man-pages/man3/pthread_sigmask.3.html
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<H1>PTHREAD_SIGMASK</H1>
Section: Linux Programmer's Manual (3)<BR>Updated: 2019-03-06<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
pthread_sigmask - examine and change mask of blocked signals
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<PRE>
<B>#include &lt;<A HREF="file:///usr/include/signal.h">signal.h</A>&gt;</B>
<B>int pthread_sigmask(int </B><I>how</I><B>, const sigset_t *</B><I>set</I><B>, sigset_t *</B><I>oldset</I><B>);</B>
</PRE>
<P>
Compile and link with <I>-pthread</I>.
<P>
Feature Test Macro Requirements for glibc (see
<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
<P>
<B>pthread_sigmask</B>():
<DL COMPACT><DT id="1"><DD>
_POSIX_C_SOURCE&nbsp;&gt;=&nbsp;199506L || _XOPEN_SOURCE&nbsp;&gt;=&nbsp;500
</DL>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
The
<B>pthread_sigmask</B>()
function is just like
<B><A HREF="/cgi-bin/man/man2html?2+sigprocmask">sigprocmask</A></B>(2),
with the difference that its use in multithreaded programs
is explicitly specified by POSIX.1.
Other differences are noted in this page.
<P>
For a description of the arguments and operation of this function, see
<B><A HREF="/cgi-bin/man/man2html?2+sigprocmask">sigprocmask</A></B>(2).
<A NAME="lbAE">&nbsp;</A>
<H2>RETURN VALUE</H2>
On success,
<B>pthread_sigmask</B>()
returns 0;
on error, it returns an error number.
<A NAME="lbAF">&nbsp;</A>
<H2>ERRORS</H2>
See
<B><A HREF="/cgi-bin/man/man2html?2+sigprocmask">sigprocmask</A></B>(2).
<A NAME="lbAG">&nbsp;</A>
<H2>ATTRIBUTES</H2>
For an explanation of the terms used in this section, see
<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
<TABLE BORDER>
<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
<TR VALIGN=top><TD>
<B>pthread_sigmask</B>()
</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
</TABLE>
<A NAME="lbAH">&nbsp;</A>
<H2>CONFORMING TO</H2>
POSIX.1-2001, POSIX.1-2008.
<A NAME="lbAI">&nbsp;</A>
<H2>NOTES</H2>
A new thread inherits a copy of its creator's signal mask.
<P>
The glibc
<B>pthread_sigmask</B>()
function silently ignores attempts to block the two real-time signals that
are used internally by the NPTL threading implementation.
See
<B><A HREF="/cgi-bin/man/man2html?7+nptl">nptl</A></B>(7)
for details.
<A NAME="lbAJ">&nbsp;</A>
<H2>EXAMPLE</H2>
The program below blocks some signals in the main thread,
and then creates a dedicated thread to fetch those signals via
<B><A HREF="/cgi-bin/man/man2html?3+sigwait">sigwait</A></B>(3).
The following shell session demonstrates its use:
<P>
$<B> ./a.out &amp;</B>
[1] 5423
$<B> kill -QUIT %1</B>
Signal handling thread got signal 3
$<B> kill -USR1 %1</B>
Signal handling thread got signal 10
$<B> kill -TERM %1</B>
[1]+ Terminated ./a.out
<A NAME="lbAK">&nbsp;</A>
<H3>Program source</H3>
#include &lt;<A HREF="file:///usr/include/pthread.h">pthread.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/stdio.h">stdio.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/stdlib.h">stdlib.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/unistd.h">unistd.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/signal.h">signal.h</A>&gt;
#include &lt;<A HREF="file:///usr/include/errno.h">errno.h</A>&gt;
<P>
/* Simple error handling functions */
<P>
#define handle_error_en(en, msg) \
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;do&nbsp;{&nbsp;errno&nbsp;=&nbsp;en;&nbsp;perror(msg);&nbsp;exit(EXIT_FAILURE);&nbsp;}&nbsp;while&nbsp;(0)
<P>
static void *
sig_thread(void *arg)
{
<BR>&nbsp;&nbsp;&nbsp;&nbsp;sigset_t&nbsp;*set&nbsp;=&nbsp;arg;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;int&nbsp;s,&nbsp;sig;
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;for&nbsp;(;;)&nbsp;{
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;sigwait(set,&nbsp;&amp;sig);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;handle_error_en(s,&nbsp;&quot;sigwait&quot;);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf(&quot;Signal&nbsp;handling&nbsp;thread&nbsp;got&nbsp;signal&nbsp;%d\n&quot;,&nbsp;sig);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;}
}
<P>
int
main(int argc, char *argv[])
{
<BR>&nbsp;&nbsp;&nbsp;&nbsp;pthread_t&nbsp;thread;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;sigset_t&nbsp;set;
<BR>&nbsp;&nbsp;&nbsp;&nbsp;int&nbsp;s;
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;Block&nbsp;SIGQUIT&nbsp;and&nbsp;SIGUSR1;&nbsp;other&nbsp;threads&nbsp;created&nbsp;by&nbsp;main()
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;will&nbsp;inherit&nbsp;a&nbsp;copy&nbsp;of&nbsp;the&nbsp;signal&nbsp;mask.&nbsp;*/
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;sigemptyset(&amp;set);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;sigaddset(&amp;set,&nbsp;SIGQUIT);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;sigaddset(&amp;set,&nbsp;SIGUSR1);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;pthread_sigmask(SIG_BLOCK,&nbsp;&amp;set,&nbsp;NULL);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;handle_error_en(s,&nbsp;&quot;pthread_sigmask&quot;);
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;=&nbsp;pthread_create(&amp;thread,&nbsp;NULL,&nbsp;&amp;sig_thread,&nbsp;(void&nbsp;*)&nbsp;&amp;set);
<BR>&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(s&nbsp;!=&nbsp;0)
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;handle_error_en(s,&nbsp;&quot;pthread_create&quot;);
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;Main&nbsp;thread&nbsp;carries&nbsp;on&nbsp;to&nbsp;create&nbsp;other&nbsp;threads&nbsp;and/or&nbsp;do
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;other&nbsp;work&nbsp;*/
<P>
<BR>&nbsp;&nbsp;&nbsp;&nbsp;pause();&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;Dummy&nbsp;pause&nbsp;so&nbsp;we&nbsp;can&nbsp;test&nbsp;program&nbsp;*/
}
<A NAME="lbAL">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?2+sigaction">sigaction</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+sigpending">sigpending</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?2+sigprocmask">sigprocmask</A></B>(2),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_create">pthread_create</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+pthread_kill">pthread_kill</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+sigsetops">sigsetops</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?7+pthreads">pthreads</A></B>(7),
<B><A HREF="/cgi-bin/man/man2html?7+signal">signal</A></B>(7)
<A NAME="lbAM">&nbsp;</A>
<H2>COLOPHON</H2>
This page is part of release 5.05 of the Linux
<I>man-pages</I>
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="2"><A HREF="#lbAB">NAME</A><DD>
<DT id="3"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="4"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="5"><A HREF="#lbAE">RETURN VALUE</A><DD>
<DT id="6"><A HREF="#lbAF">ERRORS</A><DD>
<DT id="7"><A HREF="#lbAG">ATTRIBUTES</A><DD>
<DT id="8"><A HREF="#lbAH">CONFORMING TO</A><DD>
<DT id="9"><A HREF="#lbAI">NOTES</A><DD>
<DT id="10"><A HREF="#lbAJ">EXAMPLE</A><DD>
<DL>
<DT id="11"><A HREF="#lbAK">Program source</A><DD>
</DL>
<DT id="12"><A HREF="#lbAL">SEE ALSO</A><DD>
<DT id="13"><A HREF="#lbAM">COLOPHON</A><DD>
</DL>
<HR>
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Time: 00:05:53 GMT, March 31, 2021
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