12:44 p.m.
I found a bug in PacketAssert test module. It was caused by processing the
last line twice - inside the interrupt handler and in the run() function
as well. I've cleaned up the code a bit, too.
The changes include
- removal of the tcpdump's output processing from the interrupt handler
- tcpdump termination polling is done in separate loop
- tcpdump's output is stored into temporary file instead of using pipes
- tcpdump's output is processed after the tcpdump command terminates
I have tested this heavily and it looks much more reliable now.
Signed-off-by: Jan Tluka <jtluka(a)redhat.com>
---
test_modules/PacketAssert.py | 72 ++++++++++++++++++--------------------------
1 file changed, 29 insertions(+), 43 deletions(-)
diff --git a/test_modules/PacketAssert.py b/test_modules/PacketAssert.py
index c716c66..0611179 100644
--- a/test_modules/PacketAssert.py
+++ b/test_modules/PacketAssert.py
@@ -15,6 +15,9 @@ import logging
import subprocess
import re
import signal
+import time
+import os
+import tempfile
from lnst.Common.TestsCommon import TestGeneric
class PacketAssert(TestGeneric):
@@ -25,6 +28,7 @@ class PacketAssert(TestGeneric):
_cmd = ""
_tcpdump = None
+ _tcpdump_capture_file = None
_grep_filters = []
_min_cond = 1
@@ -38,29 +42,10 @@ class PacketAssert(TestGeneric):
def _interrupt_handler(self, signum, frame):
""" Kill tcpdump when interrupted """
- self._tcpdump.terminate()
-
- tcpdump_output = self._tcpdump.stdout
- while True:
- try:
- next_line = tcpdump_output.readline()
- except IOError: # Interrupted system call
- break
-
- if next_line == "":
- break
-
- next_line = next_line.strip("\n")
-
- if re.match("[0-9]+\:[0-9]+\:[0-9\.]+", next_line) and\
- self.line != "":
- self._process_captured_line(self.line)
- self.line = next_line
- else:
- self.line += next_line
- if self.line != "":
- self._process_captured_line(self.line)
-
+ try:
+ self._tcpdump.terminate()
+ except OSError:
+ raise Exception("Caught exception in interrupt handler")
def _prepare_grep_filters(self):
""" Parse `grep_for' test options """
@@ -96,8 +81,11 @@ class PacketAssert(TestGeneric):
def _execute_tcpdump(self):
""" Start tcpdump in the background """
cmd = self._cmd
- proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE,
- stderr=subprocess.PIPE)
+ tcpdump_file = tempfile.NamedTemporaryFile(delete=False)
+ self._tcpdump_capture_file = tcpdump_file.name
+
+ proc = subprocess.Popen(cmd, shell=True, stdout=tcpdump_file,
+ stderr=None)
self._tcpdump = proc
def _process_captured_line(self, line):
@@ -128,34 +116,32 @@ class PacketAssert(TestGeneric):
logging.info("Capturing started")
- self.line = ""
- tcpdump_output = self._tcpdump.stdout
while True:
if self._tcpdump.poll() != None:
if self._tcpdump.returncode > 0:
raise Exception("tcpdump terminated with error")
else:
break
-
- try:
- next_line = tcpdump_output.readline()
- except IOError: # Interrupted system call
- continue
-
- if next_line == "":
+ else:
+ time.sleep(1)
continue
- next_line = next_line.strip("\n")
+ # get and evalute the tcpdump's output
+ # empty string returned by readline() means the EOF has been reached
+ tcpdump_file = open(self._tcpdump_capture_file, 'r')
+ line = "\n"
+ while line != "":
+ try:
+ line = tcpdump_file.readline()
+ except (OSError, IOError):
+ logging.debug("Caught exception while reading tcpdump output")
+ break
- if re.match("[0-9]+\:[0-9]+\:[0-9\.]+", next_line) and\
- self.line != "":
- self._process_captured_line(self.line)
- self.line = next_line
- else:
- self.line += next_line
+ line = line.strip("\n")
+ self._process_captured_line(line)
- if self.line != "":
- self._process_captured_line(self.line)
+ tcpdump_file.close()
+ os.remove(tcpdump_file.name)
logging.info("Capturing finished. Received %d packets",
self._num_recv)
res = {"received": self._num_recv,
--
1.8.1.4