| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> | |
| <HTML> | |
| <HEAD> | |
| <META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=utf-8"> | |
| <TITLE>PTHREAD_SIGNAL(3) manual page</TITLE> | |
| <META NAME="GENERATOR" CONTENT="OpenOffice.org 1.1.3 (Linux)"> | |
| <META NAME="CREATED" CONTENT="20050504;18500100"> | |
| <META NAME="CHANGED" CONTENT="20050504;23005800"> | |
| <!-- manual page source format generated by PolyglotMan v3.2, --> | |
| <!-- available at http://polyglotman.sourceforge.net/ --> | |
| </HEAD> | |
| <BODY LANG="en-GB" BGCOLOR="#ffffff" DIR="LTR"> | |
| <H4>POSIX Threads for Windows – REFERENCE - <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A></H4> | |
| <P><A HREF="index.html">Reference Index</A></P> | |
| <P><A HREF="#toc">Table of Contents</A></P> | |
| <H2><A HREF="#toc0" NAME="sect0">Name</A></H2> | |
| <P>pthread_sigmask, pthread_kill, sigwait - handling of signals in | |
| threads | |
| </P> | |
| <H2><A HREF="#toc1" NAME="sect1">Synopsis</A></H2> | |
| <P><B>#include <pthread.h></B> <BR><B>#include <signal.h></B> | |
| </P> | |
| <P><B>int pthread_sigmask(int </B><I>how</I><B>, const sigset_t | |
| *</B><I>newmask</I><B>, sigset_t *</B><I>oldmask</I><B>);</B> | |
| </P> | |
| <P><B>int pthread_kill(pthread_t </B><I>thread</I><B>, int </B><I>signo</I><B>);</B> | |
| </P> | |
| <P><B>int sigwait(const sigset_t *</B>set, <B>int</B> *sig);</P> | |
| <H2><A HREF="#toc2" NAME="sect2">Description</A></H2> | |
| <P><B>pthread_sigmask</B> changes the signal mask for the calling | |
| thread as described by the <I>how</I> and <I>newmask</I> arguments. | |
| If <I>oldmask</I> is not <B>NULL</B>, the previous signal mask is | |
| stored in the location pointed to by <I>oldmask</I>. <B>Pthreads-w32</B> | |
| implements this function but no other function uses the signal mask | |
| yet.</P> | |
| <P>The meaning of the <I>how</I> and <I>newmask</I> arguments is the | |
| same as for <B><SPAN STYLE="font-style: normal">sigprocmask</SPAN></B>(2). | |
| If <I>how</I> is <B>SIG_SETMASK</B>, the signal mask is set to | |
| <I>newmask</I>. If <I>how</I> is <B>SIG_BLOCK</B>, the signals | |
| specified to <I>newmask</I> are added to the current signal mask. If | |
| <I>how</I> is <B>SIG_UNBLOCK</B>, the signals specified to <I>newmask</I> | |
| are removed from the current signal mask. | |
| </P> | |
| <P>Recall that signal masks are set on a per-thread basis, but signal | |
| actions and signal handlers, as set with <B>sigaction</B>(2), are | |
| shared between all threads. | |
| </P> | |
| <P><B>pthread_kill</B> send signal number <I>signo</I> to the thread | |
| <I>thread</I>. <B>Pthreads-w32</B> only supports signal number 0, | |
| which does not send any signal but causes <B>pthread_kill</B> to | |
| return an error if <I>thread</I> is not valid.</P> | |
| <P><B>sigwait</B> suspends the calling thread until one of the | |
| signals in <I>set</I> is delivered to the calling thread. It then | |
| stores the number of the signal received in the location pointed to | |
| by <I>sig</I> and returns. The signals in <I>set</I> must be blocked | |
| and not ignored on entrance to <B>sigwait</B>. If the delivered | |
| signal has a signal handler function attached, that function is <I>not</I> | |
| called. <B>Pthreads-w32</B> implements this function as a | |
| cancellation point only - it does not wait for any signals and does | |
| not change the location pointed to by <I>sig</I>.</P> | |
| <H2><A HREF="#toc3" NAME="sect3">Cancellation</A></H2> | |
| <P><B>sigwait</B> is a cancellation point. | |
| </P> | |
| <H2><A HREF="#toc4" NAME="sect4">Return Value</A></H2> | |
| <P>On success, 0 is returned. On failure, a non-zero error code is | |
| returned. | |
| </P> | |
| <H2><A HREF="#toc5" NAME="sect5">Errors</A></H2> | |
| <P>The <B>pthread_sigmask</B> function returns the following error | |
| codes on error: | |
| </P> | |
| <DL> | |
| <DL> | |
| <DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm"><B>EINVAL</B> | |
| </DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm"> | |
| <I>how</I> is not one of <B>SIG_SETMASK</B>, <B>SIG_BLOCK</B>, or | |
| <B>SIG_UNBLOCK</B> | |
| </DD></DL> | |
| </DL> | |
| <P> | |
| The <B>pthread_kill</B> function returns the following error codes on | |
| error: | |
| </P> | |
| <DL> | |
| <DL> | |
| <DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm"><B>EINVAL</B> | |
| </DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm"> | |
| <I>signo</I> is not a valid signal number or is unsupported.</DD><DT STYLE="margin-right: 1cm; margin-bottom: 0.5cm"> | |
| <B>ESRCH</B> | |
| </DT><DD STYLE="margin-right: 1cm; margin-bottom: 0.5cm"> | |
| the thread <I>thread</I> does not exist (e.g. it has already | |
| terminated) | |
| </DD></DL> | |
| </DL> | |
| <P> | |
| The <B>sigwait</B> function never returns an error. | |
| </P> | |
| <H2><A HREF="#toc6" NAME="sect6">Author</A></H2> | |
| <P>Xavier Leroy <Xavier.Leroy@inria.fr> | |
| </P> | |
| <P>Modified by Ross Johnson for use with <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A>.</P> | |
| <H2><A HREF="#toc7" NAME="sect7">See Also</A></H2> | |
| <P> | |
| </P> | |
| <H2><A HREF="#toc8" NAME="sect8">Notes</A></H2> | |
| <P>In any implementation, for <B>sigwait</B> to work reliably, the | |
| signals being waited for must be blocked in all threads, not only in | |
| the calling thread, since otherwise the POSIX semantics for signal | |
| delivery do not guarantee that it’s the thread doing the <B>sigwait</B> | |
| that will receive the signal. The best way to achieve this is to | |
| block those signals before any threads are created, and never unblock | |
| them in the program other than by calling <B>sigwait</B>. This works | |
| because all threads inherit their initial sigmask from their creating | |
| thread.</P> | |
| <H2><A HREF="#toc9" NAME="sect9">Bugs</A></H2> | |
| <P><B>Pthreads-w32</B> does not implement signals yet and so these | |
| routines have almost no use except to prevent the compiler or linker | |
| from complaining. <B>pthread_kill</B> is useful in determining if the | |
| thread is a valid thread, but since many threads implementations | |
| reuse thread IDs, the valid thread may no longer be the thread you | |
| think it is, and so this method of determining thread validity is not | |
| portable, and very risky. <B>Pthreads-w32</B> from version 1.0.0 | |
| onwards implements pseudo-unique thread IDs, so applications that use | |
| this technique (but really shouldn't) have some protection.</P> | |
| <HR> | |
| <P><A NAME="toc"></A><B>Table of Contents</B></P> | |
| <UL> | |
| <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect0" NAME="toc0">Name</A> | |
| </P> | |
| <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect1" NAME="toc1">Synopsis</A> | |
| </P> | |
| <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect2" NAME="toc2">Description</A> | |
| </P> | |
| <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect3" NAME="toc3">Cancellation</A> | |
| </P> | |
| <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect4" NAME="toc4">Return | |
| Value</A> | |
| </P> | |
| <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect5" NAME="toc5">Errors</A> | |
| </P> | |
| <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect6" NAME="toc6">Author</A> | |
| </P> | |
| <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect7" NAME="toc7">See | |
| Also</A> | |
| </P> | |
| <LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect8" NAME="toc8">Notes</A> | |
| </P> | |
| <LI><P><A HREF="#sect9" NAME="toc9">Bugs</A> | |
| </P> | |
| </UL> | |
| </BODY> | |
| </HTML> |