fs: refactor maybeCallback function

lib/fs.js

@@ -179,12 +179,6 @@ function showTruncateDeprecation() {
   }
 }
 
-function maybeCallback(cb) {
-  validateFunction(cb, 'cb');
-
-  return cb;
-}
-
 // Ensure that callbacks run in the global context. Only use this function
 // for callbacks that are passed to the binding layer, callbacks that are
 // invoked from JS already run in the proper scope.
@@ -258,7 +252,7 @@ function accessSync(path, mode) {
  * @returns {void}
  */
 function exists(path, callback) {
-  maybeCallback(callback);
+  validateFunction(callback, 'cb');
 
   function suppressedCallback(err) {
     callback(err ? false : true);
@@ -368,7 +362,8 @@ function checkAborted(signal, callback) {
  * @returns {void}
  */
 function readFile(path, options, callback) {
-  callback = maybeCallback(callback || options);
+  callback ||= options;
+  validateFunction(callback, 'cb');
   options = getOptions(options, { flag: 'r' });
   const ReadFileContext = require('internal/fs/read/context');
   const context = new ReadFileContext(callback, options.encoding);
@@ -650,7 +645,7 @@ function read(fd, buffer, offsetOrOptions, length, position, callback) {
   }
 
   validateBuffer(buffer);
-  callback = maybeCallback(callback);
+  validateFunction(callback, 'cb');
 
   if (offset == null) {
     offset = 0;
@@ -773,7 +768,8 @@ function readv(fd, buffers, position, callback) {
 
   fd = getValidatedFd(fd);
   validateBufferArray(buffers);
-  callback = maybeCallback(callback || position);
+  callback ||= position;
+  validateFunction(callback, 'cb');
 
   const req = new FSReqCallback();
   req.oncomplete = wrapper;
@@ -830,7 +826,8 @@ function write(fd, buffer, offsetOrOptions, length, position, callback) {
 
   let offset = offsetOrOptions;
   if (isArrayBufferView(buffer)) {
-    callback = maybeCallback(callback || position || length || offset);
+    callback ||= position || length || offset;
+    validateFunction(callback, 'cb');
 
     if (typeof offset === 'object') {
       ({
@@ -871,7 +868,8 @@ function write(fd, buffer, offsetOrOptions, length, position, callback) {
 
   const str = buffer;
   validateEncoding(str, length);
-  callback = maybeCallback(position);
+  callback = position;
+  validateFunction(callback, 'cb');
 
   const req = new FSReqCallback();
   req.oncomplete = wrapper;
@@ -952,7 +950,8 @@ function writev(fd, buffers, position, callback) {
 
   fd = getValidatedFd(fd);
   validateBufferArray(buffers);
-  callback = maybeCallback(callback || position);
+  callback ||= position;
+  validateFunction(callback, 'cb');
 
   if (buffers.length === 0) {
     process.nextTick(callback, null, 0, buffers);
@@ -1053,7 +1052,7 @@ function truncate(path, len, callback) {
 
   validateInteger(len, 'len');
   len = MathMax(0, len);
-  callback = maybeCallback(callback);
+  validateFunction(callback, 'cb');
   fs.open(path, 'r+', (er, fd) => {
     if (er) return callback(er);
     const req = new FSReqCallback();
@@ -1587,7 +1586,7 @@ function statfs(path, options = { bigint: false }, callback) {
     callback = options;
     options = kEmptyObject;
   }
-  callback = maybeCallback(callback);
+  validateFunction(callback, 'cb');
   path = getValidatedPath(path);
   const req = new FSReqCallback(options.bigint);
   req.oncomplete = (err, stats) => {
@@ -1909,7 +1908,7 @@ function fchmodSync(fd, mode) {
  * @returns {void}
  */
 function lchmod(path, mode, callback) {
-  callback = maybeCallback(callback);
+  validateFunction(callback, 'cb');
   mode = parseFileMode(mode, 'mode');
   fs.open(path, O_WRONLY | O_SYMLINK, (err, fd) => {
     if (err) {
@@ -2267,7 +2266,8 @@ function writeAll(fd, isUserFd, buffer, offset, length, signal, flush, callback)
  * @returns {void}
  */
 function writeFile(path, data, options, callback) {
-  callback = maybeCallback(callback || options);
+  callback ||= options;
+  validateFunction(callback, 'cb');
   options = getOptions(options, {
     encoding: 'utf8',
     mode: 0o666,
@@ -2383,7 +2383,8 @@ function writeFileSync(path, data, options) {
  * @returns {void}
  */
 function appendFile(path, data, options, callback) {
-  callback = maybeCallback(callback || options);
+  callback ||= options;
+  validateFunction(callback, 'cb');
   options = getOptions(options, { encoding: 'utf8', mode: 0o666, flag: 'a' });
 
   // Don't make changes directly on options object
@@ -2778,7 +2779,11 @@ realpathSync.native = (path, options) => {
  * @returns {void}
  */
 function realpath(p, options, callback) {
-  callback = typeof options === 'function' ? options : maybeCallback(callback);
+  if (typeof options === 'function') {
+    callback = options;
+  } else {
+    validateFunction(callback, 'cb');
+  }
   options = getOptions(options);
   p = toPathIfFileURL(p);