StubVolume as first class Volume in Vold

StubVolume is a Volume that is maintained by external party such as the
ChromeOS processes in ARC++.

Bug: 110380403
Test: Tested on ARC++

Change-Id: I3198bd7283d5f60a524da3707dea7385ffec599d
diff --git a/model/StubVolume.h b/model/StubVolume.h
new file mode 100644
index 0000000..538cae9
--- /dev/null
+++ b/model/StubVolume.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2018 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 ANDROID_VOLD_STUB_VOLUME_H
+#define ANDROID_VOLD_STUB_VOLUME_H
+
+#include "VolumeBase.h"
+
+namespace android {
+namespace vold {
+
+/*
+ * A vold representation of volumes managed from outside Android (e.g., ARC++).
+ *
+ * Used for the case when events such that mounting and unmounting are
+ * actually handled from outside vold, and vold only need to keep track on those
+ * vents instead of talking to kernel directly.
+ */
+class StubVolume : public VolumeBase {
+  public:
+    StubVolume(int id, const std::string& sourcePath, const std::string& mountPath,
+               const std::string& fsType, const std::string& fsUuid, const std::string& fsLabel);
+    virtual ~StubVolume();
+
+  protected:
+    status_t doCreate() override;
+    status_t doDestroy() override;
+    status_t doMount() override;
+    status_t doUnmount() override;
+    status_t doFormat(const std::string& fsType) override;
+
+  private:
+    const std::string mSourcePath;
+    const std::string mMountPath;
+    const std::string mFsType;
+    const std::string mFsUuid;
+    const std::string mFsLabel;
+
+    DISALLOW_COPY_AND_ASSIGN(StubVolume);
+};
+
+}  // namespace vold
+}  // namespace android
+
+#endif