#define _XOPEN_SOURCE 600

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>

int main(void)
{
	char tmpfname[256];
	long page_size;
	void *data;
	char *pa;
	size_t len;
	int fd, i, fail = 0;

	page_size = sysconf(_SC_PAGE_SIZE);

	snprintf(tmpfname, sizeof(tmpfname), "/tmp/test");
	
	/* Create file */
	unlink(tmpfname);
	fd = open(tmpfname, O_CREAT | O_RDWR | O_EXCL,
		  S_IRUSR | S_IWUSR);
	if (fd == -1) {
		printf("Error at open(): %s\n", strerror(errno));
		return 1;
	}
	
	/* Fill it to the size of the page with 'a' */
	data = malloc(page_size);
	memset(data, 'a', page_size);
	if (write(fd, data, page_size) != page_size) {
		printf("Error at write(): %s\n", strerror(errno));
		return 1;
	}
	free(data);

	/* mmap half of the page */
	pa = mmap(NULL, page_size/2, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (pa == MAP_FAILED) {
		printf("Error at mmap(): %s\n", strerror(errno));
		return 1;
	}
	
	for (i = 0; i < page_size; i++) {
		if (i > page_size/2 && pa[i] != 0)
			fail++;
		printf("%4i %2x\n", i, pa[i]);
	}

	close(fd);
	munmap(pa, len);
	
	if (fail)
		printf("FAILED: Page not zeroed\n");
	else
		printf("SUCCEDED\n");

	return 0;
}