stdlib.subproj/getenv.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1987, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  */
  54
  55
  56 #include <stdlib.h>
  57 #include <stddef.h>
  58 #include <string.h>
  59
  60 #include <crt_externs.h>
  61
  62 char *__findenv __P((const char *, int *));
  63
  64 /*
  65  * getenv --
  66  *      Returns ptr to value associated with name, if any, else NULL.
  67  */
  68 char *
  69 getenv(name)
  70         const char *name;
  71 {
  72         int offset;
  73
  74         return (__findenv(name, &offset));
  75 }
  76
  77 /*
  78  * __findenv --
  79  *      Returns pointer to value associated with name, if any, else NULL.
  80  *      Sets offset to be the offset of the name/value combination in the
  81  *      environmental array, for use by setenv(3) and unsetenv(3).
  82  *      Explicitly removes '=' in argument name.
  83  *
  84  *      This routine *should* be a static; don't use it.
  85  */
  86 char *
  87 __findenv(name, offset)
  88         register const char *name;
  89         int *offset;
  90 {
  91         register int len;
  92         register const char *np;
  93         register char **p, *c;
  94
  95         char **environ = *_NSGetEnviron();
  96
  97         if (name == NULL || environ == NULL)
  98                 return (NULL);
  99         for (np = name; *np && *np != '='; ++np)
 100                 continue;
 101         len = np - name;
 102         for (p = environ; (c = *p) != NULL; ++p)
 103                 if (strncmp(c, name, len) == 0 && c[len] == '=') {
 104                         *offset = p - environ;
 105                         return (c + len + 1);
 106                 }
 107         return (NULL);
 108 }