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 2, or (at your option)
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 along
15 with this program; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
25 # define __set_errno(ev) ((errno) = (ev))
30 #if _LIBC || HAVE_UNISTD_H
34 #if _LIBC || !HAVE_SETENV
41 # define __environ environ
42 # ifndef HAVE_ENVIRON_DECL
43 extern char **environ;
48 /* This lock protects against simultaneous modifications of `environ'. */
49 # include <bits/libc-lock.h>
50 __libc_lock_define_initialized (static, envlock)
51 # define LOCK __libc_lock_lock (envlock)
52 # define UNLOCK __libc_lock_unlock (envlock)
58 /* In the GNU C library we must keep the namespace clean. */
60 # define setenv __setenv
61 # define clearenv __clearenv
62 # define tfind __tfind
63 # define tsearch __tsearch
66 /* In the GNU C library implementation we try to be more clever and
67 allow arbitrarily many changes of the environment given that the used
68 values are from a small set. Outside glibc this will eat up all
69 memory after a while. */
70 #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
72 # define USE_TSEARCH 1
74 typedef int (*compar_fn_t) (const void *, const void *);
76 /* This is a pointer to the root of the search tree with the known
78 static void *known_values;
80 # define KNOWN_VALUE(Str) \
82 void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \
83 value != NULL ? *(char **) value : NULL; \
85 # define STORE_VALUE(Str) \
86 tsearch (Str, &known_values, (compar_fn_t) strcmp)
91 # define KNOWN_VALUE(Str) NULL
92 # define STORE_VALUE(Str) do { } while (0)
97 /* If this variable is not a null pointer we allocated the current
99 static char **last_environ;
102 /* This function is used by `setenv' and `putenv'. The difference between
103 the two functions is that for the former must create a new string which
104 is then placed in the environment, while the argument of `putenv'
105 must be used directly. This is all complicated by the fact that we try
106 to reuse values once generated for a `setenv' call since we can never
109 __add_to_environ (const char *name, const char *value, const char *combined,
113 register size_t size;
114 const size_t namelen = strlen (name);
115 const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
119 /* We have to get the pointer now that we have the lock and not earlier
120 since another thread might have created a new environment. */
126 for (; *ep != NULL; ++ep)
127 if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
133 if (ep == NULL || *ep == NULL)
140 /* We allocated this space; we can extend it. */
142 (char **) (last_environ == NULL
143 ? malloc ((size + 2) * sizeof (char *))
144 : realloc (last_environ, (size + 2) * sizeof (char *)));
145 if (new_environ == NULL)
151 /* If the whole entry is given add it. */
152 if (combined != NULL)
153 /* We must not add the string to the search tree since it belongs
155 new_environ[size] = (char *) combined;
158 /* See whether the value is already known. */
161 new_value = (char *) alloca (namelen + 1 + vallen);
162 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
165 new_value = (char *) allocsa (namelen + 1 + vallen);
166 if (new_value == NULL)
168 __set_errno (ENOMEM);
172 memcpy (new_value, name, namelen);
173 new_value[namelen] = '=';
174 memcpy (&new_value[namelen + 1], value, vallen);
177 new_environ[size] = KNOWN_VALUE (new_value);
178 if (new_environ[size] == NULL)
181 new_environ[size] = (char *) malloc (namelen + 1 + vallen);
182 if (new_environ[size] == NULL)
184 #if defined USE_TSEARCH && !defined _LIBC
187 __set_errno (ENOMEM);
193 memcpy (new_environ[size], new_value, namelen + 1 + vallen);
195 memcpy (new_environ[size], name, namelen);
196 new_environ[size][namelen] = '=';
197 memcpy (&new_environ[size][namelen + 1], value, vallen);
199 /* And save the value now. We cannot do this when we remove
200 the string since then we cannot decide whether it is a
201 user string or not. */
202 STORE_VALUE (new_environ[size]);
204 #if defined USE_TSEARCH && !defined _LIBC
209 if (__environ != last_environ)
210 memcpy ((char *) new_environ, (char *) __environ,
211 size * sizeof (char *));
213 new_environ[size + 1] = NULL;
215 last_environ = __environ = new_environ;
221 /* Use the user string if given. */
222 if (combined != NULL)
223 np = (char *) combined;
229 new_value = alloca (namelen + 1 + vallen);
230 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
233 new_value = allocsa (namelen + 1 + vallen);
234 if (new_value == NULL)
236 __set_errno (ENOMEM);
240 memcpy (new_value, name, namelen);
241 new_value[namelen] = '=';
242 memcpy (&new_value[namelen + 1], value, vallen);
245 np = KNOWN_VALUE (new_value);
249 np = malloc (namelen + 1 + vallen);
252 #if defined USE_TSEARCH && !defined _LIBC
255 __set_errno (ENOMEM);
261 memcpy (np, new_value, namelen + 1 + vallen);
263 memcpy (np, name, namelen);
265 memcpy (&np[namelen + 1], value, vallen);
267 /* And remember the value. */
270 #if defined USE_TSEARCH && !defined _LIBC
284 setenv (const char *name, const char *value, int replace)
286 return __add_to_environ (name, value, NULL, replace);
289 /* The `clearenv' was planned to be added to POSIX.1 but probably
290 never made it. Nevertheless the POSIX.9 standard (POSIX bindings
291 for Fortran 77) requires this function. */
297 if (__environ == last_environ && __environ != NULL)
299 /* We allocated this environment so we can free it. */
304 /* Clear the environment pointer removes the whole environment. */
316 /* Remove all traces. */
319 /* Now remove the search tree. */
320 __tdestroy (known_values, free);
323 text_set_element (__libc_subfreeres, free_mem);
328 weak_alias (__setenv, setenv)
329 weak_alias (__clearenv, clearenv)
332 #endif /* _LIBC || !HAVE_SETENV */