[entropy.db] EntropyRepository: commit to disk (calling Connection.commit()) before calling plugin hooks

To avoid EntropyRepositoryBase plugin hooks to not see changes
in repository not yet committed (leading to tricky hard to debug
situations) call Connection.commit() before plugin hooks.

libraries/entropy/db/__init__.py

@@ -636,15 +636,21 @@ class EntropyRepository(EntropyRepositoryBase):
         Reimplemented from EntropyRepositoryBase.
         Needs to call superclass method.
         """
-        super(EntropyRepository, self).commitChanges(force = force,
-            no_plugins = no_plugins)
-
         if force or (not self.readonly):
+            # NOTE: the actual commit MUST be executed before calling
+            # the superclass method (that is going to call EntropyRepositoryBase
+            # plugins). This to avoid that other connection to the same exact
+            # database file are opened and used before data is actually written
+            # to disk, causing a tricky race condition hard to exploit.
+            # So, FIRST commit changes, then call plugins.
             try:
                 self._connection().commit()
             except Error:
                 pass
 
+        super(EntropyRepository, self).commitChanges(force = force,
+            no_plugins = no_plugins)
+
     def initializeRepository(self):
         """
         Reimplemented from EntropyRepositoryBase.