Linux中信号处理的两种方法

NAME
<pre>       sigaction - examine and change a signal action
SYNOPSIS
       #include <signal.h>
       int sigaction(int signum, const struct sigaction *act,
                     struct sigaction *oldact);
   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
       sigaction(): _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_SOURCE
       
If act is non-NULL, the new action for signal signum is installed  from
act.  If oldact is non-NULL, the previous action is saved in oldact.
The sigaction structure is defined as something like:
   struct sigaction {
       void     (*sa_handler)(int);
       void     (*sa_sigaction)(int, siginfo_t *, void *);
       sigset_t   sa_mask;
       int        sa_flags;
       void     (*sa_restorer)(void);
   };
On  some  architectures  a  union  is  involved:  do not assign to both
sa_handler and sa_sigaction.
The sa_restorer element is obsolete and should not be used.  POSIX does
not specify a sa_restorer element.

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>

/* Define the signal handle function */
void my_func(int sig_no)
{
	switch(sig_no)
	{
		case SIGINT:
			printf("I have get SIGINT\n");
			break;
		case SIGQUIT:
			printf("I have get SIGQUIT\n");
			break;
		default:
			break;
	}
}

int main()
{
	struct sigaction action;
	printf("Waiting for signal SIGINT or SIGQUIT...\n");
	
	/* Initialize the sigaction structure*/
	action.sa_handler = my_func;
	sigemptyset(&action.sa_mask);
	action.sa_flags = 0;
	
	/* Send certain signal and go to handle_fun */
	sigaction(SIGINT, &action, 0);
	sigaction(SIGQUIT, &action, 0);
	
	pause();
	alarm(3);
	
	printf("I'm over!\n");

	exit(0);		
}

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/types.h>


/* Define the signal handle function */
void my_func(int sig_no)
{
	printf("If you want to quit, please try SIGQUIT\n");
}

int main()
{
	sigset_t set, pendset;
	struct sigaction action1, action2;
	
	/* step1: Initialize the sigset with Null. */
	if(sigemptyset(&set) < 0)
	{
		perror("sigemptyset");
		exit(1);
	}
	
	/* Add certain signal to sigset */
	if(sigaddset(&set, SIGQUIT) < 0)
	{
		perror("sigaddset");
		exit(1);
	}
	if(sigaddset(&set, SIGINT) < 0)
	{
		perror("sigaddset");
		exit(1);
	}
	
	if(sigismember(&set, SIGINT) < 0)
	{
		sigemptyset(&action1.sa_mask);
		action1.sa_handler = my_func;
		action1.sa_flags = 0;
		sigaction(SIGINT, &action1, NULL);
	}
	
	if(sigismember(&set, SIGQUIT) < 0)
	{
		sigemptyset(&action2.sa_mask);
		action2.sa_handler = my_func;
		action2.sa_flags = 0;
		sigaction(SIGQUIT, &action2, NULL);
	}
	
	/* step2: Set the value of mask word */
	if(sigprocmask(SIG_BLOCK, &set, NULL) < 0)
	{
		perror("sigprocmask");
		exit(1);
	}
	else
	{
		printf("Signal set was blocked, Press any key!\n");
		getchar();
	}

	/* Delete the signal of set */
	if(sigprocmask(SIG_UNBLOCK, &set, NULL) < 0)
	{
		perror("sigprocmask");
		exit(1);
	}
	else
	{
		printf("Signal set was unblocked, Press any key!\n");
	}
	
	while(1);
	exit(0);
}