Reland: [fuchsia] Enable running from source packages (#4634)

This relands https://github.com/flutter/engine/pull/4629 with a
tonic roll to fix the build.

DEPS

@@ -127,7 +127,7 @@ deps = {
    Var('fuchsia_git') + '/garnet' + '@' + 'b3ba6b6d6ab8ef658278cc43c9f839a8a8d1718e',
 
   'src/topaz':
-   Var('fuchsia_git') + '/topaz' + '@' + '1eb2e77be92ed968223b0cea19fe2108e689dcd5',
+   Var('fuchsia_git') + '/topaz' + '@' + '201335048e32db217493141a3ab61137aea60d78',
 
   'src/third_party/benchmark':
    Var('fuchsia_git') + '/third_party/benchmark' + '@' + '296537bc48d380adf21567c5d736ab79f5363d22',

content_handler/application_controller_impl.cc

@@ -64,6 +64,7 @@ ApplicationControllerImpl::ApplicationControllerImpl(
   fdio_ns_t* fdio_ns = SetupNamespace(startup_info->flat_namespace);
   if (fdio_ns == nullptr) {
     FXL_LOG(ERROR) << "Failed to initialize namespace";
+    return;
   }
 
   url_ = startup_info->launch_info->url;

content_handler/runtime_holder.cc

@@ -24,10 +24,12 @@
 #include "flutter/runtime/runtime_init.h"
 #include "lib/app/cpp/connect.h"
 #include "lib/fsl/vmo/vector.h"
+#include "lib/fxl/files/path.h"
 #include "lib/fxl/files/unique_fd.h"
 #include "lib/fxl/functional/make_copyable.h"
 #include "lib/fxl/logging.h"
 #include "lib/fxl/time/time_delta.h"
+#include "lib/tonic/logging/dart_error.h"
 #include "lib/zip/create_unzipper.h"
 #include "third_party/dart/runtime/include/dart_api.h"
 #include "third_party/rapidjson/rapidjson/document.h"
@@ -115,6 +117,11 @@ void RuntimeHolder::Init(
   FXL_DCHECK(rasterizer_);
 
   namespc_ = namespc;
+  dirfd_ = fdio_ns_opendir(namespc);
+  if (dirfd_ == -1) {
+    FXL_LOG(ERROR) << "Failed to get fd for namespace";
+    return;
+  }
   context_ = std::move(context);
   outgoing_services_ = std::move(outgoing_services);
 
@@ -196,11 +203,12 @@ void RuntimeHolder::CreateView(
 
   std::vector<uint8_t> kernel;
   std::vector<uint8_t> snapshot;
+  bool maybe_running_from_source = false;
   if (!Dart_IsPrecompiledRuntime()) {
     if (!GetAssetAsBuffer(kKernelKey, &kernel) &&
         !GetAssetAsBuffer(kSnapshotKey, &snapshot)) {
-      FXL_LOG(ERROR) << "Unable to load kernel or snapshot from root bundle.";
-      return;
+      maybe_running_from_source = true;
+      FXL_LOG(INFO) << "No kernel or snapshot in root bundle.";
     }
   }
 
@@ -273,7 +281,7 @@ void RuntimeHolder::CreateView(
         dlsym(dylib_handle_, "_kDartIsolateSnapshotInstructions"));
   }
   runtime_->CreateDartController(script_uri, isolate_snapshot_data,
-                                 isolate_snapshot_instr);
+                                 isolate_snapshot_instr, dirfd_);
 
   runtime_->SetViewportMetrics(viewport_metrics_);
 
@@ -281,6 +289,12 @@ void RuntimeHolder::CreateView(
     runtime_->dart_controller()->RunFromPrecompiledSnapshot();
   } else if (!kernel.empty()) {
     runtime_->dart_controller()->RunFromKernel(std::move(kernel));
+  } else if (maybe_running_from_source) {
+    std::string basename = files::GetBaseName(script_uri);
+    std::string main_dart = "pkg/data/" + basename + "/lib/main.dart";
+    FXL_LOG(INFO) << "Running from source with entrypoint: '" << main_dart
+                  << "'";
+    runtime_->dart_controller()->RunFromSource(main_dart, "pkg/data/.packages");
   } else {
     runtime_->dart_controller()->RunFromScriptSnapshot(snapshot.data(),
                                                        snapshot.size());

content_handler/runtime_holder.h

@@ -109,6 +109,7 @@ class RuntimeHolder : public blink::RuntimeDelegate,
   void Invalidate();
 
   fdio_ns_t* namespc_;
+  int dirfd_;
   std::unique_ptr<app::ApplicationContext> context_;
   fidl::InterfaceRequest<app::ServiceProvider> outgoing_services_;
   std::vector<char> root_bundle_data_;

lib/ui/ui_dart_state.cc

@@ -15,8 +15,10 @@ namespace blink {
 IsolateClient::~IsolateClient() {}
 
 UIDartState::UIDartState(IsolateClient* isolate_client,
-                         std::unique_ptr<Window> window)
-    : isolate_client_(isolate_client),
+                         std::unique_ptr<Window> window,
+                         int dirfd)
+    : tonic::DartState(dirfd),
+      isolate_client_(isolate_client),
       main_port_(ILLEGAL_PORT),
       window_(std::move(window)) {}
 

lib/ui/ui_dart_state.h

@@ -28,7 +28,9 @@ class IsolateClient {
 
 class UIDartState : public tonic::DartState {
  public:
-  UIDartState(IsolateClient* isolate_client, std::unique_ptr<Window> window);
+  UIDartState(IsolateClient* isolate_client,
+              std::unique_ptr<Window> window,
+              int dirfd = -1);
   ~UIDartState() override;
 
   static UIDartState* Current();

runtime/runtime_controller.cc

@@ -29,13 +29,15 @@ RuntimeController::~RuntimeController() {}
 void RuntimeController::CreateDartController(
     const std::string& script_uri,
     const uint8_t* isolate_snapshot_data,
-    const uint8_t* isolate_snapshot_instr) {
+    const uint8_t* isolate_snapshot_instr,
+    int dirfd) {
   FXL_DCHECK(!dart_controller_);
 
   dart_controller_.reset(new DartController());
   dart_controller_->CreateIsolateFor(
       script_uri, isolate_snapshot_data, isolate_snapshot_instr,
-      std::make_unique<UIDartState>(this, std::make_unique<Window>(this)));
+      std::make_unique<UIDartState>(this, std::make_unique<Window>(this),
+                                    dirfd));
 
   UIDartState* dart_state = dart_controller_->dart_state();
   DartState::Scope scope(dart_state);

runtime/runtime_controller.h

@@ -28,7 +28,8 @@ class RuntimeController : public WindowClient, public IsolateClient {
 
   void CreateDartController(const std::string& script_uri,
                             const uint8_t* isolate_snapshot_data,
-                            const uint8_t* isolate_snapshot_instr);
+                            const uint8_t* isolate_snapshot_instr,
+                            int dirfd = -1);
   DartController* dart_controller() const { return dart_controller_.get(); }
 
   void SetViewportMetrics(const ViewportMetrics& metrics);