[tahoe-lafs-trac-stream] [Tahoe-LAFS] #2394: ftp "ls" command is broken

[Tahoe-LAFS]

#2394: ftp "ls" command is broken
------------------------------------+------------------------
 Reporter:  warner                  |          Owner:
     Type:  defect                  |         Status:  new
 Priority:  normal                  |      Milestone:  1.10.1
Component:  code-frontend-ftp-sftp  |        Version:  1.10.0
 Keywords:  ftpd regression         |  Launchpad Bug:
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 While testing the fix for #2388, I noticed that FTP's "ls" command is
 broken. Apparently it was broken in 1.10.0 too, so I'm marking this as a
 release-blocking regression. I suspect it has to do with a change in
 Twisted, though, so maybe it worked at one point and we just got caught by
 an API change.

 {{{
 (ve)206:warner at brian-office-mini% ftp -P 8021 alice at localhost
 Trying 127.0.0.1...
 Connected to localhost.
 220 Twisted 15.0.0 FTP Server
 331 Password required for alice.
 Password:
 230 User logged in, proceed
 Remote system type is UNIX.
 Using binary mode to transfer files.
 ftp> ls
 227 Entering Passive Mode (127,0,0,1,220,56).
 125 Data connection already open, starting transfer
 <HANG>
 }}}

 twistd.log:

 {{{
 2015-03-24 10:16:13-0700 [-] Unexpected FTP error
 2015-03-24 10:16:13-0700 [-] Unhandled Error
         Traceback (most recent call last):
           File "/usr/local/lib/python2.7/site-
 packages/twisted/internet/base.py", line 824, in runUntilCurrent
             call.func(*call.args, **call.kw)
           File
 "/usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/lib/python2.7
 /site-packages/foolscap-0.7.0-py2.7.egg/foolscap/eventual.py", line 26, in
 _turn
             cb(*args, **kwargs)
           File "/usr/local/lib/python2.7/site-
 packages/twisted/internet/defer.py", line 383, in callback
             self._startRunCallbacks(result)
           File "/usr/local/lib/python2.7/site-
 packages/twisted/internet/defer.py", line 491, in _startRunCallbacks
             self._runCallbacks()
         --- <exception caught here> ---
           File "/usr/local/lib/python2.7/site-
 packages/twisted/internet/defer.py", line 578, in _runCallbacks
             current.result = callback(current.result, *args, **kw)
           File "/usr/local/lib/python2.7/site-
 packages/twisted/protocols/ftp.py", line 996, in gotListing
             self.dtpInstance.sendListResponse(name, attrs)
           File "/usr/local/lib/python2.7/site-
 packages/twisted/protocols/ftp.py", line 474, in sendListResponse
             self.sendLine(self._formatOneListResponse(name, *response))
           File "/usr/local/lib/python2.7/site-
 packages/twisted/protocols/ftp.py", line 464, in _formatOneListResponse
             'permissions': permissions.shorthand(),
         exceptions.AttributeError: 'int' object has no attribute
 'shorthand'
 }}}

 I'm guessing this involves
 `allmydata.frontends.ftpd.Handler._populate_row`, where it returns a fake
 (int) `0600` as the "permissions" key for all rows. I'm further guessing
 that Twisted's changed the API to require some sort of Permissions object.

 We need to check the range of Twisteds with which we claim compatibility,
 look at the variety of `ftp.IFTPShell` interfaces required by that set,
 and find a way to be compatible with all of them.

--
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2394>
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