/*
 * DF-3181 helper — holds an open fd on an unlinked tmpfs file and reports
 * fstat(fd).st_size every second, so we can watch tmpfs_unmount's
 * pre-vflush truncation destroy the data of a file whose vnode keeps
 * vflush() busy (EBUSY) and the mount alive.
 */

#include <sys/stat.h>

#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int
main(int argc, char **argv)
{
	struct stat st;
	char path[1024];
	int fd;
	int i;

	if (argc < 2)
		errx(1, "usage: %s <file-to-open-and-unlink>", argv[0]);
	snprintf(path, sizeof(path), "%s", argv[1]);

	fd = open(path, O_RDONLY);
	if (fd < 0)
		err(1, "open");
	if (unlink(path) < 0)
		err(1, "unlink");
	if (fstat(fd, &st) < 0)
		err(1, "fstat");
	printf("holder: opened+unlinked, initial st_size=%lld\n",
	       (long long)st.st_size);
	fflush(stdout);

	for (i = 0; i < 60; i++) {
		sleep(1);
		if (fstat(fd, &st) < 0)
			err(1, "fstat");
		printf("holder: t+%d st_size=%lld\n", i + 1,
		       (long long)st.st_size);
		fflush(stdout);
	}
	return 0;
}