Fix v8 landmines script.

build/landmines.py

 #!/usr/bin/env python
 # Copyright 2014 the V8 project 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 runs every build as a hook. If it detects that the build should
 be clobbered, it will touch the file <build_dir>/.landmine_triggered. The
 various build scripts will then check for the presence of this file and clobber
 accordingly. The script will also emit the reasons for the clobber to stdout.
@@ skipping 43 matching lines @@
   """Does the work of setting, planting, and triggering landmines."""
   out_dir = get_target_build_dir(landmine_utils.builder(), target)
 
   landmines_path = os.path.join(out_dir, '.landmines')
   if not os.path.exists(out_dir):
     return
 
   if not os.path.exists(landmines_path):
     print "Landmines tracker didn't exists."
 
-  # Make sure the landmines tracker exists.
-  open(landmines_path, 'a').close()
+  # FIXME(machenbach): Clobber deletes the .landmines tracker. Difficult
+  # to know if we are right after a clobber or if it is first-time landmines
+  # deployment. Also, a landmine-triggered clobber right after a clobber is
+  # not possible. Different clobber methods for msvs, xcode and make all
+  # have different blacklists of files that are not deleted.
+  if os.path.exists(landmines_path):
+    triggered = os.path.join(out_dir, '.landmines_triggered')
+    with open(landmines_path, 'r') as f:
+      old_landmines = f.readlines()
+    if old_landmines != new_landmines:
+      old_date = time.ctime(os.stat(landmines_path).st_ctime)
+      diff = difflib.unified_diff(old_landmines, new_landmines,
+          fromfile='old_landmines', tofile='new_landmines',
+          fromfiledate=old_date, tofiledate=time.ctime(), n=0)
 
-  triggered = os.path.join(out_dir, '.landmines_triggered')
-  with open(landmines_path, 'r') as f:
-    old_landmines = f.readlines()
-  if old_landmines != new_landmines:
-    old_date = time.ctime(os.stat(landmines_path).st_ctime)
-    diff = difflib.unified_diff(old_landmines, new_landmines,
-        fromfile='old_landmines', tofile='new_landmines',
-        fromfiledate=old_date, tofiledate=time.ctime(), n=0)
-
-    with open(triggered, 'w') as f:
-      f.writelines(diff)
-    print "Setting landmine: %s" % triggered
-  elif os.path.exists(triggered):
-    # Remove false triggered landmines.
-    os.remove(triggered)
-    print "Removing landmine: %s" % triggered
+      with open(triggered, 'w') as f:
+        f.writelines(diff)
+      print "Setting landmine: %s" % triggered
+    elif os.path.exists(triggered):
+      # Remove false triggered landmines.
+      os.remove(triggered)
+      print "Removing landmine: %s" % triggered
   with open(landmines_path, 'w') as f:
     f.writelines(new_landmines)
-  with open(landmines_path, 'r') as f:
-    print "Content of the landmines tracker:"
-    print f.read()
 
 
 def process_options():
   """Returns a list of landmine emitting scripts."""
   parser = optparse.OptionParser()
   parser.add_option(
       '-s', '--landmine-scripts', action='append',
       default=[os.path.join(SRC_DIR, 'build', 'get_landmines.py')],
       help='Path to the script which emits landmines to stdout. The target '
            'is passed to this script via option -t. Note that an extra '
@@ skipping 32 matching lines @@
     landmines.extend([('%s\n' % l.strip()) for l in output.splitlines()])
 
   for target in ('Debug', 'Release'):
     set_up_landmines(target, landmines)
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())