clib/env.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 #include "config.h"
  35
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 static const char sccsid[] = "@(#)getenv.c      8.1 (Berkeley) 6/4/93";
  38 static const char sccsid[] = "@(#)setenv.c      8.1 (Berkeley) 6/4/93";
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include <stdlib.h>
  42 #include <string.h>
  43
  44 /*
  45  * __findenv --
  46  *      Returns pointer to value associated with name, if any, else NULL.
  47  *      Sets offset to be the offset of the name/value combination in the
  48  *      environmental array, for use by setenv(3) and unsetenv(3).
  49  *      Explicitly removes '=' in argument name.
  50  *
  51  *      This routine *should* be a static; don't use it.
  52  */
  53 static char *
  54 __findenv(register char *name, int *offset)
  55 {
  56         extern char **environ;
  57         register int len;
  58         register char *np;
  59         register char **p, *c;
  60
  61         if (name == NULL || environ == NULL)
  62                 return (NULL);
  63         for (np = name; *np && *np != '='; ++np)
  64                 continue;
  65         len = np - name;
  66         for (p = environ; (c = *p) != NULL; ++p)
  67                 if (strncmp(c, name, len) == 0 && c[len] == '=') {
  68                         *offset = p - environ;
  69                         return (c + len + 1);
  70                 }
  71         return (NULL);
  72 }
  73
  74 #ifndef HAVE_SETENV
  75 /*
  76  * setenv --
  77  *      Set the value of the environmental variable "name" to be
  78  *      "value".  If rewrite is set, replace any current value.
  79  *
  80  * PUBLIC: #ifndef HAVE_SETENV
  81  * PUBLIC: int setenv __P((const char *, const char *, int));
  82  * PUBLIC: #endif
  83  */
  84 setenv(name, value, rewrite)
  85         register char *name;
  86         register char *value;
  87         int rewrite;
  88 {
  89         extern char **environ;
  90         static int alloced;                     /* if allocated space before */
  91         register char *c;
  92         int l_value, offset;
  93
  94         if (*value == '=')                      /* no `=' in value */
  95                 ++value;
  96         l_value = strlen(value);
  97         if ((c = __findenv(name, &offset))) {   /* find if already exists */
  98                 if (!rewrite)
  99                         return (0);
 100                 if (strlen(c) >= l_value) {     /* old larger; copy over */
 101                         while (*c++ = *value++);
 102                         return (0);
 103                 }
 104         } else {                                        /* create new slot */
 105                 register int cnt;
 106                 register char **p;
 107
 108                 for (p = environ, cnt = 0; *p; ++p, ++cnt);
 109                 if (alloced) {                  /* just increase size */
 110                         environ = (char **)realloc((char *)environ,
 111                             (size_t)(sizeof(char *) * (cnt + 2)));
 112                         if (!environ)
 113                                 return (-1);
 114                 }
 115                 else {                          /* get new space */
 116                         alloced = 1;            /* copy old entries into it */
 117                         p = malloc((size_t)(sizeof(char *) * (cnt + 2)));
 118                         if (!p)
 119                                 return (-1);
 120                         memmove(p, environ, cnt * sizeof(char *));
 121                         environ = p;
 122                 }
 123                 environ[cnt + 1] = NULL;
 124                 offset = cnt;
 125         }
 126         for (c = (char *)name; *c && *c != '='; ++c);   /* no `=' in name */
 127         if (!(environ[offset] =                 /* name + `=' + value */
 128             malloc((size_t)((int)(c - name) + l_value + 2))))
 129                 return (-1);
 130         for (c = environ[offset]; (*c = *name++) && *c != '='; ++c);
 131         for (*c++ = '='; *c++ = *value++;);
 132         return (0);
 133 }
 134 #endif
 135
 136 #ifndef HAVE_UNSETENV
 137 /*
 138  * unsetenv(name) --
 139  *      Delete environmental variable "name".
 140  *
 141  * PUBLIC: #ifndef HAVE_UNSETENV
 142  * PUBLIC: void unsetenv __P((const char *));
 143  * PUBLIC: #endif
 144  */
 145 void
 146 unsetenv(name)
 147         char *name;
 148 {
 149         extern char **environ;
 150         register char **p;
 151         int offset;
 152
 153         while (__findenv(name, &offset))        /* if set multiple times */
 154                 for (p = &environ[offset];; ++p)
 155                         if (!(*p = *(p + 1)))
 156                                 break;
 157 }
 158 #endif