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 <andersen@lineo.com>, <andersee@debian.org>
11 * to support 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>
70 static FILE *in_file, *out_file;
72 /* these are freed by gz_close */
73 static unsigned char *window;
74 static unsigned long *crc_table;
76 static unsigned long crc = 0xffffffffL; /* shift register contents */
78 /* Return codes from gzip */
79 static const int ERROR = 1;
82 * window size--must be a power of two, and
83 * at least 32K for zip's deflate method
85 static const int WSIZE = 0x8000;
87 /* If BMAX needs to be larger than 16, then h and x[] should be ulg. */
88 static const int BMAX = 16; /* maximum bit length of any code (16 for explode) */
89 static const int N_MAX = 288; /* maximum number of codes in any set */
91 static long bytes_out; /* number of output bytes */
92 static unsigned long outcnt; /* bytes in output buffer */
94 static unsigned hufts; /* track memory usage */
95 static unsigned long bb; /* bit buffer */
96 static unsigned bk; /* bits in bit buffer */
98 typedef struct huft_s {
99 unsigned char e; /* number of extra bits or operation */
100 unsigned char b; /* number of bits in this code or subcode */
102 unsigned short n; /* literal, length base, or distance base */
103 struct huft_s *t; /* pointer to next level of table */
107 static const unsigned short mask_bits[] = {
109 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
110 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
113 //static int error_number = 0;
114 /* ========================================================================
115 * Signal and error handler.
118 static void abort_gzip(void)
120 error_msg("gzip aborted\n");
124 static void make_crc_table(void)
126 const unsigned long poly = 0xedb88320; /* polynomial exclusive-or pattern */
127 unsigned short i; /* counter for all possible eight bit values */
129 crc_table = (unsigned long *) malloc(256 * sizeof(unsigned long));
131 /* Compute and print table of CRC's, five per line */
132 for (i = 0; i < 256; i++) {
133 unsigned long table_entry; /* crc shift register */
134 char k; /* byte being shifted into crc apparatus */
137 /* The idea to initialize the register with the byte instead of
138 * zero was stolen from Haruhiko Okumura's ar002
140 for (k = 8; k; k--) {
141 table_entry = table_entry & 1 ? (table_entry >> 1) ^ poly : table_entry >> 1;
143 crc_table[i]=table_entry;
147 /* ===========================================================================
148 * Write the output window window[0..outcnt-1] and update crc and bytes_out.
149 * (Used for the decompressed data only.)
151 static void flush_window(void)
158 for (n = 0; n < outcnt; n++) {
159 crc = crc_table[((int) crc ^ (window[n])) & 0xff] ^ (crc >> 8);
162 if (fwrite(window, 1, outcnt, out_file) != outcnt) {
163 error_msg_and_die("Couldnt write");
165 bytes_out += (unsigned long) outcnt;
170 * Free the malloc'ed tables built by huft_build(), which makes a linked
171 * list of the tables it made, with the links in a dummy first entry of
175 static int huft_free(huft_t *t)
179 /* Go through linked list, freeing from the malloced (t[-1]) address. */
181 while (p != (huft_t *) NULL) {
189 /* Given a list of code lengths and a maximum table size, make a set of
190 * tables to decode that set of codes. Return zero on success, one if
191 * the given code set is incomplete (the tables are still built in this
192 * case), two if the input is invalid (all zero length codes or an
193 * oversubscribed set of lengths), and three if not enough memory.
195 * b: code lengths in bits (all assumed <= BMAX)
196 * n: number of codes (assumed <= N_MAX)
197 * s: number of simple-valued codes (0..s-1)
198 * d: list of base values for non-simple codes
199 * e: list of extra bits for non-simple codes
200 * t: result: starting table
201 * m: maximum lookup bits, returns actual
203 static int huft_build(unsigned int *b, const unsigned int n, const unsigned int s,
204 const unsigned short *d, const unsigned short *e, huft_t **t, int *m)
206 unsigned a; /* counter for codes of length k */
207 unsigned c[BMAX + 1]; /* bit length count table */
208 unsigned f; /* i repeats in table every f entries */
209 int g; /* maximum code length */
210 int h; /* table level */
211 register unsigned i; /* counter, current code */
212 register unsigned j; /* counter */
213 register int k; /* number of bits in current code */
214 int l; /* bits per table (returned in m) */
215 register unsigned *p; /* pointer into c[], b[], or v[] */
216 register huft_t *q; /* points to current table */
217 huft_t r; /* table entry for structure assignment */
218 huft_t *u[BMAX]; /* table stack */
219 unsigned v[N_MAX]; /* values in order of bit length */
220 register int w; /* bits before this table == (l * h) */
221 unsigned x[BMAX + 1]; /* bit offsets, then code stack */
222 unsigned *xp; /* pointer into x */
223 int y; /* number of dummy codes added */
224 unsigned z; /* number of entries in current table */
226 /* Generate counts for each bit length */
227 memset ((void *)(c), 0, sizeof(c));
231 c[*p]++; /* assume all entries <= BMAX */
232 p++; /* Can't combine with above line (Solaris bug) */
234 if (c[0] == n) { /* null input--all zero length codes */
235 *t = (huft_t *) NULL;
240 /* Find minimum and maximum length, bound *m by those */
242 for (j = 1; j <= BMAX; j++)
245 k = j; /* minimum code length */
246 if ((unsigned) l < j)
248 for (i = BMAX; i; i--)
251 g = i; /* maximum code length */
252 if ((unsigned) l > i)
256 /* Adjust last length count to fill out codes, if needed */
257 for (y = 1 << j; j < i; j++, y <<= 1)
259 return 2; /* bad input: more codes than bits */
264 /* Generate starting offsets into the value table for each length */
268 while (--i) { /* note that i == g from above */
272 /* Make a table of values in order of bit lengths */
280 /* Generate the Huffman codes and for each, make the table entries */
281 x[0] = i = 0; /* first Huffman code is zero */
282 p = v; /* grab values in bit order */
283 h = -1; /* no tables yet--level -1 */
284 w = -l; /* bits decoded == (l * h) */
285 u[0] = (huft_t *) NULL; /* just to keep compilers happy */
286 q = (huft_t *) NULL; /* ditto */
289 /* go through the bit lengths (k already is bits in shortest code) */
290 for (; k <= g; k++) {
293 /* here i is the Huffman code of length k bits for value *p */
294 /* make tables up to required level */
297 w += l; /* previous table always l bits */
299 /* compute minimum size table less than or equal to l bits */
300 z = (z = g - w) > (unsigned) l ? l : z; /* upper limit on table size */
301 if ((f = 1 << (j = k - w)) > a + 1) { /* try a k-w bit table *//* too few codes for k-w bit table */
302 f -= a + 1; /* deduct codes from patterns left */
304 while (++j < z) { /* try smaller tables up to z bits */
305 if ((f <<= 1) <= *++xp)
306 break; /* enough codes to use up j bits */
307 f -= *xp; /* else deduct codes from patterns */
310 z = 1 << j; /* table entries for j-bit table */
312 /* allocate and link in new table */
313 if ((q = (huft_t *) xmalloc((z + 1) * sizeof(huft_t))) == NULL) {
317 return 3; /* not enough memory */
319 hufts += z + 1; /* track memory usage */
320 *t = q + 1; /* link to list for huft_free() */
321 *(t = &(q->v.t)) = NULL;
322 u[h] = ++q; /* table starts after link */
324 /* connect to last table, if there is one */
326 x[h] = i; /* save pattern for backing up */
327 r.b = (unsigned char) l; /* bits to dump before this table */
328 r.e = (unsigned char) (16 + j); /* bits in this table */
329 r.v.t = q; /* pointer to this table */
330 j = i >> (w - l); /* (get around Turbo C bug) */
331 u[h - 1][j] = r; /* connect to last table */
335 /* set up table entry in r */
336 r.b = (unsigned char) (k - w);
338 r.e = 99; /* out of values--invalid code */
340 r.e = (unsigned char) (*p < 256 ? 16 : 15); /* 256 is end-of-block code */
341 r.v.n = (unsigned short) (*p); /* simple code is just the value */
342 p++; /* one compiler does not like *p++ */
344 r.e = (unsigned char) e[*p - s]; /* non-simple--look up in lists */
348 /* fill code-like entries with r */
350 for (j = i >> w; j < z; j += f)
353 /* backwards increment the k-bit code i */
354 for (j = 1 << (k - 1); i & j; j >>= 1)
358 /* backup over finished tables */
359 while ((i & ((1 << w) - 1)) != x[h]) {
360 h--; /* don't need to update q */
365 /* Return true (1) if we were given an incomplete table */
366 return y != 0 && g != 1;
370 * inflate (decompress) the codes in a deflated (compressed) block.
371 * Return an error code or zero if it all goes ok.
373 * tl, td: literal/length and distance decoder tables
374 * bl, bd: number of bits decoded by tl[] and td[]
376 static int inflate_codes(huft_t *tl, huft_t *td, int bl, int bd)
378 register unsigned long e; /* table entry flag/number of extra bits */
379 unsigned long n, d; /* length and index for copy */
380 unsigned long w; /* current window position */
381 huft_t *t; /* pointer to table entry */
382 unsigned ml, md; /* masks for bl and bd bits */
383 register unsigned long b; /* bit buffer */
384 register unsigned k; /* number of bits in bit buffer */
386 /* make local copies of globals */
387 b = bb; /* initialize bit buffer */
389 w = outcnt; /* initialize window position */
391 /* inflate the coded data */
392 ml = mask_bits[bl]; /* precompute masks for speed */
394 for (;;) { /* do until end of block */
395 while (k < (unsigned) bl) {
396 b |= ((unsigned long)fgetc(in_file)) << k;
399 if ((e = (t = tl + ((unsigned) b & ml))->e) > 16)
408 b |= ((unsigned long)fgetc(in_file)) << k;
411 } while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
414 if (e == 16) { /* then it's a literal */
415 window[w++] = (unsigned char) t->v.n;
421 } else { /* it's an EOB or a length */
423 /* exit if end of block */
428 /* get length of block to copy */
430 b |= ((unsigned long)fgetc(in_file)) << k;
433 n = t->v.n + ((unsigned) b & mask_bits[e]);
437 /* decode distance of block to copy */
438 while (k < (unsigned) bd) {
439 b |= ((unsigned long)fgetc(in_file)) << k;
443 if ((e = (t = td + ((unsigned) b & md))->e) > 16)
451 b |= ((unsigned long)fgetc(in_file)) << k;
454 } while ((e = (t = t->v.t + ((unsigned) b & mask_bits[e]))->e) > 16);
458 b |= ((unsigned long)fgetc(in_file)) << k;
461 d = w - t->v.n - ((unsigned) b & mask_bits[e]);
467 n -= (e = (e = WSIZE - ((d &= WSIZE - 1) > w ? d : w)) > n ? n : e);
468 #if !defined(NOMEMCPY) && !defined(DEBUG)
469 if (w - d >= e) { /* (this test assumes unsigned comparison) */
470 memcpy(window + w, window + d, e);
473 } else /* do it slow to avoid memcpy() overlap */
474 #endif /* !NOMEMCPY */
476 window[w++] = window[d++];
487 /* restore the globals from the locals */
488 outcnt = w; /* restore global window pointer */
489 bb = b; /* restore global bit buffer */
497 * decompress an inflated block
500 * GLOBAL VARIABLES: bb, kk,
502 static int inflate_block(int *e)
504 unsigned t; /* block type */
505 register unsigned long b; /* bit buffer */
506 register unsigned k; /* number of bits in bit buffer */
507 static unsigned short cplens[] = { /* Copy lengths for literal codes 257..285 */
508 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
509 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0
511 /* note: see note #13 above about the 258 in this list. */
512 static unsigned short cplext[] = { /* Extra bits for literal codes 257..285 */
513 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
514 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99
516 static unsigned short cpdist[] = { /* Copy offsets for distance codes 0..29 */
517 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
518 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
519 8193, 12289, 16385, 24577
521 static unsigned short cpdext[] = { /* Extra bits for distance codes */
522 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
523 7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
527 /* make local bit buffer */
531 /* read in last block bit */
533 b |= ((unsigned long)fgetc(in_file)) << k;
540 /* read in block type */
542 b |= ((unsigned long)fgetc(in_file)) << k;
545 t = (unsigned) b & 3;
549 /* restore the global bit buffer */
553 /* inflate that block type */
555 case 0: /* Inflate stored */
557 unsigned long n; /* number of bytes in block */
558 unsigned long w; /* current window position */
559 register unsigned long b_stored; /* bit buffer */
560 register unsigned long k_stored; /* number of bits in bit buffer */
562 /* make local copies of globals */
563 b_stored = bb; /* initialize bit buffer */
565 w = outcnt; /* initialize window position */
567 /* go to byte boundary */
572 /* get the length and its complement */
573 while (k_stored < 16) {
574 b_stored |= ((unsigned long)fgetc(in_file)) << k_stored;
577 n = ((unsigned) b_stored & 0xffff);
580 while (k_stored < 16) {
581 b_stored |= ((unsigned long)fgetc(in_file)) << k_stored;
584 if (n != (unsigned) ((~b_stored) & 0xffff)) {
585 return 1; /* error in compressed data */
590 /* read and output the compressed data */
592 while (k_stored < 8) {
593 b_stored |= ((unsigned long)fgetc(in_file)) << k_stored;
596 window[w++] = (unsigned char) b_stored;
597 if (w == (unsigned long)WSIZE) {
606 /* restore the globals from the locals */
607 outcnt = w; /* restore global window pointer */
608 bb = b_stored; /* restore global bit buffer */
612 case 1: /* Inflate fixed
613 * decompress an inflated type 1 (fixed Huffman codes) block. We should
614 * either replace this with a custom decoder, or at least precompute the
618 int i; /* temporary variable */
619 huft_t *tl; /* literal/length code table */
620 huft_t *td; /* distance code table */
621 int bl; /* lookup bits for tl */
622 int bd; /* lookup bits for td */
623 unsigned int l[288]; /* length list for huft_build */
625 /* set up literal table */
626 for (i = 0; i < 144; i++) {
629 for (; i < 256; i++) {
632 for (; i < 280; i++) {
635 for (; i < 288; i++) { /* make a complete, but wrong code set */
639 if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) {
643 /* set up distance table */
644 for (i = 0; i < 30; i++) { /* make an incomplete code set */
648 if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1) {
653 /* decompress until an end-of-block code */
654 if (inflate_codes(tl, td, bl, bd))
657 /* free the decoding tables, return */
662 case 2: /* Inflate dynamic */
664 /* Tables for deflate from PKZIP's appnote.txt. */
665 static unsigned border[] = { /* Order of the bit length code lengths */
666 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
668 int dbits = 6; /* bits in base distance lookup table */
669 int lbits = 9; /* bits in base literal/length lookup table */
671 int i; /* temporary variables */
673 unsigned l; /* last length */
674 unsigned m; /* mask for bit lengths table */
675 unsigned n; /* number of lengths to get */
676 huft_t *tl; /* literal/length code table */
677 huft_t *td; /* distance code table */
678 int bl; /* lookup bits for tl */
679 int bd; /* lookup bits for td */
680 unsigned nb; /* number of bit length codes */
681 unsigned nl; /* number of literal/length codes */
682 unsigned nd; /* number of distance codes */
684 unsigned ll[286 + 30]; /* literal/length and distance code lengths */
685 register unsigned long b_dynamic; /* bit buffer */
686 register unsigned k_dynamic; /* number of bits in bit buffer */
688 /* make local bit buffer */
692 /* read in table lengths */
693 while (k_dynamic < 5) {
694 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
697 nl = 257 + ((unsigned) b_dynamic & 0x1f); /* number of literal/length codes */
700 while (k_dynamic < 5) {
701 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
704 nd = 1 + ((unsigned) b_dynamic & 0x1f); /* number of distance codes */
707 while (k_dynamic < 4) {
708 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
711 nb = 4 + ((unsigned) b_dynamic & 0xf); /* number of bit length codes */
714 if (nl > 286 || nd > 30) {
715 return 1; /* bad lengths */
718 /* read in bit-length-code lengths */
719 for (j = 0; j < nb; j++) {
720 while (k_dynamic < 3) {
721 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
724 ll[border[j]] = (unsigned) b_dynamic & 7;
728 for (; j < 19; j++) {
732 /* build decoding table for trees--single level, 7 bit lookup */
734 if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0) {
738 return i; /* incomplete code set */
741 /* read in literal and distance code lengths */
745 while ((unsigned) i < n) {
746 while (k_dynamic < (unsigned) bl) {
747 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
750 j = (td = tl + ((unsigned) b_dynamic & m))->b;
754 if (j < 16) { /* length of code in bits (0..15) */
755 ll[i++] = l = j; /* save last length in l */
757 else if (j == 16) { /* repeat last length 3 to 6 times */
758 while (k_dynamic < 2) {
759 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
762 j = 3 + ((unsigned) b_dynamic & 3);
765 if ((unsigned) i + j > n) {
771 } else if (j == 17) { /* 3 to 10 zero length codes */
772 while (k_dynamic < 3) {
773 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
776 j = 3 + ((unsigned) b_dynamic & 7);
779 if ((unsigned) i + j > n) {
786 } else { /* j == 18: 11 to 138 zero length codes */
787 while (k_dynamic < 7) {
788 b_dynamic |= ((unsigned long)fgetc(in_file)) << k_dynamic;
791 j = 11 + ((unsigned) b_dynamic & 0x7f);
794 if ((unsigned) i + j > n) {
804 /* free decoding table for trees */
807 /* restore the global bit buffer */
811 /* build the decoding tables for literal/length and distance codes */
813 if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) {
815 error_msg("Incomplete literal tree");
818 return i; /* incomplete code set */
821 if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) {
823 error_msg("incomplete distance tree");
827 return i; /* incomplete code set */
830 /* decompress until an end-of-block code */
831 if (inflate_codes(tl, td, bl, bd))
834 /* free the decoding tables, return */
846 * decompress an inflated entry
848 * GLOBAL VARIABLES: outcnt, bk, bb, hufts, inptr
850 static int inflate(void)
852 int e; /* last block flag */
853 int r; /* result code */
854 unsigned h = 0; /* maximum struct huft's malloc'ed */
856 /* initialize window, bit buffer */
861 /* decompress until the last block */
864 if ((r = inflate_block(&e)) != 0) {
872 /* Undo too much lookahead. The next read will be byte aligned so we
873 * can discard unused bits in the last meaningful byte.
877 ungetc((bb << bk), in_file);
880 /* flush out window */
887 /* ===========================================================================
888 * Unzip in to out. This routine works on both gzip and pkzip files.
890 * IN assertions: the buffer inbuf contains already the beginning of
891 * the compressed data, from offsets inptr to insize-1 included.
892 * The magic header has already been checked. The output buffer is cleared.
893 * in, out: input and output file descriptors
895 extern int unzip(FILE *l_in_file, FILE *l_out_file)
897 const int extra_field = 0x04; /* bit 2 set: extra field present */
898 const int orig_name = 0x08; /* bit 3 set: original file name present */
899 const int comment = 0x10; /* bit 4 set: file comment present */
900 unsigned char buf[8]; /* extended local header */
901 unsigned char flags; /* compression flags */
902 char magic[2]; /* magic header */
904 typedef void (*sig_type) (int);
905 int exit_code=0; /* program exit code */
909 out_file = l_out_file;
911 if (signal(SIGINT, SIG_IGN) != SIG_IGN) {
912 (void) signal(SIGINT, (sig_type) abort_gzip);
915 // if (signal(SIGTERM, SIG_IGN) != SIG_IGN) {
916 // (void) signal(SIGTERM, (sig_type) abort_gzip);
920 if (signal(SIGHUP, SIG_IGN) != SIG_IGN) {
921 (void) signal(SIGHUP, (sig_type) abort_gzip);
925 /* Allocate all global buffers (for DYN_ALLOC option) */
926 window = xmalloc((size_t)(((2L*WSIZE)+1L)*sizeof(unsigned char)));
930 magic[0] = fgetc(in_file);
931 magic[1] = fgetc(in_file);
933 /* Magic header for gzip files, 1F 8B = \037\213 */
934 if (memcmp(magic, "\037\213", 2) != 0) {
935 error_msg("Invalid gzip magic");
939 method = (int) fgetc(in_file);
941 error_msg("unknown method %d -- get newer version of gzip", method);
946 flags = (unsigned char) fgetc(in_file);
948 /* Ignore time stamp(4), extra flags(1), OS type(1) */
949 for (i = 0; i < 6; i++)
952 if ((flags & extra_field) != 0) {
954 extra = fgetc(in_file);
955 extra += fgetc(in_file) << 8;
957 for (i = 0; i < extra; i++)
961 /* Discard original name if any */
962 if ((flags & orig_name) != 0) {
963 while (fgetc(in_file) != 0); /* null */
966 /* Discard file comment if any */
967 if ((flags & comment) != 0) {
968 while (fgetc(in_file) != 0); /* null */
972 printf("it failed\n");
973 return(exit_code); /* error message already emitted */
984 error_msg(memory_exhausted);
985 } else if (res != 0) {
986 error_msg("invalid compressed data--format violated");
990 error_msg("internal error, invalid method");
993 /* Get the crc and original length
994 * crc32 (see algorithm.doc)
995 * uncompressed input size modulo 2^32
997 fread(buf, 1, 8, in_file);
999 /* Validate decompression - crc */
1000 if ((unsigned int)((buf[0] | (buf[1] << 8)) |((buf[2] | (buf[3] << 8)) << 16)) != (crc ^ 0xffffffffL)) {
1001 error_msg("invalid compressed data--crc error");
1003 /* Validate decompression - size */
1004 if (((buf[4] | (buf[5] << 8)) |((buf[6] | (buf[7] << 8)) << 16)) != (unsigned long) bytes_out) {
1005 error_msg("invalid compressed data--length error");
1015 * This needs access to global variables wondow and crc_table, so its not in its own file.
1017 extern void gz_close(int gunzip_pid)
1019 if (kill(gunzip_pid, SIGTERM) == -1) {
1020 error_msg_and_die("*** Couldnt kill old gunzip process *** aborting");
1023 if (waitpid(gunzip_pid, NULL, 0) == -1) {
1024 printf("Couldnt wait ?");