1: /* Copyright (C) 1992,1995-1999,2000-2003,2005-2008 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: /* Specification. */
23: #include <stdlib.h>
24:
25: #include <errno.h>
26: #ifndef __set_errno
27: # define __set_errno(ev) ((errno) = (ev))
28: #endif
29:
30: #include <string.h>
31: #if _LIBC || HAVE_UNISTD_H
32: # include <unistd.h>
33: #endif
34:
35: #if _LIBC || !HAVE_SETENV
36:
37: #if !_LIBC
38: # include "malloca.h"
39: #endif
40:
41: #if !_LIBC
42: # define __environ environ
43: #endif
44:
45: #if _LIBC
46: /* This lock protects against simultaneous modifications of `environ'. */
47: # include <bits/libc-lock.h>
48: __libc_lock_define_initialized (static, envlock)
49: # define LOCK __libc_lock_lock (envlock)
50: # define UNLOCK __libc_lock_unlock (envlock)
51: #else
52: # define LOCK
53: # define UNLOCK
54: #endif
55:
56: /* In the GNU C library we must keep the namespace clean. */
57: #ifdef _LIBC
58: # define setenv __setenv
59: # define clearenv __clearenv
60: # define tfind __tfind
61: # define tsearch __tsearch
62: #endif
63:
64: /* In the GNU C library implementation we try to be more clever and
65: allow arbitrarily many changes of the environment given that the used
66: values are from a small set. Outside glibc this will eat up all
67: memory after a while. */
68: #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
69: && defined __GNUC__)
70: # define USE_TSEARCH 1
71: # include <search.h>
72: typedef int (*compar_fn_t) (const void *, const void *);
73:
74: /* This is a pointer to the root of the search tree with the known
75: values. */
76: static void *known_values;
77:
78: # define KNOWN_VALUE(Str) \
79: ({ \
80: void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \
81: value != NULL ? *(char **) value : NULL; \
82: })
83: # define STORE_VALUE(Str) \
84: tsearch (Str, &known_values, (compar_fn_t) strcmp)
85:
86: #else
87: # undef USE_TSEARCH
88:
89: # define KNOWN_VALUE(Str) NULL
90: # define STORE_VALUE(Str) do { } while (0)
91:
92: #endif
93:
94:
95: /* If this variable is not a null pointer we allocated the current
96: environment. */
97: static char **last_environ;
98:
99:
100: /* This function is used by `setenv' and `putenv'. The difference between
101: the two functions is that for the former must create a new string which
102: is then placed in the environment, while the argument of `putenv'
103: must be used directly. This is all complicated by the fact that we try
104: to reuse values once generated for a `setenv' call since we can never
105: free the strings. */
106: int
107: __add_to_environ (const char *name, const char *value, const char *combined,
108: int replace)
109: {
110: register char **ep;
111: register size_t size;
112: const size_t namelen = strlen (name);
113: const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
114:
115: LOCK;
116:
117: /* We have to get the pointer now that we have the lock and not earlier
118: since another thread might have created a new environment. */
119: ep = __environ;
120:
121: size = 0;
122: if (ep != NULL)
123: {
124: for (; *ep != NULL; ++ep)
125: if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
126: break;
127: else
128: ++size;
129: }
130:
131: if (ep == NULL || *ep == NULL)
132: {
133: char **new_environ;
134: #ifdef USE_TSEARCH
135: char *new_value;
136: #endif
137:
138: /* We allocated this space; we can extend it. */
139: new_environ =
140: (char **) (last_environ == NULL
141: ? malloc ((size + 2) * sizeof (char *))
142: : realloc (last_environ, (size + 2) * sizeof (char *)));
143: if (new_environ == NULL)
144: {
145: UNLOCK;
146: return -1;
147: }
148:
149: /* If the whole entry is given add it. */
150: if (combined != NULL)
151: /* We must not add the string to the search tree since it belongs
152: to the user. */
153: new_environ[size] = (char *) combined;
154: else
155: {
156: /* See whether the value is already known. */
157: #ifdef USE_TSEARCH
158: # ifdef _LIBC
159: new_value = (char *) alloca (namelen + 1 + vallen);
160: __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
161: value, vallen);
162: # else
163: new_value = (char *) malloca (namelen + 1 + vallen);
164: if (new_value == NULL)
165: {
166: __set_errno (ENOMEM);
167: UNLOCK;
168: return -1;
169: }
170: memcpy (new_value, name, namelen);
171: new_value[namelen] = '=';
172: memcpy (&new_value[namelen + 1], value, vallen);
173: # endif
174:
175: new_environ[size] = KNOWN_VALUE (new_value);
176: if (new_environ[size] == NULL)
177: #endif
178: {
179: new_environ[size] = (char *) malloc (namelen + 1 + vallen);
180: if (new_environ[size] == NULL)
181: {
182: #if defined USE_TSEARCH && !defined _LIBC
183: freea (new_value);
184: #endif
185: __set_errno (ENOMEM);
186: UNLOCK;
187: return -1;
188: }
189:
190: #ifdef USE_TSEARCH
191: memcpy (new_environ[size], new_value, namelen + 1 + vallen);
192: #else
193: memcpy (new_environ[size], name, namelen);
194: new_environ[size][namelen] = '=';
195: memcpy (&new_environ[size][namelen + 1], value, vallen);
196: #endif
197: /* And save the value now. We cannot do this when we remove
198: the string since then we cannot decide whether it is a
199: user string or not. */
200: STORE_VALUE (new_environ[size]);
201: }
202: #if defined USE_TSEARCH && !defined _LIBC
203: freea (new_value);
204: #endif
205: }
206:
207: if (__environ != last_environ)
208: memcpy ((char *) new_environ, (char *) __environ,
209: size * sizeof (char *));
210:
211: new_environ[size + 1] = NULL;
212:
213: last_environ = __environ = new_environ;
214: }
215: else if (replace)
216: {
217: char *np;
218:
219: /* Use the user string if given. */
220: if (combined != NULL)
221: np = (char *) combined;
222: else
223: {
224: #ifdef USE_TSEARCH
225: char *new_value;
226: # ifdef _LIBC
227: new_value = alloca (namelen + 1 + vallen);
228: __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
229: value, vallen);
230: # else
231: new_value = malloca (namelen + 1 + vallen);
232: if (new_value == NULL)
233: {
234: __set_errno (ENOMEM);
235: UNLOCK;
236: return -1;
237: }
238: memcpy (new_value, name, namelen);
239: new_value[namelen] = '=';
240: memcpy (&new_value[namelen + 1], value, vallen);
241: # endif
242:
243: np = KNOWN_VALUE (new_value);
244: if (np == NULL)
245: #endif
246: {
247: np = malloc (namelen + 1 + vallen);
248: if (np == NULL)
249: {
250: #if defined USE_TSEARCH && !defined _LIBC
251: freea (new_value);
252: #endif
253: __set_errno (ENOMEM);
254: UNLOCK;
255: return -1;
256: }
257:
258: #ifdef USE_TSEARCH
259: memcpy (np, new_value, namelen + 1 + vallen);
260: #else
261: memcpy (np, name, namelen);
262: np[namelen] = '=';
263: memcpy (&np[namelen + 1], value, vallen);
264: #endif
265: /* And remember the value. */
266: STORE_VALUE (np);
267: }
268: #if defined USE_TSEARCH && !defined _LIBC
269: freea (new_value);
270: #endif
271: }
272:
273: *ep = np;
274: }
275:
276: UNLOCK;
277:
278: return 0;
279: }
280:
281: int
282: setenv (const char *name, const char *value, int replace)
283: {
284: return __add_to_environ (name, value, NULL, replace);
285: }
286:
287: /* The `clearenv' was planned to be added to POSIX.1 but probably
288: never made it. Nevertheless the POSIX.9 standard (POSIX bindings
289: for Fortran 77) requires this function. */
290: int
291: clearenv (void)
292: {
293: LOCK;
294:
295: if (__environ == last_environ && __environ != NULL)
296: {
297: /* We allocated this environment so we can free it. */
298: free (__environ);
299: last_environ = NULL;
300: }
301:
302: /* Clear the environment pointer removes the whole environment. */
303: __environ = NULL;
304:
305: UNLOCK;
306:
307: return 0;
308: }
309:
310: #ifdef _LIBC
311: static void
312: free_mem (void)
313: {
314: /* Remove all traces. */
315: clearenv ();
316:
317: /* Now remove the search tree. */
318: __tdestroy (known_values, free);
319: known_values = NULL;
320: }
321: text_set_element (__libc_subfreeres, free_mem);
322:
323:
324: # undef setenv
325: # undef clearenv
326: weak_alias (__setenv, setenv)
327: weak_alias (__clearenv, clearenv)
328: #endif
329:
330: #endif /* _LIBC || !HAVE_SETENV */
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