usr/src/lib/libbc/libc/gen/common/getenv.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*      Copyright (c) 1984 AT&T */
  23 /*        All Rights Reserved   */
  24
  25 #pragma ident   "%Z%%M% %I%     %E% SMI"  /* from S5R2 1.2 */
  26
  27 /*LINTLIBRARY*/
  28 /*
  29  *      getenv(name)
  30  *      returns ptr to value associated with name, if any, else NULL
  31  */
  32 #define NULL    0
  33 extern char **environ;
  34 static char *nvmatch();
  35
  36 char *
  37 getenv(name)
  38 register char *name;
  39 {
  40         register char *v, **p=environ;
  41
  42         if(p == NULL)
  43                 return(NULL);
  44         while(*p != NULL)
  45                 if((v = nvmatch(name, *p++)) != NULL)
  46                         return(v);
  47         return(NULL);
  48 }
  49
  50 /*
  51  *      s1 is either name, or name=value
  52  *      s2 is name=value
  53  *      if names match, return value of s2, else NULL
  54  *      used for environment searching: see getenv
  55  */
  56
  57 static char *
  58 nvmatch(s1, s2)
  59 register char *s1, *s2;
  60 {
  61         while(*s1 == *s2++)
  62                 if(*s1++ == '=')
  63                         return(s2);
  64         if(*s1 == '\0' && *(s2-1) == '=')
  65                 return(s2);
  66         return(NULL);
  67 }