Support references to args files in MB.

tools/mb/mb.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.
 
 """MB - the Meta-Build wrapper around GYP and GN
 
 MB is a wrapper script for GYP and GN that can be used to generate build files
 for sets of canned configurations and analyze them.
 """
@@ skipping 299 matching lines @@
 
     # Read the file to make sure it parses.
     self.ReadConfigFile()
 
     # Build a list of all of the configs referenced by builders.
     all_configs = {}
     for master in self.masters:
       for config in self.masters[master].values():
         all_configs[config] = master
 
-    # Check that every referenced config actually exists.
+    # Check that every referenced args file or config actually exists.
     for config, loc in all_configs.items():
-      if not config in self.configs:
+      if config.startswith('//'):
+        if not self.Exists(self.ToAbsPath(config)):
+          errs.append('Unknown args file "%s" referenced from "%s".' %
+                      (config, loc))
+      elif not config in self.configs:
         errs.append('Unknown config "%s" referenced from "%s".' %
                     (config, loc))
 
     # Check that every actual config is actually referenced.
     for config in self.configs:
       if not config in all_configs:
         errs.append('Unused config "%s".' % config)
 
     # Figure out the whole list of mixins, and check that every mixin
     # listed by a config or another mixin actually exists.
@@ skipping 210 matching lines @@
     return {
       'gn_args': ' '.join(gn_args),
       'type': 'gn',
     }
 
   def Lookup(self):
     vals = self.ReadBotConfig()
     if not vals:
       self.ReadConfigFile()
       config = self.ConfigFromArgs()
-      if not config in self.configs:
-        raise MBErr('Config "%s" not found in %s' %
-                    (config, self.args.config_file))
-
-      vals = self.FlattenConfig(config)
+      if config.startswith('//'):
+        if not self.Exists(self.ToAbsPath(config)):
+          raise MBErr('args file "%s" not found' % config)
+        vals = {
+          'type': 'gn',
+          'args_file': config,
+          'gn_args': '',
+        }
+      else:
+        if not config in self.configs:
+          raise MBErr('Config "%s" not found in %s' %
+                      (config, self.args.config_file))
+        vals = self.FlattenConfig(config)
 
     # Do some basic sanity checking on the config so that we
     # don't have to do this in every caller.
     assert 'type' in vals, 'No meta-build type specified in the config'
     assert vals['type'] in ('gn', 'gyp'), (
         'Unknown meta-build type "%s"' % vals['gn_args'])
 
     return vals
 
   def ReadBotConfig(self):
@@ skipping 298 matching lines @@
   def GNArgs(self, vals):
     gn_args = vals['gn_args']
     if self.args.goma_dir:
       gn_args += ' goma_dir="%s"' % self.args.goma_dir
 
     # Canonicalize the arg string into a sorted, newline-separated list
     # of key-value pairs, and de-dup the keys if need be so that only
     # the last instance of each arg is listed.
     gn_args = gn_helpers.ToGNString(gn_helpers.FromGNArgs(gn_args))
 
+    args_file = vals.get('args_file', None)
+    if args_file:
+      gn_args = ('import("%s")\n' % vals['args_file']) + gn_args
     return gn_args
 
   def RunGYPGen(self, vals):
     path = self.args.path[0]
 
     output_dir = self.ParseGYPConfigPath(path)
     cmd, env = self.GYPCmd(output_dir, vals)
     ret, _, _ = self.Run(cmd, env=env)
     return ret
 
@@ skipping 489 matching lines @@
   # Then check to see if the arg contains any metacharacters other than
   # double quotes; if it does, quote everything (including the double
   # quotes) for safety.
   if any(a in UNSAFE_FOR_CMD for a in arg):
     arg = ''.join('^' + a if a in ALL_META_CHARS else a for a in arg)
   return arg
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))