Move even more vold commands over to Binder.

This moves fstrim, obb and appfuse commands over to the new Binder
interface.  This change also separates creating/destroying and
mounting/unmounting of OBB volumes, which means they finally flow
nicely into the modern VolumeInfo/VolumeBase design.

We now generate unique identifiers for all OBB volumes, instead of
using a shady MD5 hash.

Change all "loop" and "dm" devices to tag the kernel resources with
a vold-specific prefix so that we can clean them up if vold crashes;
there are new destroyAll() methods that handle this cleanup.

Move appfuse mounting/unmounting into VolumeManager so it can be
shared.  Move various model objects into a separate directory to
tidy things up.

Test: cts-tradefed run commandAndExit cts-dev -m CtsOsTestCases -t android.os.storage.cts.StorageManagerTest
Bug: 13758960
Change-Id: I7294e32b3fb6efe07cb3b77bd20166e70b66958f
diff --git a/model/ObbVolume.h b/model/ObbVolume.h
new file mode 100644
index 0000000..5ec0cde
--- /dev/null
+++ b/model/ObbVolume.h
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2017 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_OBB_VOLUME_H
+#define ANDROID_VOLD_OBB_VOLUME_H
+
+#include "VolumeBase.h"
+
+#include <cutils/multiuser.h>
+
+namespace android {
+namespace vold {
+
+/*
+ * OBB container.
+ */
+class ObbVolume : public VolumeBase {
+public:
+    ObbVolume(int id, const std::string& sourcePath, const std::string& sourceKey,
+            gid_t ownerGid);
+    virtual ~ObbVolume();
+
+protected:
+    status_t doCreate() override;
+    status_t doDestroy() override;
+    status_t doMount() override;
+    status_t doUnmount() override;
+
+private:
+    std::string mSourcePath;
+    std::string mSourceKey;
+    gid_t mOwnerGid;
+
+    std::string mLoopPath;
+    std::string mDmPath;
+    std::string mMountPath;
+
+    DISALLOW_COPY_AND_ASSIGN(ObbVolume);
+};
+
+}  // namespace vold
+}  // namespace android
+
+#endif