upload android base code part6

android/system/update_engine/update_manager/policy_utils.h

@@ -0,0 +1,38 @@
+//
+// Copyright (C) 2014 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef UPDATE_ENGINE_UPDATE_MANAGER_POLICY_UTILS_H_
+#define UPDATE_ENGINE_UPDATE_MANAGER_POLICY_UTILS_H_
+
+#include "update_engine/update_manager/policy.h"
+
+// Checks that the passed pointer value is not null, returning kFailed on the
+// current context and setting the *error description when it is null. The
+// intended use is to validate variable failures while using
+// EvaluationContext::GetValue, for example:
+//
+//   const int* my_value = ec->GetValue(state->my_provider()->var_my_value());
+//   POLICY_CHECK_VALUE_AND_FAIL(my_value, error);
+//
+#define POLICY_CHECK_VALUE_AND_FAIL(ptr, error) \
+    do { \
+      if ((ptr) == nullptr) { \
+        *(error) = #ptr " is required but is null."; \
+        return EvalStatus::kFailed; \
+      } \
+    } while (false)
+
+#endif  // UPDATE_ENGINE_UPDATE_MANAGER_POLICY_UTILS_H_