Extend the readdir program to traverse the file hierarchy recursively and list all the sub directories and the files in these sub directories. Note that you have to modify the given readdir.c (or readdir_v2.c) program to use a function to perform the file traversal and then invoke it recursively. The readdir.c is as follows: #include #include #include int main (int argc, char **argv) { struct dirent *dirent; DIR *parentDir; if (argc d_name, filetype(dirent->d_type)); count++; } closedir (parentDir); return 0; }