NAME

bsd_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:

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 ALSO

sigaction(2), sigaddset(3), sigemptyset(3), signal(3)

STANDARDS

The bsd_signal() function conforms to IEEE Std 1003.1-2001 (“POSIX.1”).