Kinder, gentler Python 3 compatibility

Looking at trying to minimize code changes for Python 3.

For now we are keeping byte str() in py2 and unicode str()
in py3. It's a pain to rewrite all string code to usee
u'' for py2 compatibility. However we may need to revisit
this for pexpect().

Created compatibility wrappers in util.py:

BaseString (replacement for basestring)
decode() (optionally decode utf-8 for py3)
encode() (optionally encode utf-8 for py3)

Also we've switched from the .iter*() flavors to their
static alternatives for py2 (note they are iterators in py3!)

Changed util.errRun and clean.sh to call decode()

bin/mn

@@ -256,7 +256,7 @@ class MininetRunner( object ):
         opts.add_option( '--arp', action='store_true',
                          default=False, help='set all-pairs ARP entries' )
         opts.add_option( '--verbosity', '-v', type='choice',
-                         choices=LEVELS.keys(), default = 'info',
+                         choices=list( LEVELS.keys() ), default = 'info',
                          help = '|'.join( LEVELS.keys() )  )
         opts.add_option( '--innamespace', action='store_true',
                          default=False, help='sw and ctrl in namespace?' )
@@ -286,7 +286,7 @@ class MininetRunner( object ):
                          metavar='server1,server2...',
                          help=( 'run on multiple servers (experimental!)' ) )
         opts.add_option( '--placement', type='choice',
-                         choices=PLACEMENT.keys(), default='block',
+                         choices=list( PLACEMENT.keys() ), default='block',
                          metavar='block|random',
                          help=( 'node placement for --cluster '
                                 '(experimental!) ' ) )

mininet/clean.py

@@ -16,12 +16,13 @@ import time
 
 from mininet.log import info
 from mininet.term import cleanUpScreens
-
+from mininet.util import decode
 
 def sh( cmd ):
     "Print a command and send it to the shell"
     info( cmd + '\n' )
-    return Popen( [ '/bin/sh', '-c', cmd ], stdout=PIPE ).communicate()[ 0 ]
+    result = Popen( [ '/bin/sh', '-c', cmd ], stdout=PIPE ).communicate()[ 0 ]
+    return decode( result )
 
 def killprocs( pattern ):
     "Reliably terminate processes matching a pattern (including args)"
@@ -76,7 +77,6 @@ class Cleanup( object ):
         for dp in dps:
             if dp:
                 sh( 'dpctl deldp ' + dp )
-
         info( "***  Removing OVS datapaths\n" )
         dps = sh("ovs-vsctl --timeout=1 list-br").strip().splitlines()
         if dps:

mininet/link.py

@@ -164,7 +164,7 @@ class Intf( object ):
            method: config method name
            param: arg=value (ignore if value=None)
            value may also be list or dict"""
-        name, value = param.items()[ 0 ]
+        name, value = list( param.items() )[ 0 ]
         f = getattr( self, method, None )
         if not f or value is None:
             return

mininet/moduledeps.py

@@ -1,6 +1,6 @@
 "Module dependency utility functions for Mininet."
 
-from mininet.util import quietRun
+from mininet.util import quietRun, BaseString
 from mininet.log import info, error, debug
 from os import environ
 
@@ -28,9 +28,9 @@ def moduleDeps( subtract=None, add=None ):
        add: string or list of module names to add, if not already loaded"""
     subtract = subtract if subtract is not None else []
     add = add if add is not None else []
-    if isinstance( subtract, basestring ):
+    if isinstance( subtract, BaseString ):
         subtract = [ subtract ]
-    if isinstance( add, basestring ):
+    if isinstance( add, BaseString ):
         add = [ add ]
     for mod in subtract:
         if mod in lsmod():

mininet/net.py

@@ -104,7 +104,7 @@ from mininet.nodelib import NAT
 from mininet.link import Link, Intf
 from mininet.util import ( quietRun, fixLimits, numCores, ensureRoot,
                            macColonHex, ipStr, ipParse, netParse, ipAdd,
-                           waitListening )
+                           waitListening, BaseString )
 from mininet.term import cleanUpScreens, makeTerms
 
 # Mininet version: should be consistent with README and LICENSE
@@ -383,8 +383,8 @@ class Mininet( object ):
             params: additional link params (optional)
             returns: link object"""
         # Accept node objects or names
-        node1 = node1 if not isinstance( node1, basestring ) else self[ node1 ]
+        node1 = node1 if not isinstance( node1, BaseString ) else self[ node1 ]
-        node2 = node2 if not isinstance( node2, basestring ) else self[ node2 ]
+        node2 = node2 if not isinstance( node2, BaseString ) else self[ node2 ]
         options = dict( params )
         # Port is optional
         if port1 is not None:

mininet/node.py

@@ -62,7 +62,8 @@ from time import sleep
 
 from mininet.log import info, error, warn, debug
 from mininet.util import ( quietRun, errRun, errFail, moveIntf, isShellBuiltin,
-                           numCores, retry, mountCgroups )
+                           numCores, retry, mountCgroups, BaseString, decode,
+                           encode )
 from mininet.moduledeps import moduleDeps, pathCheck, TUN
 from mininet.link import Link, Intf, TCIntf, OVSIntf
 from re import findall
@@ -144,7 +145,9 @@ class Node( object ):
         master, slave = pty.openpty()
         self.shell = self._popen( cmd, stdin=slave, stdout=slave, stderr=slave,
                                   close_fds=False )
-        self.stdin = os.fdopen( master, 'rw' )
+        # XXX BL: This doesn't seem right, and we should also probably
+        # close our files when we exit...
+        self.stdin = os.fdopen( master, 'r' )
         self.stdout = self.stdin
         self.pid = self.shell.pid
         self.pollOut = select.poll()
@@ -171,7 +174,7 @@ class Node( object ):
     def mountPrivateDirs( self ):
         "mount private directories"
         # Avoid expanding a string into a list of chars
-        assert not isinstance( self.privateDirs, basestring )
+        assert not isinstance( self.privateDirs, BaseString )
         for directory in self.privateDirs:
             if isinstance( directory, tuple ):
                 # mount given private directory
@@ -218,7 +221,7 @@ class Node( object ):
            maxbytes: maximum number of bytes to return"""
         count = len( self.readbuf )
         if count < maxbytes:
-            data = os.read( self.stdout.fileno(), maxbytes - count )
+            data = decode( os.read( self.stdout.fileno(), maxbytes - count ) )
             self.readbuf += data
         if maxbytes >= len( self.readbuf ):
             result = self.readbuf
@@ -242,7 +245,7 @@ class Node( object ):
     def write( self, data ):
         """Write data to node.
            data: string"""
-        os.write( self.stdin.fileno(), data )
+        os.write( self.stdin.fileno(), encode( data ) )
 
     def terminate( self ):
         "Send kill signal to Node and clean up after it."
@@ -376,7 +379,7 @@ class Node( object ):
             if isinstance( args[ 0 ], list ):
                 # popen([cmd, arg1, arg2...])
                 cmd = args[ 0 ]
-            elif isinstance( args[ 0 ], basestring ):
+            elif isinstance( args[ 0 ], BaseString ):
                 # popen("cmd arg1 arg2...")
                 cmd = args[ 0 ].split()
             else:
@@ -462,7 +465,7 @@ class Node( object ):
         """
         if not intf:
             return self.defaultIntf()
-        elif isinstance( intf, basestring):
+        elif isinstance( intf, BaseString):
             return self.nameToIntf[ intf ]
         else:
             return intf
@@ -514,7 +517,7 @@ class Node( object ):
         """Set the default route to go through intf.
            intf: Intf or {dev <intfname> via <gw-ip> ...}"""
         # Note setParam won't call us if intf is none
-        if isinstance( intf, basestring ) and ' ' in intf:
+        if isinstance( intf, BaseString ) and ' ' in intf:
             params = intf
         else:
             params = 'dev %s' % intf
@@ -561,7 +564,7 @@ class Node( object ):
            method: config method name
            param: arg=value (ignore if value=None)
            value may also be list or dict"""
-        name, value = param.items()[ 0 ]
+        name, value = list( param.items() )[ 0 ]
         if value is None:
             return
         f = getattr( self, method, None )
@@ -610,7 +613,7 @@ class Node( object ):
 
     def intfList( self ):
         "List of our interfaces sorted by port number"
-        return [ self.intfs[ p ] for p in sorted( self.intfs.iterkeys() ) ]
+        return [ self.intfs[ p ] for p in sorted( self.intfs.keys() ) ]
 
     def intfNames( self ):
         "The names of our interfaces sorted by port number"
@@ -1232,7 +1235,7 @@ class OVSSwitch( Switch ):
             run( cmds, shell=True )
         # Reapply link config if necessary...
         for switch in switches:
-            for intf in switch.intfs.itervalues():
+            for intf in switch.intfs.values():
                 if isinstance( intf, TCIntf ):
                     intf.config( **intf.params )
         return switches

mininet/topo.py

@@ -57,12 +57,12 @@ class MultiGraph( object ):
 
     def edges_iter( self, data=False, keys=False ):
         "Iterator: return graph edges, optionally with data and keys"
-        for src, entry in self.edge.iteritems():
+        for src, entry in self.edge.items():
-            for dst, entrykeys in entry.iteritems():
+            for dst, entrykeys in entry.items():
                 if src > dst:
                     # Skip duplicate edges
                     continue
-                for k, attrs in entrykeys.iteritems():
+                for k, attrs in entrykeys.items():
                     if data:
                         if keys:
                             yield( src, dst, k, attrs )

mininet/util.py

@@ -12,6 +12,18 @@ from fcntl import fcntl, F_GETFL, F_SETFL
 from os import O_NONBLOCK
 import os
 from functools import partial
+import sys
+
+# Python 2/3 compatibility
+Python3 = sys.version_info[0] == 3
+BaseString = str if Python3 else basestring
+Encoding = 'utf-8' if Python3 else None
+def decode( s ):
+    "Decode a byte string if needed for Python 3"
+    return s.decode( Encoding ) if Python3 else s
+def encode( s ):
+    "Encode a byte string if needed for Python 3"
+    return s.encode( Encoding ) if Python3 else s
 
 # Command execution support
 
@@ -98,6 +110,8 @@ def errRun( *cmd, **kwargs ):
             f = fdtofile[ fd ]
             if event & POLLIN:
                 data = f.read( 1024 )
+                if Python3:
+                    data = data.decode( Encoding )
                 if echo:
                     output( data )
                 if f == popen.stdout:
@@ -374,7 +388,7 @@ def pmonitor(popens, timeoutms=500, readline=True,
        terminates: when all EOFs received"""
     poller = poll()
     fdToHost = {}
-    for host, popen in popens.iteritems():
+    for host, popen in popens.items():
         fd = popen.stdout.fileno()
         fdToHost[ fd ] = host
         poller.register( fd, POLLIN )