455 lines
12 KiB
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455 lines
12 KiB
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>DosSetFileLocks()--Lock and Unlock a Byte Range of an Open File</title>
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<!-- Begin Header Records ========================================== -->
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Change History: -->
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<!-- YYMMDD USERID Change description -->
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<!-- Unix2 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 -->
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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<!-- Change History: -->
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<!-- 011022 JTROUS: Changes from API Review 1, V5R2 -->
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<!-- 010514 JET: This file has undergone html cleanup -->
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<!-- 020719 MFENLON: updated for QFileSvr.400 threadsafety, V5R3 -->
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<!-- 020905 JTROUS: Changes for scan processing, V5R3a, DCR 98680 -->
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<!-- 021118 JTROUS: Correct ERROR_GEN_FAILURE (no change flag) -->
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<!-- 050413 JTROUS: Minor fixups, V5R4 review (no change flag) -->
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<!-- End Header Records -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<!-- Java sync-link -->
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<script language="Javascript" src="../rzahg/synch.js" type="text/javascript">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>DosSetFileLocks()--Lock and Unlock a Byte Range of an Open File</h2>
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<div class="box" style="width: 80%;">
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<br>
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Syntax
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<pre>
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#define INCL_DOSERRORS
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#define INCL_DOSFILEMGR
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#include <os2.h>
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APIRET APIENTRY DosSetFileLocks(HFILE <em>FileHandle</em>,
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PFILELOCK <em>ppUnLockRange</em>,
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PFILELOCK <em>ppLockRange</em>,
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ULONG <em>ulTimeOut</em>,
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ULONG <em>ulFlags</em>);
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</pre>
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Service Program Name: QP0LLIB1<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Conditional; see <a href="#HDRDSFLUSG">Usage Notes</a>.<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>DosSetFileLocks()</strong> function locks and unlocks a range of
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an open file. A non-zero range indicates that a lock or unlock request is being
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made.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong><em>FileHandle</em></strong></dt>
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<dd>(Input) The file descriptor of the file in which a range is to be
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locked.</dd>
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<dt><strong><em>ppUnlockRange</em></strong></dt>
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<dd>(Input) Address of the structure containing the offset and length of a
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range to be unlocked. The structure is as follows:
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<dl compact>
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<dt><em>FileOffset</em></dt>
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<dd>The offset to the beginning of the range to be unlocked.</dd>
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<dt><em>RangeLength</em></dt>
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<dd>The length of the range to be unlocked. A value of zero means that
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unlocking is not required.</dd>
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</dl>
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</dd>
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<dt><strong><em>ppLockRange</em></strong></dt>
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<dd>(Input) Address of the structure containing the offset and length of a
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range to be locked. The structure is as follows:
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<dl compact>
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<dt><em>FileOffset</em></dt>
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<dd>The offset to the beginning of the range to be locked.</dd>
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<dt><em>RangeLength</em></dt>
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<dd>The length of the range to be locked. A value of zero means that locking is
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not required.</dd>
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</dl>
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</dd>
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<dt><strong><em>ulTimeOut</em></strong></dt>
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<dd>(Input) The maximum time, in milliseconds, that the process is to wait for
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the requested locks.</dd>
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<dt><strong><em>ulFlags</em></strong></dt>
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<dd>(Input) Flags that describe the action to be taken. If any flags other than
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those listed below are specified, the error ERROR_INVALID_PARAMETER will be
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returned.
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<p>The following values are to be specified in <em>ulFlags</em>:</p>
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<dl compact>
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<dt><em>'0x0002' or QP0L_DOSSETFILELOCKS_ATOMIC</em></dt>
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<dd>Atomic. This bit defines a request for atomic locking. If this bit is set
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to 1 and the lock range is equal to the unlock range, an atomic lock occurs. If
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this bit is set to 1 and the lock range is not equal to the unlock range,
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ERROR_LOCK_VIOLATION is returned.</dd>
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<dt><em>'0x0001' or QP0L_DOSSETFILELOCKS_SHARE</em></dt>
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<dd>Share. This bit defines the type of access that other processes may have to
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the file range that is being locked.
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<p>If this bit is set to 0 (the default), other processes have no access to the
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locked file range. The current process has exclusive access to the locked file
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range, which must not overlap any other locked file range.</p>
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<p>If this bit is set to 1, the current process and other processes have shared
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access to the locked file range. A file range with shared access may overlap
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any other file range with shared access, but must not overlap any other file
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range with exclusive access.</p>
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</dd>
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</dl>
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</dd>
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</dl>
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<br>
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<h3>Authorities</h3>
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<p>No authorization is required.</p>
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<br>
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<h3>Return Value</h3>
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<dl compact>
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<dt><em>NO_ERROR (0)</em></dt>
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<dd><strong>DosSetFileLocks()</strong> was successful.</dd>
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<dt><em>value (non-zero)</em></dt>
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<dd><strong>DosSetFileLocks()</strong> was not successful.
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The <em>value</em> that is returned indicates the error.</dd>
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</dl>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>DosSetFileLocks()</strong> is not successful, the value that is
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returned is one of the following errors. The <<strong>bseerr.h</strong>>
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header file defines these values.</p>
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<dl compact>
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<dt><em>[ERROR_GEN_FAILURE]</em></dt>
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<dd>
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<p>A general failure occurred.</p>
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<p>This may result from damage in the system. Refer to messages in the job log
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for other possible causes.</p>
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</dd>
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<dt><em>[ERROR_INVALID_HANDLE]</em></dt>
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<dd>
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<p>An invalid file handle was found.</p>
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<p>The file handle passed to this function is not valid.</p>
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</dd>
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<dt><em>[ERROR_LOCK_VIOLATION]</em></dt>
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<dd>
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<p>A lock violation was found.</p>
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<p>The requested lock and unlock ranges are both zero.</p>
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</dd>
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<dt><em>[ERROR_INVALID_PARAMETER]</em></dt>
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<dd>
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<p>An invalid parameter was found.</p>
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<p>A parameter passed to this function is not valid.</p>
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<p>The byte range specified by the offset and length in the ppUnlockRange or
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ppLockRange parameters extends beyond 2GB minus 1 byte.</p>
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</dd>
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<dt><em>[ERROR_ATOMIC_LOCK_NOT_SUPPORTED]</em></dt>
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<dd>
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<p>The atomic lock operation is not supported.</p>
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<p>The file system does not support atomic lock operations.</p>
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</dd>
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<dt><em>[ERROR_TIMER_NOT_SUPPORTED]</em></dt>
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<dd>
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<p>The lock timer value is not supported.</p>
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<p>The file system does not support the lock timer value.</p>
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</dd>
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</dl>
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<br>
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<h3>Error Messages</h3>
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<p>The system may send the following messages from this function.</p>
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<table width="100%" cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<th align="left" valign="top">Message ID</th>
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<th align="left" valign="top">Error Message Text</th>
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</tr>
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<tr>
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<td width="15%" valign="top">CPE3418 E</td>
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<td width="85%" valign="top">Possible APAR condition or hardware failure.</td>
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</tr>
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<tr>
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<td valign="top">CPFA0D4 E</td>
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<td valign="top">File system error occurred. Error number &1.</td>
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</tr>
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<tr>
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<td valign="top">CPF3CF2 E</td>
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<td valign="top">Error(s) occurred during running of &1 API.</td>
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</tr>
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<tr>
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<td valign="top">CPF9872 E</td>
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<td valign="top">Program or service program &1 in library &2 ended.
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Reason code &3.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3><a name="HDRDSFLUSG">Usage Notes</a></h3>
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<ol type="1">
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<li>If this function is called
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by a thread executing one of the scan-related exit programs (or any of its
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created threads), it will fail with error code [ENOTSUP]. See <a href=
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"ifsopenexit.htm">Integrated File System Scan on Open Exit Programs</a> and <a
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href="ifscloseexit.htm">Integrated File System Scan on Close Exit Programs</a>
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for more information.
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<br><br>
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</li>
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<li>This function will fail with error code [ERROR_GEN_FAILURE] when all the
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following conditions are true:
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<ul>
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<li>Where multiple threads exist in the job.</li>
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<li>The object this function is operating on resides in a file system that is
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not threadsafe. Only the following file systems are threadsafe for this
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function:
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<ul>
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<li>"Root" (/)</li>
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<li>QOpenSys</li>
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<li>User-defined</li>
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<li>QNTC</li>
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<li>QSYS.LIB</li>
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<li>Independent ASP QSYS.LIB</li>
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<li>QOPT</li>
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<li>QFileSvr.400</li>
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</ul>
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</li>
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</ul>
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<br>
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</li>
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<li>The following file systems do not support timer values other than 0. An
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attempt to a value other than 0 for the timer value results in an
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ERROR_TIMER_NOT_SUPPORTED error.
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<p>Also, the following file systems do not support the atomic locking flag. If you
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turn on the atomic locking flag, an ERROR_ATOMIC_LOCKS_NOT_SUPPORTED error is
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returned.</p>
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<ul>
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<li>"Root" (/)</li>
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<li>QOpenSys</li>
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<li>User-Defined File System</li>
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<li>QDLS</li>
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<li>QOPT</li>
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<li>QNetWare</li>
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</ul>
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<br>
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</li>
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<li>The following file systems do not support byte range locks. An attempt to
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use this API results in an ERROR_GEN_FAILURE error.
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<ul>
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<li>QSYS.LIB</li>
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<li>Independent ASP QSYS.LIB</li>
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<li>Network File System</li>
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<li>QFileSvr.400</li>
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</ul>
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<br>
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</li>
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<li>When you develop in C-based languages and this function is compiled with
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the _LARGE_FILES macro defined, it will be mapped to <strong>
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DosSetFileLocks64()</strong>. Additionally, the <samp>PFILELOCK</samp> data
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type will be mapped to a type <samp>PFILELOCK64</samp>.
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<br><br></li>
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<li>Locks placed on character special files result in advisory locks. For
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more information on advisory locking, please see the <a href="fcntl.htm">
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fcntl()--Perform File Control Command</a>.
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</li>
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</ol>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li>The <<strong>fcntl.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)</li>
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|
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<li>The <<strong>os2.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)</li>
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|
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<li>The <<strong>os2def.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)</li>
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|
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<li>The <<strong>bse.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)</li>
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<li>The <<strong>bsedos.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)</li>
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|
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<li>The <<strong>bseerr.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)</li>
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||
|
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<li><a href="dossfl64.htm">DosSetFileLocks64()</a>--Lock and Unlock a Byte
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Range of an Open File (Large File Enabled)</li>
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||
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</ul>
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||
|
|
|
||
|
|
<br>
|
||
|
|
<h3>Example</h3>
|
||
|
|
|
||
|
|
<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
|
||
|
|
for information pertaining to code examples.</p>
|
||
|
|
|
||
|
|
<p>The following example opens, locks, and unlocks a file.</p>
|
||
|
|
|
||
|
|
<pre>
|
||
|
|
#define INCL_DOSERRORS
|
||
|
|
#define INCL_DOSFILEMGR
|
||
|
|
#include <os2.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
|
||
|
|
#define NULL_RANGE 0L
|
||
|
|
#define LOCK_FLAGS 0
|
||
|
|
|
||
|
|
main() {
|
||
|
|
char fn[]="lock.file";
|
||
|
|
char buf[] =
|
||
|
|
"Test data for locking and unlocking range of a file";
|
||
|
|
int fd;
|
||
|
|
ULONG lockTimeout = 2000; /* lock timeout of 2 seconds */
|
||
|
|
FILELOCK Area; /* area of file to lock/unlock */
|
||
|
|
|
||
|
|
Area.Offset = 4; /* start locking at byte 4 */
|
||
|
|
Area.Range = 10; /* lock 10 bytes for the file */
|
||
|
|
|
||
|
|
/* Create a file for this example */
|
||
|
|
fd = creat(fn, S_IWUSR | S_IRUSR);
|
||
|
|
/* Write some data to the file */
|
||
|
|
write(fd, buf, sizof(buf) -1);
|
||
|
|
close(fd);
|
||
|
|
|
||
|
|
/* Open the file */
|
||
|
|
if ((fd = open(fn, O_RDWR) < 0)
|
||
|
|
{
|
||
|
|
perror("open() error");
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Lock a range */
|
||
|
|
rc = DosSetFileLocks((HFILE)fd,
|
||
|
|
NULL_RANGE,
|
||
|
|
&Area,
|
||
|
|
&LockTimeout,
|
||
|
|
LOCK_FLAGS);
|
||
|
|
if(rc != 0) /* Lock failed */
|
||
|
|
{
|
||
|
|
perror("DosSetFileLocks() error");
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/* Unlock a range */
|
||
|
|
rc = DosSetFileLocks((HFILE)fd,
|
||
|
|
&Area,
|
||
|
|
NULL_RANGE,
|
||
|
|
&LockTimeout,
|
||
|
|
LOCK_FLAGS);
|
||
|
|
if(rc != 0) /* Unlock failed */
|
||
|
|
{
|
||
|
|
perror("DosSetFileLocks() error");
|
||
|
|
}
|
||
|
|
|
||
|
|
close(fd);
|
||
|
|
unlink(fn);
|
||
|
|
}
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
API introduced: V4R2
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<center>
|
||
|
|
<table cellpadding="2" cellspacing="2">
|
||
|
|
<tr align="center">
|
||
|
|
<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
|
||
|
|
"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a></td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
</center>
|
||
|
|
</body>
|
||
|
|
</html>
|
||
|
|
|