#include <stdint.h>

#include <sys/mman.h>

#include <fcntl.h>

#include <unistd.h>

#include <limits.h>

#include "test.h"

#ifndef PAGE_SIZE

	#define PAGE_SIZE sysconf(_SC_PAGE_SIZE)

#endif

/* max mmap size, *start is the largest power-of-2 size considered */

static size_t mmax(int fd, size_t *start)

{

	size_t i, n;

	void *p;

	for (i=n=*start; i>=PAGE_SIZE; i/=2) {

		if ((p=mmap(0, n, PROT_NONE, MAP_PRIVATE, fd, 0)) == MAP_FAILED) {

			n -= i/2;

		} else {

			munmap(p, n);

			if (n == i)

				*start = n;

			n += i/2;

		}

	}

	return n & -PAGE_SIZE;

}

/*

fills the virtual memory with anonymous PROT_NONE mmaps,

returns the mappings in *p and *n in decreasing size order,

the return value is the number of mappings or -1 on failure.

*/

int t_vmfill(void **p, size_t *n, int len)

{

	int fd = open("/dev/zero", O_RDWR);

	size_t start = SIZE_MAX/2 + 1;

	size_t m;

	void *q;

	int i;

	for (i=0;;i++) {

		m = mmax(fd, &start;;

		if (!m)

			break;

		q = mmap(0, m, PROT_NONE, MAP_PRIVATE, fd, 0);

		if (q == MAP_FAILED)

			return -1;

		if (i < len) {

			p[i] = q;

			n[i] = m;

		}

	}

	return i;

}