xref: /freebsd/crypto/heimdal/lib/roken/unsetenv.c (revision 0b3105a37d7adcadcb720112fed4dc4e8040be99)
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 
70