89 lines
2.1 KiB
C
89 lines
2.1 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1997,2008 Oracle. All rights reserved.
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*
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* $Id: os_flock.c 63573 2008-05-23 21:43:21Z trent.nelson $
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*/
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#include "db_config.h"
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#include "db_int.h"
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/*
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* __os_fdlock --
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* Acquire/release a lock on a byte in a file.
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*/
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int
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__os_fdlock(env, fhp, offset, acquire, nowait)
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ENV *env;
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DB_FH *fhp;
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int acquire, nowait;
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off_t offset;
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{
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#ifdef DB_WINCE
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/*
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* This functionality is not supported by WinCE, so just fail.
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*
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* Should only happen if an app attempts to open an environment
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* with the DB_REGISTER flag.
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*/
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__db_errx(env, "fdlock API not implemented for WinCE, DB_REGISTER "
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"environment flag not supported.");
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return (EFAULT);
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#else
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DWORD low, high;
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DB_ENV *dbenv;
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OVERLAPPED over;
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int ret;
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dbenv = env == NULL ? NULL : env->dbenv;
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DB_ASSERT(env,
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F_ISSET(fhp, DB_FH_OPENED) && fhp->handle != INVALID_HANDLE_VALUE);
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if (dbenv != NULL && FLD_ISSET(dbenv->verbose, DB_VERB_FILEOPS_ALL))
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__db_msg(env,
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"fileops: flock %s %s offset %lu",
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fhp->name, acquire ? "acquire": "release", (u_long)offset);
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/*
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* Windows file locking interferes with read/write operations, so we
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* map the ranges to an area past the end of the file.
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*/
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DB_ASSERT(env, offset < (u_int64_t)INT64_MAX);
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offset = UINT64_MAX - offset;
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low = (DWORD)offset;
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high = (DWORD)(offset >> 32);
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if (acquire) {
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if (nowait)
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RETRY_CHK_EINTR_ONLY(
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!LockFile(fhp->handle, low, high, 1, 0), ret);
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else if (__os_is_winnt()) {
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memset(&over, 0, sizeof(over));
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over.Offset = low;
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over.OffsetHigh = high;
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RETRY_CHK_EINTR_ONLY(
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!LockFileEx(fhp->handle, LOCKFILE_EXCLUSIVE_LOCK,
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0, 1, 0, &over),
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ret);
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} else {
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/* Windows 9x/ME doesn't support a blocking call. */
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for (;;) {
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RETRY_CHK_EINTR_ONLY(
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!LockFile(fhp->handle, low, high, 1, 0),
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ret);
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if (__os_posix_err(ret) != EAGAIN)
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break;
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__os_yield(env, 1, 0);
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}
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}
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} else
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RETRY_CHK_EINTR_ONLY(
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!UnlockFile(fhp->handle, low, high, 1, 0), ret);
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return (__os_posix_err(ret));
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#endif
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}
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