lib/roken/unsetenv.c

   1 /*
   2  * Copyright (c) 1995, 1996, 1997 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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 #include <stdlib.h>
  37 #include <string.h>
  38
  39 #include "roken.h"
  40
  41 #if !HAVE_DECL_ENVIRON
  42 extern char **environ;
  43 #endif
  44
  45 /*
  46  * unsetenv --
  47  */
  48 ROKEN_LIB_FUNCTION void ROKEN_LIB_CALL
  49 unsetenv(const char *name)
  50 {
  51   int len;
  52   const char *np;
  53   char **p;
  54
  55   if (name == 0 || environ == 0)
  56     return;
  57
  58   for (np = name; *np && *np != '='; np++)
  59     /* nop */;
  60   len = np - name;
  61
  62   for (p = environ; *p != 0; p++)
  63     if (strncmp(*p, name, len) == 0 && (*p)[len] == '=')
  64       break;
  65
  66   for (; *p != 0; p++)
  67     *p = *(p + 1);
  68 }
  69