Add methods to query the private storage.

This is used by Settings and the Storage Manager to calculate the
amount of space left on a device.

Bug: 30895163
Test: m RunStorageManagerRoboTests <-- These tests exercise this code.
Change-Id: I0978020645dff455c7d60067c7d6fae338b5f89a

packages/SettingsLib/src/com/android/settingslib/deviceinfo/PrivateStorageInfo.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+package com.android.settingslib.deviceinfo;
+
+import android.os.storage.StorageManager;
+import android.os.storage.VolumeInfo;
+import android.util.Log;
+
+import java.io.File;
+import java.util.Objects;
+
+/**
+ * PrivateStorageInfo provides information about the total and free storage on the device.
+ */
+public class PrivateStorageInfo {
+    private static final String TAG = "PrivateStorageInfo";
+    public final long freeBytes;
+    public final long totalBytes;
+
+    private PrivateStorageInfo(long freeBytes, long totalBytes) {
+        this.freeBytes = freeBytes;
+        this.totalBytes = totalBytes;
+    }
+
+    public static PrivateStorageInfo getPrivateStorageInfo(StorageVolumeProvider sm) {
+        long totalInternalStorage = sm.getPrimaryStorageSize();
+        long privateFreeBytes = 0;
+        long privateTotalBytes = 0;
+        for (VolumeInfo info : sm.getVolumes()) {
+            final File path = info.getPath();
+            if (info.getType() != VolumeInfo.TYPE_PRIVATE || path == null) {
+                continue;
+            }
+            privateTotalBytes += getTotalSize(info, totalInternalStorage);
+            privateFreeBytes += path.getFreeSpace();
+        }
+        return new PrivateStorageInfo(privateFreeBytes, privateTotalBytes);
+    }
+
+    /**
+     * Returns the total size in bytes for a given volume info.
+     * @param info Info of the volume to check.
+     * @param totalInternalStorage Total number of bytes in the internal storage to use if the
+     *                             volume is the internal disk.
+     */
+    public static long getTotalSize(VolumeInfo info, long totalInternalStorage) {
+        // Device could have more than one primary storage, which could be located in the
+        // internal flash (UUID_PRIVATE_INTERNAL) or in an external disk.
+        // If it's internal, try to get its total size from StorageManager first
+        // (totalInternalStorage), because that size is more precise because it accounts for
+        // the system partition.
+        if (info.getType() == VolumeInfo.TYPE_PRIVATE
+                && Objects.equals(info.getFsUuid(), StorageManager.UUID_PRIVATE_INTERNAL)
+                && totalInternalStorage > 0) {
+            return totalInternalStorage;
+        } else {
+            final File path = info.getPath();
+            if (path == null) {
+                // Should not happen, caller should have checked.
+                Log.e(TAG, "info's path is null on getTotalSize(): " + info);
+                return 0;
+            }
+            return path.getTotalSpace();
+        }
+    }
+
+}

packages/SettingsLib/src/com/android/settingslib/deviceinfo/StorageManagerVolumeProvider.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+package com.android.settingslib.deviceinfo;
+
+import android.os.storage.StorageManager;
+import android.os.storage.VolumeInfo;
+
+import java.util.List;
+
+/**
+ * StorageManagerVolumeProvider is a thin wrapper around the StorageManager to provide insight into
+ * the storage volumes on a device.
+ */
+public class StorageManagerVolumeProvider implements StorageVolumeProvider {
+    private StorageManager mStorageManager;
+
+    public StorageManagerVolumeProvider(StorageManager sm) {
+        mStorageManager = sm;
+    }
+
+    @Override
+    public long getPrimaryStorageSize() {
+        return mStorageManager.getPrimaryStorageSize();
+    }
+
+    @Override
+    public List<VolumeInfo> getVolumes() {
+        return mStorageManager.getVolumes();
+    }
+}

packages/SettingsLib/src/com/android/settingslib/deviceinfo/StorageVolumeProvider.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+package com.android.settingslib.deviceinfo;
+
+import android.os.storage.VolumeInfo;
+
+import java.util.List;
+
+/**
+ * StorageVolumeProvider provides access to the storage volumes on a device for free space
+ * calculations.
+ */
+public interface StorageVolumeProvider {
+    /**
+     * Returns the number of bytes of total storage on the primary storage.
+     */
+    long getPrimaryStorageSize();
+
+    /**
+     * Returns a list of VolumeInfos for the device.
+     */
+    List<VolumeInfo> getVolumes();
+}