Implementing "withFileTypes" option for fs.readdir method

lib/binding.js

@@ -12,6 +12,16 @@ const getPathParts = require('./filesystem').getPathParts;
 const bufferFrom = require('./buffer').from;
 const bufferAlloc = require('./buffer').alloc;
 
+const MODE_TO_KTYPE = {
+  [constants.S_IFREG]: constants.UV_DIRENT_FILE,
+  [constants.S_IFDIR]: constants.UV_DIRENT_DIR,
+  [constants.S_IFBLK]: constants.UV_DIRENT_BLOCK,
+  [constants.S_IFCHR]: constants.UV_DIRENT_CHAR,
+  [constants.S_IFLNK]: constants.UV_DIRENT_LINK,
+  [constants.S_IFIFO]: constants.UV_DIRENT_FIFO,
+  [constants.S_IFSOCK]: constants.UV_DIRENT_SOCKET
+};
+
 /** Workaround for optimizations in node 8+ */
 const fsBinding = process.binding('fs');
 const kUsePromises = fsBinding.kUsePromises;
@@ -140,6 +150,16 @@ function wrapStatsCallback(callback) {
   }
 }
 
+function getDirentType(mode) {
+  const ktype = MODE_TO_KTYPE[mode & constants.S_IFMT];
+
+  if (ktype === undefined) {
+    return constants.UV_DIRENT_UNKNOWN;
+  }
+
+  return ktype;
+}
+
 function notImplemented() {
   throw new Error('Method not implemented');
 }
@@ -914,9 +934,6 @@ Binding.prototype.readdir = function(
   } else if (arguments.length === 3) {
     callback = withFileTypes;
   }
-  if (withFileTypes === true) {
-    notImplemented();
-  }
 
   markSyscall(ctx, 'scandir');
 
@@ -933,12 +950,23 @@ Binding.prototype.readdir = function(
     if (!(dir instanceof Directory)) {
       throw new FSError('ENOTDIR', dirpath);
     }
+
     let list = dir.list();
     if (encoding === 'buffer') {
       list = list.map(function(item) {
         return bufferFrom(item);
       });
     }
+
+    if (withFileTypes === true) {
+      const types = list.map(function(name) {
+        const stats = dir.getItem(name).getStats();
+
+        return getDirentType(stats.mode);
+      });
+      list = [list, types];
+    }
+
     return list;
   });
 };

test/lib/fs.readdir.spec.js

@@ -7,6 +7,7 @@ const path = require('path');
 
 const assert = helper.assert;
 const withPromise = helper.withPromise;
+const inVersion = helper.inVersion;
 
 describe('fs.readdir(path, callback)', function() {
   beforeEach(function() {
@@ -81,6 +82,95 @@ describe('fs.readdir(path, callback)', function() {
       }
     );
   });
+
+  inVersion('>=10.10').it('should support "withFileTypes" option', function(
+    done
+  ) {
+    fs.readdir(
+      path.join('nested', 'sub', 'dir'),
+      {withFileTypes: true},
+      function(err, items) {
+        assert.isNull(err);
+        assert.isArray(items);
+        assert.deepEqual(items, [
+          {name: 'empty'},
+          {name: 'one.txt'},
+          {name: 'two.txt'}
+        ]);
+        assert.ok(items[0].isDirectory());
+        assert.ok(items[1].isFile());
+        assert.ok(items[2].isFile());
+        done();
+      }
+    );
+  });
+
+  withPromise.it('should support "withFileTypes" option', function(done) {
+    fs.promises
+      .readdir(path.join('nested', 'sub', 'dir'), {withFileTypes: true})
+      .then(function(items) {
+        assert.isArray(items);
+        assert.deepEqual(items, [
+          {name: 'empty'},
+          {name: 'one.txt'},
+          {name: 'two.txt'}
+        ]);
+        assert.ok(items[0].isDirectory());
+        assert.ok(items[1].isFile());
+        assert.ok(items[2].isFile());
+        done();
+      }, done);
+  });
+
+  inVersion('>=10.10').it(
+    'should support "withFileTypes" option with "encoding" option',
+    function(done) {
+      fs.readdir(
+        path.join('nested', 'sub', 'dir'),
+        {withFileTypes: true, encoding: 'buffer'},
+        function(err, items) {
+          assert.isNull(err);
+          assert.isArray(items);
+          items.forEach(function(item) {
+            assert.equal(Buffer.isBuffer(item.name), true);
+          });
+          const names = items.map(function(item) {
+            return item.name.toString();
+          });
+          assert.deepEqual(names, ['empty', 'one.txt', 'two.txt']);
+          assert.ok(items[0].isDirectory());
+          assert.ok(items[1].isFile());
+          assert.ok(items[2].isFile());
+          done();
+        }
+      );
+    }
+  );
+
+  withPromise.it(
+    'should support "withFileTypes" option with "encoding" option',
+    function(done) {
+      fs.promises
+        .readdir(path.join('nested', 'sub', 'dir'), {
+          withFileTypes: true,
+          encoding: 'buffer'
+        })
+        .then(function(items) {
+          assert.isArray(items);
+          items.forEach(function(item) {
+            assert.equal(Buffer.isBuffer(item.name), true);
+          });
+          const names = items.map(function(item) {
+            return item.name.toString();
+          });
+          assert.deepEqual(names, ['empty', 'one.txt', 'two.txt']);
+          assert.ok(items[0].isDirectory());
+          assert.ok(items[1].isFile());
+          assert.ok(items[2].isFile());
+          done();
+        });
+    }
+  );
 });
 
 describe('fs.readdirSync(path)', function() {