[WasmFS] Skip root directory setup under NODERAWFS

system/lib/wasmfs/backend.h

@@ -21,6 +21,8 @@ class Backend {
   virtual std::shared_ptr<Directory> createDirectory(mode_t mode) = 0;
   virtual std::shared_ptr<Symlink> createSymlink(std::string target) = 0;
 
+  virtual void populateRoot(Directory::Handle& lockedRoot) {}
+
   virtual ~Backend() = default;
 };
 

system/lib/wasmfs/backends/ignore_case_backend.cpp

@@ -225,6 +225,10 @@ class IgnoreCaseBackend : public Backend {
   std::shared_ptr<Symlink> createSymlink(std::string target) override {
     return virtualize(backend->createSymlink(target), this);
   }
+
+  void populateRoot(Directory::Handle& lockedRoot) override {
+    backend->populateRoot(lockedRoot);
+  }
 };
 
 // Create an ignore case backend by supplying another backend.

system/lib/wasmfs/backends/memory_backend.cpp

@@ -7,6 +7,7 @@
 
 #include "memory_backend.h"
 #include "backend.h"
+#include "special_files.h"
 #include "wasmfs.h"
 
 namespace wasmfs {
@@ -104,6 +105,27 @@ class MemoryBackend : public Backend {
   std::shared_ptr<Symlink> createSymlink(std::string target) override {
     return std::make_shared<MemorySymlink>(target, this);
   }
+
+  // Initializes default directories including /dev/stdin, /dev/stdout,
+  // /dev/stderr. Refers to the same std streams in the open file table.
+  void populateRoot(Directory::Handle& lockedRoot) override {
+    // If the /dev/ directory does not already exist, create it. (It may already
+    // exist if those files have been preloaded.)
+    auto devDir = lockedRoot.insertDirectory("dev", S_IRUGO | S_IXUGO);
+    if (devDir) {
+      auto lockedDev = devDir->locked();
+      lockedDev.mountChild("null", SpecialFiles::getNull());
+      lockedDev.mountChild("stdin", SpecialFiles::getStdin());
+      lockedDev.mountChild("stdout", SpecialFiles::getStdout());
+      lockedDev.mountChild("stderr", SpecialFiles::getStderr());
+      lockedDev.mountChild("random", SpecialFiles::getRandom());
+      lockedDev.mountChild("urandom", SpecialFiles::getURandom());
+    }
+
+    // As with the /dev/ directory, it is not an error for /tmp/ to already
+    // exist.
+    lockedRoot.insertDirectory("tmp", S_IRWXUGO);
+  }
 };
 
 backend_t createMemoryBackend() {

system/lib/wasmfs/wasmfs.cpp

@@ -106,22 +106,8 @@ std::shared_ptr<Directory> WasmFS::initRootDirectory() {
   // The root directory is its own parent.
   lockedRoot.setParent(rootDirectory);
 
-  // If the /dev/ directory does not already exist, create it. (It may already
-  // exist in NODERAWFS mode, or if those files have been preloaded.)
-  auto devDir = lockedRoot.insertDirectory("dev", S_IRUGO | S_IXUGO);
-  if (devDir) {
-    auto lockedDev = devDir->locked();
-    lockedDev.mountChild("null", SpecialFiles::getNull());
-    lockedDev.mountChild("stdin", SpecialFiles::getStdin());
-    lockedDev.mountChild("stdout", SpecialFiles::getStdout());
-    lockedDev.mountChild("stderr", SpecialFiles::getStderr());
-    lockedDev.mountChild("random", SpecialFiles::getRandom());
-    lockedDev.mountChild("urandom", SpecialFiles::getURandom());
-  }
-
-  // As with the /dev/ directory, it is not an error for /tmp/ to already
-  // exist.
-  lockedRoot.insertDirectory("tmp", S_IRWXUGO);
+  // Set up the root directory.
+  rootBackend->populateRoot(lockedRoot);
 
   return rootDirectory;
 }

system/lib/wasmfs/wasmfs.h

@@ -29,8 +29,6 @@ class WasmFS {
   std::mutex mutex;
 
   // Private method to initialize root directory once.
-  // Initializes default directories including dev/stdin, dev/stdout,
-  // dev/stderr. Refers to the same std streams in the open file table.
   std::shared_ptr<Directory> initRootDirectory();
 
   // Initialize files specified by --preload-file option.

test/codesize/test_codesize_cxx_wasmfs.json

@@ -1,10 +1,10 @@
 {
   "a.out.js": 6725,
   "a.out.js.gz": 3184,
-  "a.out.nodebug.wasm": 172740,
-  "a.out.nodebug.wasm.gz": 63346,
-  "total": 179465,
-  "total_gz": 66530,
+  "a.out.nodebug.wasm": 172782,
+  "a.out.nodebug.wasm.gz": 63311,
+  "total": 179507,
+  "total_gz": 66495,
   "sent": [
     "__cxa_throw",
     "_abort_js",

test/codesize/test_codesize_files_wasmfs.json

@@ -1,10 +1,10 @@
 {
   "a.out.js": 5158,
   "a.out.js.gz": 2458,
-  "a.out.nodebug.wasm": 58520,
-  "a.out.nodebug.wasm.gz": 18224,
-  "total": 63678,
-  "total_gz": 20682,
+  "a.out.nodebug.wasm": 58562,
+  "a.out.nodebug.wasm.gz": 18269,
+  "total": 63720,
+  "total_gz": 20727,
   "sent": [
     "a (emscripten_date_now)",
     "b (emscripten_err)",
@@ -135,6 +135,7 @@
     "$wasmfs::MemoryBackend::createDirectory\\28unsigned\\20int\\29",
     "$wasmfs::MemoryBackend::createFile\\28unsigned\\20int\\29",
     "$wasmfs::MemoryBackend::createSymlink\\28std::__2::basic_string<char\\2c\\20std::__2::char_traits<char>\\2c\\20std::__2::allocator<char>>\\29",
+    "$wasmfs::MemoryBackend::populateRoot\\28wasmfs::Directory::Handle&\\29",
     "$wasmfs::MemoryDataFile::getSize\\28\\29",
     "$wasmfs::MemoryDataFile::read\\28unsigned\\20char*\\2c\\20unsigned\\20long\\2c\\20long\\20long\\29",
     "$wasmfs::MemoryDataFile::setSize\\28long\\20long\\29",

test/test_other.py

@@ -5609,6 +5609,8 @@ def test_fsync(self, args):
   def test_fs_dev_random(self):
     if WINDOWS and self.get_setting('NODERAWFS'):
       self.skipTest('Crashes on Windows and NodeFS')
+    if self.get_setting('NODERAWFS') and self.get_setting('WASMFS'):
+      self.skipTest('https://github.com/emscripten-core/emscripten/issues/24830')
     self.do_runf('fs/test_fs_dev_random.c', 'done\n')
 
   @parameterized({
@@ -13480,6 +13482,8 @@ def test_unistd_chown(self):
 
   @wasmfs_all_backends
   def test_wasmfs_getdents(self):
+    if self.get_setting('NODERAWFS'):
+      self.skipTest('test expectations assumes /dev is virtualized')
     # Run only in WASMFS for now.
     self.set_setting('FORCE_FILESYSTEM')
     self.do_run_in_out_file_test('wasmfs/wasmfs_getdents.c')