Add static code checking for style and errors

This required a change to logging, which now uses a singleton pattern.

For all future checkins, 'make codecheck' should pass.

Makefile

@@ -1,5 +1,12 @@
+all: codecheck test
+
 clean:
 	rm -rf build dist build *.egg-info *.pyc
 
+codecheck: mininet/*.py mininet/test/*.py
+	pyflakes mininet/*.py mininet/test/*.py bin/*.py
+	pylint --rcfile=.pylint mininet/*.py mininet/test/*.py bin/*.py
+	pep8 --ignore=E251 mininet/*.py mininet/test/*.py bin/*.py
+
 test: mininet/*.py mininet/test/*.py
 	mininet/test/test_nets.py

bin/mn_clean.py

@@ -12,47 +12,47 @@ irreplaceable!
 """
 
 from subprocess import Popen, PIPE
-import re
 
-from mininet.util import quietRun
 from mininet.xterm import cleanUpScreens
 
-def sh( cmd ): 
+
-   "Print a command and send it to the shell"
+def sh(cmd):
-   print cmd
+    "Print a command and send it to the shell"
-   return Popen( [ '/bin/sh', '-c', cmd ], 
+    print cmd
-      stdout=PIPE ).communicate()[ 0 ]
+    return Popen(['/bin/sh', '-c', cmd], stdout=PIPE).communicate()[0]
 
 
 def cleanup():
-   """Clean up junk which might be left over from old runs;
+    """Clean up junk which might be left over from old runs;
-      do fast stuff before slow dp and link removal!"""
+       do fast stuff before slow dp and link removal!"""
 
-   print "*** Removing excess controllers/ofprotocols/ofdatapaths/pings/noxes"
+    print "*** Removing excess controllers/ofprotocols/ofdatapaths/pings/noxes"
-   zombies = 'controller ofprotocol ofdatapath ping nox_core lt-nox_core '
+    zombies = 'controller ofprotocol ofdatapath ping nox_core lt-nox_core '
-   zombies += 'udpbwtest'
+    zombies += 'udpbwtest'
-   # Note: real zombie processes can't actually be killed, since they 
+    # Note: real zombie processes can't actually be killed, since they
-   # are already (un)dead. Then again,
+    # are already (un)dead. Then again,
-   # you can't connect to them either, so they're mostly harmless.
+    # you can't connect to them either, so they're mostly harmless.
-   sh( 'killall -9 ' + zombies + ' 2> /dev/null' )
+    sh('killall -9 ' + zombies + ' 2> /dev/null')
 
-   print "*** Removing junk from /tmp"
+    print "*** Removing junk from /tmp"
-   sh( 'rm -f /tmp/vconn* /tmp/vlogs* /tmp/*.out /tmp/*.log' )
+    sh('rm -f /tmp/vconn* /tmp/vlogs* /tmp/*.out /tmp/*.log')
 
-   print "*** Removing old screen sessions"
+    print "*** Removing old screen sessions"
-   cleanUpScreens()
+    cleanUpScreens()
 
-   print "*** Removing excess kernel datapaths"
+    print "*** Removing excess kernel datapaths"
-   dps = sh( "ps ax | egrep -o 'dp[0-9]+' | sed 's/dp/nl:/'" ).split( '\n')
+    dps = sh("ps ax | egrep -o 'dp[0-9]+' | sed 's/dp/nl:/'").split('\n')
-   for dp in dps: 
+    for dp in dps:
-      if dp != '': sh( 'dpctl deldp ' + dp )
+        if dp != '':
+            sh('dpctl deldp ' + dp)
 
-   print "*** Removing all links of the pattern foo-ethX"
+    print "*** Removing all links of the pattern foo-ethX"
-   links = sh( "ip link show | egrep -o '(\w+-eth\w+)'" ).split( '\n' )
+    links = sh("ip link show | egrep -o '(\w+-eth\w+)'").split('\n')
-   for link in links: 
+    for link in links:
-      if link != '': sh( "ip link del " + link )
+        if link != '':
+            sh("ip link del " + link)
 
-   print "*** Cleanup complete."
+    print "*** Cleanup complete."
 
 if __name__ == "__main__":
-   cleanup()
+    cleanup()

bin/mn_run.py

@@ -13,7 +13,7 @@ try:
 except ImportError:
     USE_RIPCORD = False
 
-from mininet.logging_mod import lg, set_loglevel, LEVELS
+from mininet.logging_mod import lg, LEVELS
 from mininet.net import Mininet, init
 from mininet.node import KernelSwitch, Host, Controller, ControllerParams, NOX
 from mininet.node import RemoteController, UserSwitch
@@ -21,40 +21,41 @@ from mininet.topo import SingleSwitchTopo, LinearTopo, SingleSwitchReversedTopo
 
 # built in topologies, created only when run
 TOPO_DEF = 'minimal'
-TOPOS = {'minimal' :   (lambda: SingleSwitchTopo(k = 2)),
+TOPOS = {'minimal': (lambda: SingleSwitchTopo(k = 2)),
-         'reversed' :  (lambda: SingleSwitchReversedTopo(k = 2)),
+         'reversed': (lambda: SingleSwitchReversedTopo(k = 2)),
-         'single4' :   (lambda: SingleSwitchTopo(k = 4)),
+         'single4': (lambda: SingleSwitchTopo(k = 4)),
-         'single100' : (lambda: SingleSwitchTopo(k = 100)),
+         'single100': (lambda: SingleSwitchTopo(k = 100)),
-         'linear2' :   (lambda: LinearTopo(k = 2)),
+         'linear2': (lambda: LinearTopo(k = 2)),
-         'linear100' : (lambda: LinearTopo(k = 100))}
+         'linear100': (lambda: LinearTopo(k = 100))}
 if USE_RIPCORD:
     TOPOS_RIPCORD = {
-         'tree16' :   (lambda: TreeTopo(depth = 3, fanout = 4)),
+         'tree16': (lambda: TreeTopo(depth = 3, fanout = 4)),
-         'tree64' :   (lambda: TreeTopo(depth = 4, fanout = 4)),
+         'tree64': (lambda: TreeTopo(depth = 4, fanout = 4)),
-         'tree1024' : (lambda: TreeTopo(depth = 3, fanout = 32)),
+         'tree1024': (lambda: TreeTopo(depth = 3, fanout = 32)),
-         'fattree4' : (lambda: FatTreeTopo(k = 4)),
+         'fattree4': (lambda: FatTreeTopo(k = 4)),
-         'fattree6' : (lambda: FatTreeTopo(k = 6)),
+         'fattree6': (lambda: FatTreeTopo(k = 6)),
-         'vl2'      : (lambda: VL2Topo(da = 4, di = 4))}
+         'vl2': (lambda: VL2Topo(da = 4, di = 4))}
     TOPOS.update(TOPOS_RIPCORD)
 
 SWITCH_DEF = 'kernel'
-SWITCHES = {'kernel' : KernelSwitch,
+SWITCHES = {'kernel': KernelSwitch,
-            'user' : UserSwitch}
+            'user': UserSwitch}
 
 HOST_DEF = 'process'
-HOSTS = {'process' : Host}
+HOSTS = {'process': Host}
 
 CONTROLLER_DEF = 'ref'
 # a and b are the name and inNamespace params.
-CONTROLLERS = {'ref' : Controller,
+CONTROLLERS = {'ref': Controller,
-               'nox_dump' : lambda a, b: NOX(a, b, 'packetdump'),
+               'nox_dump': lambda a, b: NOX(a, b, 'packetdump'),
-               'nox_pysw' : lambda a, b: NOX(a, b, 'pyswitch'),
+               'nox_pysw': lambda a, b: NOX(a, b, 'pyswitch'),
-               'remote' : lambda a, b: None,
+               'remote': lambda a, b: None,
-               'none' :     lambda a, b: None}
+               'none': lambda a, b: None}
 
 # optional tests to run
 TESTS = ['cli', 'build', 'ping_all', 'ping_pair', 'iperf', 'all', 'iperf_udp']
 
+
 def add_dict_option(opts, choices_dict, default, name, help_str = None):
     '''Convenience function to add choices dicts to OptionParser.
 
@@ -124,7 +125,7 @@ class MininetRunner(object):
         '''Setup and validate environment.'''
 
         # set logging verbosity
-        set_loglevel(self.options.verbosity)
+        lg.set_loglevel(self.options.verbosity)
 
         # validate environment setup
         init()

mininet/__init__.py

@@ -0,0 +1 @@
+'''Docstring to silence pylint; ignores --ignore option for __init__.py'''

mininet/logging_mod.py

@@ -1,6 +1,7 @@
 '''Logging functions for Mininet.'''
 
 import logging
+from logging import Logger
 import types
 
 LEVELS = {'debug': logging.DEBUG,
@@ -16,7 +17,6 @@ LOG_LEVEL_DEFAULT = logging.WARNING
 LOG_MSG_FORMAT = '%(message)s'
 
 
-
 # Modified from python2.5/__init__.py
 class StreamHandlerNoNewline(logging.StreamHandler):
     '''StreamHandler that doesn't print newlines by default.
@@ -53,31 +53,52 @@ class StreamHandlerNoNewline(logging.StreamHandler):
             self.handleError(record)
 
 
-def set_loglevel(level_name = None):
+class Singleton(type):
-    '''Setup loglevel.
+    '''Singleton pattern from Wikipedia
 
-    @param level_name level name from LEVELS
+    See http://en.wikipedia.org/wiki/Singleton_pattern#Python
+
+    Intended to be used as a __metaclass_ param, as shown for the class below.
+
+    Changed cls first args to mcs to satsify pylint.
     '''
-    level = LOG_LEVEL_DEFAULT
-    if level_name != None:
-        if level_name not in LEVELS:
-            raise Exception('unknown loglevel seen in set_loglevel')
-        else:
-            level = LEVELS.get(level_name, level)
 
-    lg.setLevel(level)
+    def __init__(mcs, name, bases, dict_):
-    if len(lg.handlers) != 1:
+        super(Singleton, mcs).__init__(name, bases, dict_)
-        raise Exception('lg.handlers length not zero in logging_mod')
+        mcs.instance = None
-    lg.handlers[0].setLevel(level)
+
+    def __call__(mcs, *args, **kw):
+        if mcs.instance is None:
+            mcs.instance = super(Singleton, mcs).__call__(*args, **kw)
+            return mcs.instance
 
 
-def _setup_logging():
+class MininetLogger(Logger, object):
-    '''Setup logging for Mininet.'''
+    '''Mininet-specific logger
-    global lg
+
+    Enable each mininet .py file to with one import:
+
+       from mininet.logging_mod import lg
+
+    ...get a default logger that doesn't require one newline per logging call.
+
+    Inherit from object to ensure that we have at least one new-style base
+    class, and can then use the __metaclass__ directive, to prevent this error:
+
+      TypeError: Error when calling the metaclass bases
+       a new-style class can't have only classic bases
+
+    If Python2.5/logging/__init__.py defined Filterer as a new-style class,
+    via Filterer(object): rather than Filterer, we wouldn't need this.
+
+    Use singleton pattern to ensure only one logger is ever created.
+    '''
+    __metaclass__ = Singleton
+
+    def __init__(self):
+
+        Logger.__init__(self, "mininet")
 
-    # create logger if first time
-    if 'lg' not in globals():
-        lg = logging.getLogger('mininet')
         # create console handler
         ch = StreamHandlerNoNewline()
         # create formatter
@@ -85,15 +106,26 @@ def _setup_logging():
         # add formatter to ch
         ch.setFormatter(formatter)
         # add ch to lg
-        lg.addHandler(ch)
+        self.addHandler(ch)
-    else:
-        raise Exception('setup_logging called twice')
 
-    set_loglevel()
+        self.set_loglevel()
+
+    def set_loglevel(self, levelname = None):
+        '''Setup loglevel.
+
+        Convenience function to support lowercase names.
+
+        @param level_name level name from LEVELS
+        '''
+        level = LOG_LEVEL_DEFAULT
+        if levelname != None:
+            if levelname not in LEVELS:
+                raise Exception('unknown loglevel seen in set_loglevel')
+            else:
+                level = LEVELS.get(levelname, level)
+
+        self.setLevel(level)
+        self.handlers[0].setLevel(level)
 
 
-# There has to be some better way to ensure we only ever have one logging
+lg = MininetLogger()
-# variable.  If this check isn't in, the order in which imports occur can
-# affect whether a program runs, because the variable lg may get rebound.
-if 'lg' not in globals():
-    _setup_logging()

mininet/net.py

@@ -210,7 +210,7 @@ class Mininet(object):
 
         For use with the user datapath only right now.
 
-        @todo(brandonh) Test this code and verify that user-space works!
+        @todo(brandonh) Test this code!
         '''
         # params were: controller, switches, ips
 
@@ -242,12 +242,12 @@ class Mininet(object):
             while not switch.intfIsUp(switch.intfs[0]):
                 lg.info('*** Waiting for %s to come up\n' % switch.intfs[0])
                 sleep(1)
-            if self.ping_test(hosts=[switch, controller]) != 0:
+            if self.ping(hosts = [switch, controller]) != 0:
                 lg.error('*** Error: control network test failed\n')
                 exit(1)
         lg.info('\n')
 
-    def _config_hosts( self ):
+    def _config_hosts(self):
         '''Configure a set of hosts.'''
         # params were: hosts, ips
         for host_dpid in self.topo.hosts():
@@ -343,7 +343,7 @@ class Mininet(object):
     def start(self):
         '''Start controller and switches\n'''
         lg.info('*** Starting controller\n')
-        for cname, cnode in self.controllers.iteritems():
+        for cnode in self.controllers.values():
             cnode.start()
         lg.info('*** Starting %s switches\n' % len(self.topo.switches()))
         for switch_dpid in self.topo.switches():
@@ -371,7 +371,7 @@ class Mininet(object):
             switch.stop()
         lg.info('\n')
         lg.info('*** Stopping controller\n')
-        for cname, cnode in self.controllers.iteritems():
+        for cnode in self.controllers.values():
             cnode.stop()
         lg.info('*** Test complete\n')
 
@@ -387,7 +387,7 @@ class Mininet(object):
     def _parse_ping(pingOutput):
         '''Parse ping output and return packets sent, received.'''
         r = r'(\d+) packets transmitted, (\d+) received'
-        m = re.search( r, pingOutput )
+        m = re.search(r, pingOutput)
         if m == None:
             lg.error('*** Error: could not parse ping output: %s\n' %
                      pingOutput)
@@ -422,7 +422,7 @@ class Mininet(object):
                         lg.error('*** Error: received too many packets')
                         lg.error('%s' % result)
                         node.cmdPrint('route')
-                        exit( 1 )
+                        exit(1)
                     lost += sent - received
                     lg.info(('%s ' % dest.name) if received else 'X ')
             lg.info('\n')
@@ -490,7 +490,8 @@ class Mininet(object):
         server = host0.cmd(iperf_args + '-s &')
         if verbose:
             lg.info('%s\n' % server)
-        client = host1.cmd(iperf_args + '-t 5 -c ' + host0.IP() + ' ' + bw_args)
+        client = host1.cmd(iperf_args + '-t 5 -c ' + host0.IP() + ' ' +
+                           bw_args)
         if verbose:
             lg.info('%s\n' % client)
         server = host0.cmd('killall -9 iperf')
@@ -529,6 +530,10 @@ class MininetCLI(object):
         self.nodelist = self.nodemap.values()
         self.run()
 
+    # Disable pylint "Unused argument: 'arg's'" messages.
+    # Each CLI function needs the same interface.
+    # pylint: disable-msg=W0613
+
     # Commands
     def help(self, args):
         '''Semi-useful help for CLI.'''
@@ -561,7 +566,7 @@ class MininetCLI(object):
             switch = self.mn.nodes[switch_dpid]
             lg.info('%s <->', switch.name)
             for intf in switch.intfs:
-                node, remoteIntf = switch.connection[intf]
+                node = switch.connection[intf]
                 lg.info(' %s' % node.name)
             lg.info('\n')
 
@@ -588,25 +593,28 @@ class MininetCLI(object):
 
     def intfs(self, args):
         '''List interfaces.'''
-        for dpid, node in self.mn.nodes.iteritems():
+        for node in self.mn.nodes.values():
             lg.info('%s: %s\n' % (node.name, ' '.join(node.intfs)))
 
     def dump(self, args):
         '''Dump node info.'''
-        for dpid, node in self.mn.nodes.iteritems():
+        for node in self.mn.nodes.values():
             lg.info('%s\n' % node)
 
+    # Re-enable pylint "Unused argument: 'arg's'" messages.
+    # pylint: enable-msg=W0613
+
     def run(self):
         '''Read and execute commands.'''
         lg.warn('*** Starting CLI:\n')
         while True:
             lg.warn('mininet> ')
-            input = sys.stdin.readline()
+            input_line = sys.stdin.readline()
-            if input == '':
+            if input_line == '':
                 break
-            if input[-1] == '\n':
+            if input_line[-1] == '\n':
-                input = input[:-1]
+                input_line = input_line[:-1]
-            cmd = input.split(' ')
+            cmd = input_line.split(' ')
             first = cmd[0]
             rest = cmd[1:]
             if first in self.cmds and hasattr(self, first):
@@ -634,7 +642,7 @@ class MininetCLI(object):
             elif first in ['exit', 'quit']:
                 break
             elif first == '?':
-                self.help( rest )
+                self.help(rest)
             else:
                 lg.error('CLI: unknown node or command: < %s >\n' % first)
             #lg.info('*** CLI: command complete\n')

mininet/node.py

@@ -2,13 +2,17 @@
 '''Node objects for Mininet.'''
 
 from subprocess import Popen, PIPE, STDOUT
-import os, signal, sys, select
+import os
+import signal
+import sys
+import select
 
 flush = sys.stdout.flush
 
 from mininet.logging_mod import lg
 from mininet.util import quietRun, macColonHex, ipStr
 
+
 class Node(object):
     '''A virtual network node is simply a shell in a network namespace.
        We communicate with it using pipes.'''
@@ -129,7 +133,8 @@ class Node(object):
             if len(data) > 0  and data[-1] == chr(0177):
                 output += data[:-1]
                 break
-            else: output += data
+            else:
+                output += data
         self.waiting = False
         return output
 
@@ -215,7 +220,7 @@ class Node(object):
     def IP(self):
         '''Return IP address of first interface'''
         if len(self.intfs) > 0:
-            return self.ips.get(self.intfs[ 0 ], None)
+            return self.ips.get(self.intfs[0], None)
 
     def intfIsUp(self):
         '''Check if one of our interfaces is up.'''
@@ -258,6 +263,7 @@ class Switch(Node):
         else:
             return True, ''
 
+
 class UserSwitch(Switch):
     '''User-space switch.
 
@@ -269,7 +275,7 @@ class UserSwitch(Switch):
 
         @param name
         '''
-        Node.__init__(self, name, inNamespace = False)
+        Switch.__init__(self, name, inNamespace = False)
 
     def start(self, controllers):
         '''Start OpenFlow reference user datapath.
@@ -298,6 +304,12 @@ class UserSwitch(Switch):
 
 
 class KernelSwitch(Switch):
+    '''Kernel-space switch.
+
+    Much faster than user-space!
+
+    Currently only works in the root namespace.
+    '''
 
     def __init__(self, name, dp = None, dpid = None):
         '''Init.
@@ -306,7 +318,7 @@ class KernelSwitch(Switch):
         @param dp netlink id (0, 1, 2, ...)
         @param dpid datapath ID as unsigned int; random value if None
         '''
-        Node.__init__(self, name, inNamespace = False)
+        Switch.__init__(self, name, inNamespace = False)
         self.dp = dp
         self.dpid = dpid
 
@@ -333,7 +345,7 @@ class KernelSwitch(Switch):
                       controllers['c0'].IP() + ':' +
                       str(controllers['c0'].port) +
                       ' --fail=closed 1> ' + ofplog + ' 2>' + ofplog + ' &')
-        self.execed = False # XXX until I fix it
+        self.execed = False
 
     def stop(self):
         '''Terminate reference kernel datapath.'''
@@ -372,7 +384,7 @@ class Controller(Node):
             self.cmdPrint('cd ' + self.cdir)
         self.cmdPrint(self.controller + ' ' + self.cargs +
             ' 1> ' + cout + ' 2> ' + cout + ' &')
-        self.execed = False # XXX Until I fix it
+        self.execed = False
 
     def stop(self):
         '''Stop controller.'''
@@ -386,6 +398,7 @@ class Controller(Node):
 
 class ControllerParams(object):
     '''Container for controller IP parameters.'''
+
     def __init__(self, ip, subnet_size):
         '''Init.
 
@@ -398,6 +411,7 @@ class ControllerParams(object):
 
 class NOX(Controller):
     '''Controller to run a NOX application.'''
+
     def __init__(self, name, inNamespace = False, nox_args = None, **kwargs):
         '''Init.
 
@@ -420,6 +434,7 @@ class NOX(Controller):
 
 class RemoteController(Controller):
     '''Controller running outside of Mininet's control.'''
+
     def __init__(self, name, inNamespace = False, ip_address = '127.0.0.1',
                  port = 6633):
         '''Init.

mininet/test/test_nets.py

@@ -4,7 +4,6 @@
 Test creation and all-pairs ping for each included mininet topo type.
 '''
 
-from time import sleep
 import unittest
 
 from mininet.net import init, Mininet
@@ -12,7 +11,7 @@ from mininet.node import KernelSwitch, Host, Controller, ControllerParams
 from mininet.topo import SingleSwitchTopo, LinearTopo
 
 # temporary, until user-space side is tested
-SWITCHES = {'kernel' : KernelSwitch}
+SWITCHES = {'kernel': KernelSwitch}
 
 
 class testSingleSwitch(unittest.TestCase):

mininet/topo.py

@@ -11,7 +11,7 @@ A Topo object can be a topology database for NOX, can represent a physical
 setup for testing, and can even be emulated with the Mininet package.
 '''
 
-from networkx import Graph
+from networkx.classes.graph import Graph
 
 
 class NodeID(object):
@@ -87,6 +87,7 @@ class Edge(object):
 
 class Topo(object):
     '''Data center network representation for structured multi-trees.'''
+
     def __init__(self):
         '''Create Topo object.
 
@@ -182,6 +183,7 @@ class Topo(object):
 
         @return dpids list of dpids
         '''
+
         def is_switch(n):
             '''Returns true if node is a switch.'''
             return self.node_info[n].is_switch
@@ -196,6 +198,7 @@ class Topo(object):
 
         @return dpids list of dpids
         '''
+
         def is_host(n):
             '''Returns true if node is a host.'''
             return not self.node_info[n].is_switch

mininet/util.py

@@ -99,6 +99,7 @@ def move_intf(intf, node):
 # live in the root namespace and thus do not have to be
 # explicitly moved.
 
+
 def makeIntfPair(intf1, intf2):
     '''Make a veth pair.
 
@@ -111,7 +112,7 @@ def makeIntfPair(intf1, intf2):
     quietRun('ip link del ' + intf2)
     # Create new pair
     cmd = 'ip link add name ' + intf1 + ' type veth peer name ' + intf2
-    return checkRun( cmd )
+    return checkRun(cmd)
 
 
 def moveIntf(intf, node, print_error = False):
@@ -132,7 +133,7 @@ def moveIntf(intf, node, print_error = False):
     return True
 
 
-def retry(n, retry_delay, fn, *args):
+def retry(n, retry_delay, fn, *args, **keywords):
     '''Try something N times before giving up.
 
     @param n number of times to retry
@@ -141,12 +142,12 @@ def retry(n, retry_delay, fn, *args):
     @param args args to apply to function call
     '''
     tries = 0
-    while not apply(fn, args) and tries < n:
+    while not fn(*args, **keywords) and tries < n:
         sleep(retry_delay)
         tries += 1
     if tries >= n:
         lg.error("*** gave up after %i retries\n" % tries)
-        exit( 1 )
+        exit(1)
 
 
 # delay between interface move checks in seconds
@@ -154,6 +155,7 @@ MOVEINTF_DELAY = 0.0001
 
 CREATE_LINK_RETRIES = 10
 
+
 def createLink(node1, node2):
     '''Create a link between nodes, making an interface for each.
 
@@ -174,8 +176,8 @@ def createLink(node1, node2):
 
 def fixLimits():
     '''Fix ridiculously small resource limits.'''
-    setrlimit( RLIMIT_NPROC, (4096, 8192))
+    setrlimit(RLIMIT_NPROC, (4096, 8192))
-    setrlimit( RLIMIT_NOFILE, (16384, 32768))
+    setrlimit(RLIMIT_NOFILE, (16384, 32768))
 
 
 def _colonHex(val, bytes):
@@ -186,7 +188,7 @@ def _colonHex(val, bytes):
     @return ch_str colon-hex string
     '''
     pieces = []
-    for i in range (bytes - 1, -1, -1):
+    for i in range(bytes - 1, -1, -1):
         pieces.append('%02x' % (((0xff << (i * 8)) & val) >> (i * 8)))
     ch_str = ':'.join(pieces)
     return ch_str

mininet/xterm.py

@@ -6,12 +6,12 @@ Utility functions to run an xterm (connected via screen(1)) on each host.
 Requires xterm(1) and GNU screen(1).
 """
 
-import os
 import re
 from subprocess import Popen
 
 from mininet.util import quietRun
 
+
 def makeXterm(node, title):
     '''Run screen on a node, and hook up an xterm.