Linuxネーミングパイプ

//      :
//1.                     ，          ，      
//     open
//      ，        open(DEF_FIFO_PATH,O_RDWR)
//            
//       ，      
//       
//2.     
//3.    ，    
//    

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>

#define DEF_FIFO_PATH ("./FIFO")
#define DEF_STD_ERROR (-1)

int main(int argc,char *argv[])
{
        int ret;
        int fd;
        char str[1024];
        //if argv[1] > 0,writer
        if(atoi(argv[1])>0)
		{
			ret = mkfifo(DEF_FIFO_PATH,S_IWUSR | S_IRUSR);
			if(ret == DEF_STD_ERROR)
			{
					if(errno == EEXIST)
					{
							printf("Fifo always exist
");
					}
					else
					{
							printf("%d
",strerror(errno));
							return -1;
					}
			}
			//open fifo
			fd = open(DEF_FIFO_PATH,O_WRONLY)//O_WRONLY        ，    
			if(fd == DEF_STD_ERROR)
			{
					printf("%d
",strerror(errno));
					//delete pipe        （  ）
					unlink(DEF_FIFO_PATH);
					return -1;
			}
			//write
			while(1)
			{
					printf("Please input string:
");
					scanf("%s",str);
					write(fd,str,strlen(str)+1);
					if(!strcmp(str,"goodbye"))
					{
							break;
					}
			}
			//close fifo
			close(fd);
	}
    else 
	{
			//if argv[1] <= 0,reader
			//check fifo
			ret = access(DEF_FIFO_PATH,W_OK);
			if(ret == DEF_STD_ERROR)
			{
					printf("%d
",strerror(errno));
					return -1;
			}
			//open fifo
			fd = open(DEF_FIFO_PATH,O_RDONLY);
			if(fd == DEF_STD_ERROR)
			{
					printf("%d
",strerror(errno));
					return -1;
			}
			//read fifo
			while(1)
			{
					read(fd,str,sizeof(str));
					printf("Receive data:[%s]
",str);
					if(strcmp("goodbye",str)==0)
					{
							break;
					}
			}
			//close fifo
			close(fd);
	}
        return 0;
}