1 files changed, 174 insertions, 0 deletions
diff --git a/packages/BackupEncryption/src/com/android/server/backup/encryption/chunking/ProtoStore.java b/packages/BackupEncryption/src/com/android/server/backup/encryption/chunking/ProtoStore.java
new file mode 100644
index 000000000000..3ba5f2b741b8
--- /dev/null
+++ b/packages/BackupEncryption/src/com/android/server/backup/encryption/chunking/ProtoStore.java
@@ -0,0 +1,174 @@
+/*
+ * Copyright (C) 2019 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.server.backup.encryption.chunking;
+
+import static com.android.internal.util.Preconditions.checkNotNull;
+
+import android.content.Context;
+import android.text.TextUtils;
+import android.util.AtomicFile;
+import android.util.Slog;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.server.backup.encryption.protos.nano.ChunksMetadataProto;
+import com.android.server.backup.encryption.protos.nano.KeyValueListingProto;
+
+import com.google.protobuf.nano.MessageNano;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.Optional;
+
+/**
+ * Stores a nano proto for each package, persisting the proto to disk.
+ *
+ * <p>This is used to store {@link ChunksMetadataProto.ChunkListing}.
+ *
+ * @param <T> the type of nano proto to store.
+ */
+public class ProtoStore<T extends MessageNano> {
+    private static final String CHUNK_LISTING_FOLDER = "backup_chunk_listings";
+    private static final String KEY_VALUE_LISTING_FOLDER = "backup_kv_listings";
+
+    private static final String TAG = "BupEncProtoStore";
+
+    private final File mStoreFolder;
+    private final Class<T> mClazz;
+
+    /** Creates a new instance which stores chunk listings at the default location. */
+    public static ProtoStore<ChunksMetadataProto.ChunkListing> createChunkListingStore(
+            Context context) throws IOException {
+        return new ProtoStore<>(
+                ChunksMetadataProto.ChunkListing.class,
+                new File(context.getFilesDir().getAbsoluteFile(), CHUNK_LISTING_FOLDER));
+    }
+
+    /** Creates a new instance which stores key value listings in the default location. */
+    public static ProtoStore<KeyValueListingProto.KeyValueListing> createKeyValueListingStore(
+            Context context) throws IOException {
+        return new ProtoStore<>(
+                KeyValueListingProto.KeyValueListing.class,
+                new File(context.getFilesDir().getAbsoluteFile(), KEY_VALUE_LISTING_FOLDER));
+    }
+
+    /**
+     * Creates a new instance which stores protos in the given folder.
+     *
+     * @param storeFolder The location where the serialized form is stored.
+     */
+    @VisibleForTesting
+    ProtoStore(Class<T> clazz, File storeFolder) throws IOException {
+        mClazz = checkNotNull(clazz);
+        mStoreFolder = ensureDirectoryExistsOrThrow(storeFolder);
+    }
+
+    private static File ensureDirectoryExistsOrThrow(File directory) throws IOException {
+        if (directory.exists() && !directory.isDirectory()) {
+            throw new IOException("Store folder already exists, but isn't a directory.");
+        }
+
+        if (!directory.exists() && !directory.mkdir()) {
+            throw new IOException("Unable to create store folder.");
+        }
+
+        return directory;
+    }
+
+    /**
+     * Returns the chunk listing for the given package, or {@link Optional#empty()} if no listing
+     * exists.
+     */
+    public Optional<T> loadProto(String packageName)
+            throws IOException, IllegalAccessException, InstantiationException,
+            NoSuchMethodException, InvocationTargetException {
+        File file = getFileForPackage(packageName);
+
+        if (!file.exists()) {
+            Slog.d(
+                    TAG,
+                    "No chunk listing existed for " + packageName + ", returning empty listing.");
+            return Optional.empty();
+        }
+
+        AtomicFile protoStore = new AtomicFile(file);
+        byte[] data = protoStore.readFully();
+
+        Constructor<T> constructor = mClazz.getDeclaredConstructor();
+        T proto = constructor.newInstance();
+        MessageNano.mergeFrom(proto, data);
+        return Optional.of(proto);
+    }
+
+    /** Saves a proto to disk, associating it with the given package. */
+    public void saveProto(String packageName, T proto) throws IOException {
+        checkNotNull(proto);
+        File file = getFileForPackage(packageName);
+
+        try (FileOutputStream os = new FileOutputStream(file)) {
+            os.write(MessageNano.toByteArray(proto));
+        } catch (IOException e) {
+            Slog.e(
+                    TAG,
+                    "Exception occurred when saving the listing for "
+                            + packageName
+                            + ", deleting saved listing.",
+                    e);
+
+            // If a problem occurred when writing the listing then it might be corrupt, so delete
+            // it.
+            file.delete();
+
+            throw e;
+        }
+    }
+
+    /** Deletes the proto for the given package, or does nothing if the package has no proto. */
+    public void deleteProto(String packageName) {
+        File file = getFileForPackage(packageName);
+        file.delete();
+    }
+
+    /** Deletes every proto of this type, for all package names. */
+    public void deleteAllProtos() {
+        File[] files = mStoreFolder.listFiles();
+
+        // We ensure that the storeFolder exists in the constructor, but check just in case it has
+        // mysteriously disappeared.
+        if (files == null) {
+            return;
+        }
+
+        for (File file : files) {
+            file.delete();
+        }
+    }
+
+    private File getFileForPackage(String packageName) {
+        checkPackageName(packageName);
+        return new File(mStoreFolder, packageName);
+    }
+
+    private static void checkPackageName(String packageName) {
+        if (TextUtils.isEmpty(packageName) || packageName.contains("/")) {
+            throw new IllegalArgumentException(
+                    "Package name must not contain '/' or be empty: " + packageName);
+        }
+    }
+}