stdlib/FreeBSD/setenv.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[] = "@(#)setenv.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/setenv.c,v 1.9 2002/03/22 21:53:10 obrien Exp $");
  39
  40 #include <stddef.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43
  44 char *__findenv(const char *, int *);
  45
  46 /*
  47  * setenv --
  48  *      Set the value of the environmental variable "name" to be
  49  *      "value".  If rewrite is set, replace any current value.
  50  */
  51 int
  52 setenv(name, value, rewrite)
  53         const char *name;
  54         const char *value;
  55         int rewrite;
  56 {
  57         extern char **environ;
  58         static char **alloced;                  /* if allocated space before */
  59         char *c;
  60         int l_value, offset;
  61
  62         if (*value == '=')                      /* no `=' in value */
  63                 ++value;
  64         l_value = strlen(value);
  65         if ((c = __findenv(name, &offset))) {   /* find if already exists */
  66                 if (!rewrite)
  67                         return (0);
  68                 if (strlen(c) >= l_value) {     /* old larger; copy over */
  69                         while ( (*c++ = *value++) );
  70                         return (0);
  71                 }
  72         } else {                                        /* create new slot */
  73                 int cnt;
  74                 char **p;
  75
  76                 for (p = environ, cnt = 0; *p; ++p, ++cnt);
  77                 if (alloced == environ) {                       /* just increase size */
  78                         p = (char **)realloc((char *)environ,
  79                             (size_t)(sizeof(char *) * (cnt + 2)));
  80                         if (!p)
  81                                 return (-1);
  82                         alloced = environ = p;
  83                 }
  84                 else {                          /* get new space */
  85                                                 /* copy old entries into it */
  86                         p = malloc((size_t)(sizeof(char *) * (cnt + 2)));
  87                         if (!p)
  88                                 return (-1);
  89                         bcopy(environ, p, cnt * sizeof(char *));
  90                         alloced = environ = p;
  91                 }
  92                 environ[cnt + 1] = NULL;
  93                 offset = cnt;
  94         }
  95         for (c = (char *)name; *c && *c != '='; ++c);   /* no `=' in name */
  96         if (!(environ[offset] =                 /* name + `=' + value */
  97             malloc((size_t)((int)(c - name) + l_value + 2))))
  98                 return (-1);
  99         for (c = environ[offset]; (*c = *name++) && *c != '='; ++c);
 100         for (*c++ = '='; (*c++ = *value++); );
 101         return (0);
 102 }
 103
 104 /*
 105  * unsetenv(name) --
 106  *      Delete environmental variable "name".
 107  */
 108 void
 109 unsetenv(name)
 110         const char *name;
 111 {
 112         extern char **environ;
 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 }