BSD_SIGNAL(3) BSD Library Functions Manual BSD_SIGNAL(3)NAMEbsd_signal — simplified signal facilities
SYNOPSIS
#include <signal.h>
void (*
bsd_signal(int sig, void (*func)(int)))(int);
or in an equivalent but easier to read typedef'd version:
typedef void (*sig_t) (int);
sig_t
bsd_signal(int sig, sig_t func);
DESCRIPTION
The bsd_signal() function provides a partially compatible interface for
programs written to historical system interfaces (see USAGE below).
The function call bsd_signal(sig, func) has the effect as if implemented
as:
void (*bsd_signal(int sig, void (*func)(int)))(int)
{
struct sigaction act, oact;
act.sa_handler = func;
act.sa_flags = SA_RESTART;
sigemptyset(&act.sa_mask);
sigaddset(&act.sa_mask, sig);
if (sigaction(sig, &act, &oact) == -1)
return(SIG_ERR);
return(oact.sa_handler);
}
The handler function should be declared:
void func(int sig)
where sig is the signal number. The behavior is undefined if func() is a
function that takes more than one argument, or an argument of a different
type.
RETURN VALUES
Upon successful completion, bsd_signal() returns the previous action for
sig. Otherwise, SIG_ERR is returned and errno is set to indicate the
error.
ERRORS
Refer to sigaction(2).
USAGE
This function is a direct replacement for the BSD signal(3) function for
simple applications that are installing a single-argument signal handler
function. If a BSD signal handler function is being installed that
expects more than one argument, the application has to be modified to use
sigaction(2). The bsd_signal() function differs from signal(3) in that
the SA_RESTART flag is set and the SA_RESETHAND will be clear when
bsd_signal() is used. The state of these flags is not specified for
signal(3).
SEE ALSOsigaction(2), sigaddset(3), sigemptyset(3), signal(3)STANDARDS
The bsd_signal() function conforms to IEEE Std 1003.1-2001 (“POSIX.1”).
BSD December 20, 2003 BSD