1 /* Copyright (C) 1992-2015 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;
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))
140 /* We allocated this space; we can extend it. */
141 new_environ = (char **) realloc (last_environ,
142 (size + 2) * sizeof (char *));
143 if (new_environ == NULL)
149 if (__environ != last_environ)
150 memcpy ((char *) new_environ, (char *) __environ,
151 size * sizeof (char *));
153 new_environ[size] = NULL;
154 new_environ[size + 1] = NULL;
155 ep = new_environ + size;
157 last_environ = __environ = new_environ;
159 if (*ep == NULL || replace)
163 /* Use the user string if given. */
164 if (combined != NULL)
165 np = (char *) combined;
168 const size_t varlen = namelen + 1 + vallen;
171 int use_alloca = __libc_use_alloca (varlen);
172 if (__builtin_expect (use_alloca, 1))
173 new_value = (char *) alloca (varlen);
176 new_value = malloc (varlen);
177 if (new_value == NULL)
184 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
187 memcpy (new_value, name, namelen);
188 new_value[namelen] = '=';
189 memcpy (&new_value[namelen + 1], value, vallen);
192 np = KNOWN_VALUE (new_value);
193 if (__glibc_likely (np == NULL))
197 if (__glibc_unlikely (! use_alloca))
202 np = malloc (varlen);
203 if (__glibc_unlikely (np == NULL))
210 memcpy (np, new_value, varlen);
212 memcpy (np, name, namelen);
214 memcpy (&np[namelen + 1], value, vallen);
217 /* And remember the value. */
223 if (__glibc_unlikely (! use_alloca))
238 setenv (name, value, replace)
243 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
245 __set_errno (EINVAL);
249 return __add_to_environ (name, value, NULL, replace);
259 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
261 __set_errno (EINVAL);
272 if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
274 /* Found it. Remove this pointer by moving later ones back. */
280 /* Continue the loop in case NAME appears again. */
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. */
313 libc_freeres_fn (free_mem)
315 /* Remove all traces. */
318 /* Now remove the search tree. */
319 __tdestroy (known_values, free);
326 weak_alias (__setenv, setenv)
327 weak_alias (__unsetenv, unsetenv)
328 weak_alias (__clearenv, clearenv)