1 /* Copyright (C) 1992,1995-1999,2000-2003,2005-2007 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
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.
8
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.
13
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/>. */
16
17 #if !_LIBC
18 # include <config.h>
19 #endif
20 #include <alloca.h>
21
22 #include <errno.h>
23 #ifndef __set_errno
24 # define __set_errno(ev) ((errno) = (ev))
25 #endif
26
27 #include <stdlib.h>
28 #include <string.h>
29 #if _LIBC || HAVE_UNISTD_H
30 # include <unistd.h>
31 #endif
32
33 #if _LIBC || !HAVE_SETENV
34
35 #if !_LIBC
36 # include "malloca.h"
37 #endif
38
39 #if !_LIBC
40 # define __environ environ
41 # ifndef HAVE_ENVIRON_DECL
42 extern char **environ;
43 # endif
44 #endif
45
46 #if _LIBC
47 /* This lock protects against simultaneous modifications of `environ'. */
48 # include <bits/libc-lock.h>
49 __libc_lock_define_initialized (static, envlock)
50 # define LOCK __libc_lock_lock (envlock)
51 # define UNLOCK __libc_lock_unlock (envlock)
52 #else
53 # define LOCK
54 # define UNLOCK
55 #endif
56
57 /* In the GNU C library we must keep the namespace clean. */
58 #ifdef _LIBC
59 # define setenv __setenv
60 # define clearenv __clearenv
61 # define tfind __tfind
62 # define tsearch __tsearch
63 #endif
64
65 /* In the GNU C library implementation we try to be more clever and
66 allow arbitrarily many changes of the environment given that the used
67 values are from a small set. Outside glibc this will eat up all
68 memory after a while. */
69 #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
70 && defined __GNUC__)
71 # define USE_TSEARCH 1
72 # include <search.h>
73 typedef int (*compar_fn_t) (const void *, const void *);
74
75 /* This is a pointer to the root of the search tree with the known
76 values. */
77 static void *known_values;
78
79 # define KNOWN_VALUE(Str) \
80 ({ \
81 void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \
82 value != NULL ? *(char **) value : NULL; \
83 })
84 # define STORE_VALUE(Str) \
85 tsearch (Str, &known_values, (compar_fn_t) strcmp)
86
87 #else
88 # undef USE_TSEARCH
89
90 # define KNOWN_VALUE(Str) NULL
91 # define STORE_VALUE(Str) do { } while (0)
92
93 #endif
94
95
96 /* If this variable is not a null pointer we allocated the current
97 environment. */
98 static char **last_environ;
99
100
101 /* This function is used by `setenv' and `putenv'. The difference between
102 the two functions is that for the former must create a new string which
103 is then placed in the environment, while the argument of `putenv'
104 must be used directly. This is all complicated by the fact that we try
105 to reuse values once generated for a `setenv' call since we can never
106 free the strings. */
107 int
__add_to_environ(const char * name,const char * value,const char * combined,int replace)108 __add_to_environ (const char *name, const char *value, const char *combined,
109 int replace)
110 {
111 register char **ep;
112 register size_t size;
113 const size_t namelen = strlen (name);
114 const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
115
116 LOCK;
117
118 /* We have to get the pointer now that we have the lock and not earlier
119 since another thread might have created a new environment. */
120 ep = __environ;
121
122 size = 0;
123 if (ep != NULL)
124 {
125 for (; *ep != NULL; ++ep)
126 if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
127 break;
128 else
129 ++size;
130 }
131
132 if (ep == NULL || *ep == NULL)
133 {
134 char **new_environ;
135 #ifdef USE_TSEARCH
136 char *new_value;
137 #endif
138
139 /* We allocated this space; we can extend it. */
140 new_environ =
141 (char **) (last_environ == NULL
142 ? malloc ((size + 2) * sizeof (char *))
143 : realloc (last_environ, (size + 2) * sizeof (char *)));
144 if (new_environ == NULL)
145 {
146 UNLOCK;
147 return -1;
148 }
149
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
153 to the user. */
154 new_environ[size] = (char *) combined;
155 else
156 {
157 /* See whether the value is already known. */
158 #ifdef USE_TSEARCH
159 # ifdef _LIBC
160 new_value = (char *) alloca (namelen + 1 + vallen);
161 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
162 value, vallen);
163 # else
164 new_value = (char *) malloca (namelen + 1 + vallen);
165 if (new_value == NULL)
166 {
167 __set_errno (ENOMEM);
168 UNLOCK;
169 return -1;
170 }
171 memcpy (new_value, name, namelen);
172 new_value[namelen] = '=';
173 memcpy (&new_value[namelen + 1], value, vallen);
174 # endif
175
176 new_environ[size] = KNOWN_VALUE (new_value);
177 if (new_environ[size] == NULL)
178 #endif
179 {
180 new_environ[size] = (char *) malloc (namelen + 1 + vallen);
181 if (new_environ[size] == NULL)
182 {
183 #if defined USE_TSEARCH && !defined _LIBC
184 freea (new_value);
185 #endif
186 __set_errno (ENOMEM);
187 UNLOCK;
188 return -1;
189 }
190
191 #ifdef USE_TSEARCH
192 memcpy (new_environ[size], new_value, namelen + 1 + vallen);
193 #else
194 memcpy (new_environ[size], name, namelen);
195 new_environ[size][namelen] = '=';
196 memcpy (&new_environ[size][namelen + 1], value, vallen);
197 #endif
198 /* And save the value now. We cannot do this when we remove
199 the string since then we cannot decide whether it is a
200 user string or not. */
201 STORE_VALUE (new_environ[size]);
202 }
203 #if defined USE_TSEARCH && !defined _LIBC
204 freea (new_value);
205 #endif
206 }
207
208 if (__environ != last_environ)
209 memcpy ((char *) new_environ, (char *) __environ,
210 size * sizeof (char *));
211
212 new_environ[size + 1] = NULL;
213
214 last_environ = __environ = new_environ;
215 }
216 else if (replace)
217 {
218 char *np;
219
220 /* Use the user string if given. */
221 if (combined != NULL)
222 np = (char *) combined;
223 else
224 {
225 #ifdef USE_TSEARCH
226 char *new_value;
227 # ifdef _LIBC
228 new_value = alloca (namelen + 1 + vallen);
229 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
230 value, vallen);
231 # else
232 new_value = malloca (namelen + 1 + vallen);
233 if (new_value == NULL)
234 {
235 __set_errno (ENOMEM);
236 UNLOCK;
237 return -1;
238 }
239 memcpy (new_value, name, namelen);
240 new_value[namelen] = '=';
241 memcpy (&new_value[namelen + 1], value, vallen);
242 # endif
243
244 np = KNOWN_VALUE (new_value);
245 if (np == NULL)
246 #endif
247 {
248 np = malloc (namelen + 1 + vallen);
249 if (np == NULL)
250 {
251 #if defined USE_TSEARCH && !defined _LIBC
252 freea (new_value);
253 #endif
254 __set_errno (ENOMEM);
255 UNLOCK;
256 return -1;
257 }
258
259 #ifdef USE_TSEARCH
260 memcpy (np, new_value, namelen + 1 + vallen);
261 #else
262 memcpy (np, name, namelen);
263 np[namelen] = '=';
264 memcpy (&np[namelen + 1], value, vallen);
265 #endif
266 /* And remember the value. */
267 STORE_VALUE (np);
268 }
269 #if defined USE_TSEARCH && !defined _LIBC
270 freea (new_value);
271 #endif
272 }
273
274 *ep = np;
275 }
276
277 UNLOCK;
278
279 return 0;
280 }
281
282 int
setenv(const char * name,const char * value,int replace)283 setenv (const char *name, const char *value, int replace)
284 {
285 return __add_to_environ (name, value, NULL, replace);
286 }
287
288 /* The `clearenv' was planned to be added to POSIX.1 but probably
289 never made it. Nevertheless the POSIX.9 standard (POSIX bindings
290 for Fortran 77) requires this function. */
291 int
clearenv(void)292 clearenv (void)
293 {
294 LOCK;
295
296 if (__environ == last_environ && __environ != NULL)
297 {
298 /* We allocated this environment so we can free it. */
299 free (__environ);
300 last_environ = NULL;
301 }
302
303 /* Clear the environment pointer removes the whole environment. */
304 __environ = NULL;
305
306 UNLOCK;
307
308 return 0;
309 }
310
311 #ifdef _LIBC
312 static void
free_mem(void)313 free_mem (void)
314 {
315 /* Remove all traces. */
316 clearenv ();
317
318 /* Now remove the search tree. */
319 __tdestroy (known_values, free);
320 known_values = NULL;
321 }
322 text_set_element (__libc_subfreeres, free_mem);
323
324
325 # undef setenv
326 # undef clearenv
327 weak_alias (__setenv, setenv)
328 weak_alias (__clearenv, clearenv)
329 #endif
330
331 #endif /* _LIBC || !HAVE_SETENV */
332