#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <signal.h>
#include <pthread.h>

#define BSIZE 512

void *kill_task(void *arg)
{
    kill(getpid(), SIGINT);
    return NULL;
}

int io_task(const char *fname, off_t size)
{
    int fd;
    int res;
    char buf[BSIZE];
    int n = 0;
    pthread_t tid;

    while (1) {
	fd = open(fname, O_RDONLY);
	if (fd < 0) {
	    perror("faild to open file:");
	    return fd;
	}

	res = lseek(fd, random() % size, SEEK_SET);
	if (res < 0) {
	    perror("stat");
	    return res;
	}

	if (n) {
	    /* try to simulate system call interrupt */
	    pthread_create(&tid, NULL, kill_task, NULL);
	}

	read(fd, buf, BSIZE);

	pthread_yield();

	res = close(fd);
	if (res < 0) {
	    perror("faild to close file:");
	    return res;
	}
	n++;
    }
    return 0;
}

int main(int argc, char *argv[])
{
    struct stat sbuf;
    const char *fname;

    if (argc != 2) {
	printf("Usage: %s: <fname>\n", argv[0]);
	exit(1);
    }

    fname = argv[1];

    if (stat(fname, &sbuf) < 0) {
	perror("stat");
	exit(1);
    }

    io_task((void *) fname, sbuf.st_size);

    return 0;
}