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  * 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
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)getenv.c    8.1 (Berkeley) 6/4/93";
  36 #endif /* LIBC_SCCS and not lint */
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD: src/lib/libc/stdlib/getenv.c,v 1.4 2002/03/21 22:48:41 obrien Exp $");
  39
  40 #include <stdlib.h>
  41 #include <stddef.h>
  42 #include <string.h>
  43
  44 inline char *__findenv(const char *, int *);
  45
  46 /*
  47  * __findenv --
  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 inline char *
  56 __findenv(name, offset)
  57         const char *name;
  58         int *offset;
  59 {
  60         extern char **environ;
  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 /*
  83  * getenv --
  84  *      Returns ptr to value associated with name, if any, else NULL.
  85  */
  86 char *
  87 getenv(name)
  88         const char *name;
  89 {
  90         int offset;
  91
  92         return (__findenv(name, &offset));
  93 }