1 /* Copyright (C) 1992,1995-1999,2000-2003,2005-2007 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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.
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.
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/>. */
27 # define __set_errno(ev) ((errno) = (ev))
31 #if _LIBC || HAVE_UNISTD_H
35 #if _LIBC || !HAVE_SETENV
42 # define __environ environ
43 # ifndef HAVE_ENVIRON_DECL
44 extern char **environ;
49 /* This lock protects against simultaneous modifications of `environ'. */
50 # include <bits/libc-lock.h>
51 __libc_lock_define_initialized (static, envlock)
52 # define LOCK __libc_lock_lock (envlock)
53 # define UNLOCK __libc_lock_unlock (envlock)
59 /* In the GNU C library we must keep the namespace clean. */
61 # define setenv __setenv
62 # define clearenv __clearenv
63 # define tfind __tfind
64 # define tsearch __tsearch
67 /* In the GNU C library implementation we try to be more clever and
68 allow arbitrarily many changes of the environment given that the used
69 values are from a small set. Outside glibc this will eat up all
70 memory after a while. */
71 #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
73 # define USE_TSEARCH 1
75 typedef int (*compar_fn_t) (const void *, const void *);
77 /* This is a pointer to the root of the search tree with the known
79 static void *known_values;
81 # define KNOWN_VALUE(Str) \
83 void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \
84 value != NULL ? *(char **) value : NULL; \
86 # define STORE_VALUE(Str) \
87 tsearch (Str, &known_values, (compar_fn_t) strcmp)
92 # define KNOWN_VALUE(Str) NULL
93 # define STORE_VALUE(Str) do { } while (0)
98 /* If this variable is not a null pointer we allocated the current
100 static char **last_environ;
103 /* This function is used by `setenv' and `putenv'. The difference between
104 the two functions is that for the former must create a new string which
105 is then placed in the environment, while the argument of `putenv'
106 must be used directly. This is all complicated by the fact that we try
107 to reuse values once generated for a `setenv' call since we can never
110 __add_to_environ (const char *name, const char *value, const char *combined,
114 register size_t size;
115 const size_t namelen = strlen (name);
116 const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
120 /* We have to get the pointer now that we have the lock and not earlier
121 since another thread might have created a new environment. */
127 for (; *ep != NULL; ++ep)
128 if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
134 if (ep == NULL || *ep == NULL)
141 /* We allocated this space; we can extend it. */
143 (char **) (last_environ == NULL
144 ? malloc ((size + 2) * sizeof (char *))
145 : realloc (last_environ, (size + 2) * sizeof (char *)));
146 if (new_environ == NULL)
152 /* If the whole entry is given add it. */
153 if (combined != NULL)
154 /* We must not add the string to the search tree since it belongs
156 new_environ[size] = (char *) combined;
159 /* See whether the value is already known. */
162 new_value = (char *) alloca (namelen + 1 + vallen);
163 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
166 new_value = (char *) malloca (namelen + 1 + vallen);
167 if (new_value == NULL)
169 __set_errno (ENOMEM);
173 memcpy (new_value, name, namelen);
174 new_value[namelen] = '=';
175 memcpy (&new_value[namelen + 1], value, vallen);
178 new_environ[size] = KNOWN_VALUE (new_value);
179 if (new_environ[size] == NULL)
182 new_environ[size] = (char *) malloc (namelen + 1 + vallen);
183 if (new_environ[size] == NULL)
185 #if defined USE_TSEARCH && !defined _LIBC
188 __set_errno (ENOMEM);
194 memcpy (new_environ[size], new_value, namelen + 1 + vallen);
196 memcpy (new_environ[size], name, namelen);
197 new_environ[size][namelen] = '=';
198 memcpy (&new_environ[size][namelen + 1], value, vallen);
200 /* And save the value now. We cannot do this when we remove
201 the string since then we cannot decide whether it is a
202 user string or not. */
203 STORE_VALUE (new_environ[size]);
205 #if defined USE_TSEARCH && !defined _LIBC
210 if (__environ != last_environ)
211 memcpy ((char *) new_environ, (char *) __environ,
212 size * sizeof (char *));
214 new_environ[size + 1] = NULL;
216 last_environ = __environ = new_environ;
222 /* Use the user string if given. */
223 if (combined != NULL)
224 np = (char *) combined;
230 new_value = alloca (namelen + 1 + vallen);
231 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
234 new_value = malloca (namelen + 1 + vallen);
235 if (new_value == NULL)
237 __set_errno (ENOMEM);
241 memcpy (new_value, name, namelen);
242 new_value[namelen] = '=';
243 memcpy (&new_value[namelen + 1], value, vallen);
246 np = KNOWN_VALUE (new_value);
250 np = malloc (namelen + 1 + vallen);
253 #if defined USE_TSEARCH && !defined _LIBC
256 __set_errno (ENOMEM);
262 memcpy (np, new_value, namelen + 1 + vallen);
264 memcpy (np, name, namelen);
266 memcpy (&np[namelen + 1], value, vallen);
268 /* And remember the value. */
271 #if defined USE_TSEARCH && !defined _LIBC
285 setenv (const char *name, const char *value, int replace)
287 return __add_to_environ (name, value, NULL, replace);
290 /* The `clearenv' was planned to be added to POSIX.1 but probably
291 never made it. Nevertheless the POSIX.9 standard (POSIX bindings
292 for Fortran 77) requires this function. */
298 if (__environ == last_environ && __environ != NULL)
300 /* We allocated this environment so we can free it. */
305 /* Clear the environment pointer removes the whole environment. */
317 /* Remove all traces. */
320 /* Now remove the search tree. */
321 __tdestroy (known_values, free);
324 text_set_element (__libc_subfreeres, free_mem);
329 weak_alias (__setenv, setenv)
330 weak_alias (__clearenv, clearenv)
333 #endif /* _LIBC || !HAVE_SETENV */