748 lines
17 KiB
HTML
748 lines
17 KiB
HTML
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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>ftruncate()--Truncate 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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<!-- file cleaned -->
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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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<!-- 010320 JTROUS Include Journal ERRNOs, should have in V5R1 -->
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<!-- also include v5r2 change from PASE DCR 98391 -->
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<!-- 011022 JTROUS Changes from API Review 1, V5R2 -->
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<!-- 020131 JTROUS Changes from API Review 3, V5R2 -->
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<!-- 020618 EMIG Updates for NFS threadsafety, V5R3 -->
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<!-- 020514 JET This file has undergone html cleanup -->
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<!-- 020718 MFENLON: updated for QFileSvr.400 threadsafety, V5R3 -->
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<!-- 030217 JTROUS : Add words about offset not updated -->
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<!-- 040721 JTROUS: fix OS/400 reference, no change flag, V5R4 -->
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<!-- 050328 JTROUS: fix enums, no change flag, V5R4 -->
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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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<!--End Header Records --><!-- 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>ftruncate()--Truncate File</h2>
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<div class="box" style="width: 70%;">
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<br>
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Syntax<br>
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<pre>
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#include <unistd.h>
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int ftruncate(int <em>file_descriptor</em>, off_t <em>length</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="#HDRFTRNUSG">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>ftruncate()</strong> function truncates the file indicated by
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the open file descriptor <em>file_descriptor</em> to the indicated <em>
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length</em>. <em>file_descriptor</em> must be a "regular file" that is open for
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writing. (A regular file is a stream file that can support positioning the file
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offset.) If the file size exceeds <em>length</em>, any extra data is discarded.
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If the file size is smaller than <em>length</em>, the file is extended and
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filled with binary zeros to the indicated length. (In the QSYS.LIB and
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independent ASP QSYS.LIB file systems blanks are used instead of zeros to pad
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records after a member is extended.)
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The <strong>ftruncate()</strong> function does not modify the current file offset
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for any open file descriptions associated with the file.
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</p>
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<p>If <strong>ftruncate()</strong> completes successfully, it marks the change
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time and modification times of the file. Also, the S_ISUID (set-user-ID) and
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S_ISGID (set-group-ID) bits of the file mode are cleared. If <strong>
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ftruncate()</strong> is not successful, the file is unchanged.</p>
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<p>If <strong>ftruncate()</strong> is used to truncate the file to 0 bytes and
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the file has a digital signature, the signature is deleted.</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>file_descriptor</em></strong></dt>
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<dd>(Input) The file descriptor of the file.<br>
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<br>
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</dd>
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<dt><strong><em>length</em></strong></dt>
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<dd>(Input) The desired size of the file in bytes.</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. Authorization is verified during <strong>
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open()</strong> or <strong>creat()</strong>.</p>
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<br>
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<h3>Return Value</h3>
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<dl>
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<dt><em>0</em></dt>
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<dd><strong>ftruncate()</strong> was successful.</dd>
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<dt><em>-1</em></dt>
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<dd><strong>ftruncate()</strong> was not successful. The <em>errno</em> global
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variable is set to indicate the error. If the file descriptor is not open for
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writing, <strong>ftruncate</strong> returns a [EBADF] error. If the file
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descriptor is a valid descriptor open for writing but is not a descriptor for a
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regular file, <strong>ftruncate()</strong> returns a [EINVAL] error.</dd>
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</dl>
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<br>
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<h3><a name="HDRFTRNERR">Error Conditions</a></h3>
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<p>If <strong>ftruncate()</strong> is not successful, <em>errno</em> usually
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indicates one of the following errors. Under some conditions, <em>errno</em>
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could indicate an error other than those listed here.</p>
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<table cellpadding="5">
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<!-- cols="25 75" -->
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<tr>
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<th align="left" valign="bottom">Error condition</th>
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<th align="left" valign="bottom">Additional information</th>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EACCES">EACCES</a>]</em></td>
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<td align="left" valign="top">
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<p>If you are accessing a remote file through the Network File System, update
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operations to file permissions at the server are not reflected at the client
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until updates to data that is stored locally by the Network File System take
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place. (Several options on the Add Mounted File System (ADDMFS) command
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determine the time between refresh operations of local data.) Access to a
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remote file may also fail due to different mappings of user IDs (UID) or group
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IDs (GID) on the local and remote systems.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EAGAIN">EAGAIN</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EBADF">EBADF</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EBADFID">EBADFID</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EBADNAME">EBADNAME</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EBUSY">EBUSY</a>]</em></td>
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<td align="left" valign="top">
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<p>The QSYS.LIB or independent ASP QSYS.LIB file system cannot get exclusive
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access to the member to clear truncated data.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ECONVERT">ECONVERT</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EDAMAGE">EDAMAGE</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EFBIG">EFBIG</a>]</em></td>
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<td align="left" valign="top">
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<p>The size of the object would exceed the system allowed maximum size or the
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process soft file size limit.
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The file is a regular file and <em>length</em> is greater than 2GB minus 1
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byte.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EINTR">EINTR</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EINVAL">EINVAL</a>]</em></td>
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<td align="left" valign="top">
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<p>For example, <em>file_descriptor</em>
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does not refer to a regular file open for writing, or the
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specified length is not correct.</p>
|
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EIO">EIO</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EISDIR">EISDIR</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EJRNDAMAGE">EJRNDAMAGE</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EJRNENTTOOLONG">EJRNENTTOOLONG</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EJRNINACTIVE">EJRNINACTIVE</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#EJRNRCVSPC">EJRNRCVSPC</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr><tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ELOCKED">ELOCKED</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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||
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<td align="left" valign="top">
|
||
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<em>[<a href="unix14.htm#ENAMETOOLONG">ENAMETOOLONG</a>]</em></td>
|
||
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<td align="left" valign="top">
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</td>
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</tr>
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||
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<tr>
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||
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<td align="left" valign="top">
|
||
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<em>[<a href="unix14.htm#ENEWJRN">ENEWJRN</a>]</em></td>
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||
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<td align="left" valign="top">
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||
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</td>
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</tr>
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<tr>
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||
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<td align="left" valign="top">
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||
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<em>[<a href="unix14.htm#ENEWJRNRCV">ENEWJRNRCV</a>]</em></td>
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||
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<td align="left" valign="top">
|
||
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||
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</td>
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||
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</tr>
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||
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<tr>
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||
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<td align="left" valign="top">
|
||
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<em>[<a href="unix14.htm#ENOENT">ENOENT</a>]</em></td>
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||
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|
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<td align="left" valign="top">
|
||
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</td>
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</tr>
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||
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<tr>
|
||
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<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENOMEM">ENOMEM</a>]</em></td>
|
||
|
|
|
||
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<td align="left" valign="top">
|
||
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||
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENOSPC">ENOSPC</a>]</em></td>
|
||
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENOSYS">ENOSYS</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
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<tr>
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<td align="left" valign="top">
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<em>[<a href="unix14.htm#ENOSYSRSC">ENOSYSRSC</a>]</em></td>
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<td align="left" valign="top">
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</td>
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</tr>
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENOTAVAIL">ENOTAVAIL</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENOTDIR">ENOTDIR</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENOTSAFE">ENOTSAFE</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENOTSUP">ENOTSUP</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#EROOBJ">EROOBJ</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ESTALE">ESTALE</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<p>If you are accessing a remote file through the Network File System, the file
|
||
|
|
may have been deleted at the server.</p>
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#EUNKNOWN">EUNKNOWN</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<p>If interaction with a file server is required to access the object, <em>
|
||
|
|
errno</em> could also indicate one of the following errors:</p>
|
||
|
|
|
||
|
|
<table cellpadding="5">
|
||
|
|
<!-- cols="25 75" -->
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<th align="left" valign="bottom">Error condition</th>
|
||
|
|
<th align="left" valign="bottom">Additional information</th>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#EADDRNOTAVAIL">EADDRNOTAVAIL</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ECONNABORTED">ECONNABORTED</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ECONNREFUSED">ECONNREFUSED</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ECONNRESET">ECONNRESET</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#EHOSTDOWN">EHOSTDOWN</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#EHOSTUNREACH">EHOSTUNREACH</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENETDOWN">ENETDOWN</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENETRESET">ENETRESET</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ENETUNREACH">ENETUNREACH</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#ETIMEDOUT">ETIMEDOUT</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td align="left" valign="top">
|
||
|
|
<em>[<a href="unix14.htm#EUNATCH">EUNATCH</a>]</em></td>
|
||
|
|
|
||
|
|
<td align="left" valign="top">
|
||
|
|
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<br>
|
||
|
|
<h3>Error Messages</h3>
|
||
|
|
|
||
|
|
<p>The following messages may be sent from this function:</p>
|
||
|
|
|
||
|
|
<table width="100%">
|
||
|
|
<tr>
|
||
|
|
<td width="15%" valign="top">CPE3418 E</td>
|
||
|
|
<td width="85%" valign="top">Possible APAR condition or hardware failure.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td valign="top">CPFA0D4 E</td>
|
||
|
|
<td valign="top">File system error occurred. Error number &1.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td valign="top">CPF3CF2 E</td>
|
||
|
|
<td valign="top">Error(s) occurred during running of &1 API.</td>
|
||
|
|
</tr>
|
||
|
|
|
||
|
|
<tr>
|
||
|
|
<td valign="top">CPF9872 E</td>
|
||
|
|
<td valign="top">Program or service program &1 in library &2 ended.
|
||
|
|
Reason code &3.</td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<h3><a name="HDRFTRNUSG">Usage Notes</a></h3>
|
||
|
|
|
||
|
|
<ol type="1">
|
||
|
|
<li>This function will fail with error code [ENOTSAFE] when all the following
|
||
|
|
conditions are true:<br>
|
||
|
|
<br>
|
||
|
|
<ul>
|
||
|
|
<li>Where multiple threads exist in the job.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>The object on which this function is operating resides in a file system
|
||
|
|
that is not threadsafe. Only the following file systems are threadsafe for this
|
||
|
|
function:<br>
|
||
|
|
<br>
|
||
|
|
<ul>
|
||
|
|
<li>"Root" (/)</li>
|
||
|
|
|
||
|
|
<li>QOpenSys</li>
|
||
|
|
|
||
|
|
<li>User-defined</li>
|
||
|
|
|
||
|
|
<li>QNTC</li>
|
||
|
|
|
||
|
|
<li>QSYS.LIB</li>
|
||
|
|
|
||
|
|
<li>Independent ASP QSYS.LIB</li>
|
||
|
|
|
||
|
|
<li>QOPT</li>
|
||
|
|
|
||
|
|
<li>Network File System</li>
|
||
|
|
|
||
|
|
|
||
|
|
<li>QFileSvr.400</li>
|
||
|
|
|
||
|
|
</ul>
|
||
|
|
</li>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>When you develop in C-based languages and this function is compiled with
|
||
|
|
_LARGE_FILES defined, it will be mapped to <strong>ftruncate64()</strong>. Note
|
||
|
|
also that the type of the <em>length</em> parameter will be remapped from off_t
|
||
|
|
to off64_t.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>For the Network File System, this function will fail with the [EFBIG] or
|
||
|
|
the [EIO] error if the length specified is greater than the largest file size
|
||
|
|
supported by the server.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>Using this function on a character special file results in a return value
|
||
|
|
of -1 and the errno global value set to EINVAL.<br>
|
||
|
|
<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>QSYS.LIB and Independent ASP QSYS.LIB File System Differences
|
||
|
|
|
||
|
|
<p>This function is not supported for save files and will fail with error code
|
||
|
|
[ENOTSUP].</p>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li>If the request exceeds the process soft file size limit, signal SIFXFSZ is
|
||
|
|
issued.</li>
|
||
|
|
</ol>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<h3>Related Information</h3>
|
||
|
|
|
||
|
|
<ul>
|
||
|
|
<li>The <<strong>unistd.h</strong>> file (see <a href="unix13.htm">Header
|
||
|
|
Files for UNIX-Type Functions</a>)<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="ftrunc64.htm">ftruncate64()</a>--Truncate File (Large File
|
||
|
|
Enabled)<br>
|
||
|
|
</li>
|
||
|
|
|
||
|
|
<li><a href="open.htm">open()</a>--Open File</li>
|
||
|
|
</ul>
|
||
|
|
|
||
|
|
<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 uses <strong>ftruncate()</strong>:</p>
|
||
|
|
|
||
|
|
<pre>
|
||
|
|
#include <unistd.h>
|
||
|
|
#include <sys/types.h>
|
||
|
|
#include <sys/stat.h>
|
||
|
|
#include <fcntl.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
|
||
|
|
#define string_len 1000
|
||
|
|
|
||
|
|
main() {
|
||
|
|
char *mega_string;
|
||
|
|
int file_descriptor;
|
||
|
|
int ret;
|
||
|
|
char fn[]="write.file";
|
||
|
|
struct stat st;
|
||
|
|
|
||
|
|
if ((mega_string = (char*) malloc(string_len)) == NULL)
|
||
|
|
perror("malloc() error");
|
||
|
|
else if ((file_descriptor = creat(fn, S_IWUSR)) < 0)
|
||
|
|
perror("creat() error");
|
||
|
|
else {
|
||
|
|
memset(mega_string, '0', string_len);
|
||
|
|
if ((ret = write(file_descriptor, mega_string, string_len)) == -1)
|
||
|
|
perror("write() error");
|
||
|
|
else {
|
||
|
|
printf("write() wrote %d bytes\n", ret);
|
||
|
|
fstat(file_descriptor, &st);
|
||
|
|
printf("the file has %ld bytes\n", (long) st.st_size);
|
||
|
|
if (ftruncate(file_descriptor, 1) != 0)
|
||
|
|
perror("ftruncate() error");
|
||
|
|
else {
|
||
|
|
fstat(file_descriptor, &st);
|
||
|
|
printf("the file has %ld bytes\n", (long) st.st_size);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
close(file_descriptor);
|
||
|
|
unlink(fn);
|
||
|
|
}
|
||
|
|
free(mega_string);
|
||
|
|
}
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<p><strong>Output:</strong></p>
|
||
|
|
|
||
|
|
<pre>
|
||
|
|
write() wrote 1000 bytes
|
||
|
|
the file has 1000 bytes
|
||
|
|
the file has 1 bytes
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<br>
|
||
|
|
<hr>
|
||
|
|
API introduced: V3R1
|
||
|
|
|
||
|
|
<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>
|
||
|
|
|