1 /* Copyright (C) 1992-2015 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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.
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.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
22 /* Pacify GCC; see the commentary about VALLEN below. This is needed
23 at least through GCC 4.9.2. Pacify GCC for the entire file, as
24 there seems to be no way to pacify GCC selectively, only for the
25 place where it's needed. Do not use DIAG_IGNORE_NEEDS_COMMENT
26 here, as it's not defined yet. */
27 #pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
31 # if !defined errno && !defined HAVE_ERRNO_DECL
34 # define __set_errno(ev) ((errno) = (ev))
37 #if _LIBC || HAVE_STDLIB_H
40 #if _LIBC || HAVE_STRING_H
43 #if _LIBC || HAVE_UNISTD_H
48 # define __environ environ
49 # ifndef HAVE_ENVIRON_DECL
50 extern char **environ
;
55 /* This lock protects against simultaneous modifications of `environ'. */
56 # include <bits/libc-lock.h>
57 __libc_lock_define_initialized (static, envlock
)
58 # define LOCK __libc_lock_lock (envlock)
59 # define UNLOCK __libc_lock_unlock (envlock)
65 /* In the GNU C library we must keep the namespace clean. */
67 # define setenv __setenv
68 # define unsetenv __unsetenv
69 # define clearenv __clearenv
70 # define tfind __tfind
71 # define tsearch __tsearch
74 /* In the GNU C library implementation we try to be more clever and
75 allow arbitrarily many changes of the environment given that the used
76 values are from a small set. Outside glibc this will eat up all
77 memory after a while. */
78 #if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
80 # define USE_TSEARCH 1
83 /* This is a pointer to the root of the search tree with the known
85 static void *known_values
;
87 # define KNOWN_VALUE(Str) \
89 void *value = tfind (Str, &known_values, (__compar_fn_t) strcmp); \
90 value != NULL ? *(char **) value : NULL; \
92 # define STORE_VALUE(Str) \
93 tsearch (Str, &known_values, (__compar_fn_t) strcmp)
98 # define KNOWN_VALUE(Str) NULL
99 # define STORE_VALUE(Str) do { } while (0)
104 /* If this variable is not a null pointer we allocated the current
106 static char **last_environ
;
109 /* This function is used by `setenv' and `putenv'. The difference between
110 the two functions is that for the former must create a new string which
111 is then placed in the environment, while the argument of `putenv'
112 must be used directly. This is all complicated by the fact that we try
113 to reuse values once generated for a `setenv' call since we can never
116 __add_to_environ (name
, value
, combined
, replace
)
119 const char *combined
;
125 /* Compute lengths before locking, so that the critical section is
126 less of a performance bottleneck. VALLEN is needed only if
127 COMBINED is null (unfortunately GCC is not smart enough to deduce
128 this; see the #pragma at the start of this file). Testing
129 COMBINED instead of VALUE causes setenv (..., NULL, ...) to dump
130 core now instead of corrupting memory later. */
131 const size_t namelen
= strlen (name
);
133 if (combined
== NULL
)
134 vallen
= strlen (value
) + 1;
138 /* We have to get the pointer now that we have the lock and not earlier
139 since another thread might have created a new environment. */
145 for (; *ep
!= NULL
; ++ep
)
146 if (!strncmp (*ep
, name
, namelen
) && (*ep
)[namelen
] == '=')
152 if (ep
== NULL
|| __builtin_expect (*ep
== NULL
, 1))
156 /* We allocated this space; we can extend it. */
157 new_environ
= (char **) realloc (last_environ
,
158 (size
+ 2) * sizeof (char *));
159 if (new_environ
== NULL
)
165 if (__environ
!= last_environ
)
166 memcpy ((char *) new_environ
, (char *) __environ
,
167 size
* sizeof (char *));
169 new_environ
[size
] = NULL
;
170 new_environ
[size
+ 1] = NULL
;
171 ep
= new_environ
+ size
;
173 last_environ
= __environ
= new_environ
;
175 if (*ep
== NULL
|| replace
)
179 /* Use the user string if given. */
180 if (combined
!= NULL
)
181 np
= (char *) combined
;
184 const size_t varlen
= namelen
+ 1 + vallen
;
187 int use_alloca
= __libc_use_alloca (varlen
);
188 if (__builtin_expect (use_alloca
, 1))
189 new_value
= (char *) alloca (varlen
);
192 new_value
= malloc (varlen
);
193 if (new_value
== NULL
)
200 __mempcpy (__mempcpy (__mempcpy (new_value
, name
, namelen
), "=", 1),
203 memcpy (new_value
, name
, namelen
);
204 new_value
[namelen
] = '=';
205 memcpy (&new_value
[namelen
+ 1], value
, vallen
);
208 np
= KNOWN_VALUE (new_value
);
209 if (__glibc_likely (np
== NULL
))
213 if (__glibc_unlikely (! use_alloca
))
218 np
= malloc (varlen
);
219 if (__glibc_unlikely (np
== NULL
))
226 memcpy (np
, new_value
, varlen
);
228 memcpy (np
, name
, namelen
);
230 memcpy (&np
[namelen
+ 1], value
, vallen
);
233 /* And remember the value. */
239 if (__glibc_unlikely (! use_alloca
))
254 setenv (name
, value
, replace
)
259 if (name
== NULL
|| *name
== '\0' || strchr (name
, '=') != NULL
)
261 __set_errno (EINVAL
);
265 return __add_to_environ (name
, value
, NULL
, replace
);
275 if (name
== NULL
|| *name
== '\0' || strchr (name
, '=') != NULL
)
277 __set_errno (EINVAL
);
288 if (!strncmp (*ep
, name
, len
) && (*ep
)[len
] == '=')
290 /* Found it. Remove this pointer by moving later ones back. */
296 /* Continue the loop in case NAME appears again. */
306 /* The `clearenv' was planned to be added to POSIX.1 but probably
307 never made it. Nevertheless the POSIX.9 standard (POSIX bindings
308 for Fortran 77) requires this function. */
314 if (__environ
== last_environ
&& __environ
!= NULL
)
316 /* We allocated this environment so we can free it. */
321 /* Clear the environment pointer removes the whole environment. */
329 libc_freeres_fn (free_mem
)
331 /* Remove all traces. */
334 /* Now remove the search tree. */
335 __tdestroy (known_values
, free
);
342 weak_alias (__setenv
, setenv
)
343 weak_alias (__unsetenv
, unsetenv
)
344 weak_alias (__clearenv
, clearenv
)