kythe/proto/generate_go_protobufs.py

#!/usr/bin/env python
#
# Copyright 2016 The Kythe Authors. All rights reserved.
#
# 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.

# This script (re)generates the source for Go protobuf packages so that
# Go packages can be fetched and installed with the "go get" command.
#
# This script must be run with its current working directory inside a Bazel
# workspace root.
#
# N.B.: This script depends on some conventions about how we name our proto
# rules. Specifically, that the name of the go_proto_library rule for
# "foo_proto" is "foo_go_proto".

from subprocess import check_output
from subprocess import call

import glob
import os
import re
import shlex
import shutil
import stat
import sys

# Find the locations of the workspace root and the generated files directory.
workspace   = check_output(['bazel', 'info', 'workspace']).strip()
bazel_bin   = check_output(['bazel', 'info', 'bazel-bin']).strip()
targets     = '//kythe/proto/...'
import_base = 'kythe.io/kythe/proto'

go_protos = check_output([
    'bazel', 'query', 'kind("go_proto_library", %s)' % targets,
]).split()

# Each rule has the form //foo/bar:baz_proto.
# First build all the rules to ensure we have the output files.
# Then strip off each :baz_proto, convert it to a filename "baz.proto",
# and copy the generated output "baz.pb.go" into the source tree.
if call(['bazel', 'build'] + go_protos) != 0:
  print 'Build failed'
  sys.exit(1)

for rule in go_protos:
  # Example: //kythe/proto:blah_go_proto -> kythe/proto, blah_go_proto
  rule_dir, proto = rule.lstrip('/').rsplit(':', 1)
  # Example: $ROOT/kythe/proto/blah_go_proto
  output_dir = os.path.join(workspace, rule_dir, proto)
  # Example: blah_go_proto -> blah.proto
  proto_file = re.sub('_go_proto$', '.proto', proto)

  print 'Copying Go protobuf source for %s' % rule
  generated_file = re.sub('.proto$', '.pb.go', proto_file)
  generated_path = glob.glob(
      os.path.join(bazel_bin, rule_dir, '*', proto+'%',
                   import_base, proto, generated_file)).pop()

  if os.path.isdir(output_dir):
    print 'Deleting and recreating old protobuf directory: %s' % output_dir
    shutil.rmtree(output_dir)
  else:
    print 'Creating new Go protobuf: %s' % generated_file

  # Ensure the output directory exists, and update permissions after copying.
  os.makedirs(output_dir, 0755)
  shutil.copy(generated_path, output_dir)
  os.chmod(os.path.join(output_dir, generated_file), 0644)