contrib/bind-9.5.2/lib/bind/bsd/setenv.c

   1 #if defined(LIBC_SCCS) && !defined(lint)
   2 static const char sccsid[] = "@(#)setenv.c      8.1 (Berkeley) 6/4/93";
   3 static const char rcsid[] = "$Id: setenv.c,v 1.2 2005/04/27 04:56:11 sra Exp $";
   4 #endif /* LIBC_SCCS and not lint */
   5
   6 /*
   7  * Copyright (c) 1987, 1993
   8  *      The Regents of the University of California.  All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  */
  38
  39 #include "port_before.h"
  40
  41 #include <stddef.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44
  45 #include "port_after.h"
  46
  47 #if !defined(NEED_SETENV)
  48 int __bindcompat_setenv;
  49 #else
  50
  51 extern char **environ;
  52
  53 static char *findenv(const char *name, int *offset);
  54
  55 /*%
  56  * setenv --
  57  *      Set the value of the environmental variable "name" to be
  58  *      "value".  If rewrite is set, replace any current value.
  59  */
  60 setenv(const char *name, const char *value, int rewrite) {
  61         extern char **environ;
  62         static int alloced;                     /*%< if allocated space before */
  63         char *c;
  64         int l_value, offset;
  65
  66         if (*value == '=')                      /*%< no `=' in value */
  67                 ++value;
  68         l_value = strlen(value);
  69         if ((c = findenv(name, &offset))) {     /*%< find if already exists */
  70                 if (!rewrite)
  71                         return (0);
  72                 if (strlen(c) >= l_value) {     /*%< old larger; copy over */
  73                         while (*c++ = *value++);
  74                         return (0);
  75                 }
  76         } else {                                        /*%< create new slot */
  77                 int cnt;
  78                 char **p;
  79
  80                 for (p = environ, cnt = 0; *p; ++p, ++cnt);
  81                 if (alloced) {                  /*%< just increase size */
  82                         environ = (char **)realloc((char *)environ,
  83                             (size_t)(sizeof(char *) * (cnt + 2)));
  84                         if (!environ)
  85                                 return (-1);
  86                 }
  87                 else {                          /*%< get new space */
  88                         alloced = 1;            /*%< copy old entries into it */
  89                         p = malloc((size_t)(sizeof(char *) * (cnt + 2)));
  90                         if (!p)
  91                                 return (-1);
  92                         memcpy(p, environ, cnt * sizeof(char *));
  93                         environ = p;
  94                 }
  95                 environ[cnt + 1] = NULL;
  96                 offset = cnt;
  97         }
  98         for (c = (char *)name; *c && *c != '='; ++c);   /*%< no `=' in name */
  99         if (!(environ[offset] =                 /*%< name + `=' + value */
 100             malloc((size_t)((int)(c - name) + l_value + 2))))
 101                 return (-1);
 102         for (c = environ[offset]; (*c = *name++) && *c != '='; ++c);
 103         for (*c++ = '='; *c++ = *value++;);
 104         return (0);
 105 }
 106
 107 /*%
 108  * unsetenv(name) --
 109  *      Delete environmental variable "name".
 110  */
 111 void
 112 unsetenv(const char *name) {
 113         char **p;
 114         int offset;
 115
 116         while (findenv(name, &offset))  /*%< if set multiple times */
 117                 for (p = &environ[offset];; ++p)
 118                         if (!(*p = *(p + 1)))
 119                                 break;
 120 }
 121
 122 /*%
 123  * findenv --
 124  *      Returns pointer to value associated with name, if any, else NULL.
 125  *      Sets offset to be the offset of the name/value combination in the
 126  *      environmental array, for use by setenv(3) and unsetenv(3).
 127  *      Explicitly removes '=' in argument name.
 128  *
 129  *      This routine *should* be a static; don't use it.
 130  */
 131 static char *
 132 findenv(const char *name, int *offset) {
 133         const char *np;
 134         char **p, *c;
 135         int len;
 136
 137         if (name == NULL || environ == NULL)
 138                 return (NULL);
 139         for (np = name; *np && *np != '='; ++np)
 140                 continue;
 141         len = np - name;
 142         for (p = environ; (c = *p) != NULL; ++p)
 143                 if (strncmp(c, name, len) == 0 && c[len] == '=') {
 144                         *offset = p - environ;
 145                         return (c + len + 1);
 146                 }
 147         return (NULL);
 148 }
 149 #endif
 150
 151 /*! \file */