1 /* Copyright (C) 1991, 1994, 1997-1998, 2000, 2003-2020 Free Software
2 Foundation, Inc.
3
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.
6
7 This program is free software: you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by the
9 Free Software Foundation; either version 3 of the License, or any
10 later version.
11
12 This program 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 General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <https://www.gnu.org/licenses/>. */
19
20 #include <config.h>
21
22 /* Specification. */
23 #include <stdlib.h>
24
25 #include <stddef.h>
26
27 /* Include errno.h *after* sys/types.h to work around header problems
28 on AIX 3.2.5. */
29 #include <errno.h>
30 #ifndef __set_errno
31 # define __set_errno(ev) ((errno) = (ev))
32 #endif
33
34 #include <string.h>
35 #include <unistd.h>
36
37 #if defined _WIN32 && ! defined __CYGWIN__
38 # define WIN32_LEAN_AND_MEAN
39 # include <windows.h>
40 #endif
41
42 #if _LIBC
43 # if HAVE_GNU_LD
44 # define environ __environ
45 # else
46 extern char **environ;
47 # endif
48 #endif
49
50 #if _LIBC
51 /* This lock protects against simultaneous modifications of 'environ'. */
52 # include <bits/libc-lock.h>
__libc_lock_define_initialized(static,envlock)53 __libc_lock_define_initialized (static, envlock)
54 # define LOCK __libc_lock_lock (envlock)
55 # define UNLOCK __libc_lock_unlock (envlock)
56 #else
57 # define LOCK
58 # define UNLOCK
59 #endif
60
61 #if defined _WIN32 && ! defined __CYGWIN__
62 /* Don't assume that UNICODE is not defined. */
63 # undef SetEnvironmentVariable
64 # define SetEnvironmentVariable SetEnvironmentVariableA
65 #endif
66
67 static int
68 _unsetenv (const char *name)
69 {
70 size_t len;
71 #if !HAVE_DECL__PUTENV
72 char **ep;
73 #endif
74
75 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
76 {
77 __set_errno (EINVAL);
78 return -1;
79 }
80
81 len = strlen (name);
82
83 #if HAVE_DECL__PUTENV
84 {
85 int putenv_result, putenv_errno;
86 char *name_ = malloc (len + 2);
87 memcpy (name_, name, len);
88 name_[len] = '=';
89 name_[len + 1] = 0;
90 putenv_result = _putenv (name_);
91 putenv_errno = errno;
92 free (name_);
93 __set_errno (putenv_errno);
94 return putenv_result;
95 }
96 #else
97
98 LOCK;
99
100 ep = environ;
101 while (*ep != NULL)
102 if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
103 {
104 /* Found it. Remove this pointer by moving later ones back. */
105 char **dp = ep;
106
107 do
108 dp[0] = dp[1];
109 while (*dp++);
110 /* Continue the loop in case NAME appears again. */
111 }
112 else
113 ++ep;
114
115 UNLOCK;
116
117 return 0;
118 #endif
119 }
120
121
122 /* Put STRING, which is of the form "NAME=VALUE", in the environment.
123 If STRING contains no '=', then remove STRING from the environment. */
124 int
putenv(char * string)125 putenv (char *string)
126 {
127 const char *name_end = strchr (string, '=');
128 char **ep;
129
130 if (name_end == NULL)
131 {
132 /* Remove the variable from the environment. */
133 return _unsetenv (string);
134 }
135
136 #if HAVE_DECL__PUTENV
137 /* Rely on _putenv to allocate the new environment. If other
138 parts of the application use _putenv, the !HAVE_DECL__PUTENV code
139 would fight over who owns the environ vector, causing a crash. */
140 if (name_end[1])
141 return _putenv (string);
142 else
143 {
144 /* _putenv ("NAME=") unsets NAME, so invoke _putenv ("NAME= ")
145 to allocate the environ vector and then replace the new
146 entry with "NAME=". */
147 int putenv_result, putenv_errno;
148 char *name_x = malloc (name_end - string + sizeof "= ");
149 if (!name_x)
150 return -1;
151 memcpy (name_x, string, name_end - string + 1);
152 name_x[name_end - string + 1] = ' ';
153 name_x[name_end - string + 2] = 0;
154 putenv_result = _putenv (name_x);
155 putenv_errno = errno;
156 for (ep = environ; *ep; ep++)
157 if (strcmp (*ep, name_x) == 0)
158 {
159 *ep = string;
160 break;
161 }
162 # if defined _WIN32 && ! defined __CYGWIN__
163 if (putenv_result == 0)
164 {
165 /* _putenv propagated "NAME= " into the subprocess environment;
166 fix that by calling SetEnvironmentVariable directly. */
167 name_x[name_end - string] = 0;
168 putenv_result = SetEnvironmentVariable (name_x, "") ? 0 : -1;
169 putenv_errno = ENOMEM; /* ENOMEM is the only way to fail. */
170 }
171 # endif
172 free (name_x);
173 __set_errno (putenv_errno);
174 return putenv_result;
175 }
176 #else
177 for (ep = environ; *ep; ep++)
178 if (strncmp (*ep, string, name_end - string) == 0
179 && (*ep)[name_end - string] == '=')
180 break;
181
182 if (*ep)
183 *ep = string;
184 else
185 {
186 static char **last_environ = NULL;
187 size_t size = ep - environ;
188 char **new_environ = malloc ((size + 2) * sizeof *new_environ);
189 if (! new_environ)
190 return -1;
191 new_environ[0] = string;
192 memcpy (new_environ + 1, environ, (size + 1) * sizeof *new_environ);
193 free (last_environ);
194 last_environ = new_environ;
195 environ = new_environ;
196 }
197
198 return 0;
199 #endif
200 }
201