#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <assert.h>
#include <sys/time.h>

int
main(int ac, char *av[])
{
    int fd = open(av[1], O_RDONLY);
    if (fd == -1) { perror("open"); exit(-1); }
    char buf[8192];
    off_t total = 0;

    for (;;) {
        struct timeval start, end, diff;
        gettimeofday(&start, NULL);
        int bytes_read = read(fd, buf, sizeof buf);
        gettimeofday(&end, NULL);
        timersub(&end, &start, &diff);
        printf("%ld: took %ldus\n", total,
                diff.tv_sec * 1000000 + diff.tv_usec);
        if (bytes_read <= 0)
            break;
        total += bytes_read;
    }
    return 0;
}