Factor clobber out of build/landmines.py

This patch factors clobbering functionality from build/landmines.py
into build/clobber.py (new file). This will allow us to reuse existing
code in the cr tool.

BUG=493023

Review URL: https://codereview.chromium.org/1199933004

Cr-Commit-Position: refs/heads/master@{#335491}

1 files changed, 2 insertions, 82 deletions

diff --git a/build/landmines.py b/build/landmines.py
index 97a250a..4db2380 100755
--- a/build/landmines.py
+++ b/build/landmines.py
@@ -19,11 +19,11 @@ import gyp_environment
 import logging
 import optparse
 import os
-import shutil
 import sys
 import subprocess
 import time
 
+import clobber
 import landmine_utils
 
 
@@ -56,79 +56,6 @@ def get_build_dir(build_tool, is_iphone=False):
   return os.path.abspath(ret)
 
 
-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_if_necessary(new_landmines):
   """Does the work of setting, planting, and triggering landmines."""
   out_dir = get_build_dir(landmine_utils.builder())
@@ -150,14 +77,7 @@ def clobber_if_necessary(new_landmines):
       sys.stdout.write('Clobbering due to:\n')
       sys.stdout.writelines(diff)
 
-      # Clobber contents of build directory but not 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)
+      clobber.clobber(out_dir)
 
   # Save current set of landmines for next time.
   with open(landmines_path, 'w') as f: