Added a simple logfile reopen mechanism

If logrotate has been run inbetween since last time the log file
was checked, the opened fd will not point at the new file.  In this
case reopen the log file and process all new events in this new file.

Signed-off-by: David Sommerseth <davids@redhat.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/LogActio/__init__.py b/LogActio/__init__.py
index 6456b91..5a7c167 100644
--- a/LogActio/__init__.py
+++ b/LogActio/__init__.py
@@ -74,6 +74,7 @@ class WatcherThread(threading.Thread):
         self.start()
 
     def run(self):
+        fp = None
         # This is started by threading.Thread
         try:
             fp = fp = open(self.__logfile, "r")
@@ -87,8 +88,21 @@ class WatcherThread(threading.Thread):
             where = fp.tell()
             line = fp.readline()
             if len(line) == 0:
+                # Before sleeping, grab a copy of the file size.
+                # If it has become truncated, we need to reopen the file
+                filesize_before = os.stat(self.__logfile).st_size
                 time.sleep(self.__polltime)
-                fp.seek(where)
+                filesize_after = os.stat(self.__logfile).st_size
+                if filesize_after < filesize_before:
+                    # Reopen is needed.
+                    fp.close()
+                    time.sleep(1) # Just in case
+                    fp = open(self.__logfile)
+                    # We will not go to end of file, so
+                    # we catch all changes in the log file
+                    # since the truncation point
+                else:
+                    fp.seek(where)
                 continue
 
             now = int(time.time())