1 /*
2 * $OpenBSD: readlink.c,v 1.28 2019/06/28 13:35:03 deraadt Exp $
3 *
4 * Copyright (c) 1997
5 * Kenneth Stailey (hereinafter referred to as the author)
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 #include <err.h>
31 #include <errno.h>
32 #include <limits.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <unistd.h>
37
38 static void usage(void);
39
40 int
main(int argc,char * argv[])41 main(int argc, char *argv[])
42 {
43 char buf[PATH_MAX];
44 int n, ch, nflag = 0, fflag = 0;
45 extern int optind;
46
47 if (pledge("stdio rpath", NULL) == -1)
48 err(1, "pledge");
49
50 while ((ch = getopt(argc, argv, "fn")) != -1)
51 switch (ch) {
52 case 'f':
53 fflag = 1;
54 break;
55 case 'n':
56 nflag = 1;
57 break;
58 default:
59 usage();
60 }
61 argc -= optind;
62 argv += optind;
63
64 if (argc != 1)
65 usage();
66
67 n = strlen(argv[0]);
68 if (n > PATH_MAX - 1) {
69 fprintf(stderr,
70 "readlink: filename longer than PATH_MAX-1 (%d)\n",
71 PATH_MAX - 1);
72 exit(1);
73 }
74
75 if (fflag) {
76 if (realpath(argv[0], buf) == NULL)
77 err(1, "%s", argv[0]);
78 } else {
79 if ((n = readlink(argv[0], buf, sizeof buf-1)) == -1)
80 exit(1);
81 buf[n] = '\0';
82 }
83
84 printf("%s", buf);
85 if (!nflag)
86 putchar('\n');
87 exit(0);
88 }
89
90 static void
usage(void)91 usage(void)
92 {
93 (void)fprintf(stderr, "usage: readlink [-fn] file\n");
94 exit(1);
95 }
96