Add fabricated RRO generation to libidmap2

Fabricated Runtime Resource Overlays are overlays that are generated
at runtime and are stored in the data/ partition.

The system can fabricate RROs at runtime to dynamically theme the
device. Idmaps can now be created from APK RROs and fabricated RROs.

Rather than operating on ApkAssets, libidmap2 now operates on abstract
resource "containers" that supply resource values. Target resource
containers implement methods needed to query overlayable and target
overlay information. Currently only APKs can be loaded as target
resource containers. Overlay resource containers implement methods to
supply the mapping of target resource to overlay value and other
overlay information.

The format of a fabricated RRO is as follows:
0x00 - 0x04 : fabricated overlay magic (always FRRO)
0x04 - 0x08 : file format version
0x08 - 0x0c : crc of version + proto data
0x0c - EOF  : proto fabricated overlay data

The magic is used to quickly detect if the file is a fabricated overlay.
The version is incremented whenever backwards incompatible changes are
made to the proto file format. Idmap must always be able to upgrade
fabricated overlays from previous versions to new versions, so all
previous versions must be checked into the tree.

Bug: 172471315
Test: libidmap2_tests && libandroidfw_tests
Change-Id: I4c9f29da278672e5695fb57d131a44c11a835180

1 files changed, 42 insertions, 38 deletions

diff --git a/libs/androidfw/AssetManager2.cpp b/libs/androidfw/AssetManager2.cpp
index 03ab62f48870..36bde5ccf267 100644
--- a/libs/androidfw/AssetManager2.cpp
+++ b/libs/androidfw/AssetManager2.cpp
@@ -102,9 +102,8 @@ AssetManager2::AssetManager2() {
   memset(&configuration_, 0, sizeof(configuration_));
 }
 
-bool AssetManager2::SetApkAssets(const std::vector<const ApkAssets*>& apk_assets,
-                                 bool invalidate_caches) {
-  apk_assets_ = apk_assets;
+bool AssetManager2::SetApkAssets(std::vector<const ApkAssets*> apk_assets, bool invalidate_caches) {
+  apk_assets_ = std::move(apk_assets);
   BuildDynamicRefTable();
   RebuildFilterList();
   if (invalidate_caches) {
@@ -137,6 +136,36 @@ void AssetManager2::BuildDynamicRefTable() {
   // 0x01 is reserved for the android package.
   int next_package_id = 0x02;
   for (const ApkAssets* apk_assets : sorted_apk_assets) {
+    std::shared_ptr<OverlayDynamicRefTable> overlay_ref_table;
+    if (auto loaded_idmap = apk_assets->GetLoadedIdmap(); loaded_idmap != nullptr) {
+      // The target package must precede the overlay package in the apk assets paths in order
+      // to take effect.
+      auto iter = apk_assets_package_ids.find(std::string(loaded_idmap->TargetApkPath()));
+      if (iter == apk_assets_package_ids.end()) {
+         LOG(INFO) << "failed to find target package for overlay "
+                   << loaded_idmap->OverlayApkPath();
+      } else {
+        uint8_t target_package_id = iter->second;
+
+        // Create a special dynamic reference table for the overlay to rewrite references to
+        // overlay resources as references to the target resources they overlay.
+        overlay_ref_table = std::make_shared<OverlayDynamicRefTable>(
+            loaded_idmap->GetOverlayDynamicRefTable(target_package_id));
+
+        // Add the overlay resource map to the target package's set of overlays.
+        const uint8_t target_idx = package_ids_[target_package_id];
+        CHECK(target_idx != 0xff) << "overlay target '" << loaded_idmap->TargetApkPath()
+                                  << "'added to apk_assets_package_ids but does not have an"
+                                  << " assigned package group";
+
+        PackageGroup& target_package_group = package_groups_[target_idx];
+        target_package_group.overlays_.push_back(
+            ConfiguredOverlay{loaded_idmap->GetTargetResourcesMap(target_package_id,
+                                                                  overlay_ref_table.get()),
+                              apk_assets_cookies[apk_assets]});
+      }
+    }
+
     const LoadedArsc* loaded_arsc = apk_assets->GetLoadedArsc();
     for (const std::unique_ptr<const LoadedPackage>& package : loaded_arsc->GetPackages()) {
       // Get the package ID or assign one if a shared library.
@@ -147,50 +176,25 @@ void AssetManager2::BuildDynamicRefTable() {
         package_id = package->GetPackageId();
       }
 
-      // Add the mapping for package ID to index if not present.
       uint8_t idx = package_ids_[package_id];
       if (idx == 0xff) {
+        // Add the mapping for package ID to index if not present.
         package_ids_[package_id] = idx = static_cast<uint8_t>(package_groups_.size());
-        package_groups_.push_back({});
-
-        if (apk_assets->IsOverlay()) {
-          // The target package must precede the overlay package in the apk assets paths in order
-          // to take effect.
-          const auto& loaded_idmap = apk_assets->GetLoadedIdmap();
-          auto target_package_iter = apk_assets_package_ids.find(
-              std::string(loaded_idmap->TargetApkPath()));
-          if (target_package_iter == apk_assets_package_ids.end()) {
-             LOG(INFO) << "failed to find target package for overlay "
-                       << loaded_idmap->OverlayApkPath();
-          } else {
-            const uint8_t target_package_id = target_package_iter->second;
-            const uint8_t target_idx = package_ids_[target_package_id];
-            CHECK(target_idx != 0xff) << "overlay added to apk_assets_package_ids but does not"
-                                      << " have an assigned package group";
-
-            PackageGroup& target_package_group = package_groups_[target_idx];
-
-            // Create a special dynamic reference table for the overlay to rewrite references to
-            // overlay resources as references to the target resources they overlay.
-            auto overlay_table = std::make_shared<OverlayDynamicRefTable>(
-                loaded_idmap->GetOverlayDynamicRefTable(target_package_id));
-            package_groups_.back().dynamic_ref_table = overlay_table;
-
-            // Add the overlay resource map to the target package's set of overlays.
-            target_package_group.overlays_.push_back(
-                ConfiguredOverlay{loaded_idmap->GetTargetResourcesMap(target_package_id,
-                                                                      overlay_table.get()),
-                                  apk_assets_cookies[apk_assets]});
-          }
+        PackageGroup& new_group = package_groups_.emplace_back();
+
+        if (overlay_ref_table != nullptr) {
+          // If this package is from an overlay, use a dynamic reference table that can rewrite
+          // overlay resource ids to their corresponding target resource ids.
+          new_group.dynamic_ref_table = overlay_ref_table;
         }
 
-        DynamicRefTable* ref_table = package_groups_.back().dynamic_ref_table.get();
+        DynamicRefTable* ref_table = new_group.dynamic_ref_table.get();
         ref_table->mAssignedPackageId = package_id;
         ref_table->mAppAsLib = package->IsDynamic() && package->GetPackageId() == 0x7f;
       }
-      PackageGroup* package_group = &package_groups_[idx];
 
       // Add the package and to the set of packages with the same ID.
+      PackageGroup* package_group = &package_groups_[idx];
       package_group->packages_.push_back(ConfiguredPackage{package.get(), {}});
       package_group->cookies_.push_back(apk_assets_cookies[apk_assets]);
 
@@ -578,7 +582,7 @@ base::expected<FindEntryResult, NullOrIOError> AssetManager2::FindEntry(
 
   const PackageGroup& package_group = package_groups_[package_idx];
   auto result = FindEntryInternal(package_group, type_idx, entry_idx, *desired_config,
-                                 stop_at_first_match, ignore_configuration);
+                                  stop_at_first_match, ignore_configuration);
   if (UNLIKELY(!result.has_value())) {
     return base::unexpected(result.error());
   }