SFTP: fix pyflakes warnings; drop 'noisy' versions of eventually_callback and eventually_errback; robustify conversion of exception messages to UTF-8.

src/allmydata/frontends/sftpd.py

@@ -43,11 +43,12 @@ warnings.filterwarnings("ignore", category=DeprecationWarning,
 noisy = True
 use_foolscap_logging = True
 
-from allmydata.util.log import NOISY, OPERATIONAL, SCARY
+from allmydata.util.log import NOISY, OPERATIONAL, \
+    msg as _msg, err as _err, PrefixingLogMixin as _PrefixingLogMixin
 
 if use_foolscap_logging:
-    from allmydata.util.log import msg as logmsg, err as logerr, PrefixingLogMixin
-else:
+    (logmsg, logerr, PrefixingLogMixin) = (_msg, _err, _PrefixingLogMixin)
+else:  # pragma: no cover
     def logmsg(s, level=None):
         print s
     def logerr(s, level=None):
@@ -58,35 +59,7 @@ else:
         def log(self, s, level=None):
             print s
 
-if noisy:
-    def eventually_callback(d):
-        s = traceback.format_stack()
-        def _cb(res):
-            try:
-                if noisy: logmsg("CALLBACK %r" % (d,), level=NOISY)
-                d.callback(res)
-            except:  # pragma: no cover
-                logerr("Failed to callback %r with %r\n"
-                       "Original stack:\n!%s" %
-                       (d, res, '!'.join(s)), level=SCARY)
-                traceback.print_exc()
-                raise
-        return lambda res: eventually(_cb, res)
 
-    def eventually_errback(d):
-        s = traceback.format_stack()
-        def _eb(err):
-            try:
-                if noisy: logmsg("ERRBACK %r %r" % (d, err), level=NOISY)
-                d.errback(err)
-            except:  # pragma: no cover
-                logerr("Failed to errback %r with %r\n"
-                       "Original stack:\n!%s" %
-                       (d, err, '!'.join(s)), level=SCARY)
-                traceback.print_exc()
-                raise
-        return lambda err: eventually(_eb, err)
-else:
 def eventually_callback(d):
     return lambda res: eventually(d.callback, res)
 
@@ -94,6 +67,14 @@ else:
     return lambda err: eventually(d.errback, err)
 
 
+def _utf8(x):
+    if isinstance(x, unicode):
+        return x.encode('utf-8')
+    if isinstance(x, str):
+        return x
+    return repr(x)
+
+
 def _convert_error(res, request):
     if not isinstance(res, Failure):
         logged_res = res
@@ -112,10 +93,10 @@ def _convert_error(res, request):
         # original raiser of SFTPError has responsibility to ensure anonymity
         raise err
     if err.check(NoSuchChildError):
-        childname = err.value.args[0].encode('utf-8')
+        childname = _utf8(err.value.args[0])
         raise SFTPError(FX_NO_SUCH_FILE, childname)
     if err.check(NotWriteableError):
-        msg = err.value.args[0].encode('utf-8')
+        msg = _utf8(err.value.args[0])
         raise SFTPError(FX_PERMISSION_DENIED, msg)
     if err.check(ExistingChildError):
         # Versions of SFTP after v3 (which is what twisted.conch implements)
@@ -124,17 +105,17 @@ def _convert_error(res, request):
         # FX_FAILURE. The gvfs SFTP backend, for example, depends on this
         # to translate the error to the equivalent of POSIX EEXIST, which is
         # necessary for some picky programs (such as gedit).
-        msg = err.value.args[0].encode('utf-8')
+        msg = _utf8(err.value.args[0])
         raise SFTPError(FX_FAILURE, msg)
     if err.check(NotImplementedError):
-        raise SFTPError(FX_OP_UNSUPPORTED, str(err.value))
+        raise SFTPError(FX_OP_UNSUPPORTED, _utf8(err.value))
     if err.check(EOFError):
         raise SFTPError(FX_EOF, "end of file reached")
     if err.check(defer.FirstError):
         _convert_error(err.value.subFailure, request)
 
     # We assume that the error message is not anonymity-sensitive.
-    raise SFTPError(FX_FAILURE, str(err.value))
+    raise SFTPError(FX_FAILURE, _utf8(err.value))
 
 
 def _repr_flags(flags):
@@ -161,7 +142,7 @@ def _lsLine(name, attrs):
     # We don't know how many links there really are to this object.
     st_nlink = 1
 
-    # From <http://twistedmatrix.com/trac/browser/trunk/twisted/conch/ls.py?rev=25412>.
+    # Based on <http://twistedmatrix.com/trac/browser/trunk/twisted/conch/ls.py?rev=25412>.
     # We can't call the version in Twisted because we might have a version earlier than
     # <http://twistedmatrix.com/trac/changeset/25412> (released in Twisted 8.2).
 
@@ -209,8 +190,7 @@ def _lsLine(name, attrs):
 
 
 def _is_readonly(parent_readonly, child):
-    """Whether child should be treated as having read-only permissions when listed
-    in parent."""
+    """Whether child should be listed as having read-only permissions in parent."""
 
     if child.is_unknown():
         return True

src/allmydata/test/test_sftp.py

@@ -1,5 +1,5 @@
 
-import re, struct
+import re, struct, traceback
 from stat import S_IFREG, S_IFDIR
 
 from twisted.trial import unittest
@@ -23,31 +23,6 @@ if have_pycrypto:
     from twisted.conch.ssh import filetransfer as sftp
     from allmydata.frontends import sftpd
 
-import traceback
-
-"""
-import sys
-def trace_exceptions(frame, event, arg):
-    if event != 'exception':
-        return
-    co = frame.f_code
-    func_name = co.co_name
-    line_no = frame.f_lineno
-    filename = co.co_filename
-    exc_type, exc_value, exc_traceback = arg
-    print 'Tracing exception: %r %r on line %r of %r in %r' % \
-        (exc_type.__name__, exc_value, line_no, func_name, filename)
-
-def trace_calls(frame, event, arg):
-    if event != 'call':
-        return
-    return trace_exceptions
-
-sys.settrace(trace_calls)
-"""
-
-timeout = 240
-
 from allmydata.interfaces import IDirectoryNode, ExistingChildError, NoSuchChildError
 from allmydata.mutable.common import NotWriteableError
 
@@ -56,6 +31,8 @@ from allmydata.immutable import upload
 from allmydata.test.no_network import GridTestMixin
 from allmydata.test.common import ShouldFailMixin
 
+timeout = 240
+
 class Handler(GridTestMixin, ShouldFailMixin, unittest.TestCase):
     """This is a no-network unit test of the SFTPHandler class."""