/* 
 * Cópia de arquivos utilizando chamadas ao sistema.
 */ 

#include <sys/types.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>

#define BUF_SIZE 4096
#define OUTPUT_MODE 0700

int main(int argc, char *argv[]) {
  int in_fd, out_fd, rd_count, wt_count;
  char buffer[BUF_SIZE];

  if (argc!=3) exit(1);

  in_fd = open(argv[1], O_RDONLY);
  if (in_fd < 0) exit(2);

  out_fd = creat(argv[2], OUTPUT_MODE);
  if (out_fd < 0) exit(3);

  while((rd_count = read(in_fd, buffer, BUF_SIZE)) > 0) {
    wt_count = write(out_fd, buffer, rd_count);
    if (wt_count <= 0) exit(4);
  }

  close(in_fd);
  close(out_fd);
 
  if (rd_count == 0) exit(0);
  else exit(5);
}