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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1997-2006
* Oracle Corporation. All rights reserved.
*
* $Id: os_flock.c,v 1.12 2006/08/24 14:46:21 bostic Exp $
*/
#include "db_config.h"
#include "db_int.h"
/*
* __os_fdlock --
* Acquire/release a lock on a byte in a file.
*/
int
__os_fdlock(dbenv, fhp, offset, acquire, nowait)
DB_ENV *dbenv;
DB_FH *fhp;
int acquire, nowait;
off_t offset;
{
int ret;
DWORD low, high;
OVERLAPPED over;
DB_ASSERT(dbenv,
F_ISSET(fhp, DB_FH_OPENED) && fhp->handle != INVALID_HANDLE_VALUE);
/*
* Windows file locking interferes with read/write operations, so we
* map the ranges to an area past the end of the file.
*/
DB_ASSERT(dbenv, offset < (u_int64_t)INT64_MAX);
offset = UINT64_MAX - offset;
low = (DWORD)offset;
high = (DWORD)(offset >> 32);
if (acquire) {
if (nowait)
RETRY_CHK_EINTR_ONLY(
!LockFile(fhp->handle, low, high, 1, 0), ret);
else if (__os_is_winnt()) {
memset(&over, 0, sizeof(over));
over.Offset = low;
over.OffsetHigh = high;
RETRY_CHK_EINTR_ONLY(
!LockFileEx(fhp->handle, LOCKFILE_EXCLUSIVE_LOCK,
0, 1, 0, &over),
ret);
} else {
/* Windows 9x/ME doesn't support a blocking call. */
for (;;) {
RETRY_CHK_EINTR_ONLY(
!LockFile(fhp->handle, low, high, 1, 0),
ret);
if (__os_posix_err(ret) != EAGAIN)
break;
__os_sleep(dbenv, 1, 0);
}
}
} else
RETRY_CHK_EINTR_ONLY(
!UnlockFile(fhp->handle, low, high, 1, 0), ret);
return (__os_posix_err(ret));
}
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