1 /* Copyright (C) 1991, 1994, 1997-1998, 2000, 2003-2024 Free Software
4 NOTE: The canonical source of this file is maintained with the GNU C
5 Library. Bugs can be reported to bug-glibc@prep.ai.mit.edu.
7 This file is free software: you can redistribute it and/or modify
8 it under the terms of the GNU Lesser General Public License as
9 published by the Free Software Foundation, either version 3 of the
10 License, or (at your option) any later version.
12 This file is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public License
18 along with this program. If not, see <https://www.gnu.org/licenses/>. */
27 /* Include errno.h *after* sys/types.h to work around header problems
31 # define __set_errno(ev) ((errno) = (ev))
37 #if defined _WIN32 && ! defined __CYGWIN__
38 # define WIN32_LEAN_AND_MEAN
44 # define environ __environ
46 extern char **environ
;
51 /* This lock protects against simultaneous modifications of 'environ'. */
52 # include <bits/libc-lock.h>
53 __libc_lock_define_initialized (static, envlock
)
54 # define LOCK __libc_lock_lock (envlock)
55 # define UNLOCK __libc_lock_unlock (envlock)
61 #if defined _WIN32 && ! defined __CYGWIN__
62 /* Don't assume that UNICODE is not defined. */
63 # undef SetEnvironmentVariable
64 # define SetEnvironmentVariable SetEnvironmentVariableA
67 /* Put STRING, which is of the form "NAME=VALUE", in the environment.
68 If STRING contains no '=', then remove STRING from the environment. */
72 const char *name_end
= strchr (string
, '=');
77 /* Remove the variable from the environment. */
78 return unsetenv (string
);
81 #if HAVE_DECL__PUTENV /* native Windows */
82 /* The Microsoft documentation
83 <https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/putenv-wputenv>
85 "Don't change an environment entry directly: instead,
86 use _putenv or _wputenv to change it."
87 Note: Microsoft's _putenv updates not only the contents of _environ but
88 also the contents of _wenviron, so that both are in kept in sync.
90 If we didn't follow this advice, our code and other parts of the
91 application (that use _putenv) would fight over who owns the environ vector
92 and thus cause a crash. */
94 return _putenv (string
);
97 /* _putenv ("NAME=") unsets NAME, so invoke _putenv ("NAME= ")
98 to allocate the environ vector and then replace the new
99 entry with "NAME=". */
101 char *name_x
= malloc (name_end
- string
+ sizeof "= ");
104 memcpy (name_x
, string
, name_end
- string
+ 1);
105 name_x
[name_end
- string
+ 1] = ' ';
106 name_x
[name_end
- string
+ 2] = 0;
107 putenv_result
= _putenv (name_x
);
108 for (ep
= environ
; *ep
; ep
++)
109 if (strcmp (*ep
, name_x
) == 0)
114 # if defined _WIN32 && ! defined __CYGWIN__
115 if (putenv_result
== 0)
117 /* _putenv propagated "NAME= " into the subprocess environment;
118 fix that by calling SetEnvironmentVariable directly. */
119 name_x
[name_end
- string
] = 0;
120 putenv_result
= SetEnvironmentVariable (name_x
, "") ? 0 : -1;
121 errno
= ENOMEM
; /* ENOMEM is the only way to fail. */
125 return putenv_result
;
128 for (ep
= environ
; *ep
; ep
++)
129 if (strncmp (*ep
, string
, name_end
- string
) == 0
130 && (*ep
)[name_end
- string
] == '=')
137 static char **last_environ
= NULL
;
138 size_t size
= ep
- environ
;
139 char **new_environ
= malloc ((size
+ 2) * sizeof *new_environ
);
142 new_environ
[0] = string
;
143 memcpy (new_environ
+ 1, environ
, (size
+ 1) * sizeof *new_environ
);
145 last_environ
= new_environ
;
146 environ
= new_environ
;