I noticed os.fwalk() produced different results as os.walk(). It turned outthat os.fwalk() skips all remaining directories when OSError occurs (e.g. dueto PermissionError).To reproduce the bug, first create a test directory structure:    $ mkdir 1; touch 1/a    $ mkdir 2; touch 2/b    $ mkdir 3; touch 3/c    $ mkdir 4; touch 4/cAt this stage, everything is okay, both os.fwalk() os.walk() produce the sameresults:    >>> import os    >>> for root, dirs, files in os.walk('.'):    ...     dirs.sort()    ...     print(root, dirs, files)    . ['1', '2', '3', '4'] []    ./1 [] ['a']    ./2 [] ['b']    ./3 [] ['c']    ./4 [] ['d']    >>> for root, dirs, files, fd in os.fwalk('.'):    ...     dirs.sort()    ...     print(root, dirs, files)    . ['1', '2', '3', '4'] []    ./1 [] ['a']    ./2 [] ['b']    ./3 [] ['c']    ./4 [] ['d']To introduce an error, force a PermissionError on one of the directories:    $ sudo chown root:root 2    $ sudo chmod 700 2Now, the os.fwalk() results are different (trust me, os.walk() is still okay):    >>> for root, dirs, files, fd in os.fwalk('.'):    ...     dirs.sort()    ...     print(root, dirs, files)    . ['1', '2', '3', '4'] []    ./1 [] ['a']So it seems that os.fwalk skips remaining directories after an error occurs.The cause of the problem is in this part of os.py:    for name in dirs:        try:            orig_st = stat(name, dir_fd=topfd, follow_symlinks=follow_symlinks)            dirfd = open(name, O_RDONLY, dir_fd=topfd)        except OSError as err:            if onerror is not None:                onerror(err)            breakTo fix it, simply replace break with continue. Patch attached.Cheers

LGTM. Here is a patch with tests.

New changeset767262c149ca by Serhiy Storchaka in branch '3.5':Issue#25860: os.fwalk() no longer skips remaining directories when error occurs.https://hg.python.org/cpython/rev/767262c149caNew changeseta85675dabb8f by Serhiy Storchaka in branch 'default':Issue#25860: os.fwalk() no longer skips remaining directories when error occurs.https://hg.python.org/cpython/rev/a85675dabb8f

New changeset7995a81236b6 by Serhiy Storchaka in branch '3.5':Issue#25860: Fixed test failure caused by inconsistency of os.walk() andhttps://hg.python.org/cpython/rev/7995a81236b6New changesetdcf9e9ae5393 by Serhiy Storchaka in branch 'default':Issue#25860: Fixed test failure caused by inconsistency of os.walk() andhttps://hg.python.org/cpython/rev/dcf9e9ae5393