You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
126 lines
5.4 KiB
HTML
126 lines
5.4 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>signal (The Red Hat newlib C Library)</title>
|
|
|
|
<meta name="description" content="signal (The Red Hat newlib C Library)">
|
|
<meta name="keywords" content="signal (The Red Hat newlib C Library)">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content="makeinfo">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<link href="index.html#Top" rel="start" title="Top">
|
|
<link href="Document-Index.html#Document-Index" rel="index" title="Document Index">
|
|
<link href="Document-Index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="Signals.html#Signals" rel="up" title="Signals">
|
|
<link href="Timefns.html#Timefns" rel="next" title="Timefns">
|
|
<link href="raise.html#raise" rel="prev" title="raise">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.indentedblock {margin-right: 0em}
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
|
blockquote.smallquotation {font-size: smaller}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
div.smalldisplay {margin-left: 3.2em}
|
|
div.smallexample {margin-left: 3.2em}
|
|
div.smalllisp {margin-left: 3.2em}
|
|
kbd {font-style: oblique}
|
|
pre.display {font-family: inherit}
|
|
pre.format {font-family: inherit}
|
|
pre.menu-comment {font-family: serif}
|
|
pre.menu-preformatted {font-family: serif}
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
|
pre.smallexample {font-size: smaller}
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
|
pre.smalllisp {font-size: smaller}
|
|
span.nolinebreak {white-space: nowrap}
|
|
span.roman {font-family: initial; font-weight: normal}
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en">
|
|
<a name="signal"></a>
|
|
<div class="header">
|
|
<p>
|
|
Previous: <a href="raise.html#raise" accesskey="p" rel="prev">raise</a>, Up: <a href="Signals.html#Signals" accesskey="u" rel="up">Signals</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<a name="signal_002d_002d_002dspecify-handler-subroutine-for-a-signal"></a>
|
|
<h3 class="section">7.3 <code>signal</code>—specify handler subroutine for a signal</h3>
|
|
<a name="index-signal"></a>
|
|
<a name="index-_005fsignal_005fr"></a>
|
|
<p><strong>Synopsis</strong>
|
|
</p><div class="example">
|
|
<pre class="example">#include <signal.h>
|
|
void (*signal(int <var>sig</var>, void(*<var>func</var>)(int))) (int);
|
|
|
|
void (*_signal_r(void *<var>reent</var>, int <var>sig</var>, void(*<var>func</var>)(int))) (int);
|
|
|
|
</pre></div>
|
|
<p><strong>Description</strong><br>
|
|
<code>signal</code> provides a simple signal-handling implementation for embedded
|
|
targets.
|
|
</p>
|
|
<p><code>signal</code> allows you to request changed treatment for a particular
|
|
signal <var>sig</var>. You can use one of the predefined macros <code>SIG_DFL</code>
|
|
(select system default handling) or <code>SIG_IGN</code> (ignore this signal)
|
|
as the value of <var>func</var>; otherwise, <var>func</var> is a function pointer
|
|
that identifies a subroutine in your program as the handler for this signal.
|
|
</p>
|
|
<p>Some of the execution environment for signal handlers is
|
|
unpredictable; notably, the only library function required to work
|
|
correctly from within a signal handler is <code>signal</code> itself, and
|
|
only when used to redefine the handler for the current signal value.
|
|
</p>
|
|
<p>Static storage is likewise unreliable for signal handlers, with one
|
|
exception: if you declare a static storage location as ‘<code>volatile
|
|
sig_atomic_t</code>’, then you may use that location in a signal handler to
|
|
store signal values.
|
|
</p>
|
|
<p>If your signal handler terminates using <code>return</code> (or implicit
|
|
return), your program’s execution continues at the point
|
|
where it was when the signal was raised (whether by your program
|
|
itself, or by an external event). Signal handlers can also
|
|
use functions such as <code>exit</code> and <code>abort</code> to avoid returning.
|
|
</p>
|
|
<p>The alternate function <code>_signal_r</code> is the reentrant version.
|
|
The extra argument <var>reent</var> is a pointer to a reentrancy structure.
|
|
</p>
|
|
|
|
<br>
|
|
<p><strong>Returns</strong><br>
|
|
If your request for a signal handler cannot be honored, the result is
|
|
<code>SIG_ERR</code>; a specific error number is also recorded in <code>errno</code>.
|
|
</p>
|
|
<p>Otherwise, the result is the previous handler (a function pointer or
|
|
one of the predefined macros).
|
|
</p>
|
|
<br>
|
|
<p><strong>Portability</strong><br>
|
|
ANSI C requires <code>signal</code>.
|
|
</p>
|
|
<p>No supporting OS subroutines are required to link with <code>signal</code>, but
|
|
it will not have any useful effects, except for software generated signals,
|
|
without an operating system that can actually raise exceptions.
|
|
</p>
|
|
<br>
|
|
<hr>
|
|
<div class="header">
|
|
<p>
|
|
Previous: <a href="raise.html#raise" accesskey="p" rel="prev">raise</a>, Up: <a href="Signals.html#Signals" accesskey="u" rel="up">Signals</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|