#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>

#define BUFFER_SIZE 4096

char input_buffer[BUFFER_SIZE];
char output_buffer[BUFFER_SIZE];

int main(int argc, char ** argv)
{
	int input_fd=0;
	if(argc>1)
	{
		input_fd=open(argv[1],O_RDONLY);
		if(input_fd==-1)
		{
			perror(argv[1]);
			exit(EXIT_FAILURE);
		}
	}
	int output_fd=1;
	if(argc>2)
	{
		output_fd=open(argv[2],O_WRONLY|O_CREAT|O_TRUNC,0644);
		if(output_fd==-1)
		{
			perror(argv[2]);
			exit(EXIT_FAILURE);
		}
	}

	int read_bytes=0;
	int written_bytes=0;

	while((read_bytes=read(input_fd,input_buffer,BUFFER_SIZE))>0)
	{
		int i;
		for(i=0;i<read_bytes;i++)
		{
			output_buffer[written_bytes++]=input_buffer[i];
			if(written_bytes==BUFFER_SIZE)
			{
				write(output_fd,output_buffer,written_bytes);
				written_bytes=0;
			}
			output_buffer[written_bytes++]='\0';
			if(written_bytes==BUFFER_SIZE)
			{
				write(output_fd,output_buffer,written_bytes);
				written_bytes=0;
			}
		}
	}
	write(output_fd,output_buffer,written_bytes);

	exit(EXIT_SUCCESS);
}