stdlib/setenv.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 <stddef.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59
  60 #include <crt_externs.h>
  61
  62 char *__findenv __P((const char *, int *));
  63
  64 /*
  65  * setenv --
  66  *      Set the value of the environmental variable "name" to be
  67  *      "value".  If rewrite is set, replace any current value.
  68  */
  69 int
  70 setenv(name, value, rewrite)
  71         register const char *name;
  72         register const char *value;
  73         int rewrite;
  74 {
  75         static int alloced;                     /* if allocated space before */
  76         register char *c;
  77         int l_value, offset;
  78         char ***environp = _NSGetEnviron();
  79
  80         if (*value == '=')                      /* no `=' in value */
  81                 ++value;
  82         l_value = strlen(value);
  83         if ((c = __findenv(name, &offset))) {   /* find if already exists */
  84                 if (!rewrite)
  85                         return (0);
  86                 if (strlen(c) >= l_value) {     /* old larger; copy over */
  87                         while (*c++ = *value++);
  88                         return (0);
  89                 }
  90         } else {                                        /* create new slot */
  91                 register int cnt;
  92                 register char **p;
  93
  94                 for (p = *environp, cnt = 0; *p; ++p, ++cnt);
  95                 if (alloced) {                  /* just increase size */
  96                         *environp = (char **)realloc((char *)*environp,
  97                             (size_t)(sizeof(char *) * (cnt + 2)));
  98                         if (!*environp)
  99                                 return (-1);
 100                 }
 101                 else {                          /* get new space */
 102                         alloced = 1;            /* copy old entries into it */
 103                         p = malloc((size_t)(sizeof(char *) * (cnt + 2)));
 104                         if (!p)
 105                                 return (-1);
 106                         bcopy(*environp, p, cnt * sizeof(char *));
 107                         *environp = p;
 108                 }
 109                 (*environp)[cnt + 1] = NULL;
 110                 offset = cnt;
 111         }
 112         for (c = (char *)name; *c && *c != '='; ++c);   /* no `=' in name */
 113         if (!((*environp)[offset] =                     /* name + `=' + value */
 114             malloc((size_t)((int)(c - name) + l_value + 2))))
 115                 return (-1);
 116         for (c = (*environp)[offset]; (*c = *name++) && *c != '='; ++c);
 117         for (*c++ = '='; *c++ = *value++;);
 118         return (0);
 119 }
 120
 121 /*
 122  * unsetenv(name) --
 123  *      Delete environmental variable "name".
 124  */
 125 void
 126 unsetenv(name)
 127         const char *name;
 128 {
 129         char **environ = *_NSGetEnviron();
 130         register char **p;
 131         int offset;
 132
 133         while (__findenv(name, &offset))        /* if set multiple times */
 134                 for (p = &environ[offset];; ++p)
 135                         if (!(*p = *(p + 1)))
 136                                 break;
 137 }