add bash8 tool (like pep8, but way hackier)

unlike our python code, we have no automatic style checking for
bash. For the most part, it's not a big deal, but errant whitespace
or incorrect indenting is sometimes annoying to have to -1 people's
patches for. Instead of constantly picking it up in manual review
maybe we can do better.

This is an uber hacky script which could be used to do just that.

   ./tools/bash8.py file1 file2 file3 ...

And it will show issues found with the files at hand. Lightly
tested in the existing devstack tree, it exposes a few issues that
we might want to think about.

This should be python 3 compatible, and includes argparse to provide
a basic '-h' support to explain how the command should be run.

Change-Id: I5009fa5852595c2953a548e430e5e1ce06ae94e0

tools/bash8.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+# bash8 - a pep8 equivalent for bash scripts
+#
+# this program attempts to be an automated style checker for bash scripts
+# to fill the same part of code review that pep8 does in most OpenStack
+# projects. It starts from humble beginnings, and will evolve over time.
+#
+# Currently Supported checks
+#
+# Errors
+# - E001: check that lines do not end with trailing whitespace
+# - E002: ensure that indents are only spaces, and not hard tabs
+# - E003: ensure all indents are a multiple of 4 spaces
+
+import argparse
+import fileinput
+import re
+import sys
+
+
+ERRORS = 0
+
+
+def print_error(error, line):
+    global ERRORS
+    ERRORS = ERRORS + 1
+    print("%s: '%s'" % (error, line.rstrip('\n')))
+    print(" - %s: L%s" % (fileinput.filename(), fileinput.filelineno()))
+
+
+def check_no_trailing_whitespace(line):
+    if re.search('[ \t]+$', line):
+        print_error('E001: Trailing Whitespace', line)
+
+
+def check_indents(line):
+    m = re.search('^(?P<indent>[ \t]+)', line)
+    if m:
+        if re.search('\t', m.group('indent')):
+            print_error('E002: Tab indents', line)
+        if (len(m.group('indent')) % 4) != 0:
+            print_error('E003: Indent not multiple of 4', line)
+
+
+def check_files(files):
+    for line in fileinput.input(files):
+        check_no_trailing_whitespace(line)
+        check_indents(line)
+
+
+def get_options():
+    parser = argparse.ArgumentParser(
+        description='A bash script style checker')
+    parser.add_argument('files', metavar='file', nargs='+',
+                        help='files to scan for errors')
+    return parser.parse_args()
+
+
+def main():
+    opts = get_options()
+    check_files(opts.files)
+
+    if ERRORS > 0:
+        print("%d bash8 error(s) found" % ERRORS)
+        return 1
+    else:
+        return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())