xref: /freebsd/crypto/heimdal/lib/roken/get_default_username.c (revision af23369a6deaaeb612ab266eb88b8bb8d560c322)
1 /*
2  * Copyright (c) 1997 - 1999 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 "roken.h"
37 
38 /*
39  * Try to return what should be considered the default username or
40  * NULL if we can't guess at all.
41  */
42 
43 ROKEN_LIB_FUNCTION const char * ROKEN_LIB_CALL
44 get_default_username (void)
45 {
46     const char *user;
47 
48     user = getenv ("USER");
49     if (user == NULL)
50 	user = getenv ("LOGNAME");
51     if (user == NULL)
52 	user = getenv ("USERNAME");
53 
54 #if defined(HAVE_GETLOGIN) && !defined(POSIX_GETLOGIN)
55     if (user == NULL) {
56 	user = (const char *)getlogin ();
57 	if (user != NULL)
58 	    return user;
59     }
60 #endif
61 #ifdef HAVE_PWD_H
62     {
63 	uid_t uid = getuid ();
64 	struct passwd *pwd;
65 
66 	if (user != NULL) {
67 	    pwd = k_getpwnam (user);
68 	    if (pwd != NULL && pwd->pw_uid == uid)
69 		return user;
70 	}
71 	pwd = k_getpwuid (uid);
72 	if (pwd != NULL)
73 	    return pwd->pw_name;
74     }
75 #endif
76 #ifdef _WIN32
77     /* TODO: We can call GetUserNameEx() and figure out a
78        username. However, callers do not free the return value of this
79        function. */
80 #endif
81 
82     return user;
83 }
84