ibm-information-center/dist/eclipse/plugins/i5OS.ic.apis_5.4.0.1/umask.htm

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<title>umask()--Set Authorization Mask for Job</title>
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<h2>umask()--Set Authorization Mask for Job</h2>
<div class="box" style="width: 50%;">
<br>
&nbsp;&nbsp;Syntax<br>
<pre>
#include &lt;sys/stat.h&gt;
mode_t umask(mode_t <em>cmask</em>);
</pre>
&nbsp;&nbsp;Service Program Name: QP0LLIB1<br>
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&nbsp;&nbsp;Default Public Authority: *USE<br>
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&nbsp;&nbsp;Threadsafe: Yes<br>
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<p>Every job has a file creation mask. When a job starts, the value of the file
creation mask is zero. The value of zero means that no permissions are masked
when a file or directory is created in the job. The <strong>umask()</strong>
function changes the value of the file creation mask for the current job to the
value specified in <em>cmask</em>.</p>
<p>The <em>cmask</em> argument controls file permission bits that should be set
whenever the job creates a file. File permission bits set to <samp>1</samp> in
the file creation mask are set to <samp>0</samp> in the file permission bits of
files that are created by the job.</p>
<p>For example, if a call to <strong>open()</strong> specifies a <em>mode</em>
argument with file permission bits, the file creation mask of the job affects
the <em>mode</em> argument; bits that are <samp>1</samp> in the mask are set to
<samp>0</samp> in the <em>mode</em> argument and, therefore, in the mode of the
created file.</p>
<p>Only the file permission bits of <em>cmask</em> are used. The other bits in
<em>cmask</em> must be cleared (not set), or the CPFA0D3 message is issued.</p>
<br>
<h3>Parameters</h3>
<dl>
<dt><strong><em>cmask</em></strong></dt>
<dd>(Input) The new value of the file creation mask. For a description of the
permission bits, see <a href="chmod.htm">chmod()--Change File
Authorizations</a>.</dd>
</dl>
<br>
<h3>Authorities</h3>
<p>No authorization is required.</p>
<br>
<h3>Return Value</h3>
<p><strong>umask()</strong> returns the previous value of the file creation
mask. It does not return -1 or set the <em>errno</em> global variable.</p>
<br>
<h3>Error Conditions</h3>
<p>None.</p>
<br>
<h3>Error Messages</h3>
<p>The following messages may be sent from this function:</p>
<table width="100%" cellpadding="5">
<tr>
<th align="left" valign="top">Message ID</th>
<th align="left" valign="top">Error Message Text</th>
</tr>
<tr>
<td width="15%" valign="top">CPE3418 E</td>
<td width="85%" valign="top">Possible APAR condition or hardware failure.</td>
</tr>
<tr>
<td width="15%" valign="top">CPFA0D3 E</td>
<td width="85%" valign="top">cmask parameter is not valid.</td>
</tr>
<tr>
<td valign="top">CPFA0D4 E</td>
<td valign="top">File system error occurred. Error number &amp;1.</td>
</tr>
<tr>
<td valign="top">CPF3CF2 E</td>
<td valign="top">Error(s) occurred during running of &amp;1 API.</td>
</tr>
<tr>
<td valign="top">CPF9872 E</td>
<td valign="top">Program or service program &amp;1 in library &amp;2 ended.
Reason code &amp;3.</td>
</tr>
</table>
<br>
<br>
<h3><a name="USAGE_NOTES">Usage Notes</a></h3>
<ol type="1">
<li>QNTC File System Differences
<p><strong>umask()</strong> does not update the file creation mask for QNTC.
The settings specified in <em>cmask</em> are ignored.</p>
</li>
</ol>
<br>
<h3>Related Information</h3>
<ul>
<li>The &lt;<strong>sys/stat.h</strong>&gt; file (see <a href="unix13.htm">
Header Files for UNIX-Type Functions</a>)<br>
</li>
<li><a href="chmod.htm">chmod()</a>--Change File Authorizations<br>
</li>
<li><a href="creat.htm">creat()</a>--Create or Rewrite File<br>
</li>
<li><a href="mkdir.htm">mkdir()</a>--Make Directory<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>umask()</strong>:</p>
<pre>
#include &lt;stdio.h&gt;
#include &lt;fcntl.h&gt;
#include &lt;sys/stat.h&gt;
main()
{
int file_descriptor;
struct stat info;
umask(S_IRWXG);
if ((file_descriptor =
creat("umask.file", S_IRWXU|S_IRWXG)) &lt; 0)
perror("creat() error");
else {
fstat(file_descriptor, &amp;info);
printf("permissions are: %08x\n", info.st_mode);
close(file_descriptor);
unlink("umask.file");
}
}
</pre>
<p><strong>Output:</strong></p>
<pre>
permissions are: 000081c0
</pre>
<br>
<hr>
API introduced: V3R1
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