xattr-helper: clean up command line interface

This uses the standard argparse fields rather than open coding things
ourselves.  It also makes it a bit easier to test as you can now pass
paths on the command line in addition to stdin.

diff --git a/bin/xattr-helper.py b/bin/xattr-helper.py
index e84d23d5e92d3079eaa89ee06cd346ecaa64ae42..6d99521af3ab5a9854e5fbd9145a742ef399b77c 100755 (executable)
--- a/bin/xattr-helper.py
+++ b/bin/xattr-helper.py
@@ -103,16 +103,13 @@ def unquote(s):
        return b''.join(result)
 
 
-def dump_xattrs(file_in, file_out):
-       """Dump the xattr data for files in |file_in| to |file_out|"""
+def dump_xattrs(pathnames, file_out):
+       """Dump the xattr data for |pathnames| to |file_out|"""
        # NOTE: Always quote backslashes, in order to ensure that they are
        # not interpreted as quotes when they are processed by unquote.
        quote_chars = b'\n\r\\\\'
 
-       for pathname in file_in.read().split(b'\0'):
-               if not pathname:
-                       continue
-
+       for pathname in pathnames:
                attrs = xattr.list(pathname)
                if not attrs:
                        continue
@@ -147,14 +144,11 @@ def restore_xattrs(file_in):
                        elif line.strip():
                                raise ValueError('line %d: malformed entry' % (i + 1,))
 
-def main(argv):
 
-       description = "Dump and restore extended attributes," \
-               " using format like that used by getfattr --dump."
-       usage = "usage: %s [--dump | --restore]\n" % \
-               os.path.basename(argv[0])
+def main(argv):
 
-       parser = ArgumentParser(description=description, usage=usage)
+       parser = ArgumentParser(description=__doc__)
+       parser.add_argument('paths', nargs='*', default=[])
 
        actions = parser.add_argument_group('Actions')
        actions.add_argument('--dump',
@@ -167,28 +161,23 @@ def main(argv):
                help='Restore extended attributes using'
                        ' a dump read from stdin.')
 
-       options, args = parser.parse_known_args(argv[1:])
-
-       if len(args) != 0:
-               parser.error("expected zero arguments, "
-                       "got %s" % len(args))
+       options = parser.parse_args(argv)
 
        if sys.hexversion >= 0x3000000:
                file_in = sys.stdin.buffer.raw
        else:
                file_in = sys.stdin
+       if not options.paths:
+               options.paths += [x for x in file_in.read().split(b'\0') if x]
 
        if options.dump:
-
                if sys.hexversion >= 0x3000000:
                        file_out = sys.stdout.buffer
                else:
                        file_out = sys.stdout
-
-               dump_xattrs(file_in, file_out)
+               dump_xattrs(options.paths, file_out)
 
        elif options.restore:
-
                restore_xattrs(file_in)
 
        else:
@@ -198,5 +187,4 @@ def main(argv):
 
 
 if __name__ == '__main__':
-       rval = main(sys.argv[:])
-       sys.exit(rval)
+       sys.exit(main(sys.argv[1:]))