xref: /freebsd/crypto/heimdal/lib/roken/get_default_username.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
1 /*
2  * Copyright (c) 1997 - 1999 Kungliga Tekniska H�gskolan
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 #ifdef HAVE_CONFIG_H
35 #include <config.h>
36 RCSID("$Id: get_default_username.c,v 1.3 1999/12/02 16:58:46 joda Exp $");
37 #endif /* HAVE_CONFIG_H */
38 
39 #include "roken.h"
40 
41 /*
42  * Try to return what should be considered the default username or
43  * NULL if we can't guess at all.
44  */
45 
46 const char *
47 get_default_username (void)
48 {
49     const char *user;
50 
51     user = getenv ("USER");
52     if (user == NULL)
53 	user = getenv ("LOGNAME");
54     if (user == NULL)
55 	user = getenv ("USERNAME");
56 
57 #if defined(HAVE_GETLOGIN) && !defined(POSIX_GETLOGIN)
58     if (user == NULL) {
59 	user = (const char *)getlogin ();
60 	if (user != NULL)
61 	    return user;
62     }
63 #endif
64 #ifdef HAVE_PWD_H
65     {
66 	uid_t uid = getuid ();
67 	struct passwd *pwd;
68 
69 	if (user != NULL) {
70 	    pwd = k_getpwnam (user);
71 	    if (pwd != NULL && pwd->pw_uid == uid)
72 		return user;
73 	}
74 	pwd = k_getpwuid (uid);
75 	if (pwd != NULL)
76 	    return pwd->pw_name;
77     }
78 #endif
79     return user;
80 }
81