1 /* Copyright (C) 1992, 1995-2002, 2005-2012 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
16
17 #include <config.h>
18
19 /* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
20 optimizes away the name == NULL test below. */
21 #define _GL_ARG_NONNULL(params)
22
23 /* Specification. */
24 #include <stdlib.h>
25
26 #include <errno.h>
27 #if !_LIBC
28 # define __set_errno(ev) ((errno) = (ev))
29 #endif
30
31 #include <string.h>
32 #include <unistd.h>
33
34 #if !_LIBC
35 # define __environ environ
36 #endif
37
38 #if _LIBC
39 /* This lock protects against simultaneous modifications of 'environ'. */
40 # include <bits/libc-lock.h>
__libc_lock_define_initialized(static,envlock)41 __libc_lock_define_initialized (static, envlock)
42 # define LOCK __libc_lock_lock (envlock)
43 # define UNLOCK __libc_lock_unlock (envlock)
44 #else
45 # define LOCK
46 # define UNLOCK
47 #endif
48
49 /* In the GNU C library we must keep the namespace clean. */
50 #ifdef _LIBC
51 # define unsetenv __unsetenv
52 #endif
53
54 #if _LIBC || !HAVE_UNSETENV
55
56 int
57 unsetenv (const char *name)
58 {
59 size_t len;
60 char **ep;
61
62 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
63 {
64 __set_errno (EINVAL);
65 return -1;
66 }
67
68 len = strlen (name);
69
70 LOCK;
71
72 ep = __environ;
73 while (*ep != NULL)
74 if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
75 {
76 /* Found it. Remove this pointer by moving later ones back. */
77 char **dp = ep;
78
79 do
80 dp[0] = dp[1];
81 while (*dp++);
82 /* Continue the loop in case NAME appears again. */
83 }
84 else
85 ++ep;
86
87 UNLOCK;
88
89 return 0;
90 }
91
92 #ifdef _LIBC
93 # undef unsetenv
94 weak_alias (__unsetenv, unsetenv)
95 #endif
96
97 #else /* HAVE_UNSETENV */
98
99 # undef unsetenv
100 # if !HAVE_DECL_UNSETENV
101 # if VOID_UNSETENV
102 extern void unsetenv (const char *);
103 # else
104 extern int unsetenv (const char *);
105 # endif
106 # endif
107
108 /* Call the underlying unsetenv, in case there is hidden bookkeeping
109 that needs updating beyond just modifying environ. */
110 int
111 rpl_unsetenv (const char *name)
112 {
113 int result = 0;
114 if (!name || !*name || strchr (name, '='))
115 {
116 errno = EINVAL;
117 return -1;
118 }
119 while (getenv (name))
120 # if !VOID_UNSETENV
121 result =
122 # endif
123 unsetenv (name);
124 return result;
125 }
126
127 #endif /* HAVE_UNSETENV */
128