1 files changed, 108 insertions, 0 deletions
diff --git a/app/src/main/java/com/android/geotz/app/GeoDataFileManagerImpl.java b/app/src/main/java/com/android/geotz/app/GeoDataFileManagerImpl.java
new file mode 100644
index 0000000..9d6f26a
--- /dev/null
+++ b/app/src/main/java/com/android/geotz/app/GeoDataFileManagerImpl.java
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2022 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.geotz.app;
+
+import android.content.Context;
+
+import androidx.annotation.NonNull;
+
+import com.android.timezone.location.provider.GeoDataFileManager;
+import com.google.common.hash.Hashing;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
+import java.util.Objects;
+import java.util.Properties;
+
+/**
+ * An implementation of {@link GeoDataFileManager} that copies the tzs2.dat classpath resource to
+ * an app file path for reading.
+ */
+public final class GeoDataFileManagerImpl implements GeoDataFileManager {
+
+    /**
+     * The config properties key to get the resource path of the tzs2.dat file to use for time zone
+     * boundaries.
+     */
+    private static final String RESOURCE_CONFIG_KEY_GEODATA_RESOURCE = "geodata.resource";
+
+    /**
+     * The config properties key to get the location of the tzs2.dat file to use for time zone
+     * boundaries.
+     */
+    private static final String RESOURCE_CONFIG_KEY_GEODATA_SHA256= "geodata.sha256";
+
+    private File mGeoDataFile;
+
+    @Override
+    public void init(@NonNull Context context, @NonNull Properties configProperties)
+            throws IOException {
+        File geoDataFile = new File(context.getFilesDir(), "tzs2.dat");
+        ClassLoader classLoader = getClass().getClassLoader();
+
+        String geoDataResource = configProperties.getProperty(RESOURCE_CONFIG_KEY_GEODATA_RESOURCE);
+        String expectedSha256 = configProperties.getProperty(RESOURCE_CONFIG_KEY_GEODATA_SHA256);
+        if (!geoDataFile.exists() || !Objects.equals(computeSha256(geoDataFile), expectedSha256)) {
+            // Copy the resource to the app persistent files dir.
+            copyResource(classLoader, geoDataResource, geoDataFile, expectedSha256);
+        }
+
+        mGeoDataFile = geoDataFile;
+    }
+
+    @Override
+    @NonNull
+    public File getGeoDataFile() {
+        return Objects.requireNonNull(mGeoDataFile);
+    }
+
+    private static void copyResource(@NonNull ClassLoader classLoader, @NonNull String resourceName,
+            @NonNull File targetPath, @NonNull String expectedSha256) {
+        boolean success = false;
+        try (InputStream resourceStream = classLoader.getResourceAsStream(resourceName)) {
+            if (resourceStream == null) {
+                throw new IllegalStateException("Unable to find "
+                        + " resource=" + resourceName);
+            }
+            Files.copy(resourceStream, targetPath.toPath(), StandardCopyOption.REPLACE_EXISTING);
+            String actualSha256 = computeSha256(targetPath);
+            if (!actualSha256.equals(expectedSha256)) {
+                throw new IllegalStateException(
+                        "SHA256 expected=" + expectedSha256 + ", actual=" + actualSha256);
+            }
+            success = true;
+        } catch (IOException e) {
+            throw new IllegalStateException("Unable to copy resource from"
+                    + " resource=" + resourceName
+                    + " to targetPath=" + targetPath, e);
+        } finally {
+            if (!success) {
+                targetPath.delete();
+            }
+        }
+    }
+
+    private static String computeSha256(File file) {
+        try {
+            return com.google.common.io.Files.asByteSource(file).hash(Hashing.sha256()).toString();
+        } catch (IOException e) {
+            throw new IllegalStateException("Unable to compute hash for file=" + file);
+        }
+    }
+}