1 /* Copyright (C) 1992,1995-1999,2000-2003 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 2, or (at your option)
7 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 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. */
17 #include <sys/cdefs.h>
18 __RCSID("$NetBSD: setenv.c,v 1.2 2016/05/17 14:00:09 christos Exp $");
19
20
21 #if HAVE_CONFIG_H
22 # include <config.h>
23 #endif
24 #include <alloca.h>
25
26 #include <errno.h>
27 #ifndef __set_errno
28 # define __set_errno(ev) ((errno) = (ev))
29 #endif
30
31 #include <stdlib.h>
32 #include <string.h>
33 #if _LIBC || HAVE_UNISTD_H
34 # include <unistd.h>
35 #endif
36
37 #if !_LIBC
38 # include "allocsa.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 clearenv __clearenv
63 # define tfind __tfind
64 # define tsearch __tsearch
65 #endif
66
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 \
72 && defined __GNUC__)
73 # define USE_TSEARCH 1
74 # include <search.h>
75 typedef int (*compar_fn_t) (const void *, const void *);
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(const char * name,const char * value,const char * combined,int replace)110 __add_to_environ (const char *name, const char *value, const char *combined,
111 int replace)
112 {
113 register char **ep;
114 register size_t size;
115 const size_t namelen = strlen (name);
116 const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
117
118 LOCK;
119
120 /* We have to get the pointer now that we have the lock and not earlier
121 since another thread might have created a new environment. */
122 ep = __environ;
123
124 size = 0;
125 if (ep != NULL)
126 {
127 for (; *ep != NULL; ++ep)
128 if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
129 break;
130 else
131 ++size;
132 }
133
134 if (ep == NULL || *ep == NULL)
135 {
136 char **new_environ;
137 #ifdef USE_TSEARCH
138 char *new_value;
139 #endif
140
141 /* We allocated this space; we can extend it. */
142 new_environ =
143 (char **) (last_environ == NULL
144 ? malloc ((size + 2) * sizeof (char *))
145 : realloc (last_environ, (size + 2) * sizeof (char *)));
146 if (new_environ == NULL)
147 {
148 UNLOCK;
149 return -1;
150 }
151
152 /* If the whole entry is given add it. */
153 if (combined != NULL)
154 /* We must not add the string to the search tree since it belongs
155 to the user. */
156 new_environ[size] = (char *) combined;
157 else
158 {
159 /* See whether the value is already known. */
160 #ifdef USE_TSEARCH
161 # ifdef _LIBC
162 new_value = (char *) alloca (namelen + 1 + vallen);
163 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
164 value, vallen);
165 # else
166 new_value = (char *) allocsa (namelen + 1 + vallen);
167 if (new_value == NULL)
168 {
169 __set_errno (ENOMEM);
170 UNLOCK;
171 return -1;
172 }
173 memcpy (new_value, name, namelen);
174 new_value[namelen] = '=';
175 memcpy (&new_value[namelen + 1], value, vallen);
176 # endif
177
178 new_environ[size] = KNOWN_VALUE (new_value);
179 if (new_environ[size] == NULL)
180 #endif
181 {
182 new_environ[size] = (char *) malloc (namelen + 1 + vallen);
183 if (new_environ[size] == NULL)
184 {
185 #if defined USE_TSEARCH && !defined _LIBC
186 freesa (new_value);
187 #endif
188 __set_errno (ENOMEM);
189 UNLOCK;
190 return -1;
191 }
192
193 #ifdef USE_TSEARCH
194 memcpy (new_environ[size], new_value, namelen + 1 + vallen);
195 #else
196 memcpy (new_environ[size], name, namelen);
197 new_environ[size][namelen] = '=';
198 memcpy (&new_environ[size][namelen + 1], value, vallen);
199 #endif
200 /* And save the value now. We cannot do this when we remove
201 the string since then we cannot decide whether it is a
202 user string or not. */
203 STORE_VALUE (new_environ[size]);
204 }
205 #if defined USE_TSEARCH && !defined _LIBC
206 freesa (new_value);
207 #endif
208 }
209
210 if (__environ != last_environ)
211 memcpy ((char *) new_environ, (char *) __environ,
212 size * sizeof (char *));
213
214 new_environ[size + 1] = NULL;
215
216 last_environ = __environ = new_environ;
217 }
218 else if (replace)
219 {
220 char *np;
221
222 /* Use the user string if given. */
223 if (combined != NULL)
224 np = (char *) combined;
225 else
226 {
227 #ifdef USE_TSEARCH
228 char *new_value;
229 # ifdef _LIBC
230 new_value = alloca (namelen + 1 + vallen);
231 __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
232 value, vallen);
233 # else
234 new_value = allocsa (namelen + 1 + vallen);
235 if (new_value == NULL)
236 {
237 __set_errno (ENOMEM);
238 UNLOCK;
239 return -1;
240 }
241 memcpy (new_value, name, namelen);
242 new_value[namelen] = '=';
243 memcpy (&new_value[namelen + 1], value, vallen);
244 # endif
245
246 np = KNOWN_VALUE (new_value);
247 if (np == NULL)
248 #endif
249 {
250 np = malloc (namelen + 1 + vallen);
251 if (np == NULL)
252 {
253 #if defined USE_TSEARCH && !defined _LIBC
254 freesa (new_value);
255 #endif
256 __set_errno (ENOMEM);
257 UNLOCK;
258 return -1;
259 }
260
261 #ifdef USE_TSEARCH
262 memcpy (np, new_value, namelen + 1 + vallen);
263 #else
264 memcpy (np, name, namelen);
265 np[namelen] = '=';
266 memcpy (&np[namelen + 1], value, vallen);
267 #endif
268 /* And remember the value. */
269 STORE_VALUE (np);
270 }
271 #if defined USE_TSEARCH && !defined _LIBC
272 freesa (new_value);
273 #endif
274 }
275
276 *ep = np;
277 }
278
279 UNLOCK;
280
281 return 0;
282 }
283
284 int
setenv(const char * name,const char * value,int replace)285 setenv (const char *name, const char *value, int replace)
286 {
287 return __add_to_environ (name, value, NULL, replace);
288 }
289
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. */
293 int
clearenv(void)294 clearenv (void)
295 {
296 LOCK;
297
298 if (__environ == last_environ && __environ != NULL)
299 {
300 /* We allocated this environment so we can free it. */
301 free (__environ);
302 last_environ = NULL;
303 }
304
305 /* Clear the environment pointer removes the whole environment. */
306 __environ = NULL;
307
308 UNLOCK;
309
310 return 0;
311 }
312
313 #ifdef _LIBC
314 static void
free_mem(void)315 free_mem (void)
316 {
317 /* Remove all traces. */
318 clearenv ();
319
320 /* Now remove the search tree. */
321 __tdestroy (known_values, free);
322 known_values = NULL;
323 }
324 text_set_element (__libc_subfreeres, free_mem);
325
326
327 # undef setenv
328 # undef clearenv
329 weak_alias (__setenv, setenv)
330 weak_alias (__clearenv, clearenv)
331 #endif
332