Add validation logic for non-nullable types.

mojo/public/cpp/bindings/lib/validation_errors.h

 // 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.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_VALIDATION_ERRORS_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_VALIDATION_ERRORS_H_
 
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
@@ skipping 10 matching lines @@
   // A struct header doesn't make sense, for example:
   // - |num_bytes| is smaller than the size of the oldest version that we
   // support.
   // - |num_fields| is smaller than the field number of the oldest version that
   // we support.
   // - |num_bytes| and |num_fields| don't match.
   VALIDATION_ERROR_UNEXPECTED_STRUCT_HEADER,
   // An array header doesn't make sense, for example:
   // - |num_bytes| is smaller than the size of the header plus the size required
   // to store |num_elements| elements.
+  // - For fixed-size arrays, |num_elements| is different than the specified
+  // size.
   VALIDATION_ERROR_UNEXPECTED_ARRAY_HEADER,
   // An encoded handle is illegal.
   VALIDATION_ERROR_ILLEGAL_HANDLE,
+  // A non-nullable handle field is set to invalid handle.
+  VALIDATION_ERROR_UNEXPECTED_INVALID_HANDLE,
   // An encoded pointer is illegal.
   VALIDATION_ERROR_ILLEGAL_POINTER,
+  // A non-nullable pointer field is set to null.
+  VALIDATION_ERROR_UNEXPECTED_NULL_POINTER,
   // |flags| in the message header is an invalid flag combination.
   VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION,
   // |flags| in the message header indicates that a request ID is required but
   // there isn't one.
   VALIDATION_ERROR_MESSAGE_HEADER_MISSING_REQUEST_ID,
 };
 
 const char* ValidationErrorToString(ValidationError error);
 
 void ReportValidationError(ValidationError error);
 
 // Only used by validation tests and when there is only one thread doing message
 // validation.
 class ValidationErrorObserverForTesting {
  public:
   ValidationErrorObserverForTesting();
   ~ValidationErrorObserverForTesting();
 
   ValidationError last_error() const { return last_error_; }
   void set_last_error(ValidationError error) { last_error_ = error; }
 
  private:
   ValidationError last_error_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(ValidationErrorObserverForTesting);
 };
 
+// Currently it only returns true when there is a
+// ValidationErrorObserverForTesting object alive. In other words, non-nullable
+// validation is only turned on during validation tests.
+//
+// TODO(yzshen): Remove this function and enable non-nullable validation by
+// default.
+bool IsNonNullableValidationEnabled();
+
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_VALIDATION_ERRORS_H_