bin/which/which.c

   1 /*      $OpenBSD: which.c,v 1.26 2016/10/28 07:22:59 schwarze Exp $     */
   2
   3 /*
   4  * Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include <sys/stat.h>
  20
  21 #include <err.h>
  22 #include <errno.h>
  23 #include <limits.h>
  24 #include <paths.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <unistd.h>
  29
  30 #define PROG_WHICH      1
  31 #define PROG_WHEREIS    2
  32
  33 extern char *__progname;
  34
  35 int findprog(char *, char *, int, int);
  36 static void __dead usage(void);
  37
  38 /*
  39  * which(1) -- find an executable(s) in the user's path
  40  * whereis(1) -- find an executable(s) in the default user path
  41  *
  42  * Return values:
  43  *      0 - all executables found
  44  *      1 - some found, some not
  45  *      2 - none found
  46  */
  47
  48 int
  49 main(int argc, char *argv[])
  50 {
  51         char *path;
  52         size_t n;
  53         int ch, allmatches = 0, notfound = 0, progmode = PROG_WHICH;
  54
  55         while ((ch = getopt(argc, argv, "a")) != -1)
  56                 switch (ch) {
  57                 case 'a':
  58                         allmatches = 1;
  59                         break;
  60                 default:
  61                         usage();
  62                 }
  63         argc -= optind;
  64         argv += optind;
  65
  66         if (argc == 0)
  67                 usage();
  68
  69         if (strcmp(__progname, "whereis") == 0) {
  70                 progmode = PROG_WHEREIS;
  71                 path = _PATH_STDPATH;
  72         } else {
  73                 if ((path = getenv("PATH")) == NULL || *path == '\0')
  74                         path = _PATH_DEFPATH;
  75         }
  76
  77         /* To make access(2) do what we want */
  78         if (setgid(getegid()))
  79                 err(1, "Can't set gid to %u", getegid());
  80         if (setuid(geteuid()))
  81                 err(1, "Can't set uid to %u", geteuid());
  82
  83         if (pledge("stdio rpath", NULL) == -1)
  84                 err(2, "pledge");
  85
  86         for (n = 0; n < argc; n++)
  87                 if (findprog(argv[n], path, progmode, allmatches) == 0)
  88                         notfound++;
  89
  90         return ((notfound == 0) ? 0 : ((notfound == argc) ? 2 : 1));
  91 }
  92
  93 int
  94 findprog(char *prog, char *path, int progmode, int allmatches)
  95 {
  96         char *p, filename[PATH_MAX];
  97         int len, rval = 0;
  98         struct stat sbuf;
  99         char *pathcpy;
 100
 101         /* Special case if prog contains '/' */
 102         if (strchr(prog, '/')) {
 103                 if ((stat(prog, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
 104                     access(prog, X_OK) == 0) {
 105                         (void)puts(prog);
 106                         return (1);
 107                 } else {
 108                         warnx("%s: Command not found.", prog);
 109                         return (0);
 110                 }
 111         }
 112
 113         if ((path = strdup(path)) == NULL)
 114                 err(1, "strdup");
 115         pathcpy = path;
 116
 117         while ((p = strsep(&pathcpy, ":")) != NULL) {
 118                 if (*p == '\0')
 119                         p = ".";
 120
 121                 len = strlen(p);
 122                 while (len > 0 && p[len-1] == '/')
 123                         p[--len] = '\0';        /* strip trailing '/' */
 124
 125                 len = snprintf(filename, sizeof(filename), "%s/%s", p, prog);
 126                 if (len < 0 || len >= sizeof(filename)) {
 127                         warnc(ENAMETOOLONG, "%s/%s", p, prog);
 128                         free(path);
 129                         return (0);
 130                 }
 131                 if ((stat(filename, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
 132                     access(filename, X_OK) == 0) {
 133                         (void)puts(filename);
 134                         rval = 1;
 135                         if (!allmatches) {
 136                                 free(path);
 137                                 return (rval);
 138                         }
 139                 }
 140         }
 141         (void)free(path);
 142
 143         /* whereis(1) is silent on failure. */
 144         if (!rval && progmode != PROG_WHEREIS)
 145                 warnx("%s: Command not found.", prog);
 146         return (rval);
 147 }
 148
 149 static void __dead
 150 usage(void)
 151 {
 152         (void)fprintf(stderr, "usage: %s [-a] name ...\n", __progname);
 153         exit(1);
 154 }