From 1704541cc9c68589a043429dfd9221dec8cae35e Mon Sep 17 00:00:00 2001
From: "julian.filter" <julian.filter@rwth-aachen.de>
Date: Thu, 9 Apr 2020 17:05:06 +0200
Subject: [PATCH 1/3] fix util.errRun

---
 mininet/util.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mininet/util.py b/mininet/util.py
index c4a5819..3f6c31c 100644
--- a/mininet/util.py
+++ b/mininet/util.py
@@ -157,7 +157,7 @@ def errRun( *cmd, **kwargs ):
         for fd, event in readable:
             f = fdToFile[ fd ]
             decoder = fdToDecoder[ fd ]
-            if event & POLLIN:
+            if event & ( POLLIN | POLLHUP ):
                 data = decoder.decode( f.read( 1024 ) )
                 if echo:
                     output( data )
@@ -169,7 +169,7 @@ def errRun( *cmd, **kwargs ):
                     err += data
                     if data == '':
                         errDone = True
-            else:  # POLLHUP or something unexpected
+            else:  # something unexpected
                 if f == popen.stdout:
                     outDone = True
                 elif f == popen.stderr:

From d5b4aa829b1ec92c57f60d1eec01e4d42bd279d4 Mon Sep 17 00:00:00 2001
From: "julian.filter" <julian.filter@rwth-aachen.de>
Date: Thu, 9 Apr 2020 17:10:52 +0200
Subject: [PATCH 2/3] Improve util.pmonitor

---
 mininet/util.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mininet/util.py b/mininet/util.py
index 3f6c31c..d724096 100644
--- a/mininet/util.py
+++ b/mininet/util.py
@@ -451,7 +451,7 @@ def pmonitor(popens, timeoutms=500, readline=True,
         fd = popen.stdout.fileno()
         fdToHost[ fd ] = host
         fdToDecoder[ fd ] = getincrementaldecoder()
-        poller.register( fd, POLLIN | POLLHUP )
+        poller.register( fd, POLLIN )
         flags = fcntl( fd, F_GETFL )
         fcntl( fd, F_SETFL, flags | O_NONBLOCK )
     while popens:
@@ -461,7 +461,7 @@ def pmonitor(popens, timeoutms=500, readline=True,
                 host = fdToHost[ fd ]
                 decoder = fdToDecoder[ fd ]
                 popen = popens[ host ]
-                if event & POLLIN or event & POLLHUP:
+                if event & ( POLLIN | POLLHUP ):
                     while True:
                         try:
                             f = popen.stdout

From 5f69bf0adeee796ce2d66b605f1e65c67bc791bb Mon Sep 17 00:00:00 2001
From: "julian.filter" <julian.filter@rwth-aachen.de>
Date: Thu, 9 Apr 2020 18:16:13 +0200
Subject: [PATCH 3/3] Add unit tests for util

---
 mininet/test/test_util.py | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100755 mininet/test/test_util.py

diff --git a/mininet/test/test_util.py b/mininet/test/test_util.py
new file mode 100755
index 0000000..66a3128
--- /dev/null
+++ b/mininet/test/test_util.py
@@ -0,0 +1,39 @@
+#!/usr/bin/env python
+
+"""Package: mininet
+   Test functions defined in mininet.util."""
+
+import unittest
+
+from mininet.util import quietRun
+
+class testQuietRun( unittest.TestCase ):
+    """Test quietRun that runs a command and returns its merged output from
+    STDOUT and STDIN"""
+
+    @staticmethod
+    def getEchoCmd( n ):
+        "Return a command that will print n characters"
+        return "echo -n " + "x" * n
+
+    def testEmpty( self ):
+        "Run a command that prints nothing"
+        output = quietRun(testQuietRun.getEchoCmd( 0 ) )
+        self.assertEqual( 0, len( output ) )
+
+    def testOneRead( self ):
+        """Run a command whose output is entirely read on the first call if
+        each call reads at most 1024 characters
+        """
+        for n in [ 42, 1024 ]:
+            output = quietRun( testQuietRun.getEchoCmd( n ) )
+            self.assertEqual( n, len( output ) )
+
+    def testMultipleReads( self ):
+        "Run a command whose output is not entirely read on the first read"
+        for n in [ 1025, 4242 ]:
+            output = quietRun(testQuietRun.getEchoCmd( n ) )
+            self.assertEqual( n, len( output ) )
+
+if __name__ == "__main__":
+    unittest.main()