backup: Close file handles

--HG--
extra : amend_source : 8ee363811f104459f8346df1fccb1950c3ffc76c

backup.py

@@ -24,10 +24,11 @@ class Backup(object):
 
     def __init__(self, destination, config=None, pretend=False):
         self.config = configparser.ConfigParser()
-        print(config)
-        if not config:
-            config = open(self.default_config)
-        self.config.read_file(config)
+        if config:
+            self.config.read_file(config)
+        else:
+            with open(self.default_config) as config:
+                self.config.read_file(config)
         self.config.filename = config.name
         self.destination = destination
         self.pretend = pretend
@@ -126,13 +127,16 @@ class Backup(object):
 
     def _run(self, *cmd):
         self.log.debug('Running command: {}'.format(' '.join(cmd)))
+        devnull = open(os.devnull)
         try:
-            subprocess.check_call(cmd, stdin=open(os.devnull),
+            subprocess.check_call(cmd, stdin=devnull,
                                   stdout=self.stdout, stderr=self.stderr)
         except (OSError, subprocess.CalledProcessError) as e:
             raise BackupError('Error executing rsync: {}'.format(e))
         except KeyboardInterrupt:
             raise BackupError('rsync interrupted')
+        finally:
+            devnull.close()
 
 
 def _parse_args():
@@ -160,6 +164,8 @@ def _parse_args():
 def main():
     args = _parse_args()
     backup = Backup(args.destination, args.config, args.pretend)
+    if args.config:
+        args.config.close()
     if not args.quiet:
         print('Backing up to {} using configuration from {}'.format(
             args.destination, backup.config.filename))