xref: /freebsd/usr.bin/printenv/printenv.c (revision 7c43148a974877188a930e4078a164f83da8e652)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1987, 1993
5  *	The Regents of the University of California.  All rights reserved.
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. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/types.h>
33 
34 #include <capsicum_helpers.h>
35 #include <err.h>
36 #include <stdlib.h>
37 #include <stdio.h>
38 #include <string.h>
39 #include <unistd.h>
40 
41 void	usage(void);
42 extern char **environ;
43 
44 /*
45  * printenv
46  *
47  * Bill Joy, UCB
48  * February, 1979
49  */
50 int
51 main(int argc, char *argv[])
52 {
53 	char *cp, **ep;
54 	size_t len;
55 	int ch;
56 
57 	if (caph_limit_stdio() < 0 || caph_enter() < 0)
58 		err(1, "capsicum");
59 
60 	while ((ch = getopt(argc, argv, "")) != -1)
61 		switch(ch) {
62 		case '?':
63 		default:
64 			usage();
65 		}
66 	argc -= optind;
67 	argv += optind;
68 
69 	if (argc == 0) {
70 		for (ep = environ; *ep; ep++)
71 			(void)printf("%s\n", *ep);
72 		exit(0);
73 	}
74 	len = strlen(*argv);
75 	for (ep = environ; *ep; ep++)
76 		if (!memcmp(*ep, *argv, len)) {
77 			cp = *ep + len;
78 			if (*cp == '=') {
79 				(void)printf("%s\n", cp + 1);
80 				exit(0);
81 			}
82 		}
83 	exit(1);
84 }
85 
86 void
87 usage(void)
88 {
89 	(void)fprintf(stderr, "usage: printenv [name]\n");
90 	exit(1);
91 }
92