1 /* Copyright (C) 1992, 1995-2003, 2005-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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.
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.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
18 /* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
19 optimizes away the name == NULL test below. */
20 # define _GL_ARG_NONNULL(params)
22 # define _GL_USE_STDLIB_ALLOC 1
33 # define __set_errno(ev) ((errno) = (ev))
37 #if _LIBC || HAVE_UNISTD_H
45 #if _LIBC || !HAVE_SETENV
48 # define __environ environ
52 /* This lock protects against simultaneous modifications of 'environ'. */
53 # include <bits/libc-lock.h>
54 __libc_lock_define_initialized (static, envlock
)
55 # define LOCK __libc_lock_lock (envlock)
56 # define UNLOCK __libc_lock_unlock (envlock)
62 /* In the GNU C library we must keep the namespace clean. */
64 # define setenv __setenv
65 # define clearenv __clearenv
66 # define tfind __tfind
67 # define tsearch __tsearch
70 /* In the GNU C library implementation we try to be more clever and
71 allow arbitrarily many changes of the environment given that the used
72 values are from a small set. Outside glibc this will eat up all
73 memory after a while. */
74 #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
75 && (defined __GNUC__ || defined __clang__))
76 # define USE_TSEARCH 1
78 typedef int (*compar_fn_t
) (const void *, const void *);
80 /* This is a pointer to the root of the search tree with the known
82 static void *known_values
;
84 # define KNOWN_VALUE(Str) \
86 void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \
87 value != NULL ? *(char **) value : NULL; \
89 # define STORE_VALUE(Str) \
90 tsearch (Str, &known_values, (compar_fn_t) strcmp)
95 # define KNOWN_VALUE(Str) NULL
96 # define STORE_VALUE(Str) do { } while (0)
101 /* If this variable is not a null pointer we allocated the current
103 static char **last_environ
;
106 /* This function is used by 'setenv' and 'putenv'. The difference between
107 the two functions is that for the former must create a new string which
108 is then placed in the environment, while the argument of 'putenv'
109 must be used directly. This is all complicated by the fact that we try
110 to reuse values once generated for a 'setenv' call since we can never
113 __add_to_environ (const char *name
, const char *value
, const char *combined
,
118 const size_t namelen
= strlen (name
);
119 const size_t vallen
= value
!= NULL
? strlen (value
) + 1 : 0;
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. */
130 for (; *ep
!= NULL
; ++ep
)
131 if (!strncmp (*ep
, name
, namelen
) && (*ep
)[namelen
] == '=')
137 if (ep
== NULL
|| *ep
== NULL
)
144 /* We allocated this space; we can extend it. */
146 (char **) (last_environ
== NULL
147 ? malloc ((size
+ 2) * sizeof (char *))
148 : realloc (last_environ
, (size
+ 2) * sizeof (char *)));
149 if (new_environ
== NULL
)
151 /* It's easier to set errno to ENOMEM than to rely on the
152 'malloc-posix' and 'realloc-posix' gnulib modules. */
153 __set_errno (ENOMEM
);
158 /* If the whole entry is given add it. */
159 if (combined
!= NULL
)
160 /* We must not add the string to the search tree since it belongs
162 new_environ
[size
] = (char *) combined
;
165 /* See whether the value is already known. */
168 new_value
= (char *) alloca (namelen
+ 1 + vallen
);
169 __mempcpy (__mempcpy (__mempcpy (new_value
, name
, namelen
), "=", 1),
172 new_value
= (char *) malloca (namelen
+ 1 + vallen
);
173 if (new_value
== NULL
)
175 __set_errno (ENOMEM
);
179 memcpy (new_value
, name
, namelen
);
180 new_value
[namelen
] = '=';
181 memcpy (&new_value
[namelen
+ 1], value
, vallen
);
184 new_environ
[size
] = KNOWN_VALUE (new_value
);
185 if (new_environ
[size
] == NULL
)
188 new_environ
[size
] = (char *) malloc (namelen
+ 1 + vallen
);
189 if (new_environ
[size
] == NULL
)
191 #if defined USE_TSEARCH && !defined _LIBC
194 __set_errno (ENOMEM
);
200 memcpy (new_environ
[size
], new_value
, namelen
+ 1 + vallen
);
202 memcpy (new_environ
[size
], name
, namelen
);
203 new_environ
[size
][namelen
] = '=';
204 memcpy (&new_environ
[size
][namelen
+ 1], value
, vallen
);
206 /* And save the value now. We cannot do this when we remove
207 the string since then we cannot decide whether it is a
208 user string or not. */
209 STORE_VALUE (new_environ
[size
]);
211 #if defined USE_TSEARCH && !defined _LIBC
216 if (__environ
!= last_environ
)
217 memcpy ((char *) new_environ
, (char *) __environ
,
218 size
* sizeof (char *));
220 new_environ
[size
+ 1] = NULL
;
222 last_environ
= __environ
= new_environ
;
228 /* Use the user string if given. */
229 if (combined
!= NULL
)
230 np
= (char *) combined
;
236 new_value
= alloca (namelen
+ 1 + vallen
);
237 __mempcpy (__mempcpy (__mempcpy (new_value
, name
, namelen
), "=", 1),
240 new_value
= malloca (namelen
+ 1 + vallen
);
241 if (new_value
== NULL
)
243 __set_errno (ENOMEM
);
247 memcpy (new_value
, name
, namelen
);
248 new_value
[namelen
] = '=';
249 memcpy (&new_value
[namelen
+ 1], value
, vallen
);
252 np
= KNOWN_VALUE (new_value
);
256 np
= (char *) malloc (namelen
+ 1 + vallen
);
259 #if defined USE_TSEARCH && !defined _LIBC
262 __set_errno (ENOMEM
);
268 memcpy (np
, new_value
, namelen
+ 1 + vallen
);
270 memcpy (np
, name
, namelen
);
272 memcpy (&np
[namelen
+ 1], value
, vallen
);
274 /* And remember the value. */
277 #if defined USE_TSEARCH && !defined _LIBC
291 setenv (const char *name
, const char *value
, int replace
)
293 if (name
== NULL
|| *name
== '\0' || strchr (name
, '=') != NULL
)
295 __set_errno (EINVAL
);
299 return __add_to_environ (name
, value
, NULL
, replace
);
302 /* The 'clearenv' was planned to be added to POSIX.1 but probably
303 never made it. Nevertheless the POSIX.9 standard (POSIX bindings
304 for Fortran 77) requires this function. */
310 if (__environ
== last_environ
&& __environ
!= NULL
)
312 /* We allocated this environment so we can free it. */
317 /* Clear the environment pointer removes the whole environment. */
329 /* Remove all traces. */
332 /* Now remove the search tree. */
333 __tdestroy (known_values
, free
);
336 text_set_element (__libc_subfreeres
, free_mem
);
341 weak_alias (__setenv
, setenv
)
342 weak_alias (__clearenv
, clearenv
)
345 #endif /* _LIBC || !HAVE_SETENV */
347 /* The rest of this file is called into use when replacing an existing
348 but buggy setenv. Known bugs include failure to diagnose invalid
349 name, and consuming a leading '=' from value. */
353 # if !HAVE_DECL_SETENV
354 extern int setenv (const char *, const char *, int);
356 # define STREQ(a, b) (strcmp (a, b) == 0)
359 rpl_setenv (const char *name
, const char *value
, int replace
)
362 if (!name
|| !*name
|| strchr (name
, '='))
367 /* Call the real setenv even if replace is 0, in case implementation
368 has underlying data to update, such as when environ changes. */
369 result
= setenv (name
, value
, replace
);
370 if (result
== 0 && replace
&& *value
== '=')
372 char *tmp
= getenv (name
);
373 if (!STREQ (tmp
, value
))
376 size_t len
= strlen (value
);
377 tmp
= malloca (len
+ 2);
378 /* Since leading '=' is eaten, double it up. */
380 memcpy (tmp
+ 1, value
, len
+ 1);
381 result
= setenv (name
, tmp
, replace
);
390 #endif /* HAVE_SETENV */