#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#define FIFO_SERVER "/tmp/fifoserver"
main(int argc,char** argv)
{
	int fd;
	char w_buf[4096*2];
	int real_wnum;
	memset(w_buf,0,4096*2);
	if((mkfifo(FIFO_SERVER,O_CREAT|O_EXCL)<0)&&(errno!=EEXIST))
		printf("cannot create fifoserver\n");
	if(fd==-1)
		if(errno==ENXIO)
			printf("open error; no reading process\n");
		
     	fd=open(FIFO_SERVER,O_WRONLY|O_NONBLOCK,0);
	/*設置非阻塞標志
	fd=open(FIFO_SERVER,O_WRONLY,0);
	設置阻塞標志*/
	real_wnum=write(fd,w_buf,2048);
	if(real_wnum==-1)
	{
		if(errno==EAGAIN)
			printf("write to fifo error; try later\n");
	}
	else 
		printf("real write num is %d\n",real_wnum);
	real_wnum=write(fd,w_buf,5000);
	/*5000用于測試寫入字節大于4096時的非原子性
	real_wnum=write(fd,w_buf,4096);
	4096用于測試寫入字節不大于4096時的原子性*/
		if(real_wnum==-1)
		if(errno==EAGAIN)
			printf("try later\n");
}