Add assets plugin (flutter#3151)

This plugin is implemented internally by the engine to integrate with the asset
system.

DEPS

@@ -54,7 +54,7 @@ deps = {
    # and not have to specific specific hashes.
 
   'src/lib/ftl':
-   Var('fuchsia_git') + '/ftl' + '@' + '4917351099cfb11d7bd9a808fd4fce67928c9e40',
+   Var('fuchsia_git') + '/ftl' + '@' + '5e9935c7205c119ce05098dc1d9c8eaac0595ba4',
 
   'src/lib/tonic':
    Var('fuchsia_git') + '/tonic' + '@' + '5ca4053563027007ef2e7b2892efe63c26d30259',

assets/directory_asset_bundle.cc

@@ -11,6 +11,7 @@
 
 #include "flutter/glue/data_pipe_utils.h"
 #include "lib/ftl/files/eintr_wrapper.h"
+#include "lib/ftl/files/file.h"
 #include "lib/ftl/files/path.h"
 #include "lib/ftl/files/unique_fd.h"
 
@@ -22,13 +23,9 @@ void DirectoryAssetBundle::GetAsStream(
   mojo::DataPipe pipe;
   callback.Run(std::move(pipe.consumer_handle));
 
-  std::string asset_path =
-      files::SimplifyPath(directory_ + "/" + asset_name.get());
-  if (asset_path.find(directory_) != 0u) {
-    FTL_LOG(ERROR) << "Asset name '" << asset_name
-                   << "' attempted to traverse outside asset bundle.";
+  std::string asset_path = GetPathForAsset(asset_name.get());
+  if (asset_path.empty())
     return;
-  }
 
   // TODO(abarth): Consider moving the |open| call to task_runner_.
   ftl::UniqueFD fd(HANDLE_EINTR(open(asset_path.c_str(), O_RDONLY)));
@@ -38,6 +35,14 @@ void DirectoryAssetBundle::GetAsStream(
                                task_runner_, [](bool ignored) {});
 }
 
+bool DirectoryAssetBundle::GetAsBuffer(const std::string& asset_name,
+                                       std::vector<uint8_t>* data) {
+  std::string asset_path = GetPathForAsset(asset_name);
+  if (asset_path.empty())
+    return false;
+  return files::ReadFileToVector(asset_path, data);
+}
+
 DirectoryAssetBundle::~DirectoryAssetBundle() {}
 
 DirectoryAssetBundle::DirectoryAssetBundle(
@@ -48,4 +53,15 @@ DirectoryAssetBundle::DirectoryAssetBundle(
       directory_(std::move(directory)),
       task_runner_(std::move(task_runner)) {}
 
+std::string DirectoryAssetBundle::GetPathForAsset(
+    const std::string& asset_name) {
+  std::string asset_path = files::SimplifyPath(directory_ + "/" + asset_name);
+  if (asset_path.find(directory_) != 0u) {
+    FTL_LOG(ERROR) << "Asset name '" << asset_name
+                   << "' attempted to traverse outside asset bundle.";
+    return std::string();
+  }
+  return asset_path;
+}
+
 }  // namespace blink

assets/directory_asset_bundle.h

@@ -7,8 +7,8 @@
 
 #include "lib/ftl/macros.h"
 #include "lib/ftl/tasks/task_runner.h"
+#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
-#include "mojo/public/cpp/bindings/strong_binding.h"
 #include "mojo/public/cpp/environment/async_waiter.h"
 #include "mojo/services/asset_bundle/interfaces/asset_bundle.mojom.h"
 
@@ -20,17 +20,20 @@ class DirectoryAssetBundle : public mojo::asset_bundle::AssetBundle {
   DirectoryAssetBundle(mojo::InterfaceRequest<AssetBundle> request,
                        std::string directory,
                        ftl::RefPtr<ftl::TaskRunner> task_runner);
+  ~DirectoryAssetBundle() override;
 
   // mojo::assert_bundle::AssetBundle implementation:
   void GetAsStream(
       const mojo::String& asset_name,
       const mojo::Callback<void(mojo::ScopedDataPipeConsumerHandle)>& callback)
       override;
 
+  bool GetAsBuffer(const std::string& asset_name, std::vector<uint8_t>* data);
+
  private:
-  ~DirectoryAssetBundle() override;
+  std::string GetPathForAsset(const std::string& asset_name);
 
-  mojo::StrongBinding<mojo::asset_bundle::AssetBundle> binding_;
+  mojo::Binding<mojo::asset_bundle::AssetBundle> binding_;
   const std::string directory_;
   ftl::RefPtr<ftl::TaskRunner> task_runner_;
 

assets/zip_asset_bundle.h

@@ -6,8 +6,8 @@
 #define FLUTTER_ASSETS_ZIP_ASSET_BUNDLE_H_
 
 #include "flutter/assets/zip_asset_store.h"
+#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
-#include "mojo/public/cpp/bindings/strong_binding.h"
 #include "mojo/services/asset_bundle/interfaces/asset_bundle.mojom.h"
 
 namespace blink {
@@ -17,6 +17,7 @@ class ZipAssetBundle : public mojo::asset_bundle::AssetBundle {
   ZipAssetBundle(
       mojo::InterfaceRequest<mojo::asset_bundle::AssetBundle> request,
       ftl::RefPtr<ZipAssetStore> store);
+  ~ZipAssetBundle() override;
 
   // mojo::assert_bundle::AssetBundle implementation:
   void GetAsStream(
@@ -25,9 +26,7 @@ class ZipAssetBundle : public mojo::asset_bundle::AssetBundle {
       override;
 
  private:
-  ~ZipAssetBundle() override;
-
-  mojo::StrongBinding<mojo::asset_bundle::AssetBundle> binding_;
+  mojo::Binding<mojo::asset_bundle::AssetBundle> binding_;
   ftl::RefPtr<ZipAssetStore> store_;
 };
 

shell/common/engine.cc

@@ -31,6 +31,8 @@
 namespace shell {
 namespace {
 
+constexpr char kAssetPluginChannel[] = "flutter/assets";
+
 bool PathExists(const std::string& path) {
   return access(path.c_str(), R_OK) == 0;
 }
@@ -197,23 +199,27 @@ void Engine::RunFromSnapshotStream(
 void Engine::ConfigureAssetBundle(const std::string& path) {
   struct stat stat_result = {0};
 
+  directory_asset_bundle_.reset();
+  zip_asset_bundle_.reset();
+
   if (::stat(path.c_str(), &stat_result) != 0) {
     LOG(INFO) << "Could not configure asset bundle at path: " << path;
     return;
   }
 
   if (S_ISDIR(stat_result.st_mode)) {
     // Directory asset bundle.
-    new blink::DirectoryAssetBundle(mojo::GetProxy(&root_bundle_), path,
-                                    blink::Threads::IO());
+    directory_asset_bundle_ = std::make_unique<blink::DirectoryAssetBundle>(
+        mojo::GetProxy(&root_bundle_), path, blink::Threads::IO());
     return;
   }
 
   if (S_ISREG(stat_result.st_mode)) {
     // Zip asset bundle.
     asset_store_ = ftl::MakeRefCounted<blink::ZipAssetStore>(
         blink::GetUnzipperProviderForPath(path), blink::Threads::IO());
-    new blink::ZipAssetBundle(mojo::GetProxy(&root_bundle_), asset_store_);
+    zip_asset_bundle_ = std::make_unique<blink::ZipAssetBundle>(
+        mojo::GetProxy(&root_bundle_), asset_store_);
     return;
   }
 }
@@ -365,6 +371,10 @@ void Engine::UpdateSemantics(std::vector<blink::SemanticsNode> update) {
 
 void Engine::HandlePlatformMessage(
     ftl::RefPtr<blink::PlatformMessage> message) {
+  if (message->name() == kAssetPluginChannel) {
+    HandleAssetPlatformMessage(std::move(message));
+    return;
+  }
   blink::Threads::Platform()->PostTask([
     platform_view = platform_view_, message = std::move(message)
   ]() mutable {
@@ -373,4 +383,22 @@ void Engine::HandlePlatformMessage(
   });
 }
 
+void Engine::HandleAssetPlatformMessage(
+    ftl::RefPtr<blink::PlatformMessage> message) {
+  ftl::RefPtr<blink::PlatformMessageResponse> response = message->response();
+  if (!response)
+    return;
+  const auto& data = message->data();
+  std::string asset_name(reinterpret_cast<const char*>(data.data()),
+                         data.size());
+  std::vector<uint8_t> asset_data;
+  if ((directory_asset_bundle_ &&
+       directory_asset_bundle_->GetAsBuffer(asset_name, &asset_data)) ||
+      (asset_store_ && asset_store_->GetAsBuffer(asset_name, &asset_data))) {
+    response->Complete(std::move(asset_data));
+  } else {
+    response->CompleteWithError();
+  }
+}
+
 }  // namespace shell

shell/common/engine.h

@@ -23,6 +23,11 @@
 #include "mojo/services/asset_bundle/interfaces/asset_bundle.mojom.h"
 #include "third_party/skia/include/core/SkPicture.h"
 
+namespace blink {
+class DirectoryAssetBundle;
+class ZipAssetBundle;
+}  // namespace blink
+
 namespace shell {
 class PlatformView;
 class Animator;
@@ -97,6 +102,8 @@ class Engine : public sky::SkyEngine, public blink::RuntimeDelegate {
   void ConfigureAssetBundle(const std::string& path);
   void ConfigureRuntime(const std::string& script_uri);
 
+  void HandleAssetPlatformMessage(ftl::RefPtr<blink::PlatformMessage> message);
+
   ftl::WeakPtr<PlatformView> platform_view_;
   std::unique_ptr<Animator> animator_;
 
@@ -116,7 +123,10 @@ class Engine : public sky::SkyEngine, public blink::RuntimeDelegate {
   std::string country_code_;
   bool semantics_enabled_ = false;
   mojo::Binding<SkyEngine> binding_;
+
   ftl::RefPtr<blink::ZipAssetStore> asset_store_;
+  std::unique_ptr<blink::DirectoryAssetBundle> directory_asset_bundle_;
+  std::unique_ptr<blink::ZipAssetBundle> zip_asset_bundle_;
 
   // TODO(eseidel): This should move into an AnimatorStateMachine.
   bool activity_running_;