/*======================================================================    A test program to access /dev/second    This example is to help understand async IO         The initial developer of the original code is Baohua Song    <author@linuxdriver.cn>. All Rights Reserved.======================================================================*/#include <sys/types.h>#include <sys/stat.h>#include <stdio.h>#include <fcntl.h>#include <signal.h>#include <unistd.h>/*接收到異步讀信號后的動作*/void input_handler(int signum){  printf("receive a signal from globalfifo,signalnum:%d\n",signum);}main(){  int fd, oflags;  fd = open("/dev/globalfifo", O_RDWR, S_IRUSR | S_IWUSR);  if (fd !=  - 1)  {    //啟動信號驅動機制    signal(SIGIO, input_handler); //讓input_handler()處理SIGIO信號    fcntl(fd, F_SETOWN, getpid());    oflags = fcntl(fd, F_GETFL);    fcntl(fd, F_SETFL, oflags | FASYNC);    while(1)    {    	sleep(100);    }  }  else  {    printf("device open failure\n");  }}