tools/aapt2/optimize/MultiApkGenerator.cpp - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2017 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.
  */

 #include "MultiApkGenerator.h"

 #include <algorithm>
 #include <regex>
 #include <string>

 #include "androidfw/ConfigDescription.h"
 #include "androidfw/StringPiece.h"

 #include "LoadedApk.h"
 #include "ResourceUtils.h"
 #include "ValueVisitor.h"
 #include "configuration/ConfigurationParser.h"
 #include "cmd/Util.h"
 #include "filter/AbiFilter.h"
 #include "filter/Filter.h"
 #include "format/Archive.h"
 #include "format/binary/XmlFlattener.h"
 #include "optimize/VersionCollapser.h"
 #include "process/IResourceTableConsumer.h"
 #include "split/TableSplitter.h"
 #include "util/Files.h"
 #include "xml/XmlDom.h"
 #include "xml/XmlUtil.h"

 namespace aapt {

 using ::aapt::configuration::AndroidSdk;
 using ::aapt::configuration::OutputArtifact;
 using ::aapt::xml::kSchemaAndroid;
 using ::aapt::xml::XmlResource;
 using ::android::ConfigDescription;
 using ::android::StringPiece;

 /**
  * Context wrapper that allows the min Android SDK value to be overridden.
  */
 class ContextWrapper : public IAaptContext {
  public:
   explicit ContextWrapper(IAaptContext* context)
       : context_(context), min_sdk_(context_->GetMinSdkVersion()) {
   }

   PackageType GetPackageType() override {
     return context_->GetPackageType();
   }

   SymbolTable* GetExternalSymbols() override {
     return context_->GetExternalSymbols();
   }

   IDiagnostics* GetDiagnostics() override {
     if (source_diag_) {
       return source_diag_.get();
     }
     return context_->GetDiagnostics();
   }

   const std::string& GetCompilationPackage() override {
     return context_->GetCompilationPackage();
   }

   uint8_t GetPackageId() override {
     return context_->GetPackageId();
   }

   NameMangler* GetNameMangler() override {
     return context_->GetNameMangler();
   }

   bool IsVerbose() override {
     return context_->IsVerbose();
   }

   int GetMinSdkVersion() override {
     return min_sdk_;
   }

   void SetMinSdkVersion(int min_sdk) {
     min_sdk_ = min_sdk;
   }

   void SetSource(const std::string& source) {
     source_diag_ =
         util::make_unique<SourcePathDiagnostics>(Source{source}, context_->GetDiagnostics());
   }

   const std::set<std::string>& GetSplitNameDependencies() override {
     return context_->GetSplitNameDependencies();
   }

  private:
   IAaptContext* context_;
   std::unique_ptr<SourcePathDiagnostics> source_diag_;

   int min_sdk_ = -1;
 };

 class SignatureFilter : public IPathFilter {
   bool Keep(const std::string& path) override {
     static std::regex signature_regex(R"regex(^META-INF/.*\.(RSA|DSA|EC|SF)$)regex");
     if (std::regex_search(path, signature_regex)) {
       return false;
     }
     return !(path == "META-INF/MANIFEST.MF");
   }
 };

 MultiApkGenerator::MultiApkGenerator(LoadedApk* apk, IAaptContext* context)
     : apk_(apk), context_(context) {
 }

 bool MultiApkGenerator::FromBaseApk(const MultiApkGeneratorOptions& options) {
   std::unordered_set<std::string> artifacts_to_keep = options.kept_artifacts;
   std::unordered_set<std::string> filtered_artifacts;
   std::unordered_set<std::string> kept_artifacts;

   // For now, just write out the stripped APK since ABI splitting doesn't modify anything else.
   for (const OutputArtifact& artifact : options.apk_artifacts) {
     FilterChain filters;

     ContextWrapper wrapped_context{context_};
     wrapped_context.SetSource(artifact.name);

     if (!options.kept_artifacts.empty()) {
       const auto& it = artifacts_to_keep.find(artifact.name);
       if (it == artifacts_to_keep.end()) {
         filtered_artifacts.insert(artifact.name);
         if (context_->IsVerbose()) {
           context_->GetDiagnostics()->Note(DiagMessage(artifact.name) << "skipping artifact");
         }
         continue;
       } else {
         artifacts_to_keep.erase(it);
         kept_artifacts.insert(artifact.name);
       }
     }

     std::unique_ptr<ResourceTable> table =
         FilterTable(context_, artifact, *apk_->GetResourceTable(), &filters);
     if (!table) {
       return false;
     }

     IDiagnostics* diag = wrapped_context.GetDiagnostics();

     std::unique_ptr<XmlResource> manifest;
     if (!UpdateManifest(artifact, &manifest, diag)) {
       diag->Error(DiagMessage() << "could not update AndroidManifest.xml for output artifact");
       return false;
     }

     std::string out = options.out_dir;
     if (!file::mkdirs(out)) {
       diag->Warn(DiagMessage() << "could not create out dir: " << out);
     }
     file::AppendPath(&out, artifact.name);

     if (context_->IsVerbose()) {
       diag->Note(DiagMessage() << "Generating split: " << out);
     }

     std::unique_ptr<IArchiveWriter> writer = CreateZipFileArchiveWriter(diag, out);

     if (context_->IsVerbose()) {
       diag->Note(DiagMessage() << "Writing output: " << out);
     }

     filters.AddFilter(util::make_unique<SignatureFilter>());
     if (!apk_->WriteToArchive(&wrapped_context, table.get(), options.table_flattener_options,
                               &filters, writer.get(), manifest.get())) {
       return false;
     }
   }

   // Make sure all of the requested artifacts were valid. If there are any kept artifacts left,
   // either the config or the command line was wrong.
   if (!artifacts_to_keep.empty()) {
     context_->GetDiagnostics()->Error(
         DiagMessage() << "The configuration and command line to filter artifacts do not match");

     context_->GetDiagnostics()->Error(DiagMessage() << kept_artifacts.size() << " kept:");
     for (const auto& artifact : kept_artifacts) {
       context_->GetDiagnostics()->Error(DiagMessage() << "  " << artifact);
     }

     context_->GetDiagnostics()->Error(DiagMessage() << filtered_artifacts.size() << " filtered:");
     for (const auto& artifact : filtered_artifacts) {
       context_->GetDiagnostics()->Error(DiagMessage() << "  " << artifact);
     }

     context_->GetDiagnostics()->Error(DiagMessage() << artifacts_to_keep.size() << " missing:");
     for (const auto& artifact : artifacts_to_keep) {
       context_->GetDiagnostics()->Error(DiagMessage() << "  " << artifact);
     }

     return false;
   }

   return true;
 }

 std::unique_ptr<ResourceTable> MultiApkGenerator::FilterTable(IAaptContext* context,
                                                               const OutputArtifact& artifact,
                                                               const ResourceTable& old_table,
                                                               FilterChain* filters) {
   TableSplitterOptions splits;
   AxisConfigFilter axis_filter;
   ContextWrapper wrapped_context{context};
   wrapped_context.SetSource(artifact.name);

   if (!artifact.abis.empty()) {
     filters->AddFilter(AbiFilter::FromAbiList(artifact.abis));
   }

   if (!artifact.screen_densities.empty()) {
     for (const auto& density_config : artifact.screen_densities) {
       splits.preferred_densities.push_back(density_config.density);
     }
   }

   if (!artifact.locales.empty()) {
     for (const auto& locale : artifact.locales) {
       axis_filter.AddConfig(locale);
     }
     splits.config_filter = &axis_filter;
   }

   if (artifact.android_sdk) {
     wrapped_context.SetMinSdkVersion(artifact.android_sdk.value().min_sdk_version);
   }

   std::unique_ptr<ResourceTable> table = old_table.Clone();

   VersionCollapser collapser;
   if (!collapser.Consume(&wrapped_context, table.get())) {
     context->GetDiagnostics()->Error(DiagMessage() << "Failed to strip versioned resources");
     return {};
   }

   TableSplitter splitter{{}, splits};
   splitter.SplitTable(table.get());
   return table;
 }

 bool MultiApkGenerator::UpdateManifest(const OutputArtifact& artifact,
                                        std::unique_ptr<XmlResource>* updated_manifest,
                                        IDiagnostics* diag) {
   const xml::XmlResource* apk_manifest = apk_->GetManifest();
   if (apk_manifest == nullptr) {
     return false;
   }

   *updated_manifest = apk_manifest->Clone();
   XmlResource* manifest = updated_manifest->get();

   // Make sure the first element is <manifest> with package attribute.
   xml::Element* manifest_el = manifest->root.get();
   if (!manifest_el) {
     return false;
   }

   if (!manifest_el->namespace_uri.empty() || manifest_el->name != "manifest") {
     diag->Error(DiagMessage(manifest->file.source) << "root tag must be <manifest>");
     return false;
   }

   // Retrieve the versionCode attribute.
   auto version_code = manifest_el->FindAttribute(kSchemaAndroid, "versionCode");
   if (!version_code) {
     diag->Error(DiagMessage(manifest->file.source) << "manifest must have a versionCode attribute");
     return false;
   }

   auto version_code_value = ValueCast<BinaryPrimitive>(version_code->compiled_value.get());
   if (!version_code_value) {
     diag->Error(DiagMessage(manifest->file.source) << "versionCode is invalid");
     return false;
   }

   // Retrieve the versionCodeMajor attribute.
   auto version_code_major = manifest_el->FindAttribute(kSchemaAndroid, "versionCodeMajor");
   BinaryPrimitive* version_code_major_value = nullptr;
   if (version_code_major) {
     version_code_major_value = ValueCast<BinaryPrimitive>(version_code_major->compiled_value.get());
     if (!version_code_major_value) {
       diag->Error(DiagMessage(manifest->file.source) << "versionCodeMajor is invalid");
       return false;
     }
   }

   // Calculate and set the updated version code
   uint64_t major = (version_code_major_value)
                   ? ((uint64_t) version_code_major_value->value.data) << 32 : 0;
   uint64_t new_version = (major | version_code_value->value.data) + artifact.version;
   SetLongVersionCode(manifest_el, new_version);

   // Check to see if the minSdkVersion needs to be updated.
   if (artifact.android_sdk) {
     // TODO(safarmer): Handle the rest of the Android SDK.
     const AndroidSdk& android_sdk = artifact.android_sdk.value();

     if (xml::Element* uses_sdk_el = manifest_el->FindChild({}, "uses-sdk")) {
       if (xml::Attribute* min_sdk_attr =
               uses_sdk_el->FindAttribute(xml::kSchemaAndroid, "minSdkVersion")) {
         // Populate with a pre-compiles attribute to we don't need to relink etc.
         const std::string& min_sdk_str = std::to_string(android_sdk.min_sdk_version);
         min_sdk_attr->compiled_value = ResourceUtils::TryParseInt(min_sdk_str);
       } else {
         // There was no minSdkVersion. This is strange since at this point we should have been
         // through the manifest fixer which sets the default minSdkVersion.
         diag->Error(DiagMessage(manifest->file.source) << "missing minSdkVersion from <uses-sdk>");
         return false;
       }
     } else {
       // No uses-sdk present. This is strange since at this point we should have been
       // through the manifest fixer which should have added it.
       diag->Error(DiagMessage(manifest->file.source) << "missing <uses-sdk> from <manifest>");
       return false;
     }
   }

   if (!artifact.screen_densities.empty()) {
     xml::Element* screens_el = manifest_el->FindChild({}, "compatible-screens");
     if (!screens_el) {
       // create a new element.
       std::unique_ptr<xml::Element> new_screens_el = util::make_unique<xml::Element>();
       new_screens_el->name = "compatible-screens";
       screens_el = new_screens_el.get();
       manifest_el->AppendChild(std::move(new_screens_el));
     } else {
       // clear out the old element.
       screens_el->GetChildElements().clear();
     }

     for (const auto& density : artifact.screen_densities) {
       AddScreens(density, screens_el);
     }
   }

   return true;
 }

 /**
  * Adds a screen element with both screenSize and screenDensity set. Since we only know the density
  * we add it for all screen sizes.
  *
  * This requires the resource IDs for the attributes from the framework library. Since these IDs are
  * a part of the public API (and in public.xml) we hard code the values.
  *
  * The excert from the framework is as follows:
  *    <public type="attr" name="screenSize" id="0x010102ca" />
  *    <public type="attr" name="screenDensity" id="0x010102cb" />
  */
 void MultiApkGenerator::AddScreens(const ConfigDescription& config, xml::Element* parent) {
   // Hard coded integer representation of the supported screen sizes:
   //  small   = 200
   //  normal  = 300
   //  large   = 400
   //  xlarge  = 500
   constexpr const uint32_t kScreenSizes[4] = {200, 300, 400, 500,};
   constexpr const uint32_t kScreenSizeResourceId = 0x010102ca;
   constexpr const uint32_t kScreenDensityResourceId = 0x010102cb;

   for (uint32_t screen_size : kScreenSizes) {
     std::unique_ptr<xml::Element> screen = util::make_unique<xml::Element>();
     screen->name = "screen";

     xml::Attribute* size = screen->FindOrCreateAttribute(kSchemaAndroid, "screenSize");
     size->compiled_attribute = xml::AaptAttribute(Attribute(), {kScreenSizeResourceId});
     size->compiled_value = ResourceUtils::MakeInt(screen_size);

     xml::Attribute* density = screen->FindOrCreateAttribute(kSchemaAndroid, "screenDensity");
     density->compiled_attribute = xml::AaptAttribute(Attribute(), {kScreenDensityResourceId});
     density->compiled_value = ResourceUtils::MakeInt(config.density);


     parent->AppendChild(std::move(screen));
   }
 }

 }  // namespace aapt
	/*
	* Copyright (C) 2017 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.
	*/

	#include "MultiApkGenerator.h"

	#include <algorithm>
	#include <regex>
	#include <string>

	#include "androidfw/ConfigDescription.h"
	#include "androidfw/StringPiece.h"

	#include "LoadedApk.h"
	#include "ResourceUtils.h"
	#include "ValueVisitor.h"
	#include "configuration/ConfigurationParser.h"
	#include "cmd/Util.h"
	#include "filter/AbiFilter.h"
	#include "filter/Filter.h"
	#include "format/Archive.h"
	#include "format/binary/XmlFlattener.h"
	#include "optimize/VersionCollapser.h"
	#include "process/IResourceTableConsumer.h"
	#include "split/TableSplitter.h"
	#include "util/Files.h"
	#include "xml/XmlDom.h"
	#include "xml/XmlUtil.h"

	namespace aapt {

	using ::aapt::configuration::AndroidSdk;
	using ::aapt::configuration::OutputArtifact;
	using ::aapt::xml::kSchemaAndroid;
	using ::aapt::xml::XmlResource;
	using ::android::ConfigDescription;
	using ::android::StringPiece;

	/**
	* Context wrapper that allows the min Android SDK value to be overridden.
	*/
	class ContextWrapper : public IAaptContext {
	public:
	explicit ContextWrapper(IAaptContext* context)
	: context_(context), min_sdk_(context_->GetMinSdkVersion()) {
	}

	PackageType GetPackageType() override {
	return context_->GetPackageType();
	}

	SymbolTable* GetExternalSymbols() override {
	return context_->GetExternalSymbols();
	}

	IDiagnostics* GetDiagnostics() override {
	if (source_diag_) {
	return source_diag_.get();
	}
	return context_->GetDiagnostics();
	}

	const std::string& GetCompilationPackage() override {
	return context_->GetCompilationPackage();
	}

	uint8_t GetPackageId() override {
	return context_->GetPackageId();
	}

	NameMangler* GetNameMangler() override {
	return context_->GetNameMangler();
	}

	bool IsVerbose() override {
	return context_->IsVerbose();
	}

	int GetMinSdkVersion() override {
	return min_sdk_;
	}

	void SetMinSdkVersion(int min_sdk) {
	min_sdk_ = min_sdk;
	}

	void SetSource(const std::string& source) {
	source_diag_ =
	util::make_unique<SourcePathDiagnostics>(Source{source}, context_->GetDiagnostics());
	}

	const std::set<std::string>& GetSplitNameDependencies() override {
	return context_->GetSplitNameDependencies();
	}

	private:
	IAaptContext* context_;
	std::unique_ptr<SourcePathDiagnostics> source_diag_;

	int min_sdk_ = -1;
	};

	class SignatureFilter : public IPathFilter {
	bool Keep(const std::string& path) override {
	static std::regex signature_regex(R"regex(^META-INF/.*\.(RSA\|DSA\|EC\|SF)$)regex");
	if (std::regex_search(path, signature_regex)) {
	return false;
	}
	return !(path == "META-INF/MANIFEST.MF");
	}
	};

	MultiApkGenerator::MultiApkGenerator(LoadedApk* apk, IAaptContext* context)
	: apk_(apk), context_(context) {
	}

	bool MultiApkGenerator::FromBaseApk(const MultiApkGeneratorOptions& options) {
	std::unordered_set<std::string> artifacts_to_keep = options.kept_artifacts;
	std::unordered_set<std::string> filtered_artifacts;
	std::unordered_set<std::string> kept_artifacts;

	// For now, just write out the stripped APK since ABI splitting doesn't modify anything else.
	for (const OutputArtifact& artifact : options.apk_artifacts) {
	FilterChain filters;

	ContextWrapper wrapped_context{context_};
	wrapped_context.SetSource(artifact.name);

	if (!options.kept_artifacts.empty()) {
	const auto& it = artifacts_to_keep.find(artifact.name);
	if (it == artifacts_to_keep.end()) {
	filtered_artifacts.insert(artifact.name);
	if (context_->IsVerbose()) {
	context_->GetDiagnostics()->Note(DiagMessage(artifact.name) << "skipping artifact");
	}
	continue;
	} else {
	artifacts_to_keep.erase(it);
	kept_artifacts.insert(artifact.name);
	}
	}

	std::unique_ptr<ResourceTable> table =
	FilterTable(context_, artifact, *apk_->GetResourceTable(), &filters);
	if (!table) {
	return false;
	}

	IDiagnostics* diag = wrapped_context.GetDiagnostics();

	std::unique_ptr<XmlResource> manifest;
	if (!UpdateManifest(artifact, &manifest, diag)) {
	diag->Error(DiagMessage() << "could not update AndroidManifest.xml for output artifact");
	return false;
	}

	std::string out = options.out_dir;
	if (!file::mkdirs(out)) {
	diag->Warn(DiagMessage() << "could not create out dir: " << out);
	}
	file::AppendPath(&out, artifact.name);

	if (context_->IsVerbose()) {
	diag->Note(DiagMessage() << "Generating split: " << out);
	}

	std::unique_ptr<IArchiveWriter> writer = CreateZipFileArchiveWriter(diag, out);

	if (context_->IsVerbose()) {
	diag->Note(DiagMessage() << "Writing output: " << out);
	}

	filters.AddFilter(util::make_unique<SignatureFilter>());
	if (!apk_->WriteToArchive(&wrapped_context, table.get(), options.table_flattener_options,
	&filters, writer.get(), manifest.get())) {
	return false;
	}
	}

	// Make sure all of the requested artifacts were valid. If there are any kept artifacts left,
	// either the config or the command line was wrong.
	if (!artifacts_to_keep.empty()) {
	context_->GetDiagnostics()->Error(
	DiagMessage() << "The configuration and command line to filter artifacts do not match");

	context_->GetDiagnostics()->Error(DiagMessage() << kept_artifacts.size() << " kept:");
	for (const auto& artifact : kept_artifacts) {
	context_->GetDiagnostics()->Error(DiagMessage() << " " << artifact);
	}

	context_->GetDiagnostics()->Error(DiagMessage() << filtered_artifacts.size() << " filtered:");
	for (const auto& artifact : filtered_artifacts) {
	context_->GetDiagnostics()->Error(DiagMessage() << " " << artifact);
	}

	context_->GetDiagnostics()->Error(DiagMessage() << artifacts_to_keep.size() << " missing:");
	for (const auto& artifact : artifacts_to_keep) {
	context_->GetDiagnostics()->Error(DiagMessage() << " " << artifact);
	}

	return false;
	}

	return true;
	}

	std::unique_ptr<ResourceTable> MultiApkGenerator::FilterTable(IAaptContext* context,
	const OutputArtifact& artifact,
	const ResourceTable& old_table,
	FilterChain* filters) {
	TableSplitterOptions splits;
	AxisConfigFilter axis_filter;
	ContextWrapper wrapped_context{context};
	wrapped_context.SetSource(artifact.name);

	if (!artifact.abis.empty()) {
	filters->AddFilter(AbiFilter::FromAbiList(artifact.abis));
	}

	if (!artifact.screen_densities.empty()) {
	for (const auto& density_config : artifact.screen_densities) {
	splits.preferred_densities.push_back(density_config.density);
	}
	}

	if (!artifact.locales.empty()) {
	for (const auto& locale : artifact.locales) {
	axis_filter.AddConfig(locale);
	}
	splits.config_filter = &axis_filter;
	}

	if (artifact.android_sdk) {
	wrapped_context.SetMinSdkVersion(artifact.android_sdk.value().min_sdk_version);
	}

	std::unique_ptr<ResourceTable> table = old_table.Clone();

	VersionCollapser collapser;
	if (!collapser.Consume(&wrapped_context, table.get())) {
	context->GetDiagnostics()->Error(DiagMessage() << "Failed to strip versioned resources");
	return {};
	}

	TableSplitter splitter{{}, splits};
	splitter.SplitTable(table.get());
	return table;
	}

	bool MultiApkGenerator::UpdateManifest(const OutputArtifact& artifact,
	std::unique_ptr<XmlResource>* updated_manifest,
	IDiagnostics* diag) {
	const xml::XmlResource* apk_manifest = apk_->GetManifest();
	if (apk_manifest == nullptr) {
	return false;
	}

	*updated_manifest = apk_manifest->Clone();
	XmlResource* manifest = updated_manifest->get();

	// Make sure the first element is <manifest> with package attribute.
	xml::Element* manifest_el = manifest->root.get();
	if (!manifest_el) {
	return false;
	}

	if (!manifest_el->namespace_uri.empty() \|\| manifest_el->name != "manifest") {
	diag->Error(DiagMessage(manifest->file.source) << "root tag must be <manifest>");
	return false;
	}

	// Retrieve the versionCode attribute.
	auto version_code = manifest_el->FindAttribute(kSchemaAndroid, "versionCode");
	if (!version_code) {
	diag->Error(DiagMessage(manifest->file.source) << "manifest must have a versionCode attribute");
	return false;
	}

	auto version_code_value = ValueCast<BinaryPrimitive>(version_code->compiled_value.get());
	if (!version_code_value) {
	diag->Error(DiagMessage(manifest->file.source) << "versionCode is invalid");
	return false;
	}

	// Retrieve the versionCodeMajor attribute.
	auto version_code_major = manifest_el->FindAttribute(kSchemaAndroid, "versionCodeMajor");
	BinaryPrimitive* version_code_major_value = nullptr;
	if (version_code_major) {
	version_code_major_value = ValueCast<BinaryPrimitive>(version_code_major->compiled_value.get());
	if (!version_code_major_value) {
	diag->Error(DiagMessage(manifest->file.source) << "versionCodeMajor is invalid");
	return false;
	}
	}

	// Calculate and set the updated version code
	uint64_t major = (version_code_major_value)
	? ((uint64_t) version_code_major_value->value.data) << 32 : 0;
	uint64_t new_version = (major \| version_code_value->value.data) + artifact.version;
	SetLongVersionCode(manifest_el, new_version);

	// Check to see if the minSdkVersion needs to be updated.
	if (artifact.android_sdk) {
	// TODO(safarmer): Handle the rest of the Android SDK.
	const AndroidSdk& android_sdk = artifact.android_sdk.value();

	if (xml::Element* uses_sdk_el = manifest_el->FindChild({}, "uses-sdk")) {
	if (xml::Attribute* min_sdk_attr =
	uses_sdk_el->FindAttribute(xml::kSchemaAndroid, "minSdkVersion")) {
	// Populate with a pre-compiles attribute to we don't need to relink etc.
	const std::string& min_sdk_str = std::to_string(android_sdk.min_sdk_version);
	min_sdk_attr->compiled_value = ResourceUtils::TryParseInt(min_sdk_str);
	} else {
	// There was no minSdkVersion. This is strange since at this point we should have been
	// through the manifest fixer which sets the default minSdkVersion.
	diag->Error(DiagMessage(manifest->file.source) << "missing minSdkVersion from <uses-sdk>");
	return false;
	}
	} else {
	// No uses-sdk present. This is strange since at this point we should have been
	// through the manifest fixer which should have added it.
	diag->Error(DiagMessage(manifest->file.source) << "missing <uses-sdk> from <manifest>");
	return false;
	}
	}

	if (!artifact.screen_densities.empty()) {
	xml::Element* screens_el = manifest_el->FindChild({}, "compatible-screens");
	if (!screens_el) {
	// create a new element.
	std::unique_ptr<xml::Element> new_screens_el = util::make_unique<xml::Element>();
	new_screens_el->name = "compatible-screens";
	screens_el = new_screens_el.get();
	manifest_el->AppendChild(std::move(new_screens_el));
	} else {
	// clear out the old element.
	screens_el->GetChildElements().clear();
	}

	for (const auto& density : artifact.screen_densities) {
	AddScreens(density, screens_el);
	}
	}

	return true;
	}

	/**
	* Adds a screen element with both screenSize and screenDensity set. Since we only know the density
	* we add it for all screen sizes.
	*
	* This requires the resource IDs for the attributes from the framework library. Since these IDs are
	* a part of the public API (and in public.xml) we hard code the values.
	*
	* The excert from the framework is as follows:
	* <public type="attr" name="screenSize" id="0x010102ca" />
	* <public type="attr" name="screenDensity" id="0x010102cb" />
	*/
	void MultiApkGenerator::AddScreens(const ConfigDescription& config, xml::Element* parent) {
	// Hard coded integer representation of the supported screen sizes:
	// small = 200
	// normal = 300
	// large = 400
	// xlarge = 500
	constexpr const uint32_t kScreenSizes[4] = {200, 300, 400, 500,};
	constexpr const uint32_t kScreenSizeResourceId = 0x010102ca;
	constexpr const uint32_t kScreenDensityResourceId = 0x010102cb;

	for (uint32_t screen_size : kScreenSizes) {
	std::unique_ptr<xml::Element> screen = util::make_unique<xml::Element>();
	screen->name = "screen";

	xml::Attribute* size = screen->FindOrCreateAttribute(kSchemaAndroid, "screenSize");
	size->compiled_attribute = xml::AaptAttribute(Attribute(), {kScreenSizeResourceId});
	size->compiled_value = ResourceUtils::MakeInt(screen_size);

	xml::Attribute* density = screen->FindOrCreateAttribute(kSchemaAndroid, "screenDensity");
	density->compiled_attribute = xml::AaptAttribute(Attribute(), {kScreenDensityResourceId});
	density->compiled_value = ResourceUtils::MakeInt(config.density);


	parent->AppendChild(std::move(screen));
	}
	}

	} // namespace aapt