signal_rt.c

这个是专门针对实时信号做的代码 用到了各个实时信号涉及到的函数 同时对实时信号的排队问题进行的验证 本程序是经由各种不完整的代码综合而来 且验证过的 网上这方面的代码很少

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

static void sig_rt(int, siginfo_t *, void * ) ;
static int signal_rt(int, void *);

int main(int argc, char **argv)
{
	int i, j;
	pid_t pid;
	sigset_t newset;
	union sigval val;
	printf("SIGRTMIN = %d, SIGRTMAX = %d\n", (int) SIGRTMIN, (int) SIGRTMAX);
	if ( (pid = fork() ) == 0) {
	// child: block three realtime signals 
	sigemptyset(&newset);
	sigaddset(&newset, SIGRTMAX);
	sigaddset(&newset, SIGRTMAX - 1);
	sigaddset(&newset, SIGRTMAX - 2);
	sigprocmask(SIG_BLOCK, &newset,NULL);
		
	// establish signal handler with SA_SIGINFO set 
	
	signal_rt(SIGRTMAX, sig_rt);
	signal_rt(SIGRTMAX - 1, sig_rt);
	signal_rt(SIGRTMAX - 2, sig_rt);
	
	sleep(6) ; // let parent send all the signals 
	sigprocmask(SIG_UNBLOCK, &newset, NULL); //unblock 
	sleep (3 ) ; // let all queued signals be delivered 
	exit (0) ;
	}
// parent sends nine signals to child 
	sleep(3) ; // let child block all signals 
	for (i = SIGRTMAX; i >= SIGRTMAX - 2; i--) 
	{for (j = 0; j <= 2; j++) {
		val.sival_int = j;
		sigqueue (pid, i, val) ;
		printf("sent signal %d, val = %d\n", i, j);
		}
	}
exit (0) ;
}

 static void sig_rt(int signo, siginfo_t *info, void *context)
 {
 printf("received signal #%d, code = %d, ival = %d\n",signo, info->si_code, info->si_value.sival_int);
 }
 

 static int signal_rt(int signo, void *func)
{
 struct sigaction act, oact;
 act.sa_sigaction = func; //must store function addr here 
 sigemptyset(&act.sa_mask);
 act.sa_flags = SA_SIGINFO; // must specify this for realtime 
 if (signo == SIGALRM) {
 #ifdef SA_INTERRUPT
 act.sa_flags |= SA_INTERRUPT; // SunOS 4.x 
 #endif
 }else{
 #ifdef SA_RESTART
 act.sa_flags |= SA_RESTART; // SVR4, 4.4BSD 
 #endif
 }
 if (sigaction(signo, &act, &oact) < 0)
 		{perror("sigaction error");return(-1);}
 return (1);
}