#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define IOSIZE  32768

void
dcp(int sfd, int dfd)
{
       int zfd;
       int r, w;
       char *p;

	 zfd = open("/dev/zero", O_RDWR);

      p = mmap(NULL, IOSIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE, zfd, 0);
      close(zfd);

      while ((r = read(sfd, p, IOSIZE)) > 0) {
             w = write(dfd, p, r);
              if (w < r)
                      break;
     }
}

int
main(int argc, char *argv[])
{
       char c;
       int sfd, dfd;
	   int ret;

#ifdef SRC_DIRECT
       sfd = open(argv[1], O_RDONLY | O_DIRECT);
       //sfd = open(argv[1], O_RDONLY);
       dfd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0666);
printf ("sfd ret = %d\n", sfd);
printf ("dfd ret = %d\n", dfd);
#else
       sfd = open(argv[1], O_RDONLY);
       dfd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC | O_DIRECT, 0666);
printf ("sfd ret = %d\n", sfd);
printf ("dfd ret = %d\n", dfd);
#endif
#if 0
	   while ((ret = read(sfd, &c, 1)) > 0) {
		 write (dfd, &c, 1);
	   }
#endif
printf ("ret = %d\n", ret);
       dcp(sfd, dfd);
       return 0;
}