bsd_signal - simplified signal handling

Syntax	#include <signal.h> void ( *bsd_signal(int sig, void ( *func)(int))) (int);
Description	The bsd_signal() function provides a partially compatible interface for programs that were written for old-style system interfaces (see “Notes” below). The function call bsd_signal(sig, func) acts as though it were implemented as follows: 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 event handling function should be declared as follows: void handler(int sig); where sig stands for the signal number. The behavior is not defined if func is a function which has more than one argument or an argument of a different type.
Return val.	The preceding action for sig
		if successful.
	SIG_ERR	if an error occurs. errno is set to indicate the error.
Errors Notes	See sigaction() This function is a direct substitute for the BSD function signal() for simple applications for which a signal handling function with an argument is installed. If a BSD signal handling function which expects more than one argument is installed, the application must be modified such that it uses sigaction(). The bsd_signal() function differs from signal() in that the SA_RESTART flag is set and SA_RESETHAND is deleted if bsd_signal() is used. The status of these flags is not specified for signal().
See also	sigaction(), sigaddset(), sigemptyset(), signal(), signal.h .