/* * $Id: file_lock.c,v 1.2 2003/10/20 18:59:57 tomcollins Exp $ * Copyright (C) 1999-2003 Inter7 Internet Technologies, Inc. * * 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 * */#include <unistd.h>#include <sys/types.h>#include <stdio.h>	/* for perror() */#include <errno.h>	/* for perror() */#include <fcntl.h>#include "file_lock.h"#include "config.h"#ifdef FILE_LOCKINGintlock_reg(int fd, int cmd, int type, off_t offset, int whence, off_t len){	struct flock	lock;	lock.l_type	= type;		/* F_RDLCK, F_WRLCK, F_UNLCK */	lock.l_start	= offset;	/* byte offset, relative to l_whence */	lock.l_whence	= whence;	/* SEEK_SET, SEEK_CUR, SEEK_END */	lock.l_len	= len;		/* #bytes (0 means to EOF) */	return( fcntl(fd, cmd, &lock) );}pid_tlock_test(int fd, int type, off_t offset, int whence, off_t len){	struct flock	lock;	lock.l_type	= type;		/* F_RDLCK, F_WRLCK, F_UNLCK */	lock.l_start	= offset;	/* byte offset, relative to l_whence */	lock.l_whence	= whence;	/* SEEK_SET, SEEK_CUR, SEEK_END */	lock.l_len	= len;		/* #bytes (0 means to EOF) */	if (fcntl(fd, F_GETLK, &lock) < 0)	{		return(0);	}	if (lock.l_type == F_UNLCK)		return(0);	/* false, region is not locked yb another proc */	return(lock.l_pid);	/* true, return pid of lock owner */}int get_read_lock(FILE *fs){ int try = 0;	while(read_lock(fileno(fs), 0, SEEK_SET, 0) < 0)	{		if (errno == EAGAIN || errno == EACCES || errno ==ENOLCK ) 		{			/* there might be other errors cases in which			* you might try again. 			*/			if (++try < MAX_TRY_RLOCK) {				(void) sleep(2);				continue;			}			(void) fprintf(stderr,"File busy try again later!\n");			return(-1);		}		return(-2);	}	return(0);}int get_write_lock( FILE *fs ) { int try = 0;	while(write_lock(fileno(fs), 0, SEEK_SET, 0) < 0)	{		if (errno == EAGAIN || errno == EACCES || errno == ENOLCK ) 		{			/* there might be other errors cases in which			* you might try again. 			*/			if (++try < MAX_TRY_RLOCK) {				(void) sleep(2);				continue;			}			(void) fprintf(stderr,"File busy try again later!\n");			return(-1);		}		return(-2);	}	return(0);}#endif