busybox/coreutils/logname.c

/* vi: set sw=4 ts=4: */
/*
 * Mini logname implementation for busybox
 *
 * Copyright (C) 2000  Edward Betts <edward@debian.org>.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

/* BB_AUDIT SUSv3 compliant */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/logname.html */

/* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
 *
 * SUSv3 specifies the string used is that returned from getlogin().
 * The previous implementation used getpwuid() for geteuid(), which
 * is _not_ the same.  Erik apparently made this change almost 3 years
 * ago to avoid failing when no utmp was available.  However, the
 * correct course of action wrt SUSv3 for a failing getlogin() is
 * a diagnostic message and an error return.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "busybox.h"

extern int logname_main(int argc, char **argv)
{
	const char *p;

	if (argc > 1) {
		bb_show_usage();
	}

	if ((p = getlogin()) != NULL) {
		puts(p);
		bb_fflush_stdout_and_exit(EXIT_SUCCESS);
	}

	bb_perror_msg_and_die("getlogin");
}