#define _GNU_SOURCE
#include <unistd.h>
#include <sys/mman.h>
#include <signal.h>
#include <stdlib.h>

#define SIZE	(64*1024)

void check_block(const char *msg, int *b)
{
	int i;
	for (i=0; i<SIZE; i++)
		if (b[i] != i) {
			printf("%s: offset %d bad\n", msg);
			exit(1);
		}
}

int main(void)
{
	char cmd[256];
	int *block, *foo, *bar, i;
	size_t page_size = getpagesize();

	block = malloc(page_size + 2 * SIZE * sizeof(int));
	block = (int *)( ((long)block + page_size) & ~(page_size - 1) ); 

	for (i=0; i<SIZE; i++)
		block[i] = i;

	snprintf(cmd, sizeof(cmd), "cat /proc/%d/maps", getpid());

	printf("block: %p\n", block);
	check_block("initial", block);
	system(cmd);
	foo = mremap(block, SIZE * sizeof(int), 2 * SIZE * sizeof(int), MREMAP_MAYMOVE);
	if (foo == (int *)-1) {
		perror("abort: mremap failed");
		return 1;
	}
	printf("\nremapped\n");
	check_block("remapped", foo);
	system(cmd);
#if 0
	bar = mremap(foo, SIZE * sizeof int, SIZE * sizeof int, MREMAP_FIXED, block);
	if (foo == (int *)-1) {
		perror("abort: mremap(FIXED) failed");
		return 1;
	}
	if (bar != block) {
		printf("mremap fixed: %p vs %p\n", foo, bar);
		return 1;
	}
	check_block("remapped to original", bar);
#endif
	return 0;
}