envoy_build_fixer.py

#!/usr/bin/env python

# Enforce license headers on Envoy BUILD files (maybe more later?)

from __future__ import print_function

import sys

LICENSE_STRING = 'licenses(["notice"])  # Apache 2\n'
ENVOY_PACKAGE_STRING = ('load("//bazel:envoy_build_system.bzl", "envoy_package")\n'
                        '\n'
                        'envoy_package()\n')


def FixBuild(path):
  with open(path, 'r') as f:
    outlines = [LICENSE_STRING]
    first = True
    in_load = False
    seen_ebs = False
    seen_epkg = False
    for line in f:
      if line.startswith('licenses'):
        continue
      if first:
        if line != '\n':
          outlines.append('\n')
        first = False
      if path.startswith('./bazel/external/') or path.startswith('./bazel/toolchains/'):
        outlines.append(line)
        continue
      if line.startswith('package(') and not path.endswith('bazel/BUILD') and not path.endswith(
          'ci/prebuilt/BUILD') and not path.endswith('bazel/osx/BUILD') and not path.endswith(
              'bazel/osx/crosstool/BUILD'):
        continue
      if in_load == False and line.startswith('load('):
        in_load = True
      if in_load:
        if 'envoy_build_system.bzl' in line:
          seen_ebs = True
        if 'envoy_package' in line:
          seen_epkg = True
        if line.rstrip().endswith(')'):
          in_load = None  # investigate only first load() directive
          if seen_ebs:
            if not seen_epkg:
              outlines.append(line.rstrip()[:-1] + ', "envoy_package")\n')
              outlines.append('\nenvoy_package()\n')
              continue
          else:
            outlines.append(line)
            outlines.append(ENVOY_PACKAGE_STRING)
            continue
      outlines.append(line)

  return ''.join(outlines)


if __name__ == '__main__':
  if len(sys.argv) == 2:
    sys.stdout.write(FixBuild(sys.argv[1]))
    sys.exit(0)
  elif len(sys.argv) == 3:
    reorderd_source = FixBuild(sys.argv[1])
    with open(sys.argv[2], 'w') as f:
      f.write(reorderd_source)
    sys.exit(0)
  print('Usage: %s <source file path> [<destination file path>]' % sys.argv[0])
  sys.exit(1)