src: move cpSync dir copy logic completely to C++

prior to these changes cpSync would copy directories using C++
logic only if the user didn't provide a filtering function to
the cpSync call, the changes here make it so that instead C++
is used to copy directories even when a filtering function is
provided

Author: dario-piotrowicz

lib/internal/fs/cp/cp-sync.js

@@ -65,7 +65,13 @@ function getStats(src, dest, opts) {
   const destStat = statSyncFn(dest, { bigint: true, throwIfNoEntry: false });
 
   if (srcStat.isDirectory() && opts.recursive) {
-    return onDir(srcStat, destStat, src, dest, opts);
+    return fsBinding.cpSyncCopyDir(src, dest,
+                                   opts.force,
+                                   opts.dereference,
+                                   opts.errorOnExist,
+                                   opts.verbatimSymlinks,
+                                   opts.preserveTimestamps,
+                                   opts.filter);
   } else if (srcStat.isFile() ||
            srcStat.isCharacterDevice() ||
            srcStat.isBlockDevice()) {
@@ -131,60 +137,6 @@ function setDestTimestamps(src, dest) {
   return utimesSync(dest, updatedSrcStat.atime, updatedSrcStat.mtime);
 }
 
-// TODO(@anonrig): Move this function to C++.
-function onDir(srcStat, destStat, src, dest, opts) {
-  if (!destStat) return copyDir(src, dest, opts, true, srcStat.mode);
-  return copyDir(src, dest, opts);
-}
-
-function copyDir(src, dest, opts, mkDir, srcMode) {
-  if (!opts.filter) {
-    // The caller didn't provide a js filter function, in this case
-    // we can run the whole function faster in C++
-    // TODO(dario-piotrowicz): look into making cpSyncCopyDir also accept the potential filter function
-    return fsBinding.cpSyncCopyDir(src, dest,
-                                   opts.force,
-                                   opts.dereference,
-                                   opts.errorOnExist,
-                                   opts.verbatimSymlinks,
-                                   opts.preserveTimestamps);
-  }
-
-  if (mkDir) {
-    mkdirSync(dest);
-  }
-
-  const dir = opendirSync(src);
-
-  try {
-    let dirent;
-
-    while ((dirent = dir.readSync()) !== null) {
-      const { name } = dirent;
-      const srcItem = join(src, name);
-      const destItem = join(dest, name);
-      let shouldCopy = true;
-
-      if (opts.filter) {
-        shouldCopy = opts.filter(srcItem, destItem);
-        if (isPromise(shouldCopy)) {
-          throw new ERR_INVALID_RETURN_VALUE('boolean', 'filter', shouldCopy);
-        }
-      }
-
-      if (shouldCopy) {
-        getStats(srcItem, destItem, opts);
-      }
-    }
-  } finally {
-    dir.closeSync();
-
-    if (srcMode !== undefined) {
-      setDestMode(dest, srcMode);
-    }
-  }
-}
-
 // TODO(@anonrig): Move this function to C++.
 function onLink(destStat, src, dest, verbatimSymlinks) {
   let resolvedSrc = readlinkSync(src);

src/node_file.cc

@@ -3411,8 +3411,9 @@ bool isInsideDir(const std::filesystem::path& src,
 }
 
 static void CpSyncCopyDir(const FunctionCallbackInfo<Value>& args) {
-  CHECK_EQ(args.Length(), 7);  // src, dest, force, dereference, errorOnExist,
-                               // verbatimSymlinks, preserveTimestamps
+  CHECK_EQ(args.Length(),
+           8);  // src, dest, force, dereference, errorOnExist,
+                // verbatimSymlinks, preserveTimestamps, filterFunction
 
   Environment* env = Environment::GetCurrent(args);
   Isolate* isolate = env->isolate();
@@ -3431,6 +3432,27 @@ static void CpSyncCopyDir(const FunctionCallbackInfo<Value>& args) {
   bool verbatim_symlinks = args[5]->IsTrue();
   bool preserve_timestamps = args[6]->IsTrue();
 
+  std::function<bool(std::string, std::string)> filter_fn = nullptr;
+
+  if (args[7]->IsFunction()) {
+    Local<v8::Function> args_filter_fn = args[7].As<v8::Function>();
+
+    filter_fn = [env, args_filter_fn](std::string src,
+                                      std::string dest) -> bool {
+      Local<Value> argv[] = {
+          String::NewFromUtf8(
+              env->isolate(), src.c_str(), v8::NewStringType::kNormal)
+              .ToLocalChecked(),
+          String::NewFromUtf8(
+              env->isolate(), dest.c_str(), v8::NewStringType::kNormal)
+              .ToLocalChecked()};
+      auto result =
+          args_filter_fn->Call(env->context(), Null(env->isolate()), 2, argv)
+              .ToLocalChecked();
+      return result->BooleanValue(env->isolate());
+    };
+  }
+
   std::error_code error;
   std::filesystem::create_directories(*dest, error);
   if (error) {
@@ -3456,11 +3478,21 @@ static void CpSyncCopyDir(const FunctionCallbackInfo<Value>& args) {
                        force,
                        error_on_exist,
                        dereference,
-                       &isolate](std::filesystem::path src,
-                                 std::filesystem::path dest) {
+                       &isolate,
+                       &filter_fn](std::filesystem::path src,
+                                   std::filesystem::path dest) {
     std::error_code error;
     for (auto dir_entry : std::filesystem::directory_iterator(src)) {
       auto dest_file_path = dest / dir_entry.path().filename();
+
+      if (filter_fn) {
+        auto shouldSkip =
+            !filter_fn(dir_entry.path().c_str(), dest_file_path.c_str());
+        if (shouldSkip) {
+          continue;
+        }
+      }
+
       auto dest_str = PathToString(dest);
 
       if (dir_entry.is_symlink()) {