#define _GNU_SOURCE

#include <unistd.h>

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

int main()
{
    int h;
    int ps;
    char *buf;
    ssize_t n;

    ps = getpagesize();
    if (!(buf = valloc(ps)))
	return 1;
    if ((h = open("test", O_RDONLY|O_DIRECT)) < 0)
	return 1;
    do {
	n = read(h, buf, ps);
	if (n == -1) {
	    perror("read");
	    break;
	}
	printf("read %d bytes\n", n);
    } while(n);

    close(h);

    return 0;
}