Surface <overlayable> info in Java AssetManager

Add a new, hidden method to AssetManager to extract a mapping
overlayable name -> overlayable actor for all <overlayable> blocks in a
package. [This will eventually be used to check if the caller of the OMS
AIDL API is the registered actor for a given overlay.]

Also, teach AssetManager2 to not accept packages that re-use the same
overlayable name. [Such packages have always been ill-formed.]

Bug: 123894537
Test: make libandroidfw_tests
Change-Id: I1117fd3503f04fe4c73eb7114901e022508f4d9e

core/java/android/content/res/AssetManager.java

@@ -47,6 +47,7 @@ import java.nio.channels.FileLock;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.Map;
 
 /**
  * Provides access to an application's raw asset files; see {@link Resources}
@@ -1345,6 +1346,17 @@ public final class AssetManager implements AutoCloseable {
         }
     }
 
+    /**
+     * @hide
+     */
+    @GuardedBy("this")
+    public @Nullable Map<String, String> getOverlayableMap(String packageName) {
+        synchronized (this) {
+            ensureValidLocked();
+            return nativeGetOverlayableMap(mObject, packageName);
+        }
+    }
+
     @GuardedBy("this")
     private void incRefsLocked(long id) {
         if (DEBUG_REFS) {
@@ -1462,6 +1474,8 @@ public final class AssetManager implements AutoCloseable {
 
     private static native void nativeVerifySystemIdmaps();
     private static native String[] nativeCreateIdmapsForStaticOverlaysTargetingAndroid();
+    private static native @Nullable Map nativeGetOverlayableMap(long ptr,
+            @NonNull String packageName);
 
     // Global debug native methods.
     /**

core/jni/android_util_AssetManager.cpp

@@ -104,6 +104,12 @@ static struct configuration_offsets_t {
   jfieldID mScreenHeightDpOffset;
 } gConfigurationOffsets;
 
+static struct arraymap_offsets_t {
+  jclass classObject;
+  jmethodID constructor;
+  jmethodID put;
+} gArrayMapOffsets;
+
 jclass g_stringClass = nullptr;
 
 // ----------------------------------------------------------------------------
@@ -326,6 +332,50 @@ static Guarded<AssetManager2>& AssetManagerFromLong(jlong ptr) {
   return *AssetManagerForNdkAssetManager(reinterpret_cast<AAssetManager*>(ptr));
 }
 
+static jobject NativeGetOverlayableMap(JNIEnv* env, jclass /*clazz*/, jlong ptr,
+                                        jstring package_name) {
+  ScopedLock<AssetManager2> assetmanager(AssetManagerFromLong(ptr));
+  const ScopedUtfChars package_name_utf8(env, package_name);
+  CHECK(package_name_utf8.c_str() != nullptr);
+  const std::string std_package_name(package_name_utf8.c_str());
+  const std::unordered_map<std::string, std::string>* map = nullptr;
+
+  assetmanager->ForEachPackage([&](const std::string& this_package_name, uint8_t package_id) {
+    if (this_package_name == std_package_name) {
+      map = assetmanager->GetOverlayableMapForPackage(package_id);
+    }
+  });
+
+  if (map == nullptr) {
+    return nullptr;
+  }
+
+  jobject array_map = env->NewObject(gArrayMapOffsets.classObject, gArrayMapOffsets.constructor);
+  if (array_map == nullptr) {
+    return nullptr;
+  }
+
+  for (const auto& iter : *map) {
+    jstring name = env->NewStringUTF(iter.first.c_str());
+    if (env->ExceptionCheck()) {
+      return nullptr;
+    }
+
+    jstring actor = env->NewStringUTF(iter.second.c_str());
+    if (env->ExceptionCheck()) {
+      env->DeleteLocalRef(name);
+      return nullptr;
+    }
+
+    env->CallObjectMethod(array_map, gArrayMapOffsets.put, name, actor);
+
+    env->DeleteLocalRef(name);
+    env->DeleteLocalRef(actor);
+  }
+
+  return array_map;
+}
+
 static jobject ReturnParcelFileDescriptor(JNIEnv* env, std::unique_ptr<Asset> asset,
                                           jlongArray out_offsets) {
   off64_t start_offset, length;
@@ -1524,6 +1574,8 @@ static const JNINativeMethod gAssetManagerMethods[] = {
     {"nativeVerifySystemIdmaps", "()V", (void*)NativeVerifySystemIdmaps},
     {"nativeCreateIdmapsForStaticOverlaysTargetingAndroid", "()[Ljava/lang/String;",
      (void*)NativeCreateIdmapsForStaticOverlaysTargetingAndroid},
+    {"nativeGetOverlayableMap", "(JLjava/lang/String;)Ljava/util/Map;",
+     (void*)NativeGetOverlayableMap},
 
     // Global management/debug methods.
     {"getGlobalAssetCount", "()I", (void*)NativeGetGlobalAssetCount},
@@ -1575,6 +1627,14 @@ int register_android_content_AssetManager(JNIEnv* env) {
   gConfigurationOffsets.mScreenHeightDpOffset =
       GetFieldIDOrDie(env, configurationClass, "screenHeightDp", "I");
 
+  jclass arrayMapClass = FindClassOrDie(env, "android/util/ArrayMap");
+  gArrayMapOffsets.classObject = MakeGlobalRefOrDie(env, arrayMapClass);
+  gArrayMapOffsets.constructor =
+      GetMethodIDOrDie(env, gArrayMapOffsets.classObject, "<init>", "()V");
+  gArrayMapOffsets.put =
+      GetMethodIDOrDie(env, gArrayMapOffsets.classObject, "put",
+                       "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;");
+
   return RegisterMethodsOrDie(env, "android/content/res/AssetManager", gAssetManagerMethods,
                               NELEM(gAssetManagerMethods));
 }

libs/androidfw/AssetManager2.cpp

@@ -203,6 +203,27 @@ const DynamicRefTable* AssetManager2::GetDynamicRefTableForCookie(ApkAssetsCooki
   return nullptr;
 }
 
+const std::unordered_map<std::string, std::string>*
+  AssetManager2::GetOverlayableMapForPackage(uint32_t package_id) const {
+
+  if (package_id >= package_ids_.size()) {
+    return nullptr;
+  }
+
+  const size_t idx = package_ids_[package_id];
+  if (idx == 0xff) {
+    return nullptr;
+  }
+
+  const PackageGroup& package_group = package_groups_[idx];
+  if (package_group.packages_.size() == 0) {
+    return nullptr;
+  }
+
+  const auto loaded_package = package_group.packages_[0].loaded_package_;
+  return &loaded_package->GetOverlayableMap();
+}
+
 void AssetManager2::SetConfiguration(const ResTable_config& configuration) {
   const int diff = configuration_.diff(configuration);
   configuration_ = configuration;

libs/androidfw/LoadedArsc.cpp

@@ -598,6 +598,13 @@ std::unique_ptr<const LoadedPackage> LoadedPackage::Load(const Chunk& chunk,
         std::string actor;
         util::ReadUtf16StringFromDevice(header->actor, arraysize(header->actor), &actor);
 
+        if (loaded_package->overlayable_map_.find(name) !=
+            loaded_package->overlayable_map_.end()) {
+          LOG(ERROR) << "Multiple <overlayable> blocks with the same name '" << name << "'.";
+          return {};
+        }
+        loaded_package->overlayable_map_.emplace(name, actor);
+
         // Iterate over the overlayable policy chunks contained within the overlayable chunk data
         ChunkIterator overlayable_iter(child_chunk.data_ptr(), child_chunk.data_size());
         while (overlayable_iter.HasNext()) {

libs/androidfw/include/androidfw/AssetManager2.h

@@ -124,6 +124,9 @@ class AssetManager2 {
   // This may be nullptr if the APK represented by `cookie` has no resource table.
   const DynamicRefTable* GetDynamicRefTableForCookie(ApkAssetsCookie cookie) const;
 
+  const std::unordered_map<std::string, std::string>*
+    GetOverlayableMapForPackage(uint32_t package_id) const;
+
   // Sets/resets the configuration for this AssetManager. This will cause all
   // caches that are related to the configuration change to be invalidated.
   void SetConfiguration(const ResTable_config& configuration);

libs/androidfw/include/androidfw/LoadedArsc.h

@@ -20,6 +20,7 @@
 #include <memory>
 #include <set>
 #include <vector>
+#include <unordered_map>
 #include <unordered_set>
 
 #include "android-base/macros.h"
@@ -242,6 +243,10 @@ class LoadedPackage {
     return defines_overlayable_;
   }
 
+  const std::unordered_map<std::string, std::string>& GetOverlayableMap() const {
+    return overlayable_map_;
+  }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(LoadedPackage);
 
@@ -261,6 +266,7 @@ class LoadedPackage {
   ByteBucketArray<uint32_t> resource_ids_;
   std::vector<DynamicPackageEntry> dynamic_package_map_;
   std::vector<const std::pair<OverlayableInfo, std::unordered_set<uint32_t>>> overlayable_infos_;
+  std::unordered_map<std::string, std::string> overlayable_map_;
 };
 
 // Read-only view into a resource table. This class validates all data

libs/androidfw/tests/AssetManager2_test.cpp

@@ -71,6 +71,9 @@ class AssetManager2Test : public ::testing::Test {
 
     app_assets_ = ApkAssets::Load(GetTestDataPath() + "/app/app.apk");
     ASSERT_THAT(app_assets_, NotNull());
+
+    overlayable_assets_ = ApkAssets::Load(GetTestDataPath() + "/overlayable/overlayable.apk");
+    ASSERT_THAT(overlayable_assets_, NotNull());
   }
 
  protected:
@@ -83,6 +86,7 @@ class AssetManager2Test : public ::testing::Test {
   std::unique_ptr<const ApkAssets> appaslib_assets_;
   std::unique_ptr<const ApkAssets> system_assets_;
   std::unique_ptr<const ApkAssets> app_assets_;
+  std::unique_ptr<const ApkAssets> overlayable_assets_;
 };
 
 TEST_F(AssetManager2Test, FindsResourceFromSingleApkAssets) {
@@ -703,4 +707,20 @@ TEST_F(AssetManager2Test, GetLastPathAfterDisablingReturnsEmpty) {
   EXPECT_EQ("", resultDisabled);
 }
 
+TEST_F(AssetManager2Test, GetOverlayableMap) {
+  ResTable_config desired_config;
+  memset(&desired_config, 0, sizeof(desired_config));
+
+  AssetManager2 assetmanager;
+  assetmanager.SetResourceResolutionLoggingEnabled(true);
+  assetmanager.SetConfiguration(desired_config);
+  assetmanager.SetApkAssets({overlayable_assets_.get()});
+
+  const auto map = assetmanager.GetOverlayableMapForPackage(0x7f);
+  ASSERT_NE(nullptr, map);
+  ASSERT_EQ(2, map->size());
+  ASSERT_EQ(map->at("OverlayableResources1"), "overlay://theme");
+  ASSERT_EQ(map->at("OverlayableResources2"), "overlay://com.android.overlayable");
+}
+
 }  // namespace android

libs/androidfw/tests/LoadedArsc_test.cpp

@@ -331,7 +331,7 @@ TEST(LoadedArscTest, ResourceIdentifierIterator) {
 
   const std::vector<std::unique_ptr<const LoadedPackage>>& packages = loaded_arsc->GetPackages();
   ASSERT_EQ(1u, packages.size());
-  EXPECT_EQ(std::string("com.android.basic"), packages[0]->GetPackageName());
+  ASSERT_EQ(std::string("com.android.basic"), packages[0]->GetPackageName());
 
   const auto& loaded_package = packages[0];
   auto iter = loaded_package->begin();
@@ -369,6 +369,24 @@ TEST(LoadedArscTest, ResourceIdentifierIterator) {
   ASSERT_EQ(end, iter);
 }
 
+TEST(LoadedArscTest, GetOverlayableMap) {
+  std::string contents;
+  ASSERT_TRUE(ReadFileFromZipToString(GetTestDataPath() + "/overlayable/overlayable.apk",
+                                      "resources.arsc", &contents));
+
+  std::unique_ptr<const LoadedArsc> loaded_arsc = LoadedArsc::Load(StringPiece(contents));
+  ASSERT_NE(nullptr, loaded_arsc);
+
+  const std::vector<std::unique_ptr<const LoadedPackage>>& packages = loaded_arsc->GetPackages();
+  ASSERT_EQ(1u, packages.size());
+  ASSERT_EQ(std::string("com.android.overlayable"), packages[0]->GetPackageName());
+
+  const auto map = packages[0]->GetOverlayableMap();
+  ASSERT_EQ(2, map.size());
+  ASSERT_EQ(map.at("OverlayableResources1"), "overlay://theme");
+  ASSERT_EQ(map.at("OverlayableResources2"), "overlay://com.android.overlayable");
+}
+
 // structs with size fields (like Res_value, ResTable_entry) should be
 // backwards and forwards compatible (aka checking the size field against
 // sizeof(Res_value) might not be backwards compatible.