Mohamed Heikal c769403631 Resource Path Obfuscation
This CL allows aapt2 to obfuscate resource paths within the output apk
and move resources to shorter obfuscated paths. This reduces apk size
when there is a large number of resources since the path metadata exists
in 4 places in the apk.

This CL adds two arguments to aapt2, one to enable resource path
obfuscation and one to point to a path to output the path map to (for
later debugging).

Test: make aapt2_tests
Bug: b/75965637

Change-Id: I9cacafe1d17800d673566b2d61b0b88f3fb8d60c
2018-12-20 18:19:25 -05:00

352 lines
12 KiB
C++

/*
* Copyright (C) 2016 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 "LoadedApk.h"
#include "ResourceValues.h"
#include "ValueVisitor.h"
#include "format/Archive.h"
#include "format/binary/TableFlattener.h"
#include "format/binary/XmlFlattener.h"
#include "format/proto/ProtoDeserialize.h"
#include "format/proto/ProtoSerialize.h"
#include "io/BigBufferStream.h"
#include "io/Util.h"
#include "xml/XmlDom.h"
using ::aapt::io::IFile;
using ::aapt::io::IFileCollection;
using ::aapt::xml::XmlResource;
using ::android::StringPiece;
using ::std::unique_ptr;
namespace aapt {
static ApkFormat DetermineApkFormat(io::IFileCollection* apk) {
if (apk->FindFile(kApkResourceTablePath) != nullptr) {
return ApkFormat::kBinary;
} else if (apk->FindFile(kProtoResourceTablePath) != nullptr) {
return ApkFormat::kProto;
} else {
// If the resource table is not present, attempt to read the manifest.
io::IFile* manifest_file = apk->FindFile(kAndroidManifestPath);
if (manifest_file == nullptr) {
return ApkFormat::kUnknown;
}
// First try in proto format.
std::unique_ptr<io::InputStream> manifest_in = manifest_file->OpenInputStream();
if (manifest_in != nullptr) {
pb::XmlNode pb_node;
io::ProtoInputStreamReader proto_reader(manifest_in.get());
if (proto_reader.ReadMessage(&pb_node)) {
return ApkFormat::kProto;
}
}
// If it didn't work, try in binary format.
std::unique_ptr<io::IData> manifest_data = manifest_file->OpenAsData();
if (manifest_data != nullptr) {
std::string error;
std::unique_ptr<xml::XmlResource> manifest =
xml::Inflate(manifest_data->data(), manifest_data->size(), &error);
if (manifest != nullptr) {
return ApkFormat::kBinary;
}
}
return ApkFormat::kUnknown;
}
}
std::unique_ptr<LoadedApk> LoadedApk::LoadApkFromPath(const StringPiece& path, IDiagnostics* diag) {
Source source(path);
std::string error;
std::unique_ptr<io::ZipFileCollection> apk = io::ZipFileCollection::Create(path, &error);
if (apk == nullptr) {
diag->Error(DiagMessage(path) << "failed opening zip: " << error);
return {};
}
ApkFormat apkFormat = DetermineApkFormat(apk.get());
switch (apkFormat) {
case ApkFormat::kBinary:
return LoadBinaryApkFromFileCollection(source, std::move(apk), diag);
case ApkFormat::kProto:
return LoadProtoApkFromFileCollection(source, std::move(apk), diag);
default:
diag->Error(DiagMessage(path) << "could not identify format of APK");
return {};
}
}
std::unique_ptr<LoadedApk> LoadedApk::LoadProtoApkFromFileCollection(
const Source& source, unique_ptr<io::IFileCollection> collection, IDiagnostics* diag) {
std::unique_ptr<ResourceTable> table;
io::IFile* table_file = collection->FindFile(kProtoResourceTablePath);
if (table_file != nullptr) {
pb::ResourceTable pb_table;
std::unique_ptr<io::InputStream> in = table_file->OpenInputStream();
if (in == nullptr) {
diag->Error(DiagMessage(source) << "failed to open " << kProtoResourceTablePath);
return {};
}
io::ProtoInputStreamReader proto_reader(in.get());
if (!proto_reader.ReadMessage(&pb_table)) {
diag->Error(DiagMessage(source) << "failed to read " << kProtoResourceTablePath);
return {};
}
std::string error;
table = util::make_unique<ResourceTable>(/** validate_resources **/ false);
if (!DeserializeTableFromPb(pb_table, collection.get(), table.get(), &error)) {
diag->Error(DiagMessage(source)
<< "failed to deserialize " << kProtoResourceTablePath << ": " << error);
return {};
}
}
io::IFile* manifest_file = collection->FindFile(kAndroidManifestPath);
if (manifest_file == nullptr) {
diag->Error(DiagMessage(source) << "failed to find " << kAndroidManifestPath);
return {};
}
std::unique_ptr<io::InputStream> manifest_in = manifest_file->OpenInputStream();
if (manifest_in == nullptr) {
diag->Error(DiagMessage(source) << "failed to open " << kAndroidManifestPath);
return {};
}
pb::XmlNode pb_node;
io::ProtoInputStreamReader proto_reader(manifest_in.get());
if (!proto_reader.ReadMessage(&pb_node)) {
diag->Error(DiagMessage(source) << "failed to read proto " << kAndroidManifestPath);
return {};
}
std::string error;
std::unique_ptr<xml::XmlResource> manifest = DeserializeXmlResourceFromPb(pb_node, &error);
if (manifest == nullptr) {
diag->Error(DiagMessage(source)
<< "failed to deserialize proto " << kAndroidManifestPath << ": " << error);
return {};
}
return util::make_unique<LoadedApk>(source, std::move(collection), std::move(table),
std::move(manifest), ApkFormat::kProto);
}
std::unique_ptr<LoadedApk> LoadedApk::LoadBinaryApkFromFileCollection(
const Source& source, unique_ptr<io::IFileCollection> collection, IDiagnostics* diag) {
std::unique_ptr<ResourceTable> table;
io::IFile* table_file = collection->FindFile(kApkResourceTablePath);
if (table_file != nullptr) {
table = util::make_unique<ResourceTable>(/** validate_resources **/ false);
std::unique_ptr<io::IData> data = table_file->OpenAsData();
if (data == nullptr) {
diag->Error(DiagMessage(source) << "failed to open " << kApkResourceTablePath);
return {};
}
BinaryResourceParser parser(diag, table.get(), source, data->data(), data->size(),
collection.get());
if (!parser.Parse()) {
return {};
}
}
io::IFile* manifest_file = collection->FindFile(kAndroidManifestPath);
if (manifest_file == nullptr) {
diag->Error(DiagMessage(source) << "failed to find " << kAndroidManifestPath);
return {};
}
std::unique_ptr<io::IData> manifest_data = manifest_file->OpenAsData();
if (manifest_data == nullptr) {
diag->Error(DiagMessage(source) << "failed to open " << kAndroidManifestPath);
return {};
}
std::string error;
std::unique_ptr<xml::XmlResource> manifest =
xml::Inflate(manifest_data->data(), manifest_data->size(), &error);
if (manifest == nullptr) {
diag->Error(DiagMessage(source)
<< "failed to parse binary " << kAndroidManifestPath << ": " << error);
return {};
}
return util::make_unique<LoadedApk>(source, std::move(collection), std::move(table),
std::move(manifest), ApkFormat::kBinary);
}
bool LoadedApk::WriteToArchive(IAaptContext* context, const TableFlattenerOptions& options,
IArchiveWriter* writer) {
FilterChain empty;
return WriteToArchive(context, table_.get(), options, &empty, writer);
}
bool LoadedApk::WriteToArchive(IAaptContext* context, ResourceTable* split_table,
const TableFlattenerOptions& options, FilterChain* filters,
IArchiveWriter* writer, XmlResource* manifest) {
std::set<std::string> referenced_resources;
// List the files being referenced in the resource table.
for (auto& pkg : split_table->packages) {
for (auto& type : pkg->types) {
for (auto& entry : type->entries) {
for (auto& config_value : entry->values) {
FileReference* file_ref = ValueCast<FileReference>(config_value->value.get());
if (file_ref) {
referenced_resources.insert(*file_ref->path);
}
}
}
}
}
std::unique_ptr<io::IFileCollectionIterator> iterator = apk_->Iterator();
while (iterator->HasNext()) {
io::IFile* file = iterator->Next();
std::string path = file->GetSource().path;
std::string output_path = path;
bool is_resource = path.find("res/") == 0;
if (is_resource) {
auto it = options.shortened_path_map.find(path);
if (it != options.shortened_path_map.end()) {
output_path = it->second;
}
}
// Skip resources that are not referenced if requested.
if (is_resource && referenced_resources.find(output_path) == referenced_resources.end()) {
if (context->IsVerbose()) {
context->GetDiagnostics()->Note(DiagMessage()
<< "Removing resource '" << path << "' from APK.");
}
continue;
}
if (!filters->Keep(path)) {
if (context->IsVerbose()) {
context->GetDiagnostics()->Note(DiagMessage() << "Filtered '" << path << "' from APK.");
}
continue;
}
// The resource table needs to be re-serialized since it might have changed.
if (format_ == ApkFormat::kBinary && path == kApkResourceTablePath) {
BigBuffer buffer(4096);
// TODO(adamlesinski): How to determine if there were sparse entries (and if to encode
// with sparse entries) b/35389232.
TableFlattener flattener(options, &buffer);
if (!flattener.Consume(context, split_table)) {
return false;
}
io::BigBufferInputStream input_stream(&buffer);
if (!io::CopyInputStreamToArchive(context,
&input_stream,
path,
ArchiveEntry::kAlign,
writer)) {
return false;
}
} else if (format_ == ApkFormat::kProto && path == kProtoResourceTablePath) {
pb::ResourceTable pb_table;
SerializeTableToPb(*split_table, &pb_table, context->GetDiagnostics());
if (!io::CopyProtoToArchive(context,
&pb_table,
path,
ArchiveEntry::kAlign, writer)) {
return false;
}
} else if (manifest != nullptr && path == "AndroidManifest.xml") {
BigBuffer buffer(8192);
XmlFlattenerOptions xml_flattener_options;
xml_flattener_options.use_utf16 = true;
XmlFlattener xml_flattener(&buffer, xml_flattener_options);
if (!xml_flattener.Consume(context, manifest)) {
context->GetDiagnostics()->Error(DiagMessage(path) << "flattening failed");
return false;
}
uint32_t compression_flags = file->WasCompressed() ? ArchiveEntry::kCompress : 0u;
io::BigBufferInputStream manifest_buffer_in(&buffer);
if (!io::CopyInputStreamToArchive(context, &manifest_buffer_in, path, compression_flags,
writer)) {
return false;
}
} else {
if (!io::CopyFileToArchivePreserveCompression(
context, file, output_path, writer)) {
return false;
}
}
}
return true;
}
std::unique_ptr<xml::XmlResource> LoadedApk::LoadXml(const std::string& file_path,
IDiagnostics* diag) const {
io::IFile* file = apk_->FindFile(file_path);
if (file == nullptr) {
diag->Error(DiagMessage() << "failed to find file");
return nullptr;
}
std::unique_ptr<xml::XmlResource> doc;
if (format_ == ApkFormat::kProto) {
std::unique_ptr<io::InputStream> in = file->OpenInputStream();
if (!in) {
diag->Error(DiagMessage() << "failed to open file");
return nullptr;
}
pb::XmlNode pb_node;
io::ProtoInputStreamReader proto_reader(in.get());
if (!proto_reader.ReadMessage(&pb_node)) {
diag->Error(DiagMessage() << "failed to parse file as proto XML");
return nullptr;
}
std::string err;
doc = DeserializeXmlResourceFromPb(pb_node, &err);
if (!doc) {
diag->Error(DiagMessage() << "failed to deserialize proto XML: " << err);
return nullptr;
}
} else if (format_ == ApkFormat::kBinary) {
std::unique_ptr<io::IData> data = file->OpenAsData();
if (!data) {
diag->Error(DiagMessage() << "failed to open file");
return nullptr;
}
std::string err;
doc = xml::Inflate(data->data(), data->size(), &err);
if (!doc) {
diag->Error(DiagMessage() << "failed to parse file as binary XML: " << err);
return nullptr;
}
}
return doc;
}
} // namespace aapt