1 /* Copyright (C) 1992,1995-2001,2004 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
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.
8
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.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, write to the Free
16 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
17 02111-1307 USA. */
18
19 #if HAVE_CONFIG_H
20 # include <config.h>
21 #endif
22
23 #include <errno.h>
24 #if !_LIBC
25 # if !defined errno && !defined HAVE_ERRNO_DECL
26 extern int errno;
27 # endif
28 # define __set_errno(ev) ((errno) = (ev))
29 #endif
30
31 #if _LIBC || HAVE_STDLIB_H
32 # include <stdlib.h>
33 #endif
34 #if _LIBC || HAVE_STRING_H
35 # include <string.h>
36 #endif
37 #if _LIBC || HAVE_UNISTD_H
38 # include <unistd.h>
39 #endif
40
41 #if !_LIBC
42 # define __environ environ
43 # ifndef HAVE_ENVIRON_DECL
44 extern char **environ;
45 # endif
46 #endif
47
48 #if _LIBC
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)
54 #else
55 # define LOCK
56 # define UNLOCK
57 #endif
58
59 /* In the GNU C library we must keep the namespace clean. */
60 #ifdef _LIBC
61 # define setenv __setenv
62 # define unsetenv __unsetenv
63 # define clearenv __clearenv
64 # define tfind __tfind
65 # define tsearch __tsearch
66 #endif
67
68 /* In the GNU C library implementation we try to be more clever and
69 allow arbitrarily many changes of the environment given that the used
70 values are from a small set. Outside glibc this will eat up all
71 memory after a while. */
72 #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
73 && defined __GNUC__)
74 # define USE_TSEARCH 1
75 # include <search.h>
76
77 /* This is a pointer to the root of the search tree with the known
78 values. */
79 static void *known_values;
80
81 # define KNOWN_VALUE(Str) \
82 ({ \
83 void *value = tfind (Str, &known_values, (__compar_fn_t) strcmp); \
84 value != NULL ? *(char **) value : NULL; \
85 })
86 # define STORE_VALUE(Str) \
87 tsearch (Str, &known_values, (__compar_fn_t) strcmp)
88
89 #else
90 # undef USE_TSEARCH
91
92 # define KNOWN_VALUE(Str) NULL
93 # define STORE_VALUE(Str) do { } while (0)
94
95 #endif
96
97
98 /* If this variable is not a null pointer we allocated the current
99 environment. */
100 static char **last_environ;
101
102
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
108 free the strings. */
109 int
__add_to_environ(name,value,combined,replace)110 __add_to_environ (name, value, combined, replace)
111 const char *name;
112 const char *value;
113 const char *combined;
114 int replace;
115 {
116 register char **ep;
117 register size_t size;
118 const size_t namelen = strlen (name);
119 const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
120
121 LOCK;
122
123 /* We have to get the pointer now that we have the lock and not earlier
124 since another thread might have created a new environment. */
125 ep = __environ;
126
127 size = 0;
128 if (ep != NULL)
129 {
130 for (; *ep != NULL; ++ep)
131 if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
132 break;
133 else
134 ++size;
135 }
136
137 if (ep == NULL || __builtin_expect (*ep == NULL, 1))
138 {
139 char **new_environ;
140
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)
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 __GNUC__
160 char new_value[namelen + 1 + vallen];
161 # else
162 char *new_value = (char *) alloca (namelen + 1 + vallen);
163 # endif
164 # ifdef _LIBC
165 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
166 value, vallen);
167 # else
168 memcpy (new_value, name, namelen);
169 new_value[namelen] = '=';
170 memcpy (&new_value[namelen + 1], value, vallen);
171 # endif
172
173 new_environ[size] = KNOWN_VALUE (new_value);
174 if (__builtin_expect (new_environ[size] == NULL, 1))
175 #endif
176 {
177 new_environ[size] = (char *) malloc (namelen + 1 + vallen);
178 if (__builtin_expect (new_environ[size] == NULL, 0))
179 {
180 __set_errno (ENOMEM);
181 UNLOCK;
182 return -1;
183 }
184
185 #ifdef USE_TSEARCH
186 memcpy (new_environ[size], new_value, namelen + 1 + vallen);
187 #else
188 memcpy (new_environ[size], name, namelen);
189 new_environ[size][namelen] = '=';
190 memcpy (&new_environ[size][namelen + 1], value, vallen);
191 #endif
192 /* And save the value now. We cannot do this when we remove
193 the string since then we cannot decide whether it is a
194 user string or not. */
195 STORE_VALUE (new_environ[size]);
196 }
197 }
198
199 if (__environ != last_environ)
200 memcpy ((char *) new_environ, (char *) __environ,
201 size * sizeof (char *));
202
203 new_environ[size + 1] = NULL;
204
205 last_environ = __environ = new_environ;
206 }
207 else if (replace)
208 {
209 char *np;
210
211 /* Use the user string if given. */
212 if (combined != NULL)
213 np = (char *) combined;
214 else
215 {
216 #ifdef USE_TSEARCH
217 # ifdef __GNUC__
218 char new_value[namelen + 1 + vallen];
219 # else
220 char *new_value = (char *) alloca (namelen + 1 + vallen);
221 # endif
222 # ifdef _LIBC
223 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
224 value, vallen);
225 # else
226 memcpy (new_value, name, namelen);
227 new_value[namelen] = '=';
228 memcpy (&new_value[namelen + 1], value, vallen);
229 # endif
230
231 np = KNOWN_VALUE (new_value);
232 if (__builtin_expect (np == NULL, 1))
233 #endif
234 {
235 np = malloc (namelen + 1 + vallen);
236 if (__builtin_expect (np == NULL, 0))
237 {
238 UNLOCK;
239 return -1;
240 }
241
242 #ifdef USE_TSEARCH
243 memcpy (np, new_value, namelen + 1 + vallen);
244 #else
245 memcpy (np, name, namelen);
246 np[namelen] = '=';
247 memcpy (&np[namelen + 1], value, vallen);
248 #endif
249 /* And remember the value. */
250 STORE_VALUE (np);
251 }
252 }
253
254 *ep = np;
255 }
256
257 UNLOCK;
258
259 return 0;
260 }
261
262 int
setenv(name,value,replace)263 setenv (name, value, replace)
264 const char *name;
265 const char *value;
266 int replace;
267 {
268 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
269 {
270 __set_errno (EINVAL);
271 return -1;
272 }
273
274 return __add_to_environ (name, value, NULL, replace);
275 }
276
277 int
unsetenv(name)278 unsetenv (name)
279 const char *name;
280 {
281 size_t len;
282 char **ep;
283
284 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
285 {
286 __set_errno (EINVAL);
287 return -1;
288 }
289
290 len = strlen (name);
291
292 LOCK;
293
294 ep = __environ;
295 while (*ep != NULL)
296 if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
297 {
298 /* Found it. Remove this pointer by moving later ones back. */
299 char **dp = ep;
300
301 do
302 dp[0] = dp[1];
303 while (*dp++);
304 /* Continue the loop in case NAME appears again. */
305 }
306 else
307 ++ep;
308
309 UNLOCK;
310
311 return 0;
312 }
313
314 /* The `clearenv' was planned to be added to POSIX.1 but probably
315 never made it. Nevertheless the POSIX.9 standard (POSIX bindings
316 for Fortran 77) requires this function. */
317 int
clearenv()318 clearenv ()
319 {
320 LOCK;
321
322 if (__environ == last_environ && __environ != NULL)
323 {
324 /* We allocated this environment so we can free it. */
325 free (__environ);
326 last_environ = NULL;
327 }
328
329 /* Clear the environment pointer removes the whole environment. */
330 __environ = NULL;
331
332 UNLOCK;
333
334 return 0;
335 }
336 #ifdef _LIBC
libc_freeres_fn(free_mem)337 libc_freeres_fn (free_mem)
338 {
339 /* Remove all traces. */
340 clearenv ();
341
342 /* Now remove the search tree. */
343 __tdestroy (known_values, free);
344 known_values = NULL;
345 }
346
347 # undef setenv
348 # undef unsetenv
349 # undef clearenv
350 weak_alias (__setenv, setenv)
351 weak_alias (__unsetenv, unsetenv)
352 weak_alias (__clearenv, clearenv)
353 #endif
354