Reland "mc: Copy over checked-in outputs on non-Windows hosts."

This reverts commit ea662297506102da12eb1ee04e40fad15b77a1d5.

This also reverts https://chromium-review.googlesource.com/c/chromium/src/+/584691
for non-iOS to make sure that remoting .mc outputs are not different in
official and unofficial builds.

Change-Id: I58fc96c40d1639c9145f576136afca2468459389
Bug: 756607,747637
Reviewed-on: https://chromium-review.googlesource.com/648113
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#499409}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 6cff7e77ad345f90dcc46b106620baf4cab3cef8

win/message_compiler.py

@@ -7,22 +7,67 @@
 #
 # Usage: message_compiler.py <environment_file> [<args to mc.exe>*]
 
+import distutils.dir_util
+import filecmp
 import os
+import re
+import shutil
 import subprocess
 import sys
+import tempfile
 
 def main():
+  env_file, rest = sys.argv[1], sys.argv[2:]
+
+  # Parse some argument flags.
+  header_dir = None
+  resource_dir = None
+  input_file = None
+  for i, arg in enumerate(rest):
+    if arg == '-h' and len(rest) > i + 1:
+      assert header_dir == None
+      header_dir = rest[i + 1]
+    elif arg == '-r' and len(rest) > i + 1:
+      assert resource_dir == None
+      resource_dir = rest[i + 1]
+    elif arg.endswith('.mc') or arg.endswith('.man'):
+      assert input_file == None
+      input_file = arg
+
+  # Copy checked-in outputs to final location.
+  THIS_DIR = os.path.abspath(os.path.dirname(__file__))
+  assert header_dir == resource_dir
+  source = os.path.join(THIS_DIR, "..", "..",
+      "third_party", "win_build_output",
+      re.sub(r'^(?:[^/]+/)?gen/', 'mc/', header_dir))
+  distutils.dir_util.copy_tree(source, header_dir, preserve_times=False)
+
+  # On non-Windows, that's all we can do.
+  if sys.platform != 'win32':
+    return
+
+  # On Windows, run mc.exe on the input and check that its outputs are
+  # identical to the checked-in outputs.
+
   # Read the environment block from the file. This is stored in the format used
   # by CreateProcess. Drop last 2 NULs, one for list terminator, one for
   # trailing vs. separator.
-  env_pairs = open(sys.argv[1]).read()[:-2].split('\0')
+  env_pairs = open(env_file).read()[:-2].split('\0')
   env_dict = dict([item.split('=', 1) for item in env_pairs])
 
   # mc writes to stderr, so this explicitly redirects to stdout and eats it.
   try:
+    tmp_dir = tempfile.mkdtemp()
+    delete_tmp_dir = True
+    if header_dir:
+      rest[rest.index('-h') + 1] = tmp_dir
+      header_dir = tmp_dir
+    if resource_dir:
+      rest[rest.index('-r') + 1] = tmp_dir
+      resource_dir = tmp_dir
+
     # This needs shell=True to search the path in env_dict for the mc
     # executable.
-    rest = sys.argv[2:]
     subprocess.check_output(['mc.exe'] + rest,
                             env=env_dict,
                             stderr=subprocess.STDOUT,
@@ -35,15 +80,6 @@ def main():
     # it generates an ANSI header, and includes broken versions of the message
     # text in the comment before the value. To work around this, for any invalid
     # // comment lines, we simply drop the line in the header after building it.
-    header_dir = None
-    input_file = None
-    for i, arg in enumerate(rest):
-      if arg == '-h' and len(rest) > i + 1:
-        assert header_dir == None
-        header_dir = rest[i + 1]
-      elif arg.endswith('.mc') or arg.endswith('.man'):
-        assert input_file == None
-        input_file = arg
     if header_dir:
       header_file = os.path.join(
           header_dir, os.path.splitext(os.path.basename(input_file))[0] + '.h')
@@ -55,9 +91,21 @@ def main():
           header_contents.append(line)
       with open(header_file, 'wb') as f:
         f.write(''.join(header_contents))
+
+    # mc.exe invocation and post-processing are complete, now compare the output
+    # in tmp_dir to the checked-in outputs.
+    diff = filecmp.dircmp(tmp_dir, source)
+    if diff.diff_files or set(diff.left_list) != set(diff.right_list):
+      print >>sys.stderr, 'mc.exe output different from files in %s, see %s' % (
+          source, tmp_dir)
+      delete_tmp_dir = False
+      sys.exit(1)
   except subprocess.CalledProcessError as e:
     print e.output
     sys.exit(e.returncode)
+  finally:
+    if os.path.exists(tmp_dir) and delete_tmp_dir:
+      shutil.rmtree(tmp_dir)
 
 if __name__ == '__main__':
   main()