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      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 Hgskolan
      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
     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