[해결] 시리얼 통신 코드 질문요..;;

#include <termios.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
 
//#define BAUDRATE B9600
//#define MODEMDEVICE "/dev/ttySNX0"
#define ENDMINITERM 2 
 
#define _POSIX_SOURCE 1 
 
#define FALSE 0
#define TRUE 1
 
volatile int STOP=FALSE; 
 
void child_handler(int s)
{
   STOP=TRUE;
}
 
int open_serial(char *dev_name, int baud)
{
	int fd;
	fd = open(dev_name, O_RDWR | O_NOCTTY);
	if(fd < 0)
	{
		printf("Device open fail\n");
		return -1;
	}
	return fd;
}
 
int main( int arg, char **argv)
//int main (int arg)
{
	int fd, c, baud, res1, res2;
	char dev_name[256];
	struct termios oldtio,newtio,oldstdtio,newstdtio;
	struct sigaction sa;
 
	char buf1[255], buf2[255];	
 
 
	strcpy(dev_name, argv[1]);
//	strcpy(dev_name, argv);
	baud = strtoul(argv[2], NULL, 10); 
//	baud = 115200;
 
	fd = open_serial(dev_name, baud);
 
	 if (fd <0)
	 {
		exit(-1);
 	 }
 
	 tcgetattr(fd,&oldtio);  
 
 
	 newtio.c_cflag = CRTSCTS | CS8 | CLOCAL | CREAD | B115200;
 
 
	 newtio.c_iflag = IGNPAR | ICRNL;
 
 
	 newtio.c_oflag = 0;
 
 
	 newtio.c_lflag = 0;
 
 
	 newtio.c_cc[VMIN]=1;
	 newtio.c_cc[VTIME]=0;
 
 
	 tcflush(fd, TCIFLUSH);
	 tcsetattr(fd,TCSANOW,&newtio);
 
 
//	 tcsetattr(1,TCSANOW,&newtio);
 
 
	 tcgetattr(0,&oldstdtio);
	 tcgetattr(0,&newstdtio); 
	 newstdtio.c_lflag &= ~(ICANON | ECHO);
	 tcsetattr(0,TCSANOW,&newstdtio);
 
 
	 switch (fork())
	 {
		  case 0: 
 
		   close(1); 
		   for (c=getchar(); c!= ENDMINITERM ; c=getchar())
 
 
 
//			res2 = write(fd,buf2,1);
//			printf("%s",res2);
//
 
 
		   write(fd,&c,1);
 
		   tcsetattr(fd,TCSANOW,&oldtio); 
		   tcsetattr(0,TCSANOW,&oldstdtio); 
		   close(fd);
		   exit(-1);
 
		  case -1:
		   perror("fork");
		   tcsetattr(fd,TCSANOW,&oldtio);
		   close(fd);
		   exit(-1);
 
		  default: 
		   close(0);
		//   sa.sa_handler = child_handler;
		 //  sa.sa_flags = 0;
		 //  sigaction(SIGCHLD,&sa,NULL); 
 
		  while (STOP==FALSE) 
		   {
			  res1 =  read(fd,buf1,255);
			buf1[res1] = 0;
			    printf("%s", buf1);
			   // write(1,&c,1);
				write(0,buf1,1);
		   }
		   wait(NULL);
		   break;
	 }
}