TST: Revert changes for filter testcase open statement

Also merging python3 support

fail2ban/tests/filtertestcase.py

@@ -22,6 +22,7 @@
 __copyright__ = "Copyright (c) 2004 Cyril Jaquier; 2012 Yaroslav Halchenko"
 __license__ = "GPL"
 
+from __builtin__ import open as fopen
 import unittest
 import os
 import sys
@@ -44,13 +45,18 @@ TEST_FILES_DIR = os.path.join(os.path.dirname(__file__), "files")
 # https://github.com/fail2ban/fail2ban/issues/103#issuecomment-15542836
 # adding a sufficiently large buffer might help to guarantee that
 # writes happen atomically.
-# Overload also for python3 to use utf-8 encoding by default
-if sys.version_info >= (3,):
-	def open_(filename, mode):
-		return open(filename, mode, 50000, encoding='utf-8', errors='ignore')
-else:
-	def open_(filename, mode):
-		return open(filename, mode, 50000)
+def open(*args):
+	"""Overload built in open so we could assure sufficiently large buffer
+
+	Explicit .flush would be needed to assure that changes leave the buffer
+	"""
+	if len(args) == 2:
+		# ~50kB buffer should be sufficient for all tests here.
+		args = args + (50000,)
+	if sys.version_info >= (3,):
+		return fopen(*args, encoding='utf-8', errors='ignore')
+	else:
+		return fopen(*args)
 
 def _killfile(f, name):
 	try:
@@ -126,7 +132,7 @@ def _copy_lines_between_files(fin, fout, n=None, skip=0, mode='a', terminal_line
 		# polling filter could detect the change
 		time.sleep(1)
 	if isinstance(fin, str): # pragma: no branch - only used with str in test cases
-		fin = open_(fin, 'r')
+		fin = open(fin, 'r')
 	# Skip
 	for i in xrange(skip):
 		_ = fin.readline()
@@ -141,7 +147,7 @@ def _copy_lines_between_files(fin, fout, n=None, skip=0, mode='a', terminal_line
 		i += 1
 	# Write: all at once and flush
 	if isinstance(fout, str):
-		fout = open_(fout, mode)
+		fout = open(fout, mode)
 	fout.write('\n'.join(lines))
 	fout.flush()
 	# to give other threads possibly some time to crunch
@@ -209,7 +215,7 @@ class LogFileMonitor(unittest.TestCase):
 		"""Call before every test case."""
 		self.filter = self.name = 'NA'
 		_, self.name = tempfile.mkstemp('fail2ban', 'monitorfailures')
-		self.file = open_(self.name, 'a')
+		self.file = open(self.name, 'a')
 		self.filter = FilterPoll(None)
 		self.filter.addLogPath(self.name)
 		self.filter.setActive(True)
@@ -251,7 +257,7 @@ class LogFileMonitor(unittest.TestCase):
 		# we are not signaling as modified whenever
 		# it gets away
 		self.assertTrue(self.notModified())
-		f = open_(self.name, 'a')
+		f = open(self.name, 'a')
 		self.assertTrue(self.isModified())
 		self.assertTrue(self.notModified())
 		_sleep_4_poll()
@@ -360,7 +366,7 @@ def get_monitor_failures_testcase(Filter_):
 			self.filter = self.name = 'NA'
 			self.name = '%s-%d' % (testclass_name, self.count)
 			MonitorFailures.count += 1 # so we have unique filenames across tests
-			self.file = open_(self.name, 'a')
+			self.file = open(self.name, 'a')
 			self.jail = DummyJail()
 			self.filter = Filter_(self.jail)
 			self.filter.addLogPath(self.name)
@@ -483,7 +489,7 @@ def get_monitor_failures_testcase(Filter_):
 			self.assert_correct_last_attempt(GetFailures.FAILURES_01)
 
 			# create a bogus file in the same directory and see if that doesn't affect
-			open_(self.name + '.bak2', 'w').write('')
+			open(self.name + '.bak2', 'w').write('')
 			_copy_lines_between_files(GetFailures.FILENAME_01, self.name, n=100)
 			self.assert_correct_last_attempt(GetFailures.FAILURES_01)
 			self.assertEqual(self.filter.failManager.getFailTotal(), 6)