Merge "add storage java internal reader" into main

tools/aconfig/aconfig_storage_read_api/srcs/android/aconfig/storage/StorageInternalReader.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2024 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 android.aconfig.storage;
+
+public class StorageInternalReader {
+
+    private static final String MAP_PATH = "/metadata/aconfig/maps/";
+    private static final String BOOT_PATH = "/metadata/aconfig/boot/";
+
+    private PackageTable mPackageTable;
+    private FlagValueList mFlagValueList;
+
+    private int mPackageBooleanStartOffset;
+
+    public StorageInternalReader(String container, String packageName) {
+        this(container, packageName, MAP_PATH, BOOT_PATH);
+    }
+
+    public StorageInternalReader(
+            String container, String packageName, String mapPath, String bootPath) {
+
+        String packageMapFile = mapPath + container + ".package.map";
+        String flagValueFile = bootPath + container + ".val";
+
+        mPackageTable = PackageTable.fromBytes(mapStorageFile(packageMapFile));
+        mFlagValueList = FlagValueList.fromBytes(mapStorageFile(flagValueFile));
+        mPackageBooleanStartOffset = getPackageBooleanStartOffset(packageName);
+    }
+
+    public boolean getBooleanFlagValue(int index) {
+        index += mPackageBooleanStartOffset;
+        if (index >= mFlagValueList.size()) {
+            throw new AconfigStorageException("Fail to get boolean flag value");
+        }
+        return mFlagValueList.get(index);
+    }
+
+    private int getPackageBooleanStartOffset(String packageName) {
+        PackageTable.Node pNode = mPackageTable.get(packageName);
+        if (pNode == null) {
+            PackageTable.Header header = mPackageTable.getHeader();
+            throw new AconfigStorageException(
+                    String.format(
+                            "Fail to get package %s from container %s",
+                            packageName, header.getContainer()));
+        }
+        return pNode.getBooleanStartIndex();
+    }
+
+    // Map a storage file given file path
+    private static MappedByteBuffer mapStorageFile(String file) {
+        try {
+            FileInputStream stream = new FileInputStream(file);
+            FileChannel channel = stream.getChannel();
+            return channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());
+        } catch (IOException e) {
+            throw new AconfigStorageException(
+                    String.format("Fail to mmap storage file %s", file), e);
+        }
+    }
+}