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.cpp b/model/StubVolume.cpp
new file mode 100644
index 0000000..edd0861
--- /dev/null
+++ b/model/StubVolume.cpp
@@ -0,0 +1,67 @@
+/*
+ * 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.
+ */
+
+#include "StubVolume.h"
+
+#include <android-base/logging.h>
+#include <android-base/stringprintf.h>
+
+using android::base::StringPrintf;
+
+namespace android {
+namespace vold {
+
+StubVolume::StubVolume(int id, const std::string& sourcePath, const std::string& mountPath,
+                       const std::string& fsType, const std::string& fsUuid,
+                       const std::string& fsLabel)
+    : VolumeBase(Type::kStub),
+      mSourcePath(sourcePath),
+      mMountPath(mountPath),
+      mFsType(fsType),
+      mFsUuid(fsUuid),
+      mFsLabel(fsLabel) {
+    setId(StringPrintf("stub:%d", id));
+}
+
+StubVolume::~StubVolume() {}
+
+status_t StubVolume::doCreate() {
+    return OK;
+}
+
+status_t StubVolume::doDestroy() {
+    return OK;
+}
+
+status_t StubVolume::doMount() {
+    auto listener = getListener();
+    if (listener) listener->onVolumeMetadataChanged(getId(), mFsType, mFsUuid, mFsLabel);
+    setInternalPath(mSourcePath);
+    setPath(mMountPath);
+    return OK;
+}
+
+status_t StubVolume::doUnmount() {
+    return OK;
+}
+
+// TODO: return error instead.
+status_t StubVolume::doFormat(const std::string& fsType) {
+    return OK;
+}
+
+}  // namespace vold
+}  // namespace android