aboutsummaryrefslogtreecommitdiff
path: root/archival/libunarchive/decompress_unzip.c
blob: 770e4141daecf0014f846e879ec257b348057b9e (plain)
1
2
3
4
5
6
7
8
9
10
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
106
107
108
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
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
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
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
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
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
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
557
558
559
560
561
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
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
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
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
/* vi: set sw=4 ts=4: */
/*
 * gunzip implementation for busybox
 *
 * Based on GNU gzip v1.2.4 Copyright (C) 1992-1993 Jean-loup Gailly.
 *
 * Originally adjusted for busybox by Sven Rudolph <sr1@inf.tu-dresden.de>
 * based on gzip sources
 *
 * Adjusted further by Erik Andersen <andersee@debian.org> to support
 * files as well as stdin/stdout, and to generally behave itself wrt
 * command line handling.
 *
 * General cleanup to better adhere to the style guide and make use of standard
 * busybox functions by Glenn McGrath <bug1@optushome.com.au>
 * 
 * read_gz interface + associated hacking by Laurence Anderson
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 *
 * gzip (GNU zip) -- compress files with zip algorithm and 'compress' interface
 * Copyright (C) 1992-1993 Jean-loup Gailly
 * The unzip code was written and put in the public domain by Mark Adler.
 * Portions of the lzw code are derived from the public domain 'compress'
 * written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
 * Ken Turkowski, Dave Mack and Peter Jannesen.
 *
 * See the license_msg below and the file COPYING for the software license.
 * See the file algorithm.doc for the compression algorithms and file formats.
 */

#if 0
static char *license_msg[] = {
	"   Copyright (C) 1992-1993 Jean-loup Gailly",
	"   This program is free software; you can redistribute it and/or modify",
	"   it under the terms of the GNU General Public License as published by",
	"   the Free Software Foundation; either version 2, or (at your option)",
	"   any later version.",
	"",
	"   This program is distributed in the hope that it will be useful,",
	"   but WITHOUT ANY WARRANTY; without even the implied warranty of",
	"   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the",
	"   GNU General Public License for more details.",
	"",
	"   You should have received a copy of the GNU General Public License",
	"   along with this program; if not, write to the Free Software",
	"   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.",
	0
};
#endif

#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include "config.h"
#include "busybox.h"
#include "unarchive.h"

typedef struct huft_s {
	unsigned char e;	/* number of extra bits or operation */
	unsigned char b;	/* number of bits in this code or subcode */
	union {
		unsigned short n;	/* literal, length base, or distance base */
		struct huft_s *t;	/* pointer to next level of table */
	} v;
} huft_t;

static int gunzip_src_fd;
unsigned int gunzip_bytes_out;	/* number of output bytes */
static unsigned int gunzip_outbuf_count;	/* bytes in output buffer */

/* This is used to sanify any unused bits from the bitbuffer 
 * so they arent skipped when reading trailers (trailing headers) */
//unsigned char gunzip_in_buffer_count;
//unsigned char *gunzip_in_buffer;

/* gunzip_window size--must be a power of two, and
 *  at least 32K for zip's deflate method */
static const int gunzip_wsize = 0x8000;

static unsigned char *gunzip_window;
static unsigned int *gunzip_crc_table;
unsigned int gunzip_crc;

/* 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 int gunzip_bb;	/* bit buffer */
static unsigned char gunzip_bk;	/* bits in bit buffer */

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

/* Copy lengths for literal codes 257..285 */
static const unsigned short cplens[] = {
	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. */
/* Extra bits for literal codes 257..285 */
static const unsigned char cplext[] = {
	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 */

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

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

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

#define BYTEBUFFER_MAX 0x8000
unsigned char *bytebuffer = NULL;
unsigned int bytebuffer_offset = 0;
unsigned int bytebuffer_size = 0;

static void fill_bytebuffer()
{
	if (bytebuffer_offset >= bytebuffer_size) {
		/* Leave the first 4 bytes empty so we can always unwind the bitbuffer 
		 * to the front of the bytebuffer, leave 4 bytes free at end of tail
		 * so we can easily top up buffer in check_trailer_gzip() */
		bytebuffer_size = 4 + xread(gunzip_src_fd, &bytebuffer[4], BYTEBUFFER_MAX - 8);
		bytebuffer_offset = 4;
	}
}

static unsigned int fill_bitbuffer(unsigned int bitbuffer, unsigned int *current, const unsigned int required)
{
	while (*current < required) {
		fill_bytebuffer();
		bitbuffer |= ((unsigned int) bytebuffer[bytebuffer_offset]) << *current;
		bytebuffer_offset++;
		*current += 8;
	}
	return(bitbuffer);
}

static void make_gunzip_crc_table(void)
{
	const unsigned int poly = 0xedb88320;	/* polynomial exclusive-or pattern */
	unsigned short i;	/* counter for all possible eight bit values */

	/* initial shift register value */
	gunzip_crc = 0xffffffffL;
	gunzip_crc_table = (unsigned int *) malloc(256 * sizeof(unsigned int));

	/* Compute and print table of CRC's, five per line */
	for (i = 0; i < 256; i++) {
		unsigned int table_entry;	/* crc shift register */
		unsigned char k;	/* byte being shifted into crc apparatus */

		table_entry = i;
		/* The idea to initialize the register with the byte instead of
		   * zero was stolen from Haruhiko Okumura's ar002
		 */
		for (k = 8; k; k--) {
			if (table_entry & 1) {
				table_entry = (table_entry >> 1) ^ poly;
			} else {
				table_entry >>= 1;
	}
	}
		gunzip_crc_table[i] = table_entry;
	}
}

/*
 * 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. 
 * t: table to free
 */
static int huft_free(huft_t * t)
{
	huft_t *p;
	huft_t *q;

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

/* 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.
 *
 * b:	code lengths in bits (all assumed <= BMAX)
 * n:	number of codes (assumed <= N_MAX)
 * s:	number of simple-valued codes (0..s-1)
 * d:	list of base values for non-simple codes
 * e:	list of extra bits for non-simple codes
 * t:	result: starting table
 * m:	maximum lookup bits, returns actual
 */
static int huft_build(unsigned int *b, const unsigned int n,
					  const unsigned int s, const unsigned short *d,
					  const unsigned char *e, huft_t ** t, int *m)
{
	unsigned a;			/* counter for codes of length k */
	unsigned c[BMAX + 1];	/* bit length count table */
	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 huft_t *q;	/* points to current table */
	huft_t r;			/* table entry for structure assignment */
	huft_t *u[BMAX];	/* table stack */
	unsigned v[N_MAX];	/* values in order of bit length */
	register int w;		/* bits before this table == (l * h) */
	unsigned x[BMAX + 1];	/* bit offsets, then code stack */
	unsigned *xp;		/* pointer into x */
	int y;				/* number of dummy codes added */
	unsigned z;			/* number of entries in current table */

	/* Generate counts for each bit length */
	memset((void *) (c), 0, sizeof(c));
	p = b;
	i = n;
	do {
		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 = (huft_t *) NULL;
		*m = 0;
		return 0;
	}

	/* 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;

	/* Adjust last length count to fill out codes, if needed */
	for (y = 1 << j; j < i; j++, y <<= 1) {
		if ((y -= c[j]) < 0) {
			return 2;	/* bad input: more codes than bits */
		}
	}
	if ((y -= c[i]) < 0) {
		return 2;
	}
	c[i] += y;

	/* Generate starting offsets into the value table for each length */
	x[1] = j = 0;
	p = c + 1;
	xp = x + 2;
	while (--i) {		/* note that i == g from above */
		*xp++ = (j += *p++);
	}

	/* Make a table of values in order of bit lengths */
	p = b;
	i = 0;
	do {
		if ((j = *p++) != 0) {
			v[x[j]++] = i;
		}
	} while (++i < n);

	/* 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] = (huft_t *) NULL;	/* just to keep compilers happy */
	q = (huft_t *) NULL;	/* ditto */
	z = 0;				/* ditto */

	/* go through the bit lengths (k already is bits in shortest code) */
	for (; k <= g; k++) {
		a = c[k];
		while (a--) {
			/* here i is the Huffman code of length k bits for value *p */
			/* make tables up to required level */
			while (k > w + l) {
				h++;
				w += l;	/* 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 */
					f -= a + 1;	/* deduct codes from patterns left */
					xp = c + k;
					while (++j < z) {	/* try smaller tables up to z bits */
						if ((f <<= 1) <= *++xp) {
							break;	/* enough codes to use up j bits */
						}
						f -= *xp;	/* else deduct codes from patterns */
					}
				}
				z = 1 << j;	/* table entries for j-bit table */

				/* allocate and link in new table */
				q = (huft_t *) xmalloc((z + 1) * sizeof(huft_t));

				*t = q + 1;	/* link to list for huft_free() */
				*(t = &(q->v.t)) = NULL;
				u[h] = ++q;	/* table starts after link */

				/* connect to last table, if there is one */
				if (h) {
					x[h] = i;	/* save pattern for backing up */
					r.b = (unsigned char) l;	/* bits to dump before this table */
					r.e = (unsigned char) (16 + j);	/* bits in this table */
					r.v.t = q;	/* pointer to this table */
					j = i >> (w - l);	/* (get around Turbo C bug) */
					u[h - 1][j] = r;	/* connect to last table */
				}
			}

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

			/* fill code-like entries with r */
			f = 1 << (k - w);
			for (j = i >> w; j < z; j += f) {
				q[j] = r;
			}

			/* backwards increment the k-bit code i */
			for (j = 1 << (k - 1); i & j; j >>= 1) {
				i ^= j;
			}
			i ^= j;

			/* backup over finished tables */
			while ((i & ((1 << w) - 1)) != x[h]) {
				h--;	/* don't need to update q */
				w -= l;
			}
		}
	}
	/* Return true (1) if we were given an incomplete table */
	return y != 0 && g != 1;
}

/*
 * inflate (decompress) the codes in a deflated (compressed) block.
 * Return an error code or zero if it all goes ok.
 *
 * tl, td: literal/length and distance decoder tables
 * bl, bd: number of bits decoded by tl[] and td[]
 */
static int inflate_codes(huft_t * my_tl, huft_t * my_td, const unsigned int my_bl, const unsigned int my_bd, int setup)
{
	static unsigned int e;	/* table entry flag/number of extra bits */
	static unsigned int n, d;	/* length and index for copy */
	static unsigned int w;	/* current gunzip_window position */
	static huft_t *t;			/* pointer to table entry */
	static unsigned int ml, md;	/* masks for bl and bd bits */
	static unsigned int b;	/* bit buffer */
	static unsigned int k;			/* number of bits in bit buffer */
	static huft_t *tl, *td;
	static unsigned int bl, bd;
	static int resumeCopy = 0;

	if (setup) { // 1st time we are called, copy in variables
		tl = my_tl;
		td = my_td;
		bl = my_bl;
		bd = my_bd;
		/* make local copies of globals */
		b = gunzip_bb;				/* initialize bit buffer */
		k = gunzip_bk;
		w = gunzip_outbuf_count;			/* initialize gunzip_window position */

		/* inflate the coded data */
		ml = mask_bits[bl];	/* precompute masks for speed */
		md = mask_bits[bd];
		return 0; // Don't actually do anything the first time
	}
	
	if (resumeCopy) goto do_copy;
	
	while (1) {			/* do until end of block */
		b = fill_bitbuffer(b, &k, bl);
		if ((e = (t = tl + ((unsigned) b & ml))->e) > 16)
			do {
				if (e == 99) {
					error_msg_and_die("inflate_codes error 1");;
				}
				b >>= t->b;
				k -= t->b;
				e -= 16;
				b = fill_bitbuffer(b, &k, e);
			} while ((e =
					  (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
		b >>= t->b;
		k -= t->b;
		if (e == 16) {	/* then it's a literal */
			gunzip_window[w++] = (unsigned char) t->v.n;
			if (w == gunzip_wsize) {
				gunzip_outbuf_count = (w);
				//flush_gunzip_window();
				w = 0;
				return 1; // We have a block to read
			}
		} else {		/* it's an EOB or a length */

			/* exit if end of block */
			if (e == 15) {
				break;
			}

			/* get length of block to copy */
			b = fill_bitbuffer(b, &k, e);
			n = t->v.n + ((unsigned) b & mask_bits[e]);
			b >>= e;
			k -= e;

			/* decode distance of block to copy */
			b = fill_bitbuffer(b, &k, bd);
			if ((e = (t = td + ((unsigned) b & md))->e) > 16)
				do {
					if (e == 99)
						error_msg_and_die("inflate_codes error 2");;
					b >>= t->b;
					k -= t->b;
					e -= 16;
					b = fill_bitbuffer(b, &k, e);
				} while ((e =
						  (t =
						   t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
			b >>= t->b;
			k -= t->b;
			b = fill_bitbuffer(b, &k, e);
			d = w - t->v.n - ((unsigned) b & mask_bits[e]);
			b >>= e;
			k -= e;

			/* do the copy */
do_copy:		do {
				n -= (e =
					  (e =
					   gunzip_wsize - ((d &= gunzip_wsize - 1) > w ? d : w)) > n ? n : e);
			   /* copy to new buffer to prevent possible overwrite */
				if (w - d >= e) {	/* (this test assumes unsigned comparison) */
					memcpy(gunzip_window + w, gunzip_window + d, e);
					w += e;
					d += e;
				} else {
				   /* do it slow to avoid memcpy() overlap */
				   /* !NOMEMCPY */
					do {
						gunzip_window[w++] = gunzip_window[d++];
					} while (--e);
				}
				if (w == gunzip_wsize) {
					gunzip_outbuf_count = (w);
					if (n) resumeCopy = 1;
					else resumeCopy = 0;
					//flush_gunzip_window();
					w = 0;
					return 1;
				}
			} while (n);
			resumeCopy = 0;
		}
	}

	/* restore the globals from the locals */
	gunzip_outbuf_count = w;			/* restore global gunzip_window pointer */
	gunzip_bb = b;				/* restore global bit buffer */
	gunzip_bk = k;

	/* normally just after call to inflate_codes, but save code by putting it here */
	/* free the decoding tables, return */
	huft_free(tl);
	huft_free(td);
	
	/* done */
	return 0;
}

static int inflate_stored(int my_n, int my_b_stored, int my_k_stored, int setup)
{
	static int n, b_stored, k_stored, w;
	if (setup) {
		n = my_n;
		b_stored = my_b_stored;
		k_stored = my_k_stored;
		w = gunzip_outbuf_count;		/* initialize gunzip_window position */
		return 0; // Don't do anything first time
	}
	
	/* read and output the compressed data */
	while (n--) {
		b_stored = fill_bitbuffer(b_stored, &k_stored, 8);
		gunzip_window[w++] = (unsigned char) b_stored;
		if (w == (unsigned int) gunzip_wsize) {
			gunzip_outbuf_count = (w);
			//flush_gunzip_window();
			w = 0;
			b_stored >>= 8;
			k_stored -= 8;
			return 1; // We have a block
		}
		b_stored >>= 8;
		k_stored -= 8;
	}

	/* restore the globals from the locals */
	gunzip_outbuf_count = w;		/* restore global gunzip_window pointer */
	gunzip_bb = b_stored;	/* restore global bit buffer */
	gunzip_bk = k_stored;
	return 0; // Finished
}

/*
 * decompress an inflated block
 * e: last block flag
 *
 * GLOBAL VARIABLES: bb, kk,
 */
 // Return values: -1 = inflate_stored, -2 = inflate_codes
static int inflate_block(int *e)
{
	unsigned t;			/* block type */
	register unsigned int b;	/* bit buffer */
	unsigned int k;	/* number of bits in bit buffer */

	/* make local bit buffer */

	b = gunzip_bb;
	k = gunzip_bk;

	/* read in last block bit */
	b = fill_bitbuffer(b, &k, 1);
	*e = (int) b & 1;
	b >>= 1;
	k -= 1;

	/* read in block type */
	b = fill_bitbuffer(b, &k, 2);
	t = (unsigned) b & 3;
	b >>= 2;
	k -= 2;

	/* restore the global bit buffer */
	gunzip_bb = b;
	gunzip_bk = k;

	/* inflate that block type */
	switch (t) {
	case 0:			/* Inflate stored */
	{
		unsigned int n;	/* number of bytes in block */
		unsigned int b_stored;	/* bit buffer */
		unsigned int k_stored;	/* number of bits in bit buffer */

		/* make local copies of globals */
		b_stored = gunzip_bb;	/* initialize bit buffer */
		k_stored = gunzip_bk;

		/* go to byte boundary */
		n = k_stored & 7;
		b_stored >>= n;
		k_stored -= n;

		/* get the length and its complement */
		b_stored = fill_bitbuffer(b_stored, &k_stored, 16);
		n = ((unsigned) b_stored & 0xffff);
		b_stored >>= 16;
		k_stored -= 16;

		b_stored = fill_bitbuffer(b_stored, &k_stored, 16);
		if (n != (unsigned) ((~b_stored) & 0xffff)) {
			return 1;	/* error in compressed data */
		}
		b_stored >>= 16;
		k_stored -= 16;

		inflate_stored(n, b_stored, k_stored, 1); // Setup inflate_stored
		return -1;
	}
	case 1:			/* Inflate fixed 
						   * 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 */
		huft_t *tl;		/* literal/length code table */
		huft_t *td;		/* distance code table */
		unsigned int bl;			/* lookup bits for tl */
		unsigned int bd;			/* lookup bits for td */
		unsigned int 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(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(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1) {
			huft_free(tl);
			return i;
		}

		/* decompress until an end-of-block code */
		inflate_codes(tl, td, bl, bd, 1); // Setup inflate_codes
		
		/* huft_free code moved into inflate_codes */
		
		return -2;
	}
	case 2:			/* Inflate dynamic */
	{
		const int dbits = 6;	/* bits in base distance lookup table */
		const int lbits = 9;	/* bits in base literal/length lookup table */

		huft_t *tl;		/* literal/length code table */
		huft_t *td;		/* distance code table */
		unsigned int i;			/* temporary variables */
		unsigned int j;
		unsigned int l;		/* last length */
		unsigned int m;		/* mask for bit lengths table */
		unsigned int n;		/* number of lengths to get */
		unsigned int bl;			/* lookup bits for tl */
		unsigned int bd;			/* lookup bits for td */
		unsigned int nb;	/* number of bit length codes */
		unsigned int nl;	/* number of literal/length codes */
		unsigned int nd;	/* number of distance codes */

		unsigned int ll[286 + 30];	/* literal/length and distance code lengths */
		unsigned int b_dynamic;	/* bit buffer */
		unsigned int k_dynamic;	/* number of bits in bit buffer */

		/* make local bit buffer */
		b_dynamic = gunzip_bb;
		k_dynamic = gunzip_bk;

		/* read in table lengths */
		b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 5);
		nl = 257 + ((unsigned int) b_dynamic & 0x1f);	/* number of literal/length codes */

		b_dynamic >>= 5;
		k_dynamic -= 5;
		b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 5);
		nd = 1 + ((unsigned int) b_dynamic & 0x1f);	/* number of distance codes */

		b_dynamic >>= 5;
		k_dynamic -= 5;
		b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 4);
		nb = 4 + ((unsigned int) b_dynamic & 0xf);	/* number of bit length codes */

		b_dynamic >>= 4;
		k_dynamic -= 4;
		if (nl > 286 || nd > 30) {
			return 1;	/* bad lengths */
		}

		/* read in bit-length-code lengths */
		for (j = 0; j < nb; j++) {
			b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 3);
			ll[border[j]] = (unsigned int) b_dynamic & 7;
			b_dynamic >>= 3;
			k_dynamic -= 3;
		}
		for (; j < 19; j++) {
			ll[border[j]] = 0;
		}

		/* build decoding table for trees--single level, 7 bit lookup */
		bl = 7;
		i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl);
		if (i != 0) {
			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 int) i < n) {
			b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, (unsigned int)bl);
			j = (td = tl + ((unsigned int) b_dynamic & m))->b;
			b_dynamic >>= j;
			k_dynamic -= 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 */
				b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 2);
				j = 3 + ((unsigned int) b_dynamic & 3);
				b_dynamic >>= 2;
				k_dynamic -= 2;
				if ((unsigned int) i + j > n) {
					return 1;
				}
				while (j--) {
					ll[i++] = l;
				}
			} else if (j == 17) {	/* 3 to 10 zero length codes */
				b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 3);
				j = 3 + ((unsigned int) b_dynamic & 7);
				b_dynamic >>= 3;
				k_dynamic -= 3;
				if ((unsigned int) i + j > n) {
					return 1;
				}
				while (j--) {
					ll[i++] = 0;
				}
				l = 0;
			} else {	/* j == 18: 11 to 138 zero length codes */
				b_dynamic = fill_bitbuffer(b_dynamic, &k_dynamic, 7);
				j = 11 + ((unsigned int) b_dynamic & 0x7f);
				b_dynamic >>= 7;
				k_dynamic -= 7;
				if ((unsigned int) i + j > n) {
					return 1;
				}
				while (j--) {
					ll[i++] = 0;
				}
				l = 0;
			}
		}

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

		/* restore the global bit buffer */
		gunzip_bb = b_dynamic;
		gunzip_bk = k_dynamic;

		/* build the decoding tables for literal/length and distance codes */
		bl = lbits;

		if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) {
			if (i == 1) {
				error_msg_and_die("Incomplete literal tree");
				huft_free(tl);
			}
			return i;	/* incomplete code set */
		}

		bd = dbits;
		if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) {
			if (i == 1) {
				error_msg_and_die("incomplete distance tree");
				huft_free(td);
			}
			huft_free(tl);
			return i;	/* incomplete code set */
		}

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

		/* huft_free code moved into inflate_codes */
		
		return -2;
	}
	default:
		/* bad block type */
		error_msg_and_die("bad block type %d\n", t);
	}
}

static void calculate_gunzip_crc(void)
{
	int n;
	for (n = 0; n < gunzip_outbuf_count; n++) {
		gunzip_crc = gunzip_crc_table[((int) gunzip_crc ^ (gunzip_window[n])) & 0xff] ^ (gunzip_crc >> 8);
	}
	gunzip_bytes_out += gunzip_outbuf_count;
}

static int inflate_get_next_window(void)
{
	static int needAnotherBlock = 1;
	static int method = -1; // Method == -1 for stored, -2 for codes
	static int e = 0;
	
	gunzip_outbuf_count = 0;

	while(1) {
		int ret;
	
		if (needAnotherBlock) {
			if(e) {
				calculate_gunzip_crc();
				return 0;
			} // Last block
			method = inflate_block(&e);
			needAnotherBlock = 0;
		}
	
		switch (method) {
			case -1:	ret = inflate_stored(0,0,0,0);
					break;
			case -2:	ret = inflate_codes(0,0,0,0,0);
					break;
			default:	error_msg_and_die("inflate error %d", method);
		}

		if (ret == 1) {
			calculate_gunzip_crc();
			return 1; // More data left
		} else needAnotherBlock = 1; // End of that block
	}
	/* Doesnt get here */
}

/*
 * User functions
 *
 * read_gz, GZ_gzReadOpen, GZ_gzReadClose, inflate
 */

extern ssize_t read_gz(int fd, void *buf, size_t count)
{
	static int morebytes = 0, finished = 0;
	
	if (morebytes) {
		int bytesRead = morebytes > count ? count : morebytes;
		memcpy(buf, gunzip_window + (gunzip_outbuf_count - morebytes), bytesRead);
		morebytes -= bytesRead;
		return bytesRead;
	} else if (finished) {
		return 0;
	} else if (count >= 0x8000) { // We can decompress direcly to the buffer, 32k at a time
		// Could decompress to larger buffer, but it must be a power of 2, and calculating that is probably more expensive than the benefit
		unsigned char *old_gunzip_window = gunzip_window; // Save old window
		gunzip_window = buf;
		if (inflate_get_next_window() == 0) finished = 1;
		gunzip_window = old_gunzip_window; // Restore old window
		return gunzip_outbuf_count;
	} else { // Oh well, need to split up the gunzip_window
		int bytesRead;
		if (inflate_get_next_window() == 0) finished = 1;
		morebytes = gunzip_outbuf_count;
		bytesRead = morebytes > count ? count : morebytes;
		memcpy(buf, gunzip_window, bytesRead);
		morebytes -= bytesRead;
		return bytesRead;
	}
	
}

extern void GZ_gzReadOpen(int fd, void *unused, int nUnused)
{
	typedef void (*sig_type) (int);

	/* Allocate all global buffers (for DYN_ALLOC option) */
	gunzip_window = xmalloc(gunzip_wsize);
	gunzip_outbuf_count = 0;
	gunzip_bytes_out = 0;
	gunzip_src_fd = fd;

	/* Input buffer */
	bytebuffer = xmalloc(BYTEBUFFER_MAX);

	/* initialize gunzip_window, bit buffer */
	gunzip_bk = 0;
	gunzip_bb = 0;

	/* Create the crc table */
	make_gunzip_crc_table();
}

extern void GZ_gzReadClose(void)
{
	/* Cleanup */
	free(gunzip_window);
	free(gunzip_crc_table);

	/* Store unused bytes in a global buffer so calling applets can access it */
	if (gunzip_bk >= 8) {
		/* Undo too much lookahead. The next read will be byte aligned
		 * so we can discard unused bits in the last meaningful byte. */
		bytebuffer_offset--;
		bytebuffer[bytebuffer_offset] = gunzip_bb & 0xff;
		gunzip_bb >>= 8;
		gunzip_bk -= 8;
	}
}

/*extern int inflate(int in, int out) // Useful for testing read_gz
{
	char buf[8192];
	ssize_t nread, nwrote;

	GZ_gzReadOpen(in, 0, 0);
	while(1) { // Robbed from copyfd.c
		nread = read_gz(in, buf, sizeof(buf));
		if (nread == 0) break; // no data to write
		else if (nread == -1) {
			perror_msg("read");
			return -1;
		}
		nwrote = full_write(out, buf, nread);
		if (nwrote == -1) {
			perror_msg("write");
			return -1;
		}
	}
	GZ_gzReadClose();
	return 0;
}*/

extern int inflate(int in, int out)
{
	ssize_t nwrote;
	GZ_gzReadOpen(in, 0, 0);
	while(1) {
		int ret = inflate_get_next_window();
		nwrote = full_write(out, gunzip_window, gunzip_outbuf_count);
		if (nwrote == -1) {
			perror_msg("write");
			return -1;
		}
		if (ret == 0) break;
	}
	GZ_gzReadClose();
	return 0;
}