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

int main(int argc, char **argv)
{
	struct timespec ts_100s = { .tv_sec = 100 };
	long mbytes, cnt;
	void *map, *p;
	int fd = -1;
	int flags;

	if (argc < 2 || (mbytes = atol(argv[1])) <= 0) {
		fprintf(stderr, "test-membloat SIZE_IN_MBYTES [FILENAME]\n");
		return 1;
	}

	if (argc >= 3) {
		fd = open(argv[2], O_CREAT|O_TRUNC|O_RDWR, S_IRWXU);
		if (fd < 0) {
			perror("open");
			return 1;
		}

		if (ftruncate(fd, mbytes << 20)) {
			perror("ftruncate");
			return 1;
		}

		flags = MAP_SHARED;
	} else {
		flags = MAP_ANONYMOUS | MAP_PRIVATE;
	}

	map = mmap(NULL, (size_t)mbytes << 20, PROT_READ | PROT_WRITE,
		   flags, fd, 0);
	if (map == MAP_FAILED) {
		perror("mmap");
		return 1;
	}

	for (p = map, cnt = 0; p < map + (mbytes << 20); p += 4096) {
		*(volatile unsigned long *)p = 0xdeadbeef;
		cnt++;
	}

	printf("faulted in %ld mbytes, %ld pages\n", mbytes, cnt);

	while (1)
		nanosleep(&ts_100s, NULL);

	return 0;
}