Update mojo sdk to rev 9fbbc4f0fef1187312316c0ed992342474e139f1

mojo/nacl/generator/interface_dsl.py

 # Copyright 2014 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.
 
 class Interface(object):
   def __init__(self):
     self.functions = []
 
   def Func(self, name, return_type):
     f = Function(self, len(self.functions), name, return_type)
@@ skipping 24 matching lines @@
     return [param.param_type + ' ' + param.name for param in self.params]
 
   def ParamDecl(self):
     if self.params:
       return ', '.join(self.ParamList())
     else:
       return 'void'
 
   def Finalize(self):
     self.result_param = Param(self, len(self.params), 'result')
-    self.result_param.Out(self.return_type)
+    self.result_param.Out(self.return_type).AlwaysWritten()
 
 class Param(object):
   def __init__(self, parent, uid, name, param_type=None):
     self.parent = parent
     self.uid = uid
     self.name = name
     self.base_type = param_type
     self.param_type = param_type
     self.size = None
     self.is_input = False
     self.is_output = False
     self.is_array = False
     self.is_struct = False
+    self.is_extensible = False
     self.is_optional = False
+    self.is_always_written = False
 
   def GetSizeParam(self):
     assert self.size
     return self.parent.param_by_name[self.size]
 
   def In(self, ty):
     self.base_type = ty
     self.param_type = ty
     self.is_input = True
     return self
 
   def InArray(self, ty, size):
     self.base_type = ty
     self.param_type = 'const ' + ty + '*'
     self.size = size
     self.is_input = True
     self.is_array = True
     return self
 
-  def InStruct(self, ty):
+  # An "extensible" struct is one where we don't know the exact size - rather
+  # the first 4 bytes of the struct declare the length of the struct.  This
+  # allows forwards and backwards compatibility with additive changes to the
+  # structure definition.
+  def InExtensibleStruct(self, ty):
     self.base_type = ty
     self.param_type = 'const struct ' + ty + '*'
     self.is_input = True
     self.is_struct = True
+    self.is_extensible = True
     return self
 
   def InOut(self, ty):
     self.base_type = ty
     self.param_type = ty + '*'
     self.is_input = True
     self.is_output = True
     return self
 
   def Out(self, ty):
     self.base_type = ty
     self.param_type = ty + '*'
     self.is_output = True
     return self
 
   def OutArray(self, ty, size):
     self.base_type = ty
     self.param_type = ty + '*'
     self.size = size
     self.is_array = True
     self.is_output = True
     return self
 
+  # The size of the struct is fixed by the API, it cannot be extended.
+  def OutFixedStruct(self, ty):
+    self.base_type = ty
+    self.param_type = 'struct ' + ty + '*'
+    self.is_output = True
+    self.is_struct = True
+    self.is_extensible = False
+    return self
+
+  # Declares that it is valid to pass a null pointer.
   def Optional(self):
     assert not self.IsPassedByValue()
     self.is_optional = True
     return self
 
+  def AlwaysWritten(self):
+    assert self.is_output, self
+    self.is_always_written = True
+    return self
+
   def IsScalar(self):
     return not self.is_array and not self.is_struct
 
   def IsPassedByValue(self):
     return not self.is_output and self.IsScalar()