lib/other/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
  38 #include <errno.h>
  39 #include <stddef.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43 char *__findenv(const char *, int *);
  44
  45 /*
  46  * setenv --
  47  *      Set the value of the environmental variable "name" to be
  48  *      "value".  If rewrite is set, replace any current value.
  49  */
  50 setenv(name, value, rewrite)
  51         register const char *name;
  52         register const char *value;
  53         int rewrite;
  54 {
  55         extern char **environ;
  56         static int alloced;                     /* if allocated space before */
  57         register char *c;
  58         int l_value, offset;
  59
  60         if (*value == '=')                      /* no `=' in value */
  61                 ++value;
  62         l_value = strlen(value);
  63         if ((c = __findenv(name, &offset))) {   /* find if already exists */
  64                 if (!rewrite)
  65                         return (0);
  66                 if (strlen(c) >= l_value) {     /* old larger; copy over */
  67                         while (*c++ = *value++);
  68                         return (0);
  69                 }
  70         } else {                                        /* create new slot */
  71                 register int cnt;
  72                 register char **p;
  73
  74                 for (p = environ, cnt = 0; *p; ++p, ++cnt);
  75                 if (alloced) {                  /* just increase size */
  76                         environ = (char **)realloc((char *)environ,
  77                             (size_t)(sizeof(char *) * (cnt + 2)));
  78                         if (!environ)
  79                                 return (-1);
  80                 }
  81                 else {                          /* get new space */
  82                         alloced = 1;            /* copy old entries into it */
  83                         p = malloc((size_t)(sizeof(char *) * (cnt + 2)));
  84                         if (!p)
  85                                 return (-1);
  86                         memcpy(p, environ, cnt * sizeof(char *));
  87                         environ = p;
  88                 }
  89                 environ[cnt + 1] = NULL;
  90                 offset = cnt;
  91         }
  92         for (c = (char *)name; *c && *c != '='; ++c);   /* no `=' in name */
  93         if (!(environ[offset] =                 /* name + `=' + value */
  94             malloc((size_t)((int)(c - name) + l_value + 2))))
  95                 return (-1);
  96         for (c = environ[offset]; (*c = *name++) && *c != '='; ++c);
  97         for (*c++ = '='; *c++ = *value++;);
  98         return (0);
  99 }
 100
 101 /*
 102  * unsetenv(name) --
 103  *      Delete environmental variable "name".
 104  */
 105 int
 106 unsetenv(name)
 107         const char *name;
 108 {
 109         extern char **environ;
 110         register char **p;
 111         int offset;
 112
 113         if (name == NULL || strlen(name) == 0 || strchr(name, '=') != 0)
 114         {
 115                 errno= EINVAL;
 116                 return -1;
 117         }
 118
 119         while (__findenv(name, &offset))        /* if set multiple times */
 120                 for (p = &environ[offset];; ++p)
 121                         if (!(*p = *(p + 1)))
 122                                 break;
 123         return 0;
 124 }
 125
 126 /*
 127  * __findenv --
 128  *      Returns pointer to value associated with name, if any, else NULL.
 129  *      Sets offset to be the offset of the name/value combination in the
 130  *      environmental array, for use by setenv(3) and unsetenv(3).
 131  *      Explicitly removes '=' in argument name.
 132  *
 133  *      This routine *should* be a static; don't use it.
 134  */
 135 char *
 136 __findenv(name, offset)
 137         register const char *name;
 138         int *offset;
 139 {
 140         extern char **environ;
 141         register int len;
 142         register const char *np;
 143         register char **p, *c;
 144
 145         if (name == NULL || environ == NULL)
 146                 return (NULL);
 147         for (np = name; *np && *np != '='; ++np)
 148                 continue;
 149         len = np - name;
 150         for (p = environ; (c = *p) != NULL; ++p)
 151                 if (strncmp(c, name, len) == 0 && c[len] == '=') {
 152                         *offset = p - environ;
 153                         return (c + len + 1);
 154                 }
 155         return (NULL);
 156 }
 157 /*
 158  * $PchId: setenv.c,v 1.3 1996/05/09 20:43:02 philip Exp philip $
 159  */