C signal handling: Difference between revisions

Revision as of 17:28, 11 May 2020

Revision as of 05:31, 20 May 2020

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{{C_Standard Library}}

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==Standard signals==

{{see also|Unix signal}}

The C standard defines only 6 signals. They are all defined in <code>signal.h</code> header (<code>csignal</code> header in [[C++]]):<ref name=c99>{{cite book | url=http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf | title=ISO/IEC 9899:1999 specification | at=p. 258, § 7.14 ''Signal handling''}}</ref>

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A signal handler is a [[Function (computer science)|function]] which is called by the target environment when the corresponding signal occurs. The target environment suspends execution of the program until the signal handler returns or calls <code>longjmp()</code>.

Signal handlers can be set be with <code>signal()</code> or <code>sigaction()</code>. The behavior of <code>signal()</code> has been changed multiple times across history and is now considered deprecated.<ref>http://man7.org/linux/man-pages/man2/signal.2.html Signal(2) manpage</ref>. It is only portable when used to set a signal's disposition to SIG_DFL or SIG_IGN. Signal handlers can be specified for all but two signals ([[SIGKILL]] and [[SIGSTOP]] cannot be caught, blocked or ignored).

If the signal reports an error within the program (and the signal is not asynchronous), the signal handler can terminate by calling <code>abort()</code>, <code>exit()</code>, or <code>longjmp()</code>.

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==References==

{{Reflist}}

{{Use dmy dates|date=January 2012}}

[[Category:C standard library]]