[완료]read(), write()를 이용한 복사프로그램 관련

------------------------restart.h------------------------
 
int copyfile(int fromfd, int tofd)      
{
        char *bp;
        char buf[1024];
        int bytesread, byteswritten = 0;
        int totalbytes = 0;
 
        for( ; ; )
        {
                while((bytesread = read(fromfd, buf, 1024) == -1) && (errno = EINTR));  
 
                if(bytesread <= 0)                                                      
                        break;                                                        
                bp = buf;
 
                while(bytesread > 0)                                                   
                {
                        while((byteswritten = write(tofd, bp, bytesread) == -1) && (errno == EINTR));
 
                        if(byteswritten <= 0)
                                break;
 
                        totalbytes += byteswritten;
                        bytesread -= byteswritten;
                        bp += byteswritten;
                }
                if(byteswritten == -1)
                        break;
        }
        return totalbytes;
 
}

#include<stdio.h>
#include<unistd.h>
#include"restart.h"
 
int main(void)
{
	int numbytes = copyfile(STDIN_FILENO, STDOUT_FILENO);
 
	fprintf(stderr, "Numder of bytes copied: %d\n", numbytes);
	return 0;
}