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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"
/*
* __os_fdlock --
* Acquire/release a lock on a byte in a file.
*/
int
__os_fdlock(env, fhp, offset, acquire, nowait)
ENV *env;
DB_FH *fhp;
int acquire, nowait;
off_t offset;
{
#ifdef DB_WINCE
/*
* This functionality is not supported by WinCE, so just fail.
*
* Should only happen if an app attempts to open an environment
* with the DB_REGISTER flag.
*/
__db_errx(env, "fdlock API not implemented for WinCE, DB_REGISTER "
"environment flag not supported.");
return (EFAULT);
#else
DWORD low, high;
DB_ENV *dbenv;
OVERLAPPED over;
int ret;
dbenv = env == NULL ? NULL : env->dbenv;
DB_ASSERT(env,
F_ISSET(fhp, DB_FH_OPENED) && fhp->handle != INVALID_HANDLE_VALUE);
if (dbenv != NULL && FLD_ISSET(dbenv->verbose, DB_VERB_FILEOPS_ALL))
__db_msg(env,
"fileops: flock %s %s offset %lu",
fhp->name, acquire ? "acquire": "release", (u_long)offset);
/*
* Windows file locking interferes with read/write operations, so we
* map the ranges to an area past the end of the file.
*/
DB_ASSERT(env, 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_yield(env, 1, 0);
}
}
} else
RETRY_CHK_EINTR_ONLY(
!UnlockFile(fhp->handle, low, high, 1, 0), ret);
return (__os_posix_err(ret));
#endif
}
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