Forbid files with a UTF-8 BOM

pre_commit_hooks/check_byte_order_marker.py

@@ -0,0 +1,25 @@
+from __future__ import absolute_import
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import argparse
+
+
+def main(argv=None):
+    parser = argparse.ArgumentParser()
+    parser.add_argument('filenames', nargs='*', help='Filenames to check')
+    args = parser.parse_args(argv)
+
+    retv = 0
+
+    for filename in args.filenames:
+        with open(filename, 'rb') as f:
+            if f.read(3) == b'\xef\xbb\xbf':
+                retv = 1
+                print('{0}: Has a byte-order marker'.format(filename))
+
+    return retv
+
+
+if __name__ == '__main__':
+    exit(main())