usr.bin/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  * $FreeBSD: src/usr.bin/which/which.c,v 1.5 2002/06/30 06:02:39 tjr Exp $");
  26  * $DragonFly: src/usr.bin/which/which.c,v 1.3 2005/08/31 00:42:15 liamfoy Exp $
  27  */
  28
  29 #include <sys/stat.h>
  30 #include <sys/param.h>
  31
  32 #include <err.h>
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <unistd.h>
  37
  38 static void     usage(void);
  39 static int      print_matches(char *, char *);
  40
  41 int    silent;
  42 int    allpaths;
  43
  44 int
  45 main(int argc, char **argv)
  46 {
  47        char *p, *path;
  48        ssize_t pathlen;
  49        int opt, status;
  50
  51        status = EXIT_SUCCESS;
  52
  53        while ((opt = getopt(argc, argv, "as")) != -1) {
  54                switch (opt) {
  55                case 'a':
  56                        allpaths = 1;
  57                        break;
  58                case 's':
  59                        silent = 1;
  60                        break;
  61                default:
  62                        usage();
  63                        break;
  64                }
  65        }
  66
  67        argv += optind;
  68        argc -= optind;
  69
  70        if (argc == 0)
  71              usage();
  72
  73        if ((p = getenv("PATH")) == NULL)
  74                exit(EXIT_FAILURE);
  75        pathlen = strlen(p) + 1;
  76        path = malloc(pathlen);
  77        if (path == NULL)
  78                err(EXIT_FAILURE, "malloc failed");
  79
  80        while (argc > 0) {
  81                memcpy(path, p, pathlen);
  82
  83                if (strlen(*argv) >= FILENAME_MAX ||
  84                    print_matches(path, *argv) == -1)
  85                        status = EXIT_FAILURE;
  86
  87                argv++;
  88                argc--;
  89        }
  90
  91        exit(status);
  92 }
  93
  94 static void
  95 usage(void)
  96 {
  97        fprintf(stderr, "usage: which [-as] program ...\n");
  98        exit(EXIT_FAILURE);
  99 }
 100
 101 static int
 102 is_there(const char *candidate)
 103 {
 104        struct stat fin;
 105
 106        /* XXX work around access(2) false positives for superuser */
 107        if (access(candidate, X_OK) == 0 &&
 108            stat(candidate, &fin) == 0 &&
 109            S_ISREG(fin.st_mode) &&
 110            (getuid() != 0 ||
 111            (fin.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) != 0)) {
 112                if (!silent)
 113                        printf("%s\n", candidate);
 114                return (1);
 115        }
 116        return (0);
 117 }
 118
 119 static int
 120 print_matches(char *path, char *filename)
 121 {
 122        char candidate[PATH_MAX];
 123        const char *d;
 124        int found;
 125
 126        if (strchr(filename, '/') != NULL)
 127                return (is_there(filename) ? 0 : -1);
 128        found = 0;
 129        while ((d = strsep(&path, ":")) != NULL) {
 130                if (*d == '\0')
 131                        d = ".";
 132                if (snprintf(candidate, sizeof(candidate), "%s/%s", d,
 133                    filename) >= (int)sizeof(candidate))
 134                        continue;
 135                if (is_there(candidate)) {
 136                        found = 1;
 137                        if (!allpaths)
 138                                break;
 139                }
 140        }
 141        return (found ? 0 : -1);
 142 }
 143