Adds Error Handling to swift-drive-audit for missing or unreadable /var/log/kern.log

Fixes Bug 1049081

Change-Id: If977080350cc5cdb6bc633b6af7d3c490ed23d46

AUTHORS

@@ -52,6 +52,7 @@ Dragos Manolescu (dragosm@hp.com)
 Juan J. Martinez (juan@memset.com)
 Marcelo Martins (btorch@gmail.com)
 Donagh McCabe (donagh.mccabe@hp.com)
+Andy McCrae (andy.mccrae@gmail.com)
 Paul McMillan (paul.mcmillan@nebula.com)
 Ewan Mellor (ewan.mellor@citrix.com)
 Samuel Merritt (sam@swiftstack.com)

bin/swift-drive-audit

@@ -63,6 +63,7 @@ def get_devices(device_dir, logger):
 def get_errors(minutes):
     errors = {}
     start_time = datetime.datetime.now() - datetime.timedelta(minutes=minutes)
+    try:
         for line in open('/var/log/kern.log'):
             if '[    0.000000]' in line:
                 # Ignore anything before the last boot
@@ -77,6 +78,10 @@ def get_errors(minutes):
                     for device in err.findall(line):
                         errors[device] = errors.get(device, 0) + 1
         return errors
+    except IOError:
+        logger.error("Error: Unable to open /var/log/kern.log")
+        print("Unable to open /var/log/kern.log")
+        sys.exit(1)
 
 
 def comment_fstab(mount_point):