file/compress.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.1 (the "License").  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*      $OpenBSD: compress.c,v 1.3 1997/02/09 23:58:19 millert Exp $    */
  25
  26 /*
  27  * compress routines:
  28  *      zmagic() - returns 0 if not recognized, uncompresses and prints
  29  *                 information if recognized
  30  *      uncompress(method, old, n, newch) - uncompress old into new,
  31  *                                          using method, return sizeof new
  32  */
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <unistd.h>
  36 #include <string.h>
  37 #include <sys/wait.h>
  38
  39 #include "file.h"
  40
  41 static struct {
  42    char *magic;
  43    int   maglen;
  44    char *argv[3];
  45    int   silent;
  46 } compr[] = {
  47     { "\037\235", 2, { "uncompress", "-c", NULL }, 0 }, /* compressed */
  48     { "\037\213", 2, { "gzip", "-cdq", NULL }, 1 },     /* gzipped */
  49     { "\037\236", 2, { "gzip", "-cdq", NULL }, 1 },     /* frozen */
  50     { "\037\240", 2, { "gzip", "-cdq", NULL }, 1 },     /* SCO LZH */
  51     /* the standard pack utilities do not accept standard input */
  52     { "\037\036", 2, { "gzip", "-cdq", NULL }, 0 },     /* packed */
  53 };
  54
  55 static int ncompr = sizeof(compr) / sizeof(compr[0]);
  56
  57
  58 static int uncompress __P((int, const unsigned char *, unsigned char **, int));
  59
  60 int
  61 zmagic(buf, nbytes)
  62 unsigned char *buf;
  63 int nbytes;
  64 {
  65         unsigned char *newbuf;
  66         int newsize;
  67         int i;
  68
  69         for (i = 0; i < ncompr; i++) {
  70                 if (nbytes < compr[i].maglen)
  71                         continue;
  72                 if (memcmp(buf, compr[i].magic,  compr[i].maglen) == 0)
  73                         break;
  74         }
  75
  76         if (i == ncompr)
  77                 return 0;
  78
  79         if ((newsize = uncompress(i, buf, &newbuf, nbytes)) != 0) {
  80                 tryit(newbuf, newsize, 1);
  81                 free(newbuf);
  82                 printf(" (");
  83                 tryit(buf, nbytes, 0);
  84                 printf(")");
  85         }
  86         return 1;
  87 }
  88
  89
  90 static int
  91 uncompress(method, old, newch, n)
  92 int method;
  93 const unsigned char *old;
  94 unsigned char **newch;
  95 int n;
  96 {
  97         int fdin[2], fdout[2];
  98
  99         if (pipe(fdin) == -1 || pipe(fdout) == -1) {
 100                 error("cannot create pipe (%s).\n", strerror(errno));
 101                 /*NOTREACHED*/
 102         }
 103         switch (fork()) {
 104         case 0: /* child */
 105                 (void) close(0);
 106                 (void) dup(fdin[0]);
 107                 (void) close(fdin[0]);
 108                 (void) close(fdin[1]);
 109
 110                 (void) close(1);
 111                 (void) dup(fdout[1]);
 112                 (void) close(fdout[0]);
 113                 (void) close(fdout[1]);
 114                 if (compr[method].silent)
 115                     (void) close(2);
 116
 117                 execvp(compr[method].argv[0], compr[method].argv);
 118                 error("could not execute `%s' (%s).\n",
 119                       compr[method].argv[0], strerror(errno));
 120                 /*NOTREACHED*/
 121         case -1:
 122                 error("could not fork (%s).\n", strerror(errno));
 123                 /*NOTREACHED*/
 124
 125         default: /* parent */
 126                 (void) close(fdin[0]);
 127                 (void) close(fdout[1]);
 128                 if (write(fdin[1], old, n) != n) {
 129                         error("write failed (%s).\n", strerror(errno));
 130                         /*NOTREACHED*/
 131                 }
 132                 (void) close(fdin[1]);
 133                 if ((*newch = (unsigned char *) malloc(n)) == NULL) {
 134                         error("out of memory.\n");
 135                         /*NOTREACHED*/
 136                 }
 137                 if ((n = read(fdout[0], *newch, n)) <= 0) {
 138                         free(*newch);
 139                         error("read failed (%s).\n", strerror(errno));
 140                         /*NOTREACHED*/
 141                 }
 142                 (void) close(fdout[0]);
 143                 (void) wait(NULL);
 144                 return n;
 145         }
 146 }