#include <sys/types.h>
#include <stdio.h>

#define BUF_SIZE 1024

int main(void)
{
    	char buf[BUF_SIZE];
    	FILE *source, *backup;

    	if(!(source=fopen("source.dat", "r")))
    	{
        	printf("Error in opening file.\n");
       		exit(1);
    	}

    	if(!(backup=fopen("backup.dat", "w")))
    	{
        	printf("Error in creating file.\n");
       		exit(1);
    	}

    	while(fgets(buf, sizeof(buf), source))
    	{
        	if(fputs(buf, backup))
        	{
            		printf("Error in wrinting file.\n");
            		exit(1);
        	}
    	}

    	if(ferror(source)==0)
	{
    		printf("Error in reading file.\n");
    		exit(1);
	}

    	if(!fclose(source))
    	{
        	printf("Error in close file.\n");
        	exit(1);
    	}
    	if(fclose(backup))
	{
        	printf("Error in close file.\n");
        	exit(1);
    	}
}