1 /* inflate.c -- Not copyrighted 1992 by Mark Adler
2 version c10p1, 10 January 1993 */
4 /* You can do whatever you like with this source file, though I would
5 prefer that if you modify it and redistribute it that you include
6 comments to that effect with your name and the date. Thank you.
7 [The history has been moved to the file ChangeLog.]
11 Inflate deflated (PKZIP's method 8 compressed) data. The compression
12 method searches for as much of the current string of bytes (up to a
13 length of 258) in the previous 32K bytes. If it doesn't find any
14 matches (of at least length 3), it codes the next byte. Otherwise, it
15 codes the length of the matched string and its distance backwards from
16 the current position. There is a single Huffman code that codes both
17 single bytes (called "literals") and match lengths. A second Huffman
18 code codes the distance information, which follows a length code. Each
19 length or distance code actually represents a base value and a number
20 of "extra" (sometimes zero) bits to get to add to the base value. At
21 the end of each deflated block is a special end-of-block (EOB) literal/
22 length code. The decoding process is basically: get a literal/length
23 code; if EOB then done; if a literal, emit the decoded byte; if a
24 length then get the distance and emit the referred-to bytes from the
25 sliding window of previously emitted data.
27 There are (currently) three kinds of inflate blocks: stored, fixed, and
28 dynamic. The compressor deals with some chunk of data at a time, and
29 decides which method to use on a chunk-by-chunk basis. A chunk might
30 typically be 32K or 64K. If the chunk is uncompressible, then the
31 "stored" method is used. In this case, the bytes are simply stored as
32 is, eight bits per byte, with none of the above coding. The bytes are
33 preceded by a count, since there is no longer an EOB code.
35 If the data is compressible, then either the fixed or dynamic methods
36 are used. In the dynamic method, the compressed data is preceded by
37 an encoding of the literal/length and distance Huffman codes that are
38 to be used to decode this block. The representation is itself Huffman
39 coded, and so is preceded by a description of that code. These code
40 descriptions take up a little space, and so for small blocks, there is
41 a predefined set of codes, called the fixed codes. The fixed method is
42 used if the block codes up smaller that way (usually for quite small
43 chunks), otherwise the dynamic method is used. In the latter case, the
44 codes are customized to the probabilities in the current block, and so
45 can code it much better than the pre-determined fixed codes.
47 The Huffman codes themselves are decoded using a mutli-level table
48 lookup, in order to maximize the speed of decoding plus the speed of
49 building the decoding tables. See the comments below that precede the
50 lbits and dbits tuning parameters.
55 Notes beyond the 1.93a appnote.txt:
57 1. Distance pointers never point before the beginning of the output
59 2. Distance pointers can point back across blocks, up to 32k away.
60 3. There is an implied maximum of 7 bits for the bit length table and
61 15 bits for the actual data.
62 4. If only one code exists, then it is encoded using one bit. (Zero
63 would be more efficient, but perhaps a little confusing.) If two
64 codes exist, they are coded using one bit each (0 and 1).
65 5. There is no way of sending zero distance codes--a dummy must be
66 sent if there are none. (History: a pre 2.0 version of PKZIP would
67 store blocks with no distance codes, but this was discovered to be
68 too harsh a criterion.) Valid only for 1.93a. 2.04c does allow
69 zero distance codes, which is sent as one code of zero bits in
71 6. There are up to 286 literal/length codes. Code 256 represents the
72 end-of-block. Note however that the static length tree defines
73 288 codes just to fill out the Huffman codes. Codes 286 and 287
74 cannot be used though, since there is no length base or extra bits
75 defined for them. Similarly, there are up to 30 distance codes.
76 However, static trees define 32 codes (all 5 bits) to fill out the
77 Huffman codes, but the last two had better not show up in the data.
78 7. Unzip can check dynamic Huffman blocks for complete code sets.
79 The exception is that a single code would not be complete (see #4).
80 8. The five bits following the block type is really the number of
81 literal codes sent minus 257.
82 9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
83 (1+6+6). Therefore, to output three times the length, you output
84 three codes (1+1+1), whereas to output four times the same length,
85 you only need two codes (1+3). Hmm.
86 10. In the tree reconstruction algorithm, Code = Code + Increment
87 only if BitLength(i) is not zero. (Pretty obvious.)
88 11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19)
89 12. Note: length code 284 can represent 227-258, but length code 285
90 really is 258. The last length deserves its own, short code
91 since it gets used a lot in very redundant files. The length
92 258 is special since 258 - 3 (the min match length) is 255.
93 13. The literal/length and distance code bit lengths are read as a
94 single stream of lengths. It is possible (and advantageous) for
95 a repeat code (16, 17, or 18) to go across the boundary between
96 the two sets of lengths.
100 static char rcsid
[] = "$Id$";
104 #include "stage2_priv.h"
107 typedef unsigned char uch
;
108 typedef unsigned short ush
;
109 typedef unsigned int ulg
;
111 #define memzero(a, b) memset(a, 0, b)
113 #define malloc(s) kmalloc(s)
114 #define free(p) kfree(p)
116 /* 32k sliding window */
118 static unsigned char *window
= 0;
119 static unsigned int inptr
= 0; /* index of next byte to be processed in inbuf */
120 static unsigned int outcnt
= 0; /* bytes in output buffer */
121 static const unsigned char *inbuf
= 0;
122 static unsigned char *outbuf
= 0;
124 #define get_byte() (inbuf[inptr++])
126 static void flush_window()
129 memcpy(outbuf
, window
, outcnt
);
137 #define printf dprintf
138 #define fprintf(a,b) printf(b)
140 /*#include "gzip.h"*/
143 /* Huffman code lookup table entry--this entry is four bytes for machines
144 that have 16-bit pointers (e.g. PC's in the small or medium model).
145 Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16
146 means that v is a literal, 16 < e < 32 means that v is a pointer to
147 the next table, which codes e - 16 bits, and lastly e == 99 indicates
148 an unused code. If a code with e == 99 is looked up, this implies an
149 error in the data. */
151 uch e
; /* number of extra bits or operation */
152 uch b
; /* number of bits in this code or subcode */
154 ush n
; /* literal, length base, or distance base */
155 struct huft
*t
; /* pointer to next level of table */
160 /* Function prototypes */
161 int huft_build
OF((unsigned *, unsigned, unsigned, ush
*, ush
*,
162 struct huft
**, int *));
163 int huft_free
OF((struct huft
*));
165 static int inflate_codes
OF((struct huft
*, struct huft
*, int, int));
166 static int inflate_stored
OF((void));
167 static int inflate_fixed
OF((void));
168 static int inflate_dynamic
OF((void));
169 static int inflate_block
OF((int *));
170 static int inflate
OF((void));
173 /* The inflate algorithm uses a sliding 32K byte window on the uncompressed
174 stream to find repeated byte strings. This is implemented here as a
175 circular buffer. The index is updated simply by incrementing and then
176 and'ing with 0x7fff (32K-1). */
177 /* It is left to other modules to supply the 32K area. It is assumed
178 to be usable as if it were declared "uch slide[32768];" or as just
179 "uch *slide;" and then malloc'ed in the latter case. The definition
180 must be in unzip.h, included above. */
181 /* unsigned wp; current position in slide */
183 #define flush_output(w) (wp=(w),flush_window())
185 /* Tables for deflate from PKZIP's appnote.txt. */
186 static unsigned border
[] = { /* Order of the bit length code lengths */
187 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
188 static ush cplens
[] = { /* Copy lengths for literal codes 257..285 */
189 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
190 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
191 /* note: see note #13 above about the 258 in this list. */
192 static ush cplext
[] = { /* Extra bits for literal codes 257..285 */
193 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
194 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */
195 static ush cpdist
[] = { /* Copy offsets for distance codes 0..29 */
196 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
197 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
198 8193, 12289, 16385, 24577};
199 static ush cpdext
[] = { /* Extra bits for distance codes */
200 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
201 7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
206 /* Macros for inflate() bit peeking and grabbing.
210 x = b & mask_bits[j];
213 where NEEDBITS makes sure that b has at least j bits in it, and
214 DUMPBITS removes the bits from b. The macros use the variable k
215 for the number of bits in b. Normally, b and k are register
216 variables for speed, and are initialized at the beginning of a
217 routine that uses these macros from a global bit buffer and count.
219 If we assume that EOB will be the longest code, then we will never
220 ask for bits with NEEDBITS that are beyond the end of the stream.
221 So, NEEDBITS should not read any more bytes than are needed to
222 meet the request. Then no bytes need to be "returned" to the buffer
223 at the end of the last block.
225 However, this assumption is not true for fixed blocks--the EOB code
226 is 7 bits, but the other literal/length codes can be 8 or 9 bits.
227 (The EOB code is shorter than other codes because fixed blocks are
228 generally short. So, while a block always has an EOB, many other
229 literal/length codes have a significantly lower probability of
230 showing up at all.) However, by making the first table have a
231 lookup of seven bits, the EOB code will be found in that first
232 lookup, and so will not require that too many bits be pulled from
236 ulg bb
= 0; /* bit buffer */
237 unsigned bk
= 0; /* bits in bit buffer */
241 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
242 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
247 # define NEXTBYTE() \
248 (decrypt ? (cc = get_byte(), zdecode(cc), cc) : get_byte())
250 # define NEXTBYTE() (uch)get_byte()
252 #define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE())<<k;k+=8;}}
253 #define DUMPBITS(n) {b>>=(n);k-=(n);}
257 Huffman code decoding is performed using a multi-level table lookup.
258 The fastest way to decode is to simply build a lookup table whose
259 size is determined by the longest code. However, the time it takes
260 to build this table can also be a factor if the data being decoded
261 is not very long. The most common codes are necessarily the
262 shortest codes, so those codes dominate the decoding time, and hence
263 the speed. The idea is you can have a shorter table that decodes the
264 shorter, more probable codes, and then point to subsidiary tables for
265 the longer codes. The time it costs to decode the longer codes is
266 then traded against the time it takes to make longer tables.
268 This results of this trade are in the variables lbits and dbits
269 below. lbits is the number of bits the first level table for literal/
270 length codes can decode in one step, and dbits is the same thing for
271 the distance codes. Subsequent tables are also less than or equal to
272 those sizes. These values may be adjusted either when all of the
273 codes are shorter than that, in which case the longest code length in
274 bits is used, or when the shortest code is *longer* than the requested
275 table size, in which case the length of the shortest code in bits is
278 There are two different values for the two tables, since they code a
279 different number of possibilities each. The literal/length table
280 codes 286 possible values, or in a flat code, a little over eight
281 bits. The distance table codes 30 possible values, or a little less
282 than five bits, flat. The optimum values for speed end up being
283 about one bit more than those, so lbits is 8+1 and dbits is 5+1.
284 The optimum values may differ though from machine to machine, and
285 possibly even between compilers. Your mileage may vary.
289 int lbits
= 9; /* bits in base literal/length lookup table */
290 int dbits
= 6; /* bits in base distance lookup table */
293 /* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
294 #define BMAX 16 /* maximum bit length of any code (16 for explode) */
295 #define N_MAX 288 /* maximum number of codes in any set */
298 unsigned hufts
= 0; /* track memory usage */
301 int huft_build(b
, n
, s
, d
, e
, t
, m
)
302 unsigned *b
; /* code lengths in bits (all assumed <= BMAX) */
303 unsigned n
; /* number of codes (assumed <= N_MAX) */
304 unsigned s
; /* number of simple-valued codes (0..s-1) */
305 ush
*d
; /* list of base values for non-simple codes */
306 ush
*e
; /* list of extra bits for non-simple codes */
307 struct huft
**t
; /* result: starting table */
308 int *m
; /* maximum lookup bits, returns actual */
309 /* Given a list of code lengths and a maximum table size, make a set of
310 tables to decode that set of codes. Return zero on success, one if
311 the given code set is incomplete (the tables are still built in this
312 case), two if the input is invalid (all zero length codes or an
313 oversubscribed set of lengths), and three if not enough memory. */
315 unsigned a
; /* counter for codes of length k */
316 unsigned c
[BMAX
+1]; /* bit length count table */
317 unsigned f
; /* i repeats in table every f entries */
318 int g
; /* maximum code length */
319 int h
; /* table level */
320 register unsigned i
; /* counter, current code */
321 register unsigned j
; /* counter */
322 register int k
; /* number of bits in current code */
323 int l
; /* bits per table (returned in m) */
324 register unsigned *p
; /* pointer into c[], b[], or v[] */
325 register struct huft
*q
; /* points to current table */
326 struct huft r
; /* table entry for structure assignment */
327 struct huft
*u
[BMAX
]; /* table stack */
328 unsigned v
[N_MAX
]; /* values in order of bit length */
329 register int w
; /* bits before this table == (l * h) */
330 unsigned x
[BMAX
+1]; /* bit offsets, then code stack */
331 unsigned *xp
; /* pointer into x */
332 int y
; /* number of dummy codes added */
333 unsigned z
; /* number of entries in current table */
336 /* Generate counts for each bit length */
337 memzero(c
, sizeof(c
));
340 Tracecv(*p
, (stderr
, (n
-i
>= ' ' && n
-i
<= '~' ? "%c %d\n" : "0x%x %d\n"),
342 c
[*p
]++; /* assume all entries <= BMAX */
343 p
++; /* Can't combine with above line (Solaris bug) */
345 if (c
[0] == n
) /* null input--all zero length codes */
347 *t
= (struct huft
*)NULL
;
353 /* Find minimum and maximum length, bound *m by those */
355 for (j
= 1; j
<= BMAX
; j
++)
358 k
= j
; /* minimum code length */
361 for (i
= BMAX
; i
; i
--)
364 g
= i
; /* maximum code length */
370 /* Adjust last length count to fill out codes, if needed */
371 for (y
= 1 << j
; j
< i
; j
++, y
<<= 1)
373 return 2; /* bad input: more codes than bits */
379 /* Generate starting offsets into the value table for each length */
381 p
= c
+ 1; xp
= x
+ 2;
382 while (--i
) { /* note that i == g from above */
387 /* Make a table of values in order of bit lengths */
395 /* Generate the Huffman codes and for each, make the table entries */
396 x
[0] = i
= 0; /* first Huffman code is zero */
397 p
= v
; /* grab values in bit order */
398 h
= -1; /* no tables yet--level -1 */
399 w
= -l
; /* bits decoded == (l * h) */
400 u
[0] = (struct huft
*)NULL
; /* just to keep compilers happy */
401 q
= (struct huft
*)NULL
; /* ditto */
404 /* go through the bit lengths (k already is bits in shortest code) */
410 /* here i is the Huffman code of length k bits for value *p */
411 /* make tables up to required level */
415 w
+= l
; /* previous table always l bits */
417 /* compute minimum size table less than or equal to l bits */
418 z
= (z
= g
- w
) > (unsigned)l
? (unsigned)l
: z
; /* upper limit on table size */
419 if ((f
= 1 << (j
= k
- w
)) > a
+ 1) /* try a k-w bit table */
420 { /* too few codes for k-w bit table */
421 f
-= a
+ 1; /* deduct codes from patterns left */
423 while (++j
< z
) /* try smaller tables up to z bits */
425 if ((f
<<= 1) <= *++xp
)
426 break; /* enough codes to use up j bits */
427 f
-= *xp
; /* else deduct codes from patterns */
430 z
= 1 << j
; /* table entries for j-bit table */
432 /* allocate and link in new table */
433 if ((q
= (struct huft
*)malloc((z
+ 1)*sizeof(struct huft
))) ==
438 return 3; /* not enough memory */
440 hufts
+= z
+ 1; /* track memory usage */
441 *t
= q
+ 1; /* link to list for huft_free() */
442 *(t
= &(q
->v
.t
)) = (struct huft
*)NULL
;
443 u
[h
] = ++q
; /* table starts after link */
445 /* connect to last table, if there is one */
448 x
[h
] = i
; /* save pattern for backing up */
449 r
.b
= (uch
)l
; /* bits to dump before this table */
450 r
.e
= (uch
)(16 + j
); /* bits in this table */
451 r
.v
.t
= q
; /* pointer to this table */
452 j
= i
>> (w
- l
); /* (get around Turbo C bug) */
453 u
[h
-1][j
] = r
; /* connect to last table */
457 /* set up table entry in r */
460 r
.e
= 99; /* out of values--invalid code */
463 r
.e
= (uch
)(*p
< 256 ? 16 : 15); /* 256 is end-of-block code */
464 r
.v
.n
= (ush
)(*p
); /* simple code is just the value */
465 p
++; /* one compiler does not like *p++ */
469 r
.e
= (uch
)e
[*p
- s
]; /* non-simple--look up in lists */
473 /* fill code-like entries with r */
475 for (j
= i
>> w
; j
< z
; j
+= f
)
478 /* backwards increment the k-bit code i */
479 for (j
= 1 << (k
- 1); i
& j
; j
>>= 1)
483 /* backup over finished tables */
484 while ((i
& ((1 << w
) - 1)) != x
[h
])
486 h
--; /* don't need to update q */
493 /* Return true (1) if we were given an incomplete table */
494 return y
!= 0 && g
!= 1;
500 struct huft
*t
; /* table to free */
501 /* Free the malloc'ed tables built by huft_build(), which makes a linked
502 list of the tables it made, with the links in a dummy first entry of
505 register struct huft
*p
, *q
;
508 /* Go through linked list, freeing from the malloced (t[-1]) address. */
510 while (p
!= (struct huft
*)NULL
)
520 static int inflate_codes(tl
, td
, bl
, bd
)
521 struct huft
*tl
, *td
; /* literal/length and distance decoder tables */
522 int bl
, bd
; /* number of bits decoded by tl[] and td[] */
523 /* inflate (decompress) the codes in a deflated (compressed) block.
524 Return an error code or zero if it all goes ok. */
526 register unsigned e
; /* table entry flag/number of extra bits */
527 unsigned n
, d
; /* length and index for copy */
528 unsigned w
; /* current window position */
529 struct huft
*t
; /* pointer to table entry */
530 unsigned ml
, md
; /* masks for bl and bd bits */
531 register ulg b
; /* bit buffer */
532 register unsigned k
; /* number of bits in bit buffer */
535 /* make local copies of globals */
536 b
= bb
; /* initialize bit buffer */
538 w
= wp
; /* initialize window position */
540 /* inflate the coded data */
541 ml
= mask_bits
[bl
]; /* precompute masks for speed */
543 for (;;) /* do until end of block */
545 NEEDBITS((unsigned)bl
)
546 if ((e
= (t
= tl
+ ((unsigned)b
& ml
))->e
) > 16)
553 } while ((e
= (t
= t
->v
.t
+ ((unsigned)b
& mask_bits
[e
]))->e
) > 16);
555 if (e
== 16) /* then it's a literal */
557 slide
[w
++] = (uch
)t
->v
.n
;
558 Tracevv((stderr
, "%c", slide
[w
-1]));
565 else /* it's an EOB or a length */
567 /* exit if end of block */
571 /* get length of block to copy */
573 n
= t
->v
.n
+ ((unsigned)b
& mask_bits
[e
]);
576 /* decode distance of block to copy */
577 NEEDBITS((unsigned)bd
)
578 if ((e
= (t
= td
+ ((unsigned)b
& md
))->e
) > 16)
585 } while ((e
= (t
= t
->v
.t
+ ((unsigned)b
& mask_bits
[e
]))->e
) > 16);
588 d
= w
- t
->v
.n
- ((unsigned)b
& mask_bits
[e
]);
590 Tracevv((stderr
,"\\[%d,%d]", w
-d
, n
));
594 n
-= (e
= (e
= WSIZE
- ((d
&= WSIZE
-1) > w
? d
: w
)) > n
? n
: e
);
595 #if !defined(NOMEMCPY) && !defined(DEBUG)
596 if (w
- d
>= e
) /* (this test assumes unsigned comparison) */
598 memcpy(slide
+ w
, slide
+ d
, e
);
602 else /* do it slow to avoid memcpy() overlap */
603 #endif /* !NOMEMCPY */
605 slide
[w
++] = slide
[d
++];
606 Tracevv((stderr
, "%c", slide
[w
-1]));
618 /* restore the globals from the locals */
619 wp
= w
; /* restore global window pointer */
620 bb
= b
; /* restore global bit buffer */
629 static int inflate_stored()
630 /* "decompress" an inflated type 0 (stored) block. */
632 unsigned n
; /* number of bytes in block */
633 unsigned w
; /* current window position */
634 register ulg b
; /* bit buffer */
635 register unsigned k
; /* number of bits in bit buffer */
638 /* make local copies of globals */
639 b
= bb
; /* initialize bit buffer */
641 w
= wp
; /* initialize window position */
644 /* go to byte boundary */
649 /* get the length and its complement */
651 n
= ((unsigned)b
& 0xffff);
654 if (n
!= (unsigned)((~b
) & 0xffff))
655 return 1; /* error in compressed data */
659 /* read and output the compressed data */
673 /* restore the globals from the locals */
674 wp
= w
; /* restore global window pointer */
675 bb
= b
; /* restore global bit buffer */
682 static int inflate_fixed()
683 /* decompress an inflated type 1 (fixed Huffman codes) block. We should
684 either replace this with a custom decoder, or at least precompute the
687 int i
; /* temporary variable */
688 struct huft
*tl
; /* literal/length code table */
689 struct huft
*td
; /* distance code table */
690 int bl
; /* lookup bits for tl */
691 int bd
; /* lookup bits for td */
692 unsigned l
[288]; /* length list for huft_build */
695 /* set up literal table */
696 for (i
= 0; i
< 144; i
++)
702 for (; i
< 288; i
++) /* make a complete, but wrong code set */
705 if ((i
= huft_build(l
, 288, 257, cplens
, cplext
, &tl
, &bl
)) != 0)
709 /* set up distance table */
710 for (i
= 0; i
< 30; i
++) /* make an incomplete code set */
713 if ((i
= huft_build(l
, 30, 0, cpdist
, cpdext
, &td
, &bd
)) > 1)
720 /* decompress until an end-of-block code */
721 if (inflate_codes(tl
, td
, bl
, bd
))
725 /* free the decoding tables, return */
733 static int inflate_dynamic()
734 /* decompress an inflated type 2 (dynamic Huffman codes) block. */
736 int i
; /* temporary variables */
738 unsigned l
; /* last length */
739 unsigned m
; /* mask for bit lengths table */
740 unsigned n
; /* number of lengths to get */
741 struct huft
*tl
; /* literal/length code table */
742 struct huft
*td
; /* distance code table */
743 int bl
; /* lookup bits for tl */
744 int bd
; /* lookup bits for td */
745 unsigned nb
; /* number of bit length codes */
746 unsigned nl
; /* number of literal/length codes */
747 unsigned nd
; /* number of distance codes */
748 #ifdef PKZIP_BUG_WORKAROUND
749 unsigned ll
[288+32]; /* literal/length and distance code lengths */
751 unsigned ll
[286+30]; /* literal/length and distance code lengths */
753 register ulg b
; /* bit buffer */
754 register unsigned k
; /* number of bits in bit buffer */
757 /* make local bit buffer */
762 /* read in table lengths */
764 nl
= 257 + ((unsigned)b
& 0x1f); /* number of literal/length codes */
767 nd
= 1 + ((unsigned)b
& 0x1f); /* number of distance codes */
770 nb
= 4 + ((unsigned)b
& 0xf); /* number of bit length codes */
772 #ifdef PKZIP_BUG_WORKAROUND
773 if (nl
> 288 || nd
> 32)
775 if (nl
> 286 || nd
> 30)
777 return 1; /* bad lengths */
780 /* read in bit-length-code lengths */
781 for (j
= 0; j
< nb
; j
++)
784 ll
[border
[j
]] = (unsigned)b
& 7;
791 /* build decoding table for trees--single level, 7 bit lookup */
793 if ((i
= huft_build(ll
, 19, 19, NULL
, NULL
, &tl
, &bl
)) != 0)
797 return i
; /* incomplete code set */
801 /* read in literal and distance code lengths */
805 while ((unsigned)i
< n
)
807 NEEDBITS((unsigned)bl
)
808 j
= (td
= tl
+ ((unsigned)b
& m
))->b
;
811 if (j
< 16) /* length of code in bits (0..15) */
812 ll
[i
++] = l
= j
; /* save last length in l */
813 else if (j
== 16) /* repeat last length 3 to 6 times */
816 j
= 3 + ((unsigned)b
& 3);
818 if ((unsigned)i
+ j
> n
)
823 else if (j
== 17) /* 3 to 10 zero length codes */
826 j
= 3 + ((unsigned)b
& 7);
828 if ((unsigned)i
+ j
> n
)
834 else /* j == 18: 11 to 138 zero length codes */
837 j
= 11 + ((unsigned)b
& 0x7f);
839 if ((unsigned)i
+ j
> n
)
848 /* free decoding table for trees */
852 /* restore the global bit buffer */
857 /* build the decoding tables for literal/length and distance codes */
859 if ((i
= huft_build(ll
, nl
, 257, cplens
, cplext
, &tl
, &bl
)) != 0)
862 fprintf(stderr
, " incomplete literal tree\n");
865 return i
; /* incomplete code set */
868 if ((i
= huft_build(ll
+ nl
, nd
, 0, cpdist
, cpdext
, &td
, &bd
)) != 0)
871 fprintf(stderr
, " incomplete distance tree\n");
872 #ifdef PKZIP_BUG_WORKAROUND
879 return i
; /* incomplete code set */
884 /* decompress until an end-of-block code */
885 if (inflate_codes(tl
, td
, bl
, bd
))
889 /* free the decoding tables, return */
897 static int inflate_block(e
)
898 int *e
; /* last block flag */
899 /* decompress an inflated block */
901 unsigned t
; /* block type */
902 register ulg b
; /* bit buffer */
903 register unsigned k
; /* number of bits in bit buffer */
906 /* make local bit buffer */
911 /* read in last block bit */
917 /* read in block type */
923 /* restore the global bit buffer */
927 /* inflate that block type */
929 return inflate_dynamic();
931 return inflate_stored();
933 return inflate_fixed();
943 /* decompress an inflated entry */
945 int e
; /* last block flag */
946 int r
; /* result code */
947 unsigned h
; /* maximum struct huft's malloc'ed */
950 /* initialize window, bit buffer */
956 /* decompress until the last block */
960 if ((r
= inflate_block(&e
)) != 0)
967 /* Undo too much lookahead. The next read will be byte aligned so we
968 * can discard unused bits in the last meaningful byte.
975 /* flush out slide */
981 //fprintf("<%d> ", h);
986 static ulg crc32tab
[0x100] = { 0, };
988 static void inittab()
991 for (i
=0;i
<0x100;i
++) {
994 c
= (c
& 1) ? ((c
>> 1) ^ 0xedb88320) : (c
>> 1);
1000 static ulg
crc32(uch
*buff
, int len
)
1007 c
= (c
>> 8) ^ crc32tab
[(c
^ *(buff
++)) & 0xff];
1008 return c
^ 0xffffffff;
1011 ulg
gunzip(const uch
*in
, uch
*out
, uch
*inflate_buf
)
1013 if (in
[2] != 8) panic("Unsupported compression method");
1014 if (in
[3] & 0xe3) panic("Unsupported gzip format");
1016 inbuf
= in
+ 10; /* skip header */
1017 if (in
[3] & 4) inbuf
+= in
[10] + in
[11] * 0x100;
1018 if (in
[3] & 8) while (*(inbuf
++) != 0) ; /* skip original file name */
1019 if (in
[3] & 0x10) while (*(inbuf
++) != 0) ; /* skip file comment */
1021 outbuf
= out
; inptr
= 0; outcnt
= 0;
1022 window
= inflate_buf
;
1024 if (inflate()) panic("Error inflating file");
1028 if ((ulg
)(outbuf
- out
) != *(ulg
*)(inbuf
+ 4))
1029 panic("Invalid size %d != %d\n", outbuf
- out
, *(ulg
*)(inbuf
+ 4));
1031 if (crc32(out
, outbuf
- out
) != *(ulg
*)inbuf
)
1034 return outbuf
- out
;