Handle pidfile exception for dnsmasq

Capture the exception in dnsmasq_pid_for method. If the pidfile cannot be read
for some reason, it should be treated as if it does not exist. This prevents
issues where the filesystem write delay leaves the file created but empty.
Fixes bug 865399.

Change-Id: I3b0f1211762696f925ae32d785ffa6a35c5e1d6b

1 files changed, 5 insertions, 2 deletions

diff --git a/nova/network/linux_net.py b/nova/network/linux_net.py
index 19d7b5cf7..9f2ce0828 100755
--- a/nova/network/linux_net.py
+++ b/nova/network/linux_net.py
@@ -793,8 +793,11 @@ def _dnsmasq_pid_for(dev):
     pid_file = _dhcp_file(dev, 'pid')
 
     if os.path.exists(pid_file):
-        with open(pid_file, 'r') as f:
-            return int(f.read())
+        try:
+            with open(pid_file, 'r') as f:
+                return int(f.read())
+        except (ValueError, IOError):
+            return None
 
 
 def _ra_pid_for(dev):