Implement a function that performs the equivalent of getcwd(). A useful tip for solving this problem is that you can find the name of the current working directory by using opendir() and readdir() to walk through each of the entries in the parent directory (..) to find an entry with the same i-node and device number as the current working directory (i.e., respectively, the st_ino and st_dev fields in the stat structure returned by stat() and lstat()). Thus, it is possible to construct the directory path by walking up the directory tree (chdir("..")) one step at a time and performing such scans. The walk can be finished when the parent directory is the same as the current working directory (recall that /.. is the same as /). The caller should be left in the same directory in which it started, regardless of whether your getcwd() function succeeds or fails (open() plus fchdir() are handy for this purpose).