#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 *pa;
	size_t len;
	int fd;

	pid_t child;
	char *ch;
	int exit_val;

	page_size = sysconf(_SC_PAGE_SIZE);

	len = page_size / 2;

	snprintf(tmpfname, sizeof(tmpfname), "testfile");
	child = fork();
	switch (child) {
	case 0:
		/* Create shared object */
		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;
		}
		if (ftruncate(fd, len) == -1) {
			printf("Error at ftruncate(): %s\n", strerror(errno));
			return 1;
		}

		pa = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
		if (pa == MAP_FAILED) {
			printf("Error at mmap(): %s\n", strerror(errno));
			return 1;
		}
		
		/* Check the patial page is ZERO filled */
		ch = pa + len + 1;
		if (*ch != 0) {
			printf("Test FAILED: "
			       "The partial page at the end of an object "
			       "is not zero-filled\n");
			return 1;
		}

		/* Write the partial page */
		*ch = 'b';
		msync(pa, len, MS_SYNC);
		if (*ch != 'b')
			printf("nb: byte modified beyond EOF cleared after mysync\n");
		munmap(pa, len);
		close(fd);
		return 0;
	case -1:
		printf("Error at fork(): %s\n", strerror(errno));
		return 1;
	default:
	break;
	}

	wait(&exit_val);
	if (!(WIFEXITED(exit_val) && (WEXITSTATUS(exit_val) == 0))) {
		unlink(tmpfname);
		printf("Child exited abnormally\n");
		return 1;
	}

	fd = open(tmpfname, O_RDWR, 0);
//	unlink(tmpfname);

	pa = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (pa == MAP_FAILED) {
		printf("Error at 2nd mmap(): %s\n", strerror(errno));
		return 1;
	}

	ch = pa + len + 1;
	if (*ch == 'b') {
		printf("Test FAILED: Modification of the partial page "
		       "at the end of an object is written out\n");
		return 1;
	}
	close(fd);
	munmap(pa, len);

	printf("Test PASSED\n");
	return 0;
}