xref: /freebsd/bin/kenv/kenv.c (revision 1b6c2589164a3a7b2f62d4c28c2ffa1be860959e)
1 /*
2  * Copyright (c) 2000  Peter Wemm <peter@freebsd.org>
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  *
13  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23  * SUCH DAMAGE.
24  *
25  * $FreeBSD$
26  */
27 #include <sys/types.h>
28 #include <sys/sysctl.h>
29 #include <stdlib.h>
30 #include <stdio.h>
31 #include <string.h>
32 #include <errno.h>
33 #include <err.h>
34 #include <unistd.h>
35 
36 static char sbuf[1024];
37 
38 static void
39 usage(void)
40 {
41 	errx(1, "usage: [-h] [variable]");
42 }
43 
44 int
45 main(int argc, char **argv)
46 {
47 	int name2oid_oid[2];
48 	int real_oid[CTL_MAXNAME+4];
49 	size_t oidlen;
50 	int ch, error, hflag, i, slen;
51 	char *env, *eq, *name, *var, *val;
52 
53 	hflag = 0;
54 	env = NULL;
55 	while ((ch = getopt(argc, argv, "h")) != -1) {
56 		switch (ch) {
57 		case 'h':
58 			hflag++;
59 			break;
60 		default:
61 			usage();
62 		}
63 	}
64 	argc -= optind;
65 	argv += optind;
66 	if (argc > 0) {
67 		env = argv[0];
68 		argv++;
69 		argc--;
70 	}
71 	if (argc > 0)
72 		usage();
73 	name2oid_oid[0] = 0;	/* This is magic & undocumented! */
74 	name2oid_oid[1] = 3;
75 	oidlen = sizeof(real_oid);
76 	name = "kern.environment";
77 	error = sysctl(name2oid_oid, 2, real_oid, &oidlen, name, strlen(name));
78 	if (error < 0)
79 		err(1, "cannot find kern.environment base sysctl OID");
80 	oidlen /= sizeof (int);
81 	if (oidlen >= CTL_MAXNAME)
82 		errx(1, "kern.environment OID is too large!");
83 	real_oid[oidlen] = 0;
84 	for (i = 0; ; i++) {
85 		real_oid[oidlen + 1] = i;
86 		slen = sizeof(sbuf) - 1;
87 		error = sysctl(real_oid, oidlen + 2, sbuf, &slen, NULL, 0);
88 		if (error < 0) {
89 			if (errno != ENOENT)
90 				err(1, "sysctl kern.environment.%d\n", i);
91 			break;
92 		}
93 		sbuf[sizeof(sbuf) - 1] = '\0';
94 		eq = strchr(sbuf, '=');
95 		if (eq == NULL)
96 			err(1, "malformed environment string: %s\n", sbuf);
97 		var = sbuf;
98 		*eq = '\0';
99 		val = eq + 1;
100 		if (env) {
101 			if (strcmp(var, env) != 0)
102 				continue;
103 			printf("%s\n", val);
104 			break;
105 		}
106 		if (hflag) {
107 			if (strncmp(var, "hint.", 5) != 0)
108 				continue;
109 			/* FALLTHROUGH */
110 		}
111 		printf("%s=\"", var);
112 		while (*val) {
113 			switch (*val) {
114 			case '"':
115 				putchar('\\');
116 				putchar('"');
117 				break;
118 			case '\\':
119 				putchar('\\');
120 				putchar('\\');
121 				break;
122 			default:
123 				putchar(*val);
124 				break;
125 			}
126 			val++;
127 		}
128 		printf("\"\n");
129 	}
130 	exit(0);
131 }
132