While SimpleHTTPServer from Python2 would happily spit out whatever bytes were in the directory listing, Python3's http.server logs an error and closes the connection without responding to the HTTP request.

$ mkdir $'\xff'
$ ls
\377/
$ python3 -m http.server 
Serving HTTP on 0.0.0.0 port 8000 ...
----------------------------------------
Exception happened during processing of request from ('74.125.59.145', 19648)
Traceback (most recent call last):
  File "/home/josh/local/lib/python3.5/socketserver.py", line 321, in _handle_request_noblock
    self.process_request(request, client_address)
  File "/home/josh/local/lib/python3.5/socketserver.py", line 347, in process_request
    self.finish_request(request, client_address)
  File "/home/josh/local/lib/python3.5/socketserver.py", line 360, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/home/josh/local/lib/python3.5/socketserver.py", line 681, in __init__
    self.handle()
  File "/home/josh/local/lib/python3.5/http/server.py", line 398, in handle
    self.handle_one_request()
  File "/home/josh/local/lib/python3.5/http/server.py", line 386, in handle_one_request
    method()
  File "/home/josh/local/lib/python3.5/http/server.py", line 677, in do_GET
    f = self.send_head()
  File "/home/josh/local/lib/python3.5/http/server.py", line 716, in send_head
    return self.list_directory(path)
  File "/home/josh/local/lib/python3.5/http/server.py", line 772, in list_directory
    % (urllib.parse.quote(linkname), html.escape(displayname)))
  File "/home/josh/local/lib/python3.5/urllib/parse.py", line 688, in quote
    string = string.encode(encoding, errors)
UnicodeEncodeError: 'utf-8' codec can't encode character '\udcff' in position 0: surrogates not allowed
----------------------------------------

It should return a server error, I think.

Why not treat the filename as opaque bytes, and let the client fetch it anyway?

Because http traffic is supposed to be either latin-1 or whatever charset is specified (at least, to my understanding that is the case), so sending incorrectly encoded data seems wrong.

On the other hand, we support unix files systems not having well defined charsets, so extending this to directory listings in http isn't crazy.  That does raise the question, though, of passing the bytes through python3's string model without breaking anything, so some careful thought may be required.  I haven't looked at the details, though, so it might well be pretty simple.

Here is a patch which fixes handling of undecodable paths in SimpleHTTPRequestHandler.

Attached patch looks good to me. If an unittest can be provided for this situation in test_httpservers.py it will be comprehensive and will be good to go.

Here is a patch with a test.

New changeset f180a9156cc8 by Serhiy Storchaka in branch '3.4':
Issue #22165: SimpleHTTPRequestHandler now supports undecodable file names.
http://hg.python.org/cpython/rev/f180a9156cc8

New changeset 3153a400b739 by Serhiy Storchaka in branch 'default':
Issue #22165: SimpleHTTPRequestHandler now supports undecodable file names.
http://hg.python.org/cpython/rev/3153a400b739

Thank you for the review Senthil.

Looks like we hit with an encoding issue, which is due to way os.fsdecode() and os.listdir() decode the filenames.


>>> support.TESTFN_UNDECODABLE
b'@test_99678_tmp\xe7w\xf0'
>>> dir_list = os.listdir(self.tempdir)
>>> dir_list
['@test_99678_tmp%E7w%F0.txt', 'test']
>>> filename = os.fsdecode(support.TESTFN_UNDECODABLE) + '.txt'
>>> filename
'@test_99678_tmp\udce7w\udcf0.txt'


======================================================================
FAIL: test_undecodable_filename (test.test_httpservers.SimpleHTTPServerTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.4.murray-snowleopard/build/Lib/test/test_httpservers.py", line 282, in test_undecodable_filename
    .encode('utf-8', 'surrogateescape'), body)
AssertionError: b'href="%40test_62069_tmp%ED%B3%A7w%ED%B3%B0.txt"' not found in b'<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">\n<html>\n<head>\n<meta http-equiv="Content-Type" content="text/html; charset=utf-8">\n<title>Directory listing for tmp0asrs9ei/</title>\n</head>\n<body>\n<h1>Directory listing for tmp0asrs9ei/</h1>\n<hr>\n<ul>\n<li><a href="%40test_62069_tmp%25E7w%25F0.txt">@test_62069_tmp%E7w%F0.txt</a></li>\n<li><a href="test">test</a></li>\n</ul>\n<hr>\n</body>\n</html>\n'

New changeset a894b629bbea by Serhiy Storchaka in branch '3.4':
Issue #22165: Fixed test_undecodable_filename on non-UTF-8 locales.
http://hg.python.org/cpython/rev/a894b629bbea

New changeset 7cdc941d5180 by Serhiy Storchaka in branch 'default':
Issue #22165: Fixed test_undecodable_filename on non-UTF-8 locales.
http://hg.python.org/cpython/rev/7cdc941d5180

Oh, I missed that os.listdir() on Mac returns really strange result. Thank you Senthil.

Here is a patch which try to workaround this. I'm not sure that it is enough. May be we should fix os.listdir(). Or conclude that this issue can't be fixed on Mac OS.

OSX returns a strange value in os.listdir because the HFS+ filesystem itself has unicode filenames and transforms byte strings that are assumed to contain UTF-8 into something the filesystem can handle (and seems to replace bytes that aren't valid UTF-8 into a percent-encoded value).

Well, then the workaround should work.

New changeset b05d4f3ee190 by Serhiy Storchaka in branch '3.4':
Issue #22165: Fixed test_undecodable_filename on Mac OS.
http://hg.python.org/cpython/rev/b05d4f3ee190

New changeset 58e0d2c3ead8 by Serhiy Storchaka in branch 'default':
Issue #22165: Fixed test_undecodable_filename on Mac OS.
http://hg.python.org/cpython/rev/58e0d2c3ead8

New changeset 1bc41bbbe02d by Ned Deily in branch '3.4':
Issue #22165: Skip test_undecodable_filename on OS X prior to 10.5.
https://hg.python.org/cpython/rev/1bc41bbbe02d

New changeset 85258e08b69b by Ned Deily in branch 'default':
Issue #22165: merge from 3.4
https://hg.python.org/cpython/rev/85258e08b69b