Remove process-local tempfs

shell/platform/fuchsia/dart_runner/dart_component_controller.cc

@@ -182,7 +182,7 @@ bool DartComponentController::CreateAndBindNamespace() {
             zx_status_get_string(ns_create_status));
   }
 
-  dart_utils::RunnerTemp::SetupComponent(namespace_);
+  dart_utils::BindTemp(namespace_);
 
   // Bind each directory in start_info's namespace to the controller's namespace
   // instance.

shell/platform/fuchsia/dart_runner/dart_test_component_controller.cc

@@ -195,7 +195,7 @@ bool DartTestComponentController::CreateAndBindNamespace() {
             zx_status_get_string(ns_create_status));
   }
 
-  dart_utils::RunnerTemp::SetupComponent(namespace_);
+  dart_utils::BindTemp(namespace_);
 
   // Bind each directory in start_info's namespace to the controller's namespace
   // instance.

shell/platform/fuchsia/dart_runner/main.cc

@@ -62,7 +62,6 @@ int main(int argc, const char** argv) {
 #endif  // defined(AOT_RUNTIME)
 #endif  // !defined(DART_PRODUCT)
 
-  dart_utils::RunnerTemp runner_temp;
   dart_runner::DartRunner runner(context.get());
 
   // Wait to serve until we have finished all of our setup.

shell/platform/fuchsia/dart_runner/meta/common.shard.cml

@@ -13,6 +13,11 @@
         },
     ],
     use: [
+	// This is used by the Dart VM to communicate from Dart code to C++ code.
+        {
+            storage: "tmp",
+            path: "/tmp",
+        },
         // This is used by the Dart VM to load i18n data.
         {
             directory: "config-data",

shell/platform/fuchsia/flutter/component_v2.cc

@@ -182,8 +182,7 @@ ComponentV2::ComponentV2(
     return;
   }
 
-  // Setup /tmp to be mapped to a process-local virtual filesystem.
-  dart_utils::RunnerTemp::SetupComponent(fdio_ns_.get());
+  dart_utils::BindTemp(fdio_ns_.get());
 
   // ComponentStartInfo::ns (optional)
   if (start_info.has_ns()) {

shell/platform/fuchsia/flutter/main.cc

@@ -40,9 +40,6 @@ int main(int argc, char const* argv[]) {
         &already_started);
   }
 
-  // Set up the process-wide /tmp virtual filesystem.
-  dart_utils::RunnerTemp runner_temp;
-
   fml::MessageLoop& loop = fml::MessageLoop::GetCurrent();
   flutter_runner::Runner runner(loop.GetTaskRunner(), context.get());
 

shell/platform/fuchsia/runtime/dart/utils/tempfs.cc

@@ -4,16 +4,9 @@
 
 #include "tempfs.h"
 
-#include <future>
-#include <string>
-#include <thread>
+#include <string_view>
 
-#include <lib/async-loop/cpp/loop.h>
-#include <lib/async-loop/default.h>
-#include <lib/async/cpp/task.h>
-#include <lib/fdio/namespace.h>
 #include <lib/syslog/global.h>
-#include <lib/vfs/cpp/pseudo_dir.h>
 #include <zircon/errors.h>
 #include <zircon/status.h>
 #include <zircon/syscalls.h>
@@ -28,79 +21,28 @@ constexpr char kTmpPath[] = "/tmp";
 
 namespace dart_utils {
 
-RunnerTemp::RunnerTemp()
-    : loop_(std::make_unique<async::Loop>(
-          &kAsyncLoopConfigNoAttachToCurrentThread)) {
-  loop_->StartThread("RunnerTemp");
-  Start();
-}
-
-RunnerTemp::~RunnerTemp() = default;
-
-static vfs::PseudoDir tmp_dir;
-
-void RunnerTemp::Start() {
-  std::promise<zx_status_t> finished;
-  async::PostTask(loop_->dispatcher(), [this, &finished]() {
-    finished.set_value([this]() {
-      zx::channel client, server;
-      if (zx_status_t status = zx::channel::create(0, &client, &server);
-          status != ZX_OK) {
-        return status;
-      }
-      if (zx_status_t status =
-              tmp_dir.Serve(fuchsia::io::OpenFlags::RIGHT_READABLE |
-                                fuchsia::io::OpenFlags::RIGHT_WRITABLE |
-                                fuchsia::io::OpenFlags::DIRECTORY,
-                            std::move(server), loop_->dispatcher());
-          status != ZX_OK) {
-        return status;
-      }
-      fdio_ns_t* ns;
-      if (zx_status_t status = fdio_ns_get_installed(&ns); status != ZX_OK) {
-        return status;
-      }
-      if (zx_status_t status = fdio_ns_bind(ns, kTmpPath, client.release());
-          status != ZX_OK) {
-        return status;
-      }
-      return ZX_OK;
-    }());
-  });
-  if (zx_status_t status = finished.get_future().get(); status != ZX_OK) {
-    FX_LOGF(ERROR, LOG_TAG, "Failed to install a /tmp virtual filesystem: %s",
-            zx_status_get_string(status));
-  }
-}
-
-void RunnerTemp::SetupComponent(fdio_ns_t* ns) {
+void BindTemp(fdio_ns_t* ns) {
   // TODO(zra): Should isolates share a /tmp file system within a process, or
   // should isolates each get their own private file system for /tmp? For now,
   // sharing the process-wide /tmp simplifies hot reload since the hot reload
   // devfs requires sharing between the service isolate and the app isolates.
-  zx_status_t status;
   fdio_flat_namespace_t* rootns;
-  status = fdio_ns_export_root(&rootns);
-  if (status != ZX_OK) {
+  if (zx_status_t status = fdio_ns_export_root(&rootns); status != ZX_OK) {
     FX_LOGF(ERROR, LOG_TAG, "Failed to export root ns: %s",
             zx_status_get_string(status));
     return;
   }
 
   zx_handle_t tmp_dir_handle;
   for (size_t i = 0; i < rootns->count; i++) {
-    if (strcmp(rootns->path[i], kTmpPath) == 0) {
-      tmp_dir_handle = rootns->handle[i];
-    } else {
-      zx_handle_close(rootns->handle[i]);
-      rootns->handle[i] = ZX_HANDLE_INVALID;
+    if (std::string_view{rootns->path[i]} == kTmpPath) {
+      tmp_dir_handle = std::exchange(rootns->handle[i], ZX_HANDLE_INVALID);
     }
   }
-  free(rootns);
-  rootns = nullptr;
+  fdio_ns_free_flat_ns(rootns);
 
-  status = fdio_ns_bind(ns, kTmpPath, tmp_dir_handle);
-  if (status != ZX_OK) {
+  if (zx_status_t status = fdio_ns_bind(ns, kTmpPath, tmp_dir_handle);
+      status != ZX_OK) {
     zx_handle_close(tmp_dir_handle);
     FX_LOGF(ERROR, LOG_TAG,
             "Failed to bind /tmp directory into isolate namespace: %s",

shell/platform/fuchsia/runtime/dart/utils/tempfs.h

@@ -5,34 +5,13 @@
 #ifndef FLUTTER_SHELL_PLATFORM_FUCHSIA_RUNTIME_DART_UTILS_TEMPFS_H_
 #define FLUTTER_SHELL_PLATFORM_FUCHSIA_RUNTIME_DART_UTILS_TEMPFS_H_
 
-#include <mutex>
-
-#include <lib/async-loop/cpp/loop.h>
 #include <lib/fdio/namespace.h>
 
 namespace dart_utils {
 
-// Sets up /tmp for the dart_runner and flutter_runner.
-class RunnerTemp {
- public:
-  // Sets up a virtual filesystem bound to /tmp in the process-wide namespace
-  // that has the lifetime of this instance.
-  RunnerTemp();
-  ~RunnerTemp();
-
-  // Take the virtual filesystem mapped into the process-wide namespace for
-  // /tmp, and map it to /tmp in the given namespace.
-  static void SetupComponent(fdio_ns_t* ns);
-
- private:
-  void Start();
-
-  std::unique_ptr<async::Loop> loop_;
-
-  // Disallow copy and assignment.
-  RunnerTemp(const RunnerTemp&) = delete;
-  RunnerTemp& operator=(const RunnerTemp&) = delete;
-};
+// Take the virtual filesystem mapped into the process-wide namespace for /tmp,
+// and map it to /tmp in the given namespace.
+void BindTemp(fdio_ns_t* ns);
 
 }  // namespace dart_utils