/*
    Copyright (C) 2008 Andreas Baumann <abaumann@yahoo.com>

    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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "port/unistd.h"

#if !defined HAVE_LOCKF || defined TEST_HAVE_LOCKF

#include "port/string.h"	/* for memset */
#include "port/unistd.h"	/* for getpid */

#include <errno.h>		/* for errno */

int wolf_port_lockf( int fd, int cmd, off_t len ) {
	struct flock fl;
	
	memset( (char *)&fl, 0, sizeof( fl ) );
	/* lockf is always relative to the current file position. */
	fl.l_whence = SEEK_CUR;
	fl.l_start = 0;
	fl.l_len = len;
	
	errno = 0;
	
	switch( cmd ) {
		case F_TEST:
			fl.l_type = F_RDLCK;
			if( fcntl( fd, F_GETLK, &fl ) < 0 ) {
				return -1;
			}
			if( fl.l_type == F_UNLCK ||
			    fl.l_pid == getpid( ) ) {
				return 0;
			}
			errno = EACCES;
			return -1;
			
		case F_ULOCK:
			fl.l_type = F_UNLCK;
			cmd = F_SETLK;
			break;
		
		case F_LOCK:
			fl.l_type = F_WRLCK;
			cmd = F_SETLKW;
			break;
		
		case F_TLOCK:
			fl.l_type = F_WRLCK;
			cmd = F_SETLK; 
			break;
			
		default:
			errno = EINVAL;
			return -1;
	}
	
	return fcntl( fd, cmd, &fl );
}

#endif /* !defined HAVE_LOCKF || defined TEST_HAVE_LOCKF */