share/doc/gcc-linaro-aarch64-none-elf/html/newlib/libc.html/signal.html - manifest_repos/gnu_toolchain - Git at Google

 <html lang="en">
 <head>
 <title>signal - Untitled</title>
 <meta http-equiv="Content-Type" content="text/html">
 <meta name="description" content="Untitled">
 <meta name="generator" content="makeinfo 4.13">
 <link title="Top" rel="start" href="index.html#Top">
 <link rel="up" href="Signals.html#Signals" title="Signals">
 <link rel="prev" href="raise.html#raise" title="raise">
 <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
 <meta http-equiv="Content-Style-Type" content="text/css">
 <style type="text/css"><!--
   pre.display { font-family:inherit }
   pre.format  { font-family:inherit }
   pre.smalldisplay { font-family:inherit; font-size:smaller }
   pre.smallformat  { font-family:inherit; font-size:smaller }
   pre.smallexample { font-size:smaller }
   pre.smalllisp    { font-size:smaller }
   span.sc    { font-variant:small-caps }
   span.roman { font-family:serif; font-weight:normal; }
   span.sansserif { font-family:sans-serif; font-weight:normal; }
 --></style>
 </head>
 <body>
 <div class="node">
 <a name="signal"></a>
 <p>
 Previous:&nbsp;<a rel="previous" accesskey="p" href="raise.html#raise">raise</a>,
 Up:&nbsp;<a rel="up" accesskey="u" href="Signals.html#Signals">Signals</a>
 <hr>
 </div>

 <h3 class="section">7.3 <code>signal</code>&mdash;specify handler subroutine for a signal</h3>

 <p><a name="index-signal-426"></a><a name="index-g_t_005fsignal_005fr-427"></a><strong>Synopsis</strong>
 <pre class="example">     #include &lt;signal.h&gt;
      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>
    <p><strong>Description</strong><br>
 <code>signal</code> provides a simple signal-handling implementation for embedded
 targets.

    <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>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>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>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>The alternate function <code>_signal_r</code> is the reentrant version.
 The extra argument <var>reent</var> is a pointer to a reentrancy structure.

 <!-- FIXME: do we have setjmp.h and assoc fns? -->
    <p><br>
 <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>Otherwise, the result is the previous handler (a function pointer or
 one of the predefined macros).

    <p><br>
 <strong>Portability</strong><br>
 ANSI C requires <code>signal</code>.

    <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>

    </body></html>
	<html lang="en">
	<head>
	<title>signal - Untitled</title>
	<meta http-equiv="Content-Type" content="text/html">
	<meta name="description" content="Untitled">
	<meta name="generator" content="makeinfo 4.13">
	<link title="Top" rel="start" href="index.html#Top">
	<link rel="up" href="Signals.html#Signals" title="Signals">
	<link rel="prev" href="raise.html#raise" title="raise">
	<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
	<meta http-equiv="Content-Style-Type" content="text/css">
	<style type="text/css"><!--
	pre.display { font-family:inherit }
	pre.format { font-family:inherit }
	pre.smalldisplay { font-family:inherit; font-size:smaller }
	pre.smallformat { font-family:inherit; font-size:smaller }
	pre.smallexample { font-size:smaller }
	pre.smalllisp { font-size:smaller }
	span.sc { font-variant:small-caps }
	span.roman { font-family:serif; font-weight:normal; }
	span.sansserif { font-family:sans-serif; font-weight:normal; }
	--></style>
	</head>
	<body>
	<div class="node">
	<a name="signal"></a>
	<p>
	Previous: <a rel="previous" accesskey="p" href="raise.html#raise">raise</a>,
	Up: <a rel="up" accesskey="u" href="Signals.html#Signals">Signals</a>
	<hr>
	</div>

	<h3 class="section">7.3 <code>signal</code>—specify handler subroutine for a signal</h3>

	<p><a name="index-signal-426"></a><a name="index-g_t_005fsignal_005fr-427"></a><strong>Synopsis</strong>
	<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>
	<p><strong>Description</strong><br>
	<code>signal</code> provides a simple signal-handling implementation for embedded
	targets.

	<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>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>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>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>The alternate function <code>_signal_r</code> is the reentrant version.
	The extra argument <var>reent</var> is a pointer to a reentrancy structure.

	<!-- FIXME: do we have setjmp.h and assoc fns? -->
	<p><br>
	<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>Otherwise, the result is the previous handler (a function pointer or
	one of the predefined macros).

	<p><br>
	<strong>Portability</strong><br>
	ANSI C requires <code>signal</code>.

	<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>

	</body></html>