usr/src/lib/libc/gen/getlogin.c

/*
 * Copyright (c) 1988 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)getlogin.c  5.6 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <stdio.h>
#include <pwd.h>
#include <utmp.h>

int     _logname_valid;         /* known to setlogin() */

char *
getlogin()
{
        static char logname[UT_NAMESIZE+1];

        if (_logname_valid == 0) {
                if (_getlogin(logname, sizeof(logname) - 1) < 0)
                        return ((char *)NULL);
                _logname_valid = 1;
        }
        return (*logname ? logname : (char *)NULL);
}

uid_t   geteuid();

char *
cuserid(s)
        char *s;
{
        register struct passwd *pwd;

        if ((pwd = getpwuid(geteuid())) == NULL) {
                if (s)
                        *s = '\0';
                return (s);
        }
        if (s) {
                (void)strncpy(s, pwd->pw_name, L_cuserid);
                return (s);
        }
        return (pwd->pw_name);
}