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/*
 * Copyright (c) 1997 - 1999 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * All rights reserved. 
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 *
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE. 
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
RCSID("$Id: get_default_username.c 14773 2005-04-12 11:29:18Z lha $");
#endif /* HAVE_CONFIG_H */

#include "roken.h"

/*
 * Try to return what should be considered the default username or
 * NULL if we can't guess at all.
 */

const char * ROKEN_LIB_FUNCTION
get_default_username (void)
{
    const char *user;

    user = getenv ("USER");
    if (user == NULL)
	user = getenv ("LOGNAME");
    if (user == NULL)
	user = getenv ("USERNAME");

#if defined(HAVE_GETLOGIN) && !defined(POSIX_GETLOGIN)
    if (user == NULL) {
	user = (const char *)getlogin ();
	if (user != NULL)
	    return user;
    }
#endif
#ifdef HAVE_PWD_H
    {
	uid_t uid = getuid ();
	struct passwd *pwd;

	if (user != NULL) {
	    pwd = k_getpwnam (user);
	    if (pwd != NULL && pwd->pw_uid == uid)
		return user;
	}
	pwd = k_getpwuid (uid);
	if (pwd != NULL)
	    return pwd->pw_name;
    }
#endif
    return user;
}