1 /* $NetBSD: get_default_username.c,v 1.2 2017/01/28 21:31:50 christos Exp $ */
2
3 /*
4 * Copyright (c) 1997 - 1999 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include <config.h>
37
38 #include <krb5/roken.h>
39
40 /*
41 * Try to return what should be considered the default username or
42 * NULL if we can't guess at all.
43 */
44
45 ROKEN_LIB_FUNCTION const char * ROKEN_LIB_CALL
get_default_username(void)46 get_default_username (void)
47 {
48 const char *user;
49
50 user = getenv ("USER");
51 if (user == NULL)
52 user = getenv ("LOGNAME");
53 if (user == NULL)
54 user = getenv ("USERNAME");
55
56 #if defined(HAVE_GETLOGIN) && !defined(POSIX_GETLOGIN)
57 if (user == NULL) {
58 user = (const char *)getlogin ();
59 if (user != NULL)
60 return user;
61 }
62 #endif
63 #ifdef HAVE_PWD_H
64 {
65 uid_t uid = getuid ();
66 struct passwd *pwd;
67
68 if (user != NULL) {
69 pwd = k_getpwnam (user);
70 if (pwd != NULL && pwd->pw_uid == uid)
71 return user;
72 }
73 pwd = k_getpwuid (uid);
74 if (pwd != NULL)
75 return pwd->pw_name;
76 }
77 #endif
78 #ifdef _WIN32
79 /* TODO: We can call GetUserNameEx() and figure out a
80 username. However, callers do not free the return value of this
81 function. */
82 #endif
83
84 return user;
85 }
86