1 /* vi: set sw=4 ts=4: */
3 * gunzip implementation for busybox
5 * Based on GNU gzip v1.2.4 Copyright (C) 1992-1993 Jean-loup Gailly.
7 * Originally adjusted for busybox by Sven Rudolph <sr1@inf.tu-dresden.de>
8 * based on gzip sources
10 * Adjusted further by Erik Andersen <andersee@debian.org> to support
11 * files as well as stdin/stdout, and to generally behave itself wrt
12 * command line handling.
14 * General cleanup to better adhere to the style guide and make use of standard
15 * busybox functions by Glenn McGrath <bug1@optushome.com.au>
17 * This program is free software; you can redistribute it and/or modify
18 * it under the terms of the GNU General Public License as published by
19 * the Free Software Foundation; either version 2 of the License, or
20 * (at your option) any later version.
22 * This program is distributed in the hope that it will be useful,
23 * but WITHOUT ANY WARRANTY; without even the implied warranty of
24 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
25 * General Public License for more details.
27 * You should have received a copy of the GNU General Public License
28 * along with this program; if not, write to the Free Software
29 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
32 * gzip (GNU zip) -- compress files with zip algorithm and 'compress' interface
33 * Copyright (C) 1992-1993 Jean-loup Gailly
34 * The unzip code was written and put in the public domain by Mark Adler.
35 * Portions of the lzw code are derived from the public domain 'compress'
36 * written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
37 * Ken Turkowski, Dave Mack and Peter Jannesen.
39 * See the license_msg below and the file COPYING for the software license.
40 * See the file algorithm.doc for the compression algorithms and file formats.
44 static char *license_msg[] = {
45 " Copyright (C) 1992-1993 Jean-loup Gailly",
46 " This program is free software; you can redistribute it and/or modify",
47 " it under the terms of the GNU General Public License as published by",
48 " the Free Software Foundation; either version 2, or (at your option)",
49 " any later version.",
51 " This program is distributed in the hope that it will be useful,",
52 " but WITHOUT ANY WARRANTY; without even the implied warranty of",
53 " MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the",
54 " GNU General Public License for more details.",
56 " You should have received a copy of the GNU General Public License",
57 " along with this program; if not, write to the Free Software",
58 " Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.",
63 #include <sys/types.h>
71 #ifdef CONFIG_FEATURE_UNCOMPRESS
72 int uncompress ( FILE *in, FILE *out );
75 static FILE *in_file, *out_file;
77 /* these are freed by gz_close */
78 static unsigned char *window;
79 static unsigned long *crc_table;
81 static unsigned long crc; /* shift register contents */
83 /* Return codes from gzip */
84 static const int ERROR = 1;
87 * window size--must be a power of two, and
88 * at least 32K for zip's deflate method
90 static const int WSIZE = 0x8000;
92 /* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
93 static const int BMAX = 16; /* maximum bit length of any code (16 for explode) */
94 static const int N_MAX = 288; /* maximum number of codes in any set */
96 static long bytes_out; /* number of output bytes */
97 static unsigned long outcnt; /* bytes in output buffer */
99 static unsigned hufts; /* track memory usage */
100 static unsigned long bb; /* bit buffer */
101 static unsigned bk; /* bits in bit buffer */
103 typedef struct huft_s {
104 unsigned char e; /* number of extra bits or operation */
105 unsigned char b; /* number of bits in this code or subcode */
107 unsigned short n; /* literal, length base, or distance base */
108 struct huft_s *t; /* pointer to next level of table */
112 static const unsigned short mask_bits[] = {
114 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
115 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
118 //static int error_number = 0;
119 /* ========================================================================
120 * Signal and error handler.
123 static void abort_gzip(void)
125 error_msg("gzip aborted\n");
129 static void make_crc_table(void)
131 const unsigned long poly = 0xedb88320; /* polynomial exclusive-or pattern */
132 unsigned short i; /* counter for all possible eight bit values */
134 /* initial shift register value */
136 crc_table = (unsigned long *) malloc(256 * sizeof(unsigned long));
138 /* Compute and print table of CRC's, five per line */
139 for (i = 0; i < 256; i++) {
140 unsigned long table_entry; /* crc shift register */
141 char k; /* byte being shifted into crc apparatus */
144 /* The idea to initialize the register with the byte instead of
145 * zero was stolen from Haruhiko Okumura's ar002
147 for (k = 8; k; k--) {
148 table_entry = table_entry & 1 ? (table_entry >> 1) ^ poly : table_entry >> 1;
150 crc_table[i]=table_entry;
154 /* ===========================================================================
155 * Write the output window window[0..outcnt-1] and update crc and bytes_out.
156 * (Used for the decompressed data only.)
158 static void flush_window(void)
165 for (n = 0; n < outcnt; n++) {
166 crc = crc_table[((int) crc ^ (window[n])) & 0xff] ^ (crc >> 8);
169 if (fwrite(window, 1, outcnt, out_file) != outcnt) {
170 error_msg_and_die("Couldnt write");
172 bytes_out += (unsigned long) outcnt;
177 * Free the malloc'ed tables built by huft_build(), which makes a linked
178 * list of the tables it made, with the links in a dummy first entry of
182 static int huft_free(huft_t *t)
186 /* Go through linked list, freeing from the malloced (t[-1]) address. */
188 while (p != (huft_t *) NULL) {
196 typedef unsigned char extra_bits_t;
198 /* Given a list of code lengths and a maximum table size, make a set of
199 * tables to decode that set of codes. Return zero on success, one if
200 * the given code set is incomplete (the tables are still built in this
201 * case), two if the input is invalid (all zero length codes or an
202 * oversubscribed set of lengths), and three if not enough memory.
204 * b: code lengths in bits (all assumed <= BMAX)
205 * n: number of codes (assumed <= N_MAX)
206 * s: number of simple-valued codes (0..s-1)
207 * d: list of base values for non-simple codes
208 * e: list of extra bits for non-simple codes
209 * t: result: starting table
210 * m: maximum lookup bits, returns actual
212 static int huft_build(unsigned int *b, const unsigned int n, const unsigned int s,
213 const unsigned short *d, const extra_bits_t *e, huft_t **t, int *m)
215 unsigned a; /* counter for codes of length k */
216 unsigned c[BMAX + 1]; /* bit length count table */
217 unsigned f; /* i repeats in table every f entries */
218 int g; /* maximum code length */
219 int h; /* table level */
220 register unsigned i; /* counter, current code */
221 register unsigned j; /* counter */
222 register int k; /* number of bits in current code */
223 int l; /* bits per table (returned in m) */
224 register unsigned *p; /* pointer into c[], b[], or v[] */
225 register huft_t *q; /* points to current table */
226 huft_t r; /* table entry for structure assignment */
227 huft_t *u[BMAX]; /* table stack */
228 unsigned v[N_MAX]; /* values in order of bit length */
229 register int w; /* bits before this table == (l * h) */
230 unsigned x[BMAX + 1]; /* bit offsets, then code stack */
231 unsigned *xp; /* pointer into x */
232 int y; /* number of dummy codes added */
233 unsigned z; /* number of entries in current table */
235 /* Generate counts for each bit length */
236 memset ((void *)(c), 0, sizeof(c));
240 c[*p]++; /* assume all entries <= BMAX */
241 p++; /* Can't combine with above line (Solaris bug) */
243 if (c[0] == n) { /* null input--all zero length codes */
244 *t = (huft_t *) NULL;
249 /* Find minimum and maximum length, bound *m by those */
251 for (j = 1; j <= BMAX; j++)
254 k = j; /* minimum code length */
255 if ((unsigned) l < j)
257 for (i = BMAX; i; i--)
260 g = i; /* maximum code length */
261 if ((unsigned) l > i)
265 /* Adjust last length count to fill out codes, if needed */
266 for (y = 1 << j; j < i; j++, y <<= 1)
268 return 2; /* bad input: more codes than bits */
273 /* Generate starting offsets into the value table for each length */
277 while (--i) { /* note that i == g from above */
281 /* Make a table of values in order of bit lengths */
289 /* Generate the Huffman codes and for each, make the table entries */
290 x[0] = i = 0; /* first Huffman code is zero */
291 p = v; /* grab values in bit order */
292 h = -1; /* no tables yet--level -1 */
293 w = -l; /* bits decoded == (l * h) */
294 u[0] = (huft_t *) NULL; /* just to keep compilers happy */
295 q = (huft_t *) NULL; /* ditto */
298 /* go through the bit lengths (k already is bits in shortest code) */
299 for (; k <= g; k++) {
302 /* here i is the Huffman code of length k bits for value *p */
303 /* make tables up to required level */
306 w += l; /* previous table always l bits */
308 /* compute minimum size table less than or equal to l bits */
309 z = (z = g - w) > (unsigned) l ? l : z; /* upper limit on table size */
310 if ((f = 1 << (j = k - w)) > a + 1) { /* try a k-w bit table *//* too few codes for k-w bit table */
311 f -= a + 1; /* deduct codes from patterns left */
313 while (++j < z) { /* try smaller tables up to z bits */
314 if ((f <<= 1) <= *++xp)
315 break; /* enough codes to use up j bits */
316 f -= *xp; /* else deduct codes from patterns */
319 z = 1 << j; /* table entries for j-bit table */
321 /* allocate and link in new table */
322 q = (huft_t *) xmalloc((z + 1) * sizeof(huft_t));
324 hufts += z + 1; /* track memory usage */
325 *t = q + 1; /* link to list for huft_free() */
326 *(t = &(q->v.t)) = NULL;
327 u[h] = ++q; /* table starts after link */
329 /* connect to last table, if there is one */
331 x[h] = i; /* save pattern for backing up */
332 r.b = (unsigned char) l; /* bits to dump before this table */
333 r.e = (unsigned char) (16 + j); /* bits in this table */
334 r.v.t = q; /* pointer to this table */
335 j = i >> (w - l); /* (get around Turbo C bug) */
336 u[h - 1][j] = r; /* connect to last table */
340 /* set up table entry in r */
341 r.b = (unsigned char) (k - w);
343 r.e = 99; /* out of values--invalid code */
345 r.e = (unsigned char) (*p < 256 ? 16 : 15); /* 256 is end-of-block code */
346 r.v.n = (unsigned short) (*p); /* simple code is just the value */
347 p++; /* one compiler does not like *p++ */
349 r.e = (unsigned char) e[*p - s]; /* non-simple--look up in lists */
353 /* fill code-like entries with r */
355 for (j = i >> w; j < z; j += f)
358 /* backwards increment the k-bit code i */
359 for (j = 1 << (k - 1); i & j; j >>= 1)
363 /* backup over finished tables */
364 while ((i & ((1 << w) - 1)) != x[h]) {
365 h--; /* don't need to update q */
370 /* Return true (1) if we were given an incomplete table */
371 return y != 0 && g != 1;
375 * inflate (decompress) the codes in a deflated (compressed) block.
376 * Return an error code or zero if it all goes ok.
378 * tl, td: literal/length and distance decoder tables
379 * bl, bd: number of bits decoded by tl[] and td[]
381 static int inflate_codes(huft_t *tl, huft_t *td, int bl, int bd)
383 register unsigned long e; /* table entry flag/number of extra bits */
384 unsigned long n, d; /* length and index for copy */
385 unsigned long w; /* current window position */
386 huft_t *t; /* pointer to table entry */
387 unsigned ml, md; /* masks for bl and bd bits */
388 register unsigned long b; /* bit buffer */
389 register unsigned k; /* number of bits in bit buffer */
391 /* make local copies of globals */
392 b = bb; /* initialize bit buffer */
394 w = outcnt; /* initialize window position */
396 /* inflate the coded data */
397 ml = mask_bits[bl]; /* precompute masks for speed */
399 for (;;) { /* do until end of block */
400 while (k < (unsigned) bl) {
401 b |= ((unsigned long)fgetc(in_file)) << k;
404 if ((e = (t = tl + ((unsigned) b & ml))->e) > 16)
413 b |= ((unsigned long)fgetc(in_file)) << k;
416 } while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
419 if (e == 16) { /* then it's a literal */
420 window[w++] = (unsigned char) t->v.n;
426 } else { /* it's an EOB or a length */
428 /* exit if end of block */
433 /* get length of block to copy */
435 b |= ((unsigned long)fgetc(in_file)) << k;
438 n = t->v.n + ((unsigned) b & mask_bits[e]);
442 /* decode distance of block to copy */
443 while (k < (unsigned) bd) {
444 b |= ((unsigned long)fgetc(in_file)) << k;
448 if ((e = (t = td + ((unsigned) b & md))->e) > 16)
456 b |= ((unsigned long)fgetc(in_file)) << k;
459 } while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
463 b |= ((unsigned long)fgetc(in_file)) << k;
466 d = w - t->v.n - ((unsigned) b & mask_bits[e]);
472 n -= (e = (e = WSIZE - ((d &= WSIZE - 1) > w ? d : w)) > n ? n : e);
473 #if !defined(NOMEMCPY) && !defined(DEBUG)
474 if (w - d >= e) { /* (this test assumes unsigned comparison) */
475 memcpy(window + w, window + d, e);
478 } else /* do it slow to avoid memcpy() overlap */
479 #endif /* !NOMEMCPY */
481 window[w++] = window[d++];
492 /* restore the globals from the locals */
493 outcnt = w; /* restore global window pointer */
494 bb = b; /* restore global bit buffer */
501 static const unsigned short cplens[] = { /* Copy lengths for literal codes 257..285 */
502 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
503 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0
505 /* note: see note #13 above about the 258 in this list. */
506 static const extra_bits_t cplext[] = { /* Extra bits for literal codes 257..285 */
507 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
508 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99
510 static const unsigned short cpdist[] = { /* Copy offsets for distance codes 0..29 */
511 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
512 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
513 8193, 12289, 16385, 24577
515 static const extra_bits_t cpdext[] = { /* Extra bits for distance codes */
516 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
517 7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
520 /* Tables for deflate from PKZIP's appnote.txt. */
521 static const extra_bits_t border[] = { /* Order of the bit length code lengths */
522 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
526 * decompress an inflated block
529 * GLOBAL VARIABLES: bb, kk,
531 static int inflate_block(int *e)
533 unsigned t; /* block type */
534 register unsigned long b; /* bit buffer */
535 register unsigned k; /* number of bits in bit buffer */
537 /* make local bit buffer */
541 /* read in last block bit */
543 b |= ((unsigned long)fgetc(in_file)) << k;
550 /* read in block type */
552 b |= ((unsigned long)fgetc(in_file)) << k;
555 t = (unsigned) b & 3;
559 /* restore the global bit buffer */
563 /* inflate that block type */
565 case 0: /* Inflate stored */
567 unsigned long n; /* number of bytes in block */
568 unsigned long w; /* current window position */
569 register unsigned long b_stored; /* bit buffer */
570 register unsigned long k_stored; /* number of bits in bit buffer */
572 /* make local copies of globals */
573 b_stored = bb; /* initialize bit buffer */
575 w = outcnt; /* initialize window position */
577 /* go to byte boundary */
582 /* get the length and its complement */
583 while (k_stored < 16) {
584 b_stored |= ((unsigned long)fgetc(in_file)) << k_stored;
587 n = ((unsigned) b_stored & 0xffff);
590 while (k_stored < 16) {
591 b_stored |= ((unsigned long)fgetc(in_file)) << k_stored;
594 if (n != (unsigned) ((~b_stored) & 0xffff)) {
595 return 1; /* error in compressed data */
600 /* read and output the compressed data */
602 while (k_stored < 8) {
603 b_stored |= ((unsigned long)fgetc(in_file)) << k_stored;
606 window[w++] = (unsigned char) b_stored;
607 if (w == (unsigned long)WSIZE) {
616 /* restore the globals from the locals */
617 outcnt = w; /* restore global window pointer */
618 bb = b_stored; /* restore global bit buffer */
622 case 1: /* Inflate fixed
623 * decompress an inflated type 1 (fixed Huffman codes) block. We should
624 * either replace this with a custom decoder, or at least precompute the
628 int i; /* temporary variable */
629 huft_t *tl; /* literal/length code table */
630 huft_t *td; /* distance code table */
631 int bl; /* lookup bits for tl */
632 int bd; /* lookup bits for td */
633 unsigned int l[288]; /* length list for huft_build */
635 /* set up literal table */
636 for (i = 0; i < 144; i++) {
639 for (; i < 256; i++) {
642 for (; i < 280; i++) {
645 for (; i < 288; i++) { /* make a complete, but wrong code set */
649 if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) {
653 /* set up distance table */
654 for (i = 0; i < 30; i++) { /* make an incomplete code set */
658 if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1) {
663 /* decompress until an end-of-block code */
664 if (inflate_codes(tl, td, bl, bd))
667 /* free the decoding tables, return */
672 case 2: /* Inflate dynamic */
674 const int dbits = 6; /* bits in base distance lookup table */
675 const int lbits = 9; /* bits in base literal/length lookup table */
677 int i; /* temporary variables */
679 unsigned l; /* last length */
680 unsigned m; /* mask for bit lengths table */
681 unsigned n; /* number of lengths to get */
682 huft_t *tl; /* literal/length code table */
683 huft_t *td; /* distance code table */
684 int bl; /* lookup bits for tl */
685 int bd; /* lookup bits for td */
686 unsigned nb; /* number of bit length codes */
687 unsigned nl; /* number of literal/length codes */
688 unsigned nd; /* number of distance codes */
690 unsigned ll[286 + 30]; /* literal/length and distance code lengths */
691 register unsigned long b_dynamic; /* bit buffer */
692 register unsigned k_dynamic; /* number of bits in bit buffer */
694 /* make local bit buffer */
698 /* read in table lengths */
699 while (k_dynamic < 5) {
700 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
703 nl = 257 + ((unsigned) b_dynamic & 0x1f); /* number of literal/length codes */
706 while (k_dynamic < 5) {
707 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
710 nd = 1 + ((unsigned) b_dynamic & 0x1f); /* number of distance codes */
713 while (k_dynamic < 4) {
714 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
717 nb = 4 + ((unsigned) b_dynamic & 0xf); /* number of bit length codes */
720 if (nl > 286 || nd > 30) {
721 return 1; /* bad lengths */
724 /* read in bit-length-code lengths */
725 for (j = 0; j < nb; j++) {
726 while (k_dynamic < 3) {
727 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
730 ll[border[j]] = (unsigned) b_dynamic & 7;
734 for (; j < 19; j++) {
738 /* build decoding table for trees--single level, 7 bit lookup */
740 if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0) {
744 return i; /* incomplete code set */
747 /* read in literal and distance code lengths */
751 while ((unsigned) i < n) {
752 while (k_dynamic < (unsigned) bl) {
753 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
756 j = (td = tl + ((unsigned) b_dynamic & m))->b;
760 if (j < 16) { /* length of code in bits (0..15) */
761 ll[i++] = l = j; /* save last length in l */
763 else if (j == 16) { /* repeat last length 3 to 6 times */
764 while (k_dynamic < 2) {
765 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
768 j = 3 + ((unsigned) b_dynamic & 3);
771 if ((unsigned) i + j > n) {
777 } else if (j == 17) { /* 3 to 10 zero length codes */
778 while (k_dynamic < 3) {
779 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
782 j = 3 + ((unsigned) b_dynamic & 7);
785 if ((unsigned) i + j > n) {
792 } else { /* j == 18: 11 to 138 zero length codes */
793 while (k_dynamic < 7) {
794 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
797 j = 11 + ((unsigned) b_dynamic & 0x7f);
800 if ((unsigned) i + j > n) {
810 /* free decoding table for trees */
813 /* restore the global bit buffer */
817 /* build the decoding tables for literal/length and distance codes */
819 if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) {
821 error_msg("Incomplete literal tree");
824 return i; /* incomplete code set */
827 if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) {
829 error_msg("incomplete distance tree");
833 return i; /* incomplete code set */
836 /* decompress until an end-of-block code */
837 if (inflate_codes(tl, td, bl, bd))
840 /* free the decoding tables, return */
852 * decompress an inflated entry
854 * GLOBAL VARIABLES: outcnt, bk, bb, hufts, inptr
856 extern int inflate(FILE *in, FILE *out)
858 int e; /* last block flag */
859 int r; /* result code */
860 unsigned h = 0; /* maximum struct huft's malloc'ed */
862 /* initialize window, bit buffer */
870 /* Allocate all global buffers (for DYN_ALLOC option) */
871 window = xmalloc((size_t)(((2L*WSIZE)+1L)*sizeof(unsigned char)));
874 /* Create the crc table */
877 /* decompress until the last block */
880 if ((r = inflate_block(&e)) != 0) {
888 /* Undo too much lookahead. The next read will be byte aligned so we
889 * can discard unused bits in the last meaningful byte.
893 ungetc((bb << bk), in_file);
896 /* flush out window */
905 /* ===========================================================================
906 * Unzip in to out. This routine works on gzip files only.
908 * IN assertions: the buffer inbuf contains already the beginning of
909 * the compressed data, from offsets inptr to insize-1 included.
910 * The magic header has already been checked. The output buffer is cleared.
911 * in, out: input and output file descriptors
913 extern int unzip(FILE *l_in_file, FILE *l_out_file)
915 unsigned char buf[8]; /* extended local header */
916 unsigned char flags; /* compression flags */
917 typedef void (*sig_type) (int);
919 unsigned char magic [2];
921 if (signal(SIGINT, SIG_IGN) != SIG_IGN) {
922 (void) signal(SIGINT, (sig_type) abort_gzip);
925 // if (signal(SIGTERM, SIG_IGN) != SIG_IGN) {
926 // (void) signal(SIGTERM, (sig_type) abort_gzip);
930 if (signal(SIGHUP, SIG_IGN) != SIG_IGN) {
931 (void) signal(SIGHUP, (sig_type) abort_gzip);
935 magic [0] = fgetc(l_in_file);
936 magic [1] = fgetc(l_in_file);
938 #ifdef CONFIG_FEATURE_UNCOMPRESS
939 /* Magic header for compress files, 1F 9d = \037\235 */
940 if (( magic [0] == 0x1F ) && ( magic [1] == 0x9d)) {
941 return uncompress ( l_in_file, l_out_file );
945 /* Magic header for gzip files, 1F 8B = \037\213 */
946 if (( magic [0] != 0x1F ) || ( magic [1] != 0x8b)) {
947 error_msg("Invalid gzip magic");
951 /* Check the compression method */
952 if (fgetc(l_in_file) != 8) {
953 error_msg("Unknown compression method");
957 flags = (unsigned char) fgetc(l_in_file);
959 /* Ignore time stamp(4), extra flags(1), OS type(1) */
960 for (i = 0; i < 6; i++) {
965 /* bit 2 set: extra field present */
966 const unsigned short extra = fgetc(l_in_file) + (fgetc(l_in_file) << 8);
968 for (i = 0; i < extra; i++) {
973 /* Discard original name if any */
975 /* bit 3 set: original file name present */
976 while (fgetc(l_in_file) != 0); /* null */
979 /* Discard file comment if any */
981 /* bit 4 set: file comment present */
982 while (fgetc(l_in_file) != 0); /* null */
986 if (inflate(l_in_file, l_out_file) != 0) {
987 error_msg("invalid compressed data--format violated");
990 /* Get the crc and original length
991 * crc32 (see algorithm.doc)
992 * uncompressed input size modulo 2^32
994 fread(buf, 1, 8, l_in_file);
996 /* Validate decompression - crc */
997 if ((unsigned int)((buf[0] | (buf[1] << 8)) |((buf[2] | (buf[3] << 8)) << 16)) != (crc ^ 0xffffffffL)) {
998 error_msg("invalid compressed data--crc error");
1000 /* Validate decompression - size */
1001 if (((buf[4] | (buf[5] << 8)) |((buf[6] | (buf[7] << 8)) << 16)) != (unsigned long) bytes_out) {
1002 error_msg("invalid compressed data--length error");
1009 * This needs access to global variables window and crc_table, so its not in its own file.
1011 extern void gz_close(int gunzip_pid)
1013 if (kill(gunzip_pid, SIGTERM) == -1) {
1014 error_msg_and_die("*** Couldnt kill old gunzip process *** aborting");
1017 if (waitpid(gunzip_pid, NULL, 0) == -1) {
1018 printf("Couldnt wait ?");