which/which.c

   1 /**
   2  * Copyright (c) 2000 Dan Papasian.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  * 3. The name of the author may not be used to endorse or promote products
  13  *    derived from this software without specific prior written permission.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28
  29 __FBSDID("$FreeBSD: src/usr.bin/which/which.c,v 1.6 2005/02/10 16:04:22 ru Exp $");
  30
  31 #include <sys/stat.h>
  32 #include <sys/param.h>
  33
  34 #include <err.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <unistd.h>
  39
  40 static void      usage(void);
  41 static int       print_matches(char *, char *);
  42
  43 int     silent;
  44 int     allpaths;
  45
  46 int
  47 main(int argc, char **argv)
  48 {
  49         char *p, *path;
  50         ssize_t pathlen;
  51         int opt, status;
  52
  53         status = EXIT_SUCCESS;
  54
  55         while ((opt = getopt(argc, argv, "as")) != -1) {
  56                 switch (opt) {
  57                 case 'a':
  58                         allpaths = 1;
  59                         break;
  60                 case 's':
  61                         silent = 1;
  62                         break;
  63                 default:
  64                         usage();
  65                         break;
  66                 }
  67         }
  68
  69         argv += optind;
  70         argc -= optind;
  71
  72         if (argc == 0)
  73                 usage();
  74
  75         if ((p = getenv("PATH")) == NULL)
  76                 exit(EXIT_FAILURE);
  77         pathlen = strlen(p) + 1;
  78         path = malloc(pathlen);
  79         if (path == NULL)
  80                 err(EXIT_FAILURE, NULL);
  81
  82         while (argc > 0) {
  83                 memcpy(path, p, pathlen);
  84
  85                 if (strlen(*argv) >= FILENAME_MAX ||
  86                     print_matches(path, *argv) == -1)
  87                         status = EXIT_FAILURE;
  88
  89                 argv++;
  90                 argc--;
  91         }
  92
  93         exit(status);
  94 }
  95
  96 static void
  97 usage(void)
  98 {
  99
 100         (void)fprintf(stderr, "usage: which [-as] program ...\n");
 101         exit(EXIT_FAILURE);
 102 }
 103
 104 static int
 105 is_there(char *candidate)
 106 {
 107         struct stat fin;
 108
 109         /* XXX work around access(2) false positives for superuser */
 110         if (access(candidate, X_OK) == 0 &&
 111             stat(candidate, &fin) == 0 &&
 112             S_ISREG(fin.st_mode) &&
 113             (getuid() != 0 ||
 114             (fin.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) != 0)) {
 115                 if (!silent)
 116                         printf("%s\n", candidate);
 117                 return (1);
 118         }
 119         return (0);
 120 }
 121
 122 static int
 123 print_matches(char *path, char *filename)
 124 {
 125         char candidate[PATH_MAX];
 126         const char *d;
 127         int found;
 128
 129         if (strchr(filename, '/') != NULL)
 130                 return (is_there(filename) ? 0 : -1);
 131         found = 0;
 132         while ((d = strsep(&path, ":")) != NULL) {
 133                 if (*d == '\0')
 134                         d = ".";
 135                 if (snprintf(candidate, sizeof(candidate), "%s/%s", d,
 136                     filename) >= (int)sizeof(candidate))
 137                         continue;
 138                 if (is_there(candidate)) {
 139                         found = 1;
 140                         if (!allpaths)
 141                                 break;
 142                 }
 143         }
 144         return (found ? 0 : -1);
 145 }
 146