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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1997-2009 Oracle. All rights reserved.
*
* $Id$
*/
#include "db_config.h"
#include "db_int.h"
/*
* QNX has special requirements on FSYNC: if the file is a shared memory
* object, we can not call fsync because it is not implemented, instead,
* we set the O_DSYNC flag to the file descriptor and then do an empty
* write so that all data are synced. We only sync this way if the file
* is a shared memory object, other types of ordinary files are still synced
* using fsync, to be not only faster but also atomic.
* We don't just set the O_DSYNC flag on open, since it would force all writes
* to be sync'ed. And we remove the O_DSYNC if it is not originally set to
* the file descriptor before passed in to this function.
* This is slightly different to the VxWorks and hp code above, since QNX does
* supply a fsync call, it just has a unique requirement.
*/
int
__qnx_fsync(fhp)
DB_FH *fhp;
{
int ret;
int fd, unset, flags;
fd = fhp->fd;
unset = 1;
ret = flags = 0;
if (F_ISSET(fhp, DB_FH_REGION))
{
RETRY_CHK(fcntl(fd, F_GETFL), ret);
if (ret == -1)
goto err;
/*
* if already has O_DSYNC flag, we can't remove it
* after the empty write
*/
if (ret & O_DSYNC != 0)
unset = 0;
else {
ret |= O_DSYNC;
flags = ret;
RETRY_CHK(fcntl(fd, F_SETFL, flags), ret);
if (ret == -1)
goto err;
}
/* Do an empty write, to force a sync */
RETRY_CHK(write(fd, "", 0), ret);
if (ret == -1)
goto err;
/* remove the O_DSYNC flag if necessary */
if (unset) {
RETRY_CHK(fcntl(fd, F_GETFL), ret);
if (ret == -1)
goto err;
ret &= ~O_DSYNC;
flags = ret;
RETRY_CHK(fcntl(fd, F_SETFL, flags), ret);
if (ret == -1)
goto err;
}
} else
RETRY_CHK(fdatasync(fd), ret);
err: return (ret);
}
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