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

/*
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * %sccs.include.redist.c%
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)getlogin.c  8.1 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <pwd.h>
#include <utmp.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

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

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

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