lib/libc/stdlib/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  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#)getenv.c 8.1 (Berkeley) 6/4/93
  34  * $DragonFly: src/lib/libc/stdlib/getenv.c,v 1.5 2005/04/28 13:51:55 joerg Exp $
  35  */
  36
  37 #include <stdlib.h>
  38 #include <stddef.h>
  39 #include <string.h>
  40
  41 char *__findenv(const char *, size_t *);
  42
  43 extern char **environ;
  44
  45 /*
  46  * __findenv --
  47  *      Returns pointer to value associated with name, if any, else NULL.
  48  *      Sets offset to be the offset of the name/value combination in the
  49  *      environmental array, for use by setenv(3) and unsetenv(3).
  50  *      Explicitly removes '=' in argument name.
  51  *
  52  *      This routine *should* be a static; don't use it.
  53  */
  54 char *
  55 __findenv(const char *name, size_t *offset)
  56 {
  57         size_t len, i;
  58         const char *np;
  59         char **p, *cp;
  60
  61         if (name == NULL || environ == NULL)
  62                 return (NULL);
  63         for (np = name; *np && *np != '='; ++np)
  64                 continue;
  65         len = np - name;
  66         for (p = environ; (cp = *p) != NULL; ++p) {
  67                 for (np = name, i = len; i && *cp; i--)
  68                         if (*cp++ != *np++)
  69                                 break;
  70                 if (i == 0 && *cp++ == '=') {
  71                         *offset = p - environ;
  72                         return (cp);
  73                 }
  74         }
  75         return (NULL);
  76 }
  77
  78 /*
  79  * getenv --
  80  *      Returns ptr to value associated with name, if any, else NULL.
  81  */
  82 char *
  83 getenv(const char *name)
  84 {
  85         size_t offset;
  86
  87         return (__findenv(name, &offset));
  88 }