



STATIC int INIT inflate_stored(void)
/* "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 */

DEBG("<stor");

  /* 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;

  DEBG(">");
  return 0;

 underrun:
  return 4;			/* Input underrun */
}


/*
 * We use `noinline' here to prevent gcc-3.5 from using too much stack space
 */
STATIC int noinline INIT inflate_fixed(void)
/* 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 */
774
  unsigned *l;          /* length list for huft_build */
Linus Torvalds's avatar
Linus Torvalds committed
775 776 777

DEBG("<fix");

778 779 780 781
  l = malloc(sizeof(*l) * 288);
  if (l == NULL)
    return 3;			/* out of memory */

Linus Torvalds's avatar
Linus Torvalds committed
782 783 784 785 786 787 788 789 790 791
  /* 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;
792 793
  if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) {
    free(l);
Linus Torvalds's avatar
Linus Torvalds committed
794
    return i;
795
  }
Linus Torvalds's avatar
Linus Torvalds committed
796 797 798 799 800 801 802 803

  /* 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);
804
    free(l);
Linus Torvalds's avatar
Linus Torvalds committed
805 806 807 808 809 810 811

    DEBG(">");
    return i;
  }


  /* decompress until an end-of-block code */
812 813
  if (inflate_codes(tl, td, bl, bd)) {
    free(l);
Linus Torvalds's avatar
Linus Torvalds committed
814
    return 1;
815
  }
Linus Torvalds's avatar
Linus Torvalds committed
816 817

  /* free the decoding tables, return */
818
  free(l);
Linus Torvalds's avatar
Linus Torvalds committed
819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842
  huft_free(tl);
  huft_free(td);
  return 0;
}


/*
 * We use `noinline' here to prevent gcc-3.5 from using too much stack space
 */
STATIC int noinline INIT inflate_dynamic(void)
/* 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 */
843
  unsigned *ll;         /* literal/length and distance code lengths */
Linus Torvalds's avatar
Linus Torvalds committed
844 845
  register ulg b;       /* bit buffer */
  register unsigned k;  /* number of bits in bit buffer */
846
  int ret;
Linus Torvalds's avatar
Linus Torvalds committed
847 848 849

DEBG("<dyn");

850 851 852 853 854 855
#ifdef PKZIP_BUG_WORKAROUND
  ll = malloc(sizeof(*ll) * (288+32));  /* literal/length and distance code lengths */
#else
  ll = malloc(sizeof(*ll) * (286+30));  /* literal/length and distance code lengths */
#endif

856 857 858
  if (ll == NULL)
    return 1;

Linus Torvalds's avatar
Linus Torvalds committed
859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878
  /* 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
879 880 881 882
  {
    ret = 1;             /* bad lengths */
    goto out;
  }
Linus Torvalds's avatar
Linus Torvalds committed
883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903

DEBG("dyn1 ");

  /* 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;

DEBG("dyn2 ");

  /* build decoding table for trees--single level, 7 bit lookup */
  bl = 7;
  if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0)
  {
    if (i == 1)
      huft_free(tl);
904 905
    ret = i;                   /* incomplete code set */
    goto out;
Linus Torvalds's avatar
Linus Torvalds committed
906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926
  }

DEBG("dyn3 ");

  /* 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)
927 928 929 930
      if ((unsigned)i + j > n) {
        ret = 1;
	goto out;
      }
Linus Torvalds's avatar
Linus Torvalds committed
931 932 933 934 935 936 937 938
      while (j--)
        ll[i++] = l;
    }
    else if (j == 17)           /* 3 to 10 zero length codes */
    {
      NEEDBITS(3)
      j = 3 + ((unsigned)b & 7);
      DUMPBITS(3)
939 940 941 942
      if ((unsigned)i + j > n) {
        ret = 1;
	goto out;
      }
Linus Torvalds's avatar
Linus Torvalds committed
943 944 945 946 947 948 949 950 951
      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)
952 953 954 955
      if ((unsigned)i + j > n) {
        ret = 1;
	goto out;
      }
Linus Torvalds's avatar
Linus Torvalds committed
956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983
      while (j--)
        ll[i++] = 0;
      l = 0;
    }
  }

DEBG("dyn4 ");

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

DEBG("dyn5 ");

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

DEBG("dyn5a ");

  /* build the decoding tables for literal/length and distance codes */
  bl = lbits;
  if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0)
  {
DEBG("dyn5b ");
    if (i == 1) {
      error("incomplete literal tree");
      huft_free(tl);
    }
984 985
    ret = i;                   /* incomplete code set */
    goto out;
Linus Torvalds's avatar
Linus Torvalds committed
986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000
  }
DEBG("dyn5c ");
  bd = dbits;
  if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0)
  {
DEBG("dyn5d ");
    if (i == 1) {
      error("incomplete distance tree");
#ifdef PKZIP_BUG_WORKAROUND
      i = 0;
    }
#else
      huft_free(td);
    }
    huft_free(tl);
1001 1002
    ret = i;                   /* incomplete code set */
    goto out;
Linus Torvalds's avatar
Linus Torvalds committed
1003 1004 1005 1006 1007 1008
#endif
  }

DEBG("dyn6 ");

  /* decompress until an end-of-block code */
1009 1010 1011 1012
  if (inflate_codes(tl, td, bl, bd)) {
    ret = 1;
    goto out;
  }
Linus Torvalds's avatar
Linus Torvalds committed
1013 1014 1015 1016 1017 1018 1019 1020

DEBG("dyn7 ");

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

  DEBG(">");
1021 1022 1023 1024
  ret = 0;
out:
  free(ll);
  return ret;
Linus Torvalds's avatar
Linus Torvalds committed
1025

1026 1027 1028
underrun:
  ret = 4;			/* Input underrun */
  goto out;
Linus Torvalds's avatar
Linus Torvalds committed
1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100
}



STATIC int INIT inflate_block(
	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 */

  DEBG("<blk");

  /* 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;

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

  DEBG(">");

  /* bad block type */
  return 2;

 underrun:
  return 4;			/* Input underrun */
}



STATIC int INIT inflate(void)
/* 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;
1101 1102 1103 1104 1105 1106
#ifdef ARCH_HAS_DECOMP_WDOG
    arch_decomp_wdog();
#endif
    r = inflate_block(&e);
    if (r)
	    return r;
Linus Torvalds's avatar
Linus Torvalds committed
1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309
    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 */
#ifdef DEBUG
  fprintf(stderr, "<%u> ", h);
#endif /* DEBUG */
  return 0;
}

/**********************************************************************
 *
 * The following are support routines for inflate.c
 *
 **********************************************************************/

static ulg crc_32_tab[256];
static ulg crc;		/* initialized in makecrc() so it'll reside in bss */
#define CRC_VALUE (crc ^ 0xffffffffUL)

/*
 * Code to compute the CRC-32 table. Borrowed from 
 * gzip-1.0.3/makecrc.c.
 */

static void INIT
makecrc(void)
{
/* Not copyrighted 1990 Mark Adler	*/

  unsigned long c;      /* crc shift register */
  unsigned long e;      /* polynomial exclusive-or pattern */
  int i;                /* counter for all possible eight bit values */
  int k;                /* byte being shifted into crc apparatus */

  /* terms of polynomial defining this crc (except x^32): */
  static const int p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};

  /* Make exclusive-or pattern from polynomial */
  e = 0;
  for (i = 0; i < sizeof(p)/sizeof(int); i++)
    e |= 1L << (31 - p[i]);

  crc_32_tab[0] = 0;

  for (i = 1; i < 256; i++)
  {
    c = 0;
    for (k = i | 256; k != 1; k >>= 1)
    {
      c = c & 1 ? (c >> 1) ^ e : c >> 1;
      if (k & 1)
        c ^= e;
    }
    crc_32_tab[i] = c;
  }

  /* this is initialized here so this code could reside in ROM */
  crc = (ulg)0xffffffffUL; /* shift register contents */
}

/* gzip flag byte */
#define ASCII_FLAG   0x01 /* bit 0 set: file probably ASCII text */
#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
#define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
#define ORIG_NAME    0x08 /* bit 3 set: original file name present */
#define COMMENT      0x10 /* bit 4 set: file comment present */
#define ENCRYPTED    0x20 /* bit 5 set: file is encrypted */
#define RESERVED     0xC0 /* bit 6,7:   reserved */

/*
 * Do the uncompression!
 */
static int INIT gunzip(void)
{
    uch flags;
    unsigned char magic[2]; /* magic header */
    char method;
    ulg orig_crc = 0;       /* original crc */
    ulg orig_len = 0;       /* original uncompressed length */
    int res;

    magic[0] = NEXTBYTE();
    magic[1] = NEXTBYTE();
    method   = NEXTBYTE();

    if (magic[0] != 037 ||
	((magic[1] != 0213) && (magic[1] != 0236))) {
	    error("bad gzip magic numbers");
	    return -1;
    }

    /* We only support method #8, DEFLATED */
    if (method != 8)  {
	    error("internal error, invalid method");
	    return -1;
    }

    flags  = (uch)get_byte();
    if ((flags & ENCRYPTED) != 0) {
	    error("Input is encrypted");
	    return -1;
    }
    if ((flags & CONTINUATION) != 0) {
	    error("Multi part input");
	    return -1;
    }
    if ((flags & RESERVED) != 0) {
	    error("Input has invalid flags");
	    return -1;
    }
    NEXTBYTE();	/* Get timestamp */
    NEXTBYTE();
    NEXTBYTE();
    NEXTBYTE();

    (void)NEXTBYTE();  /* Ignore extra flags for the moment */
    (void)NEXTBYTE();  /* Ignore OS type for the moment */

    if ((flags & EXTRA_FIELD) != 0) {
	    unsigned len = (unsigned)NEXTBYTE();
	    len |= ((unsigned)NEXTBYTE())<<8;
	    while (len--) (void)NEXTBYTE();
    }

    /* Get original file name if it was truncated */
    if ((flags & ORIG_NAME) != 0) {
	    /* Discard the old name */
	    while (NEXTBYTE() != 0) /* null */ ;
    } 

    /* Discard file comment if any */
    if ((flags & COMMENT) != 0) {
	    while (NEXTBYTE() != 0) /* null */ ;
    }

    /* Decompress */
    if ((res = inflate())) {
	    switch (res) {
	    case 0:
		    break;
	    case 1:
		    error("invalid compressed format (err=1)");
		    break;
	    case 2:
		    error("invalid compressed format (err=2)");
		    break;
	    case 3:
		    error("out of memory");
		    break;
	    case 4:
		    error("out of input data");
		    break;
	    default:
		    error("invalid compressed format (other)");
	    }
	    return -1;
    }
	    
    /* Get the crc and original length */
    /* crc32  (see algorithm.doc)
     * uncompressed input size modulo 2^32
     */
    orig_crc = (ulg) NEXTBYTE();
    orig_crc |= (ulg) NEXTBYTE() << 8;
    orig_crc |= (ulg) NEXTBYTE() << 16;
    orig_crc |= (ulg) NEXTBYTE() << 24;
    
    orig_len = (ulg) NEXTBYTE();
    orig_len |= (ulg) NEXTBYTE() << 8;
    orig_len |= (ulg) NEXTBYTE() << 16;
    orig_len |= (ulg) NEXTBYTE() << 24;
    
    /* Validate decompression */
    if (orig_crc != CRC_VALUE) {
	    error("crc error");
	    return -1;
    }
    if (orig_len != bytes_out) {
	    error("length error");
	    return -1;
    }
    return 0;

 underrun:			/* NEXTBYTE() goto's here if needed */
    error("out of input data");
    return -1;
}