1 /* Copyright (C) 1992-2013 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library 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 GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
24 # if !defined errno && !defined HAVE_ERRNO_DECL
27 # define __set_errno(ev) ((errno) = (ev))
30 #if _LIBC || HAVE_STDLIB_H
33 #if _LIBC || HAVE_STRING_H
36 #if _LIBC || HAVE_UNISTD_H
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 unsetenv __unsetenv
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
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 (name, value, combined, replace)
112 const char *combined;
116 register size_t size;
117 const size_t namelen = strlen (name);
118 const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
122 /* We have to get the pointer now that we have the lock and not earlier
123 since another thread might have created a new environment. */
129 for (; *ep != NULL; ++ep)
130 if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
136 if (ep == NULL || __builtin_expect (*ep == NULL, 1))
138 const size_t varlen = namelen + 1 + vallen;
141 /* We allocated this space; we can extend it. */
142 new_environ = (char **) realloc (last_environ,
143 (size + 2) * sizeof (char *));
144 if (new_environ == NULL)
150 /* If the whole entry is given add it. */
151 if (combined != NULL)
152 /* We must not add the string to the search tree since it belongs
154 new_environ[size] = (char *) combined;
157 /* See whether the value is already known. */
160 int use_alloca = __libc_use_alloca (varlen);
161 if (__builtin_expect (use_alloca, 1))
162 new_value = (char *) alloca (varlen);
165 new_value = malloc (varlen);
166 if (new_value == NULL)
169 if (last_environ == NULL)
175 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
178 memcpy (new_value, name, namelen);
179 new_value[namelen] = '=';
180 memcpy (&new_value[namelen + 1], value, vallen);
183 new_environ[size] = KNOWN_VALUE (new_value);
184 if (__builtin_expect (new_environ[size] == NULL, 1))
188 if (__builtin_expect (! use_alloca, 0))
189 new_environ[size] = new_value;
193 new_environ[size] = (char *) malloc (varlen);
194 if (__builtin_expect (new_environ[size] == NULL, 0))
201 memcpy (new_environ[size], new_value, varlen);
203 memcpy (new_environ[size], name, namelen);
204 new_environ[size][namelen] = '=';
205 memcpy (&new_environ[size][namelen + 1], value, vallen);
209 /* And save the value now. We cannot do this when we remove
210 the string since then we cannot decide whether it is a
211 user string or not. */
212 STORE_VALUE (new_environ[size]);
216 if (__environ != last_environ)
217 memcpy ((char *) new_environ, (char *) __environ,
218 size * sizeof (char *));
220 new_environ[size + 1] = NULL;
222 last_environ = __environ = new_environ;
228 /* Use the user string if given. */
229 if (combined != NULL)
230 np = (char *) combined;
233 const size_t varlen = namelen + 1 + vallen;
236 int use_alloca = __libc_use_alloca (varlen);
237 if (__builtin_expect (use_alloca, 1))
238 new_value = (char *) alloca (varlen);
241 new_value = malloc (varlen);
242 if (new_value == NULL)
249 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
252 memcpy (new_value, name, namelen);
253 new_value[namelen] = '=';
254 memcpy (&new_value[namelen + 1], value, vallen);
257 np = KNOWN_VALUE (new_value);
258 if (__builtin_expect (np == NULL, 1))
262 if (__builtin_expect (! use_alloca, 0))
267 np = malloc (varlen);
268 if (__builtin_expect (np == NULL, 0))
275 memcpy (np, new_value, varlen);
277 memcpy (np, name, namelen);
279 memcpy (&np[namelen + 1], value, vallen);
282 /* And remember the value. */
296 setenv (name, value, replace)
301 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
303 __set_errno (EINVAL);
307 return __add_to_environ (name, value, NULL, replace);
317 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
319 __set_errno (EINVAL);
330 if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
332 /* Found it. Remove this pointer by moving later ones back. */
338 /* Continue the loop in case NAME appears again. */
348 /* The `clearenv' was planned to be added to POSIX.1 but probably
349 never made it. Nevertheless the POSIX.9 standard (POSIX bindings
350 for Fortran 77) requires this function. */
356 if (__environ == last_environ && __environ != NULL)
358 /* We allocated this environment so we can free it. */
363 /* Clear the environment pointer removes the whole environment. */
371 libc_freeres_fn (free_mem)
373 /* Remove all traces. */
376 /* Now remove the search tree. */
377 __tdestroy (known_values, free);
384 weak_alias (__setenv, setenv)
385 weak_alias (__unsetenv, unsetenv)
386 weak_alias (__clearenv, clearenv)