[PATCH] PacketAssert: fix tcpdump output for daemonized lnst-slave

[Ondrej Lichtner]

From: Ondrej Lichtner <olichtne(a)redhat.com&gt;

This patch fixes the issue of tcpdump not returning any output when
lnst-slave is running as a daemon. We're not exactly sure what causes
this problem but setting the file mode to 'a' seems to solve the issue.

Thanks to Artem Savkov for proposing this workaround.

Signed-off-by: Ondrej Lichtner <olichtne(a)redhat.com&gt;
---
 test_modules/PacketAssert.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/test_modules/PacketAssert.py b/test_modules/PacketAssert.py
index 0611179..3fb8293 100644
--- a/test_modules/PacketAssert.py
+++ b/test_modules/PacketAssert.py
@@ -81,7 +81,9 @@ class PacketAssert(TestGeneric):
     def _execute_tcpdump(self):
         """ Start tcpdump in the background """
         cmd = self._cmd
-        tcpdump_file = tempfile.NamedTemporaryFile(delete=False)
+        #setting the mode to 'a' is temporary, the default mode 'w'
doesn't work
+        #when lnst-slave is running as a daemon, but we don't know why exactly
+        tcpdump_file = tempfile.NamedTemporaryFile(mode='a+b', delete=False)
         self._tcpdump_capture_file = tcpdump_file.name
 
         proc = subprocess.Popen(cmd, shell=True, stdout=tcpdump_file,
-- 
1.9.3