get_default_username.c revision 178825 
1168404Spjd/*
2168404Spjd * Copyright (c) 1997 - 1999 Kungliga Tekniska H�gskolan
3168404Spjd * (Royal Institute of Technology, Stockholm, Sweden).
4168404Spjd * All rights reserved.
5211547Srpaulo *
6179189Sjb * Redistribution and use in source and binary forms, with or without
7179189Sjb * modification, are permitted provided that the following conditions
8210693Srpaulo * are met:
9168792Sru *
10168792Sru * 1. Redistributions of source code must retain the above copyright
11168792Sru *    notice, this list of conditions and the following disclaimer.
12248571Smm *
13168792Sru * 2. Redistributions in binary form must reproduce the above copyright
14168792Sru *    notice, this list of conditions and the following disclaimer in the
15168404Spjd *    documentation and/or other materials provided with the distribution.
16168792Sru *
17248571Smm * 3. Neither the name of the Institute nor the names of its contributors
18168792Sru *    may be used to endorse or promote products derived from this software
19177714Sru *    without specific prior written permission.
20168404Spjd *
21168404Spjd * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22172404Sru * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23168404Spjd * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24242723Sjhibbits * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25242723Sjhibbits * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26211547Srpaulo * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27210693Srpaulo * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28210693Srpaulo * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29210693Srpaulo * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30168404Spjd * 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>
36RCSID("$Id: get_default_username.c 14773 2005-04-12 11:29:18Z lha $");
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
46const char * ROKEN_LIB_FUNCTION
47get_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