Removes files from //build that we don't need

build/clobber.py

-#!/usr/bin/env python
-# Copyright 2015 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-"""This script provides methods for clobbering build directories."""
-
-import argparse
-import os
-import shutil
-import sys
-
-
-def extract_gn_build_commands(build_ninja_file):
-  """Extracts from a build.ninja the commands to run GN.
-
-  The commands to run GN are the gn rule and build.ninja build step at the
-  top of the build.ninja file. We want to keep these when deleting GN builds
-  since we want to preserve the command-line flags to GN.
-
-  On error, returns the empty string."""
-  result = ""
-  with open(build_ninja_file, 'r') as f:
-    # Read until the second blank line. The first thing GN writes to the file
-    # is the "rule gn" and the second is the section for "build build.ninja",
-    # separated by blank lines.
-    num_blank_lines = 0
-    while num_blank_lines < 2:
-      line = f.readline()
-      if len(line) == 0:
-        return ''  # Unexpected EOF.
-      result += line
-      if line[0] == '\n':
-        num_blank_lines = num_blank_lines + 1
-  return result
-
-
-def delete_build_dir(build_dir):
-  # GN writes a build.ninja.d file. Note that not all GN builds have args.gn.
-  build_ninja_d_file = os.path.join(build_dir, 'build.ninja.d')
-  if not os.path.exists(build_ninja_d_file):
-    shutil.rmtree(build_dir)
-    return
-
-  # GN builds aren't automatically regenerated when you sync. To avoid
-  # messing with the GN workflow, erase everything but the args file, and
-  # write a dummy build.ninja file that will automatically rerun GN the next
-  # time Ninja is run.
-  build_ninja_file = os.path.join(build_dir, 'build.ninja')
-  build_commands = extract_gn_build_commands(build_ninja_file)
-
-  try:
-    gn_args_file = os.path.join(build_dir, 'args.gn')
-    with open(gn_args_file, 'r') as f:
-      args_contents = f.read()
-  except IOError:
-    args_contents = ''
-
-  shutil.rmtree(build_dir)
-
-  # Put back the args file (if any).
-  os.mkdir(build_dir)
-  if args_contents != '':
-    with open(gn_args_file, 'w') as f:
-      f.write(args_contents)
-
-  # Write the build.ninja file sufficiently to regenerate itself.
-  with open(os.path.join(build_dir, 'build.ninja'), 'w') as f:
-    if build_commands != '':
-      f.write(build_commands)
-    else:
-      # Couldn't parse the build.ninja file, write a default thing.
-      f.write('''rule gn
-command = gn -q gen //out/%s/
-description = Regenerating ninja files
-
-build build.ninja: gn
-generator = 1
-depfile = build.ninja.d
-''' % (os.path.split(build_dir)[1]))
-
-  # Write a .d file for the build which references a nonexistant file. This
-  # will make Ninja always mark the build as dirty.
-  with open(build_ninja_d_file, 'w') as f:
-    f.write('build.ninja: nonexistant_file.gn\n')
-
-
-def clobber(out_dir):
-  """Clobber contents of build directory.
-
-  Don't delete the directory itself: some checkouts have the build directory
-  mounted."""
-  for f in os.listdir(out_dir):
-    path = os.path.join(out_dir, f)
-    if os.path.isfile(path):
-      os.unlink(path)
-    elif os.path.isdir(path):
-      delete_build_dir(path)
-
-
-def main():
-  parser = argparse.ArgumentParser()
-  parser.add_argument('out_dir', help='The output directory to clobber')
-  args = parser.parse_args()
-  clobber(args.out_dir)
-  return 0
-
-
-if __name__ == '__main__':
-  sys.exit(main())