reduce xattr_user_crc32 writing and style update

1 files changed, 11 insertions, 9 deletions

diff --git a/scripts/xattr_user_crc32 b/scripts/xattr_user_crc32
index a13840f..8f47bdd 100755
--- a/scripts/xattr_user_crc32
+++ b/scripts/xattr_user_crc32
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# Copyright 2020 vg
+# Copyright 2022 vg
 # SPDX-License-Identifier: MIT
 
 '''
@@ -24,15 +24,15 @@ Options:
         Null instead of LF as filename separator for in and out
 '''
 
-### standard modules
+# standard modules
 import contextlib
 import functools
 import itertools
-import operator
-import os
 import sys
+from os import getxattr, setxattr
+from os.path import basename
 
-### external modules
+# external modules
 import docopt
 
 
@@ -69,16 +69,18 @@ def get_crc32(filename):
 
 
 def main():
-    args = docopt.docopt(__doc__.format(progname=os.path.basename(sys.argv[0])))
+    args = docopt.docopt(__doc__.format(progname=basename(sys.argv[0])))
     separator = '\0' if args['-z'] else '\n'
     for filename in filenames(args['FILENAME'], separator):
         tag_crc32 = None
         with contextlib.suppress(OSError):
-            tag_crc32 = os.getxattr(filename, 'user.crc32').decode('utf8')
+            tag_crc32 = getxattr(filename, 'user.crc32').decode('utf8')
         calculated_crc32 = get_crc32(filename)
-        os.setxattr(filename, 'user.crc32', calculated_crc32.encode('utf8'))
+        if tag_crc32 != calculated_crc32:
+            # write access to filesystem only if needed
+            setxattr(filename, 'user.crc32', calculated_crc32.encode('utf8'))
         print('%-8s %-8s %s'
-                % (tag_crc32, calculated_crc32, filename), end=separator)
+              % (tag_crc32, calculated_crc32, filename), end=separator)
 
 
 main()