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sysv_signal

Section: C Library Functions (3)
Updated: 202-0-08
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NAME

sysv_signal - signal handling with System V semantics

LIBRARY

Standard C library (libc,~-lc)

SYNOPSIS

#define _GNU_SOURCE         /* See feature_test_macros(7) */
#include <signal.h>
typedef typeof(void (int))  *sighandler_t;
sighandler_t sysv_signal(int signum, sighandler_t handler);

DESCRIPTION

The sysv_signal() function takes the same arguments, and performs the same task, as signal(2). However sysv_signal() provides the System V unreliable signal semantics, that is: a) the disposition of the signal is reset to the default when the handler is invoked; b) delivery of further instances of the signal is not blocked while the signal handler is executing; and c) if the handler interrupts (certain) blocking system calls, then the system call is not automatically restarted.

RETURN VALUE

The sysv_signal() function returns the previous value of the signal handler, or SIG_ERR on error.

ERRORS

As for signal(2).

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Interface	Attribute	Value
sysv_signal()	Thread safety	M-Safe

VERSIONS

Use of sysv_signal() should be avoided; use sigaction(2) instead. On older Linux systems, sysv_signal() and signal(2) were equivalent. But on newer systems, signal(2) provides reliable signal semantics; see signal(2) for details. The use of sighandler_t is a GNU extension; this type is defined only if the _GNU_SOURCE feature test macro is defined.

STANDARDS

None.