1 /* Copyright (C) 1992, 1995-2002, 2005-2024 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 This file is free software: you can redistribute it and/or modify
5 it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
9 This file 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 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17 /* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
18 optimizes away the name == NULL test below. */
19 #define _GL_ARG_NONNULL(params)
28 # define __set_errno(ev) ((errno) = (ev))
35 # define __environ environ
39 /* This lock protects against simultaneous modifications of 'environ'. */
40 # include <bits/libc-lock.h>
41 __libc_lock_define_initialized (static, envlock
)
42 # define LOCK __libc_lock_lock (envlock)
43 # define UNLOCK __libc_lock_unlock (envlock)
49 /* In the GNU C library we must keep the namespace clean. */
51 # define unsetenv __unsetenv
54 #if _LIBC || !HAVE_UNSETENV
57 unsetenv (const char *name
)
61 if (name
== NULL
|| *name
== '\0' || strchr (name
, '=') != NULL
)
69 #if HAVE_DECL__PUTENV /* native Windows */
70 /* The Microsoft documentation
71 <https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/putenv-wputenv>
73 "Don't change an environment entry directly: instead,
74 use _putenv or _wputenv to change it."
75 Note: Microsoft's _putenv updates not only the contents of _environ but
76 also the contents of _wenviron, so that both are in kept in sync.
78 The way to remove an environment variable is to pass to _putenv a string
79 of the form "NAME=". (NB: This is a different convention than with glibc
80 putenv, which expects a string of the form "NAME"!) */
83 char *name_
= malloc (len
+ 2);
86 memcpy (name_
, name
, len
);
89 putenv_result
= _putenv (name_
);
90 /* In this particular case it is OK to free() the argument passed to
99 char **ep
= __environ
;
101 if (!strncmp (*ep
, name
, len
) && (*ep
)[len
] == '=')
103 /* Found it. Remove this pointer by moving later ones back. */
109 /* Continue the loop in case NAME appears again. */
122 weak_alias (__unsetenv
, unsetenv
)
125 #else /* HAVE_UNSETENV */
128 # if !HAVE_DECL_UNSETENV
130 extern void unsetenv (const char *);
132 extern int unsetenv (const char *);
136 /* Call the underlying unsetenv, in case there is hidden bookkeeping
137 that needs updating beyond just modifying environ. */
139 rpl_unsetenv (const char *name
)
142 if (!name
|| !*name
|| strchr (name
, '='))
147 while (getenv (name
))
155 #endif /* HAVE_UNSETENV */