1 /* $NetBSD: unsetenv.c,v 1.11 2015/01/20 18:31:25 christos Exp $ */
2
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/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 #if 0
35 static char sccsid[] = "from: @(#)setenv.c 8.1 (Berkeley) 6/4/93";
36 #else
37 __RCSID("$NetBSD: unsetenv.c,v 1.11 2015/01/20 18:31:25 christos Exp $");
38 #endif
39 #endif /* LIBC_SCCS and not lint */
40
41 #include "namespace.h"
42
43 #include <assert.h>
44 #include <errno.h>
45 #include <stdlib.h>
46 #include <string.h>
47 #include <bitstring.h>
48
49 #include "env.h"
50 #include "local.h"
51
52 /*
53 * unsetenv(name) --
54 * Delete environmental variable "name".
55 */
56 int
unsetenv(const char * name)57 unsetenv(const char *name)
58 {
59 size_t l_name;
60 ssize_t r_offset, w_offset;
61
62 _DIAGASSERT(name != NULL);
63
64 l_name = __envvarnamelen(name, false);
65 if (l_name == 0) {
66 errno = EINVAL;
67 return -1;
68 }
69
70 if (!__writelockenv())
71 return -1;
72
73 /* Search for the given name in the environment. */
74 r_offset = __getenvslot(name, l_name, false);
75 if (r_offset == -1) {
76 /* Not found. */
77 (void)__unlockenv();
78 return 0;
79 }
80 __freeenvvar(environ[r_offset]);
81
82 /*
83 * Remove all matches from the environment and free the associated
84 * memory if possible.
85 */
86 w_offset = r_offset;
87 while (environ[++r_offset] != NULL) {
88 if (strncmp(environ[r_offset], name, l_name) != 0 ||
89 environ[r_offset][l_name] != '=') {
90 /* Not a match, keep this entry. */
91 environ[w_offset++] = environ[r_offset];
92 } else {
93 /* We found another match. */
94 __freeenvvar(environ[r_offset]);
95 }
96 }
97
98 /* Clear out remaining stale entries in the environment vector. */
99 do {
100 environ[w_offset++] = NULL;
101 } while (w_offset < r_offset);
102
103 (void)__unlockenv();
104 return 0;
105 }
106