stdlib/FreeBSD/getenv.c

   1 /*
   2  * Copyright (c) 1987, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)getenv.c    8.1 (Berkeley) 6/4/93";
  32 #endif /* LIBC_SCCS and not lint */
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD: src/lib/libc/stdlib/getenv.c,v 1.8 2007/05/01 16:02:41 ache Exp $");
  35
  36 #include <os/lock_private.h>
  37 #include <stdlib.h>
  38 #include <stddef.h>
  39 #include <string.h>
  40 #include <crt_externs.h>
  41
  42 __private_extern__ char *__findenv_locked(const char *, int *, char **);
  43 __private_extern__ void __environ_lock(void);
  44 __private_extern__ void __environ_unlock(void);
  45
  46 /*
  47  * __findenv_locked --
  48  *      Returns pointer to value associated with name, if any, else NULL.
  49  *      Sets offset to be the offset of the name/value combination in the
  50  *      environmental array, for use by setenv(3) and unsetenv(3).
  51  *      Explicitly removes '=' in argument name.
  52  *
  53  *      This routine *should* be a static; don't use it.
  54  */
  55 __private_extern__ char *
  56 __findenv_locked(name, offset, environ)
  57         const char *name;
  58         int *offset;
  59         char **environ;
  60 {
  61         int len, i;
  62         const char *np;
  63         char **p, *cp;
  64
  65         if (name == NULL || environ == NULL)
  66                 return (NULL);
  67         for (np = name; *np && *np != '='; ++np)
  68                 continue;
  69         len = np - name;
  70         for (p = environ; (cp = *p) != NULL; ++p) {
  71                 for (np = name, i = len; i && *cp; i--)
  72                         if (*cp++ != *np++)
  73                                 break;
  74                 if (i == 0 && *cp++ == '=') {
  75                         *offset = p - environ;
  76                         return (cp);
  77                 }
  78         }
  79         return (NULL);
  80 }
  81
  82 static os_unfair_lock __environ_lock_obj = OS_UNFAIR_LOCK_INIT;
  83 __private_extern__ void
  84 __environ_lock(void)
  85 {
  86 #if TARGET_OS_IOS && !TARGET_OS_SIMULATOR
  87         os_unfair_lock_lock_with_options_4Libc(
  88                         &__environ_lock_obj, OS_UNFAIR_LOCK_DATA_SYNCHRONIZATION);
  89 #else // TARGET_OS_IOS && !TARGET_OS_SIMULATOR
  90         os_unfair_lock_lock(&__environ_lock_obj);
  91 #endif // TARGET_OS_IOS && !TARGET_OS_SIMULATOR
  92 }
  93 __private_extern__ void
  94 __environ_unlock(void)
  95 {
  96 #if TARGET_OS_IOS && !TARGET_OS_SIMULATOR
  97         os_unfair_lock_unlock_4Libc(&__environ_lock_obj);
  98 #else // TARGET_OS_IOS && !TARGET_OS_SIMULATOR
  99         os_unfair_lock_unlock(&__environ_lock_obj);
 100 #endif // TARGET_OS_IOS && !TARGET_OS_SIMULATOR
 101 }
 102 __private_extern__ void
 103 __environ_lock_fork_child(void)
 104 {
 105         __environ_lock_obj = OS_UNFAIR_LOCK_INIT;
 106 }
 107
 108 /*
 109  * _getenvp -- SPI using an arbitrary pointer to string array (the array must
 110  * have been created with malloc) and an env state, created by _allocenvstate().
 111  *      Returns ptr to value associated with name, if any, else NULL.
 112  */
 113 char *
 114 _getenvp(const char *name, char ***envp, void *state __unused)
 115 {
 116         // envp is passed as an argument, so the lock is not protecting everything
 117         int offset;
 118         __environ_lock();
 119         char *result = (__findenv_locked(name, &offset, *envp));
 120         __environ_unlock();
 121         return result;
 122 }
 123
 124 /*
 125  * getenv --
 126  *      Returns ptr to value associated with name, if any, else NULL.
 127  */
 128 char *
 129 getenv(name)
 130         const char *name;
 131 {
 132         int offset;
 133         __environ_lock();
 134         char *result = __findenv_locked(name, &offset, *_NSGetEnviron());
 135         __environ_unlock();
 136         return result;
 137 }