Remove dependency on memfs

shell/platform/fuchsia/dart_runner/dart_component_controller.cc

@@ -194,7 +194,7 @@ bool DartComponentController::CreateAndBindNamespace() {
     }
 
     if (ns_entry.path() == kTmpPath) {
-      // /tmp is covered by the local memfs.
+      // /tmp is covered by a locally served virtual filesystem.
       continue;
     }
 

shell/platform/fuchsia/dart_runner/dart_test_component_controller.cc

@@ -207,7 +207,7 @@ bool DartTestComponentController::CreateAndBindNamespace() {
     }
 
     if (ns_entry.path() == kTmpPath) {
-      // /tmp is covered by the local memfs.
+      // /tmp is covered by a locally served virtual filesystem.
       continue;
     }
 

shell/platform/fuchsia/flutter/component_v2.cc

@@ -182,14 +182,14 @@ ComponentV2::ComponentV2(
     return;
   }
 
-  // Setup /tmp to be mapped to the process-local memfs.
+  // Setup /tmp to be mapped to a process-local virtual filesystem.
   dart_utils::RunnerTemp::SetupComponent(fdio_ns_.get());
 
   // ComponentStartInfo::ns (optional)
   if (start_info.has_ns()) {
     for (auto& entry : *start_info.mutable_ns()) {
-      // /tmp/ is mapped separately to the process-level memfs, so we ignore it
-      // here.
+      // /tmp/ is mapped separately to to a process-local virtual filesystem,
+      // so we ignore it here.
       const auto& path = entry.path();
       if (path == kTmpPath) {
         continue;

shell/platform/fuchsia/flutter/main.cc

@@ -40,7 +40,7 @@ int main(int argc, char const* argv[]) {
         &already_started);
   }
 
-  // Set up the process-wide /tmp memfs.
+  // Set up the process-wide /tmp virtual filesystem.
   dart_utils::RunnerTemp runner_temp;
 
   fml::MessageLoop& loop = fml::MessageLoop::GetCurrent();

shell/platform/fuchsia/runtime/dart/utils/BUILD.gn

@@ -43,7 +43,6 @@ template("make_utils") {
              "$fuchsia_sdk_root/pkg:async-loop-cpp",
              "$fuchsia_sdk_root/pkg:async-loop-default",
              "$fuchsia_sdk_root/pkg:fdio",
-             "$fuchsia_sdk_root/pkg:memfs",
              "$fuchsia_sdk_root/pkg:sys_cpp",
              "$fuchsia_sdk_root/pkg:sys_inspect_cpp",
              "$fuchsia_sdk_root/pkg:syslog",

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

@@ -12,8 +12,8 @@
 #include <lib/async-loop/default.h>
 #include <lib/async/cpp/task.h>
 #include <lib/fdio/namespace.h>
-#include <lib/memfs/memfs.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>
@@ -23,7 +23,6 @@
 namespace {
 
 constexpr char kTmpPath[] = "/tmp";
-[[maybe_unused]] constexpr size_t kMaxTmpPages = 1024;
 
 }  // namespace
 
@@ -38,31 +37,45 @@ RunnerTemp::RunnerTemp()
 
 RunnerTemp::~RunnerTemp() = default;
 
+static vfs::PseudoDir tmp_dir;
+
 void RunnerTemp::Start() {
-  std::promise<void> finished;
+  std::promise<zx_status_t> finished;
   async::PostTask(loop_->dispatcher(), [this, &finished]() {
-#if defined(DART_PRODUCT)
-    zx_status_t status = memfs_install_at_with_page_limit(
-        loop_->dispatcher(), kMaxTmpPages, kTmpPath);
-#else
-    memfs_filesystem_t* fs;
-    // Hot reload uses /tmp to hold the updated dills and assets so do not
-    // impose any size limitation in non product runners.
-    zx_status_t status = memfs_install_at(loop_->dispatcher(), kTmpPath, &fs);
-#endif
-    finished.set_value();
-    if (status != ZX_OK) {
-      FX_LOGF(ERROR, LOG_TAG, "Failed to install a /tmp memfs: %s",
-              zx_status_get_string(status));
-      return;
-    }
+    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;
+    }());
   });
-  finished.get_future().wait();
+  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) {
   // TODO(zra): Should isolates share a /tmp file system within a process, or
-  // should isolates each get their own private memfs for /tmp? For now,
+  // 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;

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

@@ -15,13 +15,13 @@ namespace dart_utils {
 // Sets up /tmp for the dart_runner and flutter_runner.
 class RunnerTemp {
  public:
-  // Sets up a memfs bound to /tmp in the process-wide namespace that has the
-  // lifetime of this instance.
+  // Sets up a virtual filesystem bound to /tmp in the process-wide namespace
+  // that has the lifetime of this instance.
   RunnerTemp();
   ~RunnerTemp();
 
-  // Take the memfs mapped into the process-wide namespace for /tmp, and map it
-  // to /tmp in the given namespace.
+  // 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:

tools/fuchsia/fuchsia_libs.gni

@@ -40,10 +40,6 @@ common_libs = [
     name = "libfdio.so"
     path = rebase_path("$fuchsia_sdk_dist")
   },
-  {
-    name = "libmemfs.so"
-    path = rebase_path("$fuchsia_sdk_dist")
-  },
   {
     name = "libsyslog.so"
     path = rebase_path("$fuchsia_sdk_dist")