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

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<title>sigdelset()--Delete Signal from Signal Set</title>
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<h2>sigdelset()--Delete Signal from Signal Set</h2>
<div class="box" style="width: 60%;">
<br>
&nbsp;&nbsp;Syntax<br>
<pre>
#include &lt;signal.h&gt;
int sigdelset( sigset_t <em>*set</em>, int <em>signo</em> );
</pre>
<br>
&nbsp;&nbsp;Service Program Name: QPOSSRV1<br>
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<br>
&nbsp;&nbsp;Default Public Authority: *USE<br>
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&nbsp;&nbsp;Threadsafe: Yes<br>
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<p>The <strong>sigdelset()</strong> function is part of a family of functions
that manipulate signal sets. <strong>Signal sets</strong> are data objects that
let a thread keep track of groups of signals. For example, a thread might
create a signal set to record which signals it is blocking, and another signal
set to record which signals are pending. Signal sets are used to manipulate
groups of signals used by other functions (such as <strong>
sigprocmask()</strong>) or to examine signal sets returned by other functions
(such as <strong>sigpending()</strong>).</p>
<p><strong>sigdelset()</strong> removes the specified <em>signo</em> from the
list of signals recorded in <em>set</em>.</p>
<br>
<!-- Please NOTE: DO NOT DELETE THIS SECTION if this API has no authorities and locks. -->
<!-- Instead, use the commented out coding below to indicate NONE. -->
<h3>Authorities and Locks</h3>
<!-- Use this if there are no authorities and locks. -->
<p>None.</p>
<br>
<h3>Parameters</h3>
<dl>
<dt><strong><em>*set</em></strong></dt>
<dd>(Input) A pointer to a signal set.<br>
<br>
</dd>
<dt><strong><em>signo</em></strong></dt>
<dd>(Input) A signal from the list defined in <a href="sigactn.htm#TBLSIGTBL1">
Control Signals Table</a>.</dd>
</dl>
<br>
<h3>Return Value</h3>
<table cellpadding="5">
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<tr>
<td align="left" valign="top"><em>0</em></td>
<td align="left" valign="top"><strong>sigdelset()</strong> successfully deleted
from the signal set.</td>
</tr>
<tr>
<td align="left" valign="top"><em>-1</em></td>
<td align="left" valign="top"><strong>sigdelset()</strong> was not successful.
The <em>errno</em> variable is set to indicate the error.</td>
</tr>
</table>
<br>
<br>
<h3>Error Conditions</h3>
<p>If <strong>sigdelset()</strong> is not successful, <em>errno</em> usually
indicates the following error. Under some conditions, <em>errno</em> could
indicate an error other than that listed here.</p>
<dl>
<dt><em>[EINVAL]</em></dt>
<dd>
<p>The value specified for the argument is not correct.</p>
<p>A function was passed incorrect argument values, or an operation was
attempted on an object and the operation specified is not supported for that
type of object.</p>
<p>An argument value is not valid, out of range, or NULL.</p>
<p>The value of <em>signo</em> is not within the range of valid signals or
specifies a signal that is not supported.</p>
</dd>
</dl>
<br>
<h3>Related Information</h3>
<ul>
<li>The &lt;<strong>signal.h</strong>&gt; file (see <a href="unix13.htm">Header
Files for UNIX-Type Functions</a>)<br>
<br>
</li>
<li><a href="sigactn.htm">sigaction()</a>--Examine and Change Signal Action<br>
<br>
</li>
<li><a href="sigaset.htm">sigaddset()</a>--Add Signal to Signal Set<br>
<br>
</li>
<li><a href="sigeset.htm">sigemptyset()</a>--Initialize and Empty Signal
Set<br>
<br>
</li>
<li><a href="sigfset.htm">sigfillset()</a>--Initialize and Fill Signal Set<br>
<br>
</li>
<li><a href="sigismbr.htm">sigismember()</a>--Test for Signal in Signal Set<br>
<br>
</li>
<li><a href="sigpmsk.htm">sigprocmask()</a>--Examine and Change Blocked
Signals<br>
<br>
</li>
<li><a href="sigpend.htm">sigpending()</a>--Examine Pending Signals<br>
<br>
</li>
<li><a href="sigsusp.htm">sigsuspend()</a>--Wait for Signal<br>
<br>
</li>
<li><a href="sigtwait.htm">sigtimedwait()</a>--Synchronously Accept a Signal
for Interval of Time<br>
<br>
</li>
<li><a href="sigwait.htm">sigwait()</a>--Synchronously Accept a Signal<br>
<br>
</li>
<li><a href="sigwaiti.htm">sigwaitinfo()</a>--Synchronously Accept a Signal and
Signal Data</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 deletes a signal from a set of signals:</p>
<pre>
#include &lt;stdio.h&gt;
#include &lt;unistd.h&gt;
#include &lt;signal.h&gt;
void catcher( int sig ) {
printf( "catcher() has gained control\n" );
}
int main( int argc, char *argv[] ) {
struct sigaction sigact;
sigset_t sigset;
sigemptyset( &amp;sigact.sa_mask );
sigact.sa_flags = 0;
sigact.sa_handler = catcher;
sigaction( SIGUSR1, &amp;sigact, NULL );
/*
* Blocking all signals prevents the blockable
* signals from being delivered until they are
* unblocked, so the catcher will not gain
* control.
*/
sigfillset( &amp;sigset );
sigaddset( &amp;sigset, SIGUSR1 );
sigprocmask( SIG_SETMASK, &amp;,sigset, NULL );
printf( "before kill()\n" );
kill( getpid(), SIGUSR1 );
printf( "before unblocking SIGUSR1\n" );
sigdelset( &amp;sigset, SIGUSR1 );
sigprocmask( SIG_SETMASK, &amp;sigset, NULL );
printf( "after unblocking SIGUSR1\n" );
return( 0 );
}
</pre>
<br>
<h3>Output:</h3>
<pre>
before kill()
before unblocking SIGUSR1
catcher() has gained control
after unblocking SIGUSR1
</pre>
<br>
<hr>
API introduced: V3R6
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