Revert "libandroidfw: Improve performance of AssetManager2"

This reverts commit 392132748416719e3df427e6ac8dc11af194342c.
diff --git a/libs/androidfw/LoadedArsc.cpp b/libs/androidfw/LoadedArsc.cpp
index 1d2c597..e08848f 100644
--- a/libs/androidfw/LoadedArsc.cpp
+++ b/libs/androidfw/LoadedArsc.cpp
@@ -44,6 +44,44 @@
 
 constexpr const static int kAppPackageId = 0x7f;
 
+// Element of a TypeSpec array. See TypeSpec.
+struct Type {
+  // The configuration for which this type defines entries.
+  // This is already converted to host endianness.
+  ResTable_config configuration;
+
+  // Pointer to the mmapped data where entry definitions are kept.
+  const ResTable_type* type;
+};
+
+// TypeSpec is going to be immediately proceeded by
+// an array of Type structs, all in the same block of memory.
+struct TypeSpec {
+  // Pointer to the mmapped data where flags are kept.
+  // Flags denote whether the resource entry is public
+  // and under which configurations it varies.
+  const ResTable_typeSpec* type_spec;
+
+  // Pointer to the mmapped data where the IDMAP mappings for this type
+  // exist. May be nullptr if no IDMAP exists.
+  const IdmapEntry_header* idmap_entries;
+
+  // The number of types that follow this struct.
+  // There is a type for each configuration
+  // that entries are defined for.
+  size_t type_count;
+
+  // Trick to easily access a variable number of Type structs
+  // proceeding this struct, and to ensure their alignment.
+  const Type types[0];
+};
+
+// TypeSpecPtr points to the block of memory that holds
+// a TypeSpec struct, followed by an array of Type structs.
+// TypeSpecPtr is a managed pointer that knows how to delete
+// itself.
+using TypeSpecPtr = util::unique_cptr<TypeSpec>;
+
 namespace {
 
 // Builder that helps accumulate Type structs and then create a single
@@ -57,22 +95,21 @@
   }
 
   void AddType(const ResTable_type* type) {
-    types_.push_back(type);
+    ResTable_config config;
+    config.copyFromDtoH(type->config);
+    types_.push_back(Type{config, type});
   }
 
   TypeSpecPtr Build() {
     // Check for overflow.
-    using ElementType = const ResTable_type*;
-    if ((std::numeric_limits<size_t>::max() - sizeof(TypeSpec)) / sizeof(ElementType) <
-        types_.size()) {
+    if ((std::numeric_limits<size_t>::max() - sizeof(TypeSpec)) / sizeof(Type) < types_.size()) {
       return {};
     }
-    TypeSpec* type_spec =
-        (TypeSpec*)::malloc(sizeof(TypeSpec) + (types_.size() * sizeof(ElementType)));
+    TypeSpec* type_spec = (TypeSpec*)::malloc(sizeof(TypeSpec) + (types_.size() * sizeof(Type)));
     type_spec->type_spec = header_;
     type_spec->idmap_entries = idmap_header_;
     type_spec->type_count = types_.size();
-    memcpy(type_spec + 1, types_.data(), types_.size() * sizeof(ElementType));
+    memcpy(type_spec + 1, types_.data(), types_.size() * sizeof(Type));
     return TypeSpecPtr(type_spec);
   }
 
@@ -81,7 +118,7 @@
 
   const ResTable_typeSpec* header_;
   const IdmapEntry_header* idmap_header_;
-  std::vector<const ResTable_type*> types_;
+  std::vector<Type> types_;
 };
 
 }  // namespace
@@ -125,17 +162,18 @@
   return true;
 }
 
-static bool VerifyResTableEntry(const ResTable_type* type, uint32_t entry_offset) {
+static bool VerifyResTableEntry(const ResTable_type* type, uint32_t entry_offset,
+                                size_t entry_idx) {
   // Check that the offset is aligned.
   if (entry_offset & 0x03) {
-    LOG(ERROR) << "Entry at offset " << entry_offset << " is not 4-byte aligned.";
+    LOG(ERROR) << "Entry offset at index " << entry_idx << " is not 4-byte aligned.";
     return false;
   }
 
   // Check that the offset doesn't overflow.
   if (entry_offset > std::numeric_limits<uint32_t>::max() - dtohl(type->entriesStart)) {
     // Overflow in offset.
-    LOG(ERROR) << "Entry at offset " << entry_offset << " is too large.";
+    LOG(ERROR) << "Entry offset at index " << entry_idx << " is too large.";
     return false;
   }
 
@@ -143,7 +181,7 @@
 
   entry_offset += dtohl(type->entriesStart);
   if (entry_offset > chunk_size - sizeof(ResTable_entry)) {
-    LOG(ERROR) << "Entry at offset " << entry_offset
+    LOG(ERROR) << "Entry offset at index " << entry_idx
                << " is too large. No room for ResTable_entry.";
     return false;
   }
@@ -153,13 +191,13 @@
 
   const size_t entry_size = dtohs(entry->size);
   if (entry_size < sizeof(*entry)) {
-    LOG(ERROR) << "ResTable_entry size " << entry_size << " at offset " << entry_offset
+    LOG(ERROR) << "ResTable_entry size " << entry_size << " at index " << entry_idx
                << " is too small.";
     return false;
   }
 
   if (entry_size > chunk_size || entry_offset > chunk_size - entry_size) {
-    LOG(ERROR) << "ResTable_entry size " << entry_size << " at offset " << entry_offset
+    LOG(ERROR) << "ResTable_entry size " << entry_size << " at index " << entry_idx
                << " is too large.";
     return false;
   }
@@ -167,7 +205,7 @@
   if (entry_size < sizeof(ResTable_map_entry)) {
     // There needs to be room for one Res_value struct.
     if (entry_offset + entry_size > chunk_size - sizeof(Res_value)) {
-      LOG(ERROR) << "No room for Res_value after ResTable_entry at offset " << entry_offset
+      LOG(ERROR) << "No room for Res_value after ResTable_entry at index " << entry_idx
                  << " for type " << (int)type->id << ".";
       return false;
     }
@@ -176,12 +214,12 @@
         reinterpret_cast<const Res_value*>(reinterpret_cast<const uint8_t*>(entry) + entry_size);
     const size_t value_size = dtohs(value->size);
     if (value_size < sizeof(Res_value)) {
-      LOG(ERROR) << "Res_value at offset " << entry_offset << " is too small.";
+      LOG(ERROR) << "Res_value at index " << entry_idx << " is too small.";
       return false;
     }
 
     if (value_size > chunk_size || entry_offset + entry_size > chunk_size - value_size) {
-      LOG(ERROR) << "Res_value size " << value_size << " at offset " << entry_offset
+      LOG(ERROR) << "Res_value size " << value_size << " at index " << entry_idx
                  << " is too large.";
       return false;
     }
@@ -190,76 +228,117 @@
     const size_t map_entry_count = dtohl(map->count);
     size_t map_entries_start = entry_offset + entry_size;
     if (map_entries_start & 0x03) {
-      LOG(ERROR) << "Map entries at offset " << entry_offset << " start at unaligned offset.";
+      LOG(ERROR) << "Map entries at index " << entry_idx << " start at unaligned offset.";
       return false;
     }
 
     // Each entry is sizeof(ResTable_map) big.
     if (map_entry_count > ((chunk_size - map_entries_start) / sizeof(ResTable_map))) {
-      LOG(ERROR) << "Too many map entries in ResTable_map_entry at offset " << entry_offset << ".";
+      LOG(ERROR) << "Too many map entries in ResTable_map_entry at index " << entry_idx << ".";
       return false;
     }
   }
   return true;
 }
 
-const ResTable_entry* LoadedPackage::GetEntry(const ResTable_type* type_chunk,
-                                              uint16_t entry_index) {
-  uint32_t entry_offset = GetEntryOffset(type_chunk, entry_index);
-  if (entry_offset == ResTable_type::NO_ENTRY) {
-    return nullptr;
-  }
-  return GetEntryFromOffset(type_chunk, entry_offset);
-}
+bool LoadedPackage::FindEntry(const TypeSpecPtr& type_spec_ptr, uint16_t entry_idx,
+                              const ResTable_config& config, FindEntryResult* out_entry) const {
+  const ResTable_config* best_config = nullptr;
+  const ResTable_type* best_type = nullptr;
+  uint32_t best_offset = 0;
 
-uint32_t LoadedPackage::GetEntryOffset(const ResTable_type* type_chunk, uint16_t entry_index) {
-  // The configuration matches and is better than the previous selection.
-  // Find the entry value if it exists for this configuration.
-  const size_t entry_count = dtohl(type_chunk->entryCount);
-  const size_t offsets_offset = dtohs(type_chunk->header.headerSize);
+  for (uint32_t i = 0; i < type_spec_ptr->type_count; i++) {
+    const Type* type = &type_spec_ptr->types[i];
+    const ResTable_type* type_chunk = type->type;
 
-  // Check if there is the desired entry in this type.
+    if (type->configuration.match(config) &&
+        (best_config == nullptr || type->configuration.isBetterThan(*best_config, &config))) {
+      // The configuration matches and is better than the previous selection.
+      // Find the entry value if it exists for this configuration.
+      const size_t entry_count = dtohl(type_chunk->entryCount);
+      const size_t offsets_offset = dtohs(type_chunk->header.headerSize);
 
-  if (type_chunk->flags & ResTable_type::FLAG_SPARSE) {
-    // This is encoded as a sparse map, so perform a binary search.
-    const ResTable_sparseTypeEntry* sparse_indices =
-        reinterpret_cast<const ResTable_sparseTypeEntry*>(
+      // Check if there is the desired entry in this type.
+
+      if (type_chunk->flags & ResTable_type::FLAG_SPARSE) {
+        // This is encoded as a sparse map, so perform a binary search.
+        const ResTable_sparseTypeEntry* sparse_indices =
+            reinterpret_cast<const ResTable_sparseTypeEntry*>(
+                reinterpret_cast<const uint8_t*>(type_chunk) + offsets_offset);
+        const ResTable_sparseTypeEntry* sparse_indices_end = sparse_indices + entry_count;
+        const ResTable_sparseTypeEntry* result =
+            std::lower_bound(sparse_indices, sparse_indices_end, entry_idx,
+                             [](const ResTable_sparseTypeEntry& entry, uint16_t entry_idx) {
+                               return dtohs(entry.idx) < entry_idx;
+                             });
+
+        if (result == sparse_indices_end || dtohs(result->idx) != entry_idx) {
+          // No entry found.
+          continue;
+        }
+
+        // Extract the offset from the entry. Each offset must be a multiple of 4 so we store it as
+        // the real offset divided by 4.
+        best_offset = uint32_t{dtohs(result->offset)} * 4u;
+      } else {
+        if (entry_idx >= entry_count) {
+          // This entry cannot be here.
+          continue;
+        }
+
+        const uint32_t* entry_offsets = reinterpret_cast<const uint32_t*>(
             reinterpret_cast<const uint8_t*>(type_chunk) + offsets_offset);
-    const ResTable_sparseTypeEntry* sparse_indices_end = sparse_indices + entry_count;
-    const ResTable_sparseTypeEntry* result =
-        std::lower_bound(sparse_indices, sparse_indices_end, entry_index,
-                         [](const ResTable_sparseTypeEntry& entry, uint16_t entry_idx) {
-                           return dtohs(entry.idx) < entry_idx;
-                         });
+        const uint32_t offset = dtohl(entry_offsets[entry_idx]);
+        if (offset == ResTable_type::NO_ENTRY) {
+          continue;
+        }
 
-    if (result == sparse_indices_end || dtohs(result->idx) != entry_index) {
-      // No entry found.
-      return ResTable_type::NO_ENTRY;
+        // There is an entry for this resource, record it.
+        best_offset = offset;
+      }
+
+      best_config = &type->configuration;
+      best_type = type_chunk;
     }
-
-    // Extract the offset from the entry. Each offset must be a multiple of 4 so we store it as
-    // the real offset divided by 4.
-    return uint32_t{dtohs(result->offset)} * 4u;
   }
 
-  // This type is encoded as a dense array.
-  if (entry_index >= entry_count) {
-    // This entry cannot be here.
-    return ResTable_type::NO_ENTRY;
+  if (best_type == nullptr) {
+    return false;
   }
 
-  const uint32_t* entry_offsets = reinterpret_cast<const uint32_t*>(
-      reinterpret_cast<const uint8_t*>(type_chunk) + offsets_offset);
-  return dtohl(entry_offsets[entry_index]);
+  if (UNLIKELY(!VerifyResTableEntry(best_type, best_offset, entry_idx))) {
+    return false;
+  }
+
+  const ResTable_entry* best_entry = reinterpret_cast<const ResTable_entry*>(
+      reinterpret_cast<const uint8_t*>(best_type) + best_offset + dtohl(best_type->entriesStart));
+
+  const uint32_t* flags = reinterpret_cast<const uint32_t*>(type_spec_ptr->type_spec + 1);
+  out_entry->type_flags = dtohl(flags[entry_idx]);
+  out_entry->entry = best_entry;
+  out_entry->config = best_config;
+  out_entry->type_string_ref = StringPoolRef(&type_string_pool_, best_type->id - 1);
+  out_entry->entry_string_ref = StringPoolRef(&key_string_pool_, dtohl(best_entry->key.index));
+  return true;
 }
 
-const ResTable_entry* LoadedPackage::GetEntryFromOffset(const ResTable_type* type_chunk,
-                                                        uint32_t offset) {
-  if (UNLIKELY(!VerifyResTableEntry(type_chunk, offset))) {
-    return nullptr;
+bool LoadedPackage::FindEntry(uint8_t type_idx, uint16_t entry_idx, const ResTable_config& config,
+                              FindEntryResult* out_entry) const {
+  // If the type IDs are offset in this package, we need to take that into account when searching
+  // for a type.
+  const TypeSpecPtr& ptr = type_specs_[type_idx - type_id_offset_];
+  if (UNLIKELY(ptr == nullptr)) {
+    return false;
   }
-  return reinterpret_cast<const ResTable_entry*>(reinterpret_cast<const uint8_t*>(type_chunk) +
-                                                 offset + dtohl(type_chunk->entriesStart));
+
+  // If there is an IDMAP supplied with this package, translate the entry ID.
+  if (ptr->idmap_entries != nullptr) {
+    if (!LoadedIdmap::Lookup(ptr->idmap_entries, entry_idx, &entry_idx)) {
+      // There is no mapping, so the resource is not meant to be in this overlay package.
+      return false;
+    }
+  }
+  return FindEntry(ptr, entry_idx, config, out_entry);
 }
 
 void LoadedPackage::CollectConfigurations(bool exclude_mipmap,
@@ -267,7 +346,7 @@
   const static std::u16string kMipMap = u"mipmap";
   const size_t type_count = type_specs_.size();
   for (size_t i = 0; i < type_count; i++) {
-    const TypeSpecPtr& type_spec = type_specs_[i];
+    const util::unique_cptr<TypeSpec>& type_spec = type_specs_[i];
     if (type_spec != nullptr) {
       if (exclude_mipmap) {
         const int type_idx = type_spec->type_spec->id - 1;
@@ -288,11 +367,8 @@
         }
       }
 
-      const auto iter_end = type_spec->types + type_spec->type_count;
-      for (auto iter = type_spec->types; iter != iter_end; ++iter) {
-        ResTable_config config;
-        config.copyFromDtoH((*iter)->config);
-        out_configs->insert(config);
+      for (size_t j = 0; j < type_spec->type_count; j++) {
+        out_configs->insert(type_spec->types[j].configuration);
       }
     }
   }
@@ -302,12 +378,10 @@
   char temp_locale[RESTABLE_MAX_LOCALE_LEN];
   const size_t type_count = type_specs_.size();
   for (size_t i = 0; i < type_count; i++) {
-    const TypeSpecPtr& type_spec = type_specs_[i];
+    const util::unique_cptr<TypeSpec>& type_spec = type_specs_[i];
     if (type_spec != nullptr) {
-      const auto iter_end = type_spec->types + type_spec->type_count;
-      for (auto iter = type_spec->types; iter != iter_end; ++iter) {
-        ResTable_config configuration;
-        configuration.copyFromDtoH((*iter)->config);
+      for (size_t j = 0; j < type_spec->type_count; j++) {
+        const ResTable_config& configuration = type_spec->types[j].configuration;
         if (configuration.locale != 0) {
           configuration.getBcp47Locale(temp_locale, canonicalize);
           std::string locale(temp_locale);
@@ -335,17 +409,17 @@
     return 0u;
   }
 
-  const auto iter_end = type_spec->types + type_spec->type_count;
-  for (auto iter = type_spec->types; iter != iter_end; ++iter) {
-    const ResTable_type* type = *iter;
-    size_t entry_count = dtohl(type->entryCount);
+  for (size_t ti = 0; ti < type_spec->type_count; ti++) {
+    const Type* type = &type_spec->types[ti];
+    size_t entry_count = dtohl(type->type->entryCount);
     for (size_t entry_idx = 0; entry_idx < entry_count; entry_idx++) {
       const uint32_t* entry_offsets = reinterpret_cast<const uint32_t*>(
-          reinterpret_cast<const uint8_t*>(type) + dtohs(type->header.headerSize));
+          reinterpret_cast<const uint8_t*>(type->type) + dtohs(type->type->header.headerSize));
       const uint32_t offset = dtohl(entry_offsets[entry_idx]);
       if (offset != ResTable_type::NO_ENTRY) {
-        const ResTable_entry* entry = reinterpret_cast<const ResTable_entry*>(
-            reinterpret_cast<const uint8_t*>(type) + dtohl(type->entriesStart) + offset);
+        const ResTable_entry* entry =
+            reinterpret_cast<const ResTable_entry*>(reinterpret_cast<const uint8_t*>(type->type) +
+                                                    dtohl(type->type->entriesStart) + offset);
         if (dtohl(entry->key.index) == static_cast<uint32_t>(key_idx)) {
           // The package ID will be overridden by the caller (due to runtime assignment of package
           // IDs for shared libraries).
@@ -357,7 +431,8 @@
   return 0u;
 }
 
-const LoadedPackage* LoadedArsc::GetPackageById(uint8_t package_id) const {
+const LoadedPackage* LoadedArsc::GetPackageForId(uint32_t resid) const {
+  const uint8_t package_id = get_package_id(resid);
   for (const auto& loaded_package : packages_) {
     if (loaded_package->GetPackageId() == package_id) {
       return loaded_package.get();
@@ -605,6 +680,26 @@
   return std::move(loaded_package);
 }
 
+bool LoadedArsc::FindEntry(uint32_t resid, const ResTable_config& config,
+                           FindEntryResult* out_entry) const {
+  ATRACE_CALL();
+
+  const uint8_t package_id = get_package_id(resid);
+  const uint8_t type_id = get_type_id(resid);
+  const uint16_t entry_id = get_entry_id(resid);
+
+  if (UNLIKELY(type_id == 0)) {
+    LOG(ERROR) << base::StringPrintf("Invalid ID 0x%08x.", resid);
+    return false;
+  }
+
+  for (const auto& loaded_package : packages_) {
+    if (loaded_package->GetPackageId() == package_id) {
+      return loaded_package->FindEntry(type_id - 1, entry_id, config, out_entry);
+    }
+  }
+  return false;
+}
 
 bool LoadedArsc::LoadTable(const Chunk& chunk, const LoadedIdmap* loaded_idmap,
                            bool load_as_shared_library) {