Adding support for DB downgrade

Adding a schema file for handling DB downgrade. This schema file is part of
the backup/restore set, and hence is available on a device with lower app version.

Bug: 37257575
Change-Id: I69c8ef5f28d5209be6e6679412c7459d4eeda5d0

1 files changed, 55 insertions, 0 deletions

diff --git a/src/com/android/launcher3/util/IOUtils.java b/src/com/android/launcher3/util/IOUtils.java
new file mode 100644
index 000000000..77c21fe92
--- /dev/null
+++ b/src/com/android/launcher3/util/IOUtils.java
@@ -0,0 +1,55 @@
+/*
+ * 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.
+ */
+
+package com.android.launcher3.util;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+/**
+ * Supports various IO utility functions
+ */
+public class IOUtils {
+
+    private static final int BUF_SIZE = 0x1000; // 4K
+
+    public static byte[] toByteArray(File file) throws IOException {
+        try (InputStream in = new FileInputStream(file)) {
+            return toByteArray(in);
+        }
+    }
+
+    public static byte[] toByteArray(InputStream in) throws IOException {
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        copy(in, out);
+        return out.toByteArray();
+    }
+
+    public static long copy(InputStream from, OutputStream to) throws IOException {
+        byte[] buf = new byte[BUF_SIZE];
+        long total = 0;
+        int r;
+        while ((r = from.read(buf)) != -1) {
+            to.write(buf, 0, r);
+            total += r;
+        }
+        return total;
+    }
+}