Recursively compare two directories to ensure they have the same files and subdirectories

Here’s an alternative implementation of the comparison function with filecmp module. It uses a recursion instead of os.walk, so it is a little simpler. However, it does not recurse simply by using common_dirs and subdirs attributes since in that case we would be implicitly using the default “shallow” implementation of files comparison, which is probably not what you want. In the implementation below, when comparing files with the same name, we’re always comparing only their contents.

import filecmp
import os.path

def are_dir_trees_equal(dir1, dir2):
    """
    Compare two directories recursively. Files in each directory are
    assumed to be equal if their names and contents are equal.

    @param dir1: First directory path
    @param dir2: Second directory path

    @return: True if the directory trees are the same and 
        there were no errors while accessing the directories or files, 
        False otherwise.
   """

    dirs_cmp = filecmp.dircmp(dir1, dir2)
    if len(dirs_cmp.left_only)>0 or len(dirs_cmp.right_only)>0 or \
        len(dirs_cmp.funny_files)>0:
        return False
    (_, mismatch, errors) =  filecmp.cmpfiles(
        dir1, dir2, dirs_cmp.common_files, shallow=False)
    if len(mismatch)>0 or len(errors)>0:
        return False
    for common_dir in dirs_cmp.common_dirs:
        new_dir1 = os.path.join(dir1, common_dir)
        new_dir2 = os.path.join(dir2, common_dir)
        if not are_dir_trees_equal(new_dir1, new_dir2):
            return False
    return True