fs: use consistent buffer array validation

This commit updates fs.writev() and fs.writevSync() to use the
same validation method as filehandle.writev().

PR-URL: #29186
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/fs.js

@@ -72,6 +72,7 @@ const {
   stringToFlags,
   stringToSymlinkType,
   toUnixTimestamp,
+  validateBufferArray,
   validateOffsetLengthRead,
   validateOffsetLengthWrite,
   validatePath,
@@ -142,19 +143,6 @@ function maybeCallback(cb) {
   throw new ERR_INVALID_CALLBACK(cb);
 }
 
-function isBuffersArray(value) {
-  if (!Array.isArray(value))
-    return false;
-
-  for (var i = 0; i < value.length; i += 1) {
-    if (!isArrayBufferView(value[i])) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
 // 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.
@@ -626,10 +614,7 @@ function writev(fd, buffers, position, callback) {
   }
 
   validateInt32(fd, 'fd', 0);
-
-  if (!isBuffersArray(buffers)) {
-    throw new ERR_INVALID_ARG_TYPE('buffers', 'ArrayBufferView[]', buffers);
-  }
+  validateBufferArray(buffers);
 
   const req = new FSReqCallback();
   req.oncomplete = wrapper;
@@ -647,15 +632,11 @@ Object.defineProperty(writev, internalUtil.customPromisifyArgs, {
   enumerable: false
 });
 
-// fs.writevSync(fd, buffers[, position]);
 function writevSync(fd, buffers, position) {
-
   validateInt32(fd, 'fd', 0);
-  const ctx = {};
+  validateBufferArray(buffers);
 
-  if (!isBuffersArray(buffers)) {
-    throw new ERR_INVALID_ARG_TYPE('buffers', 'ArrayBufferView[]', buffers);
-  }
+  const ctx = {};
 
   if (typeof position !== 'number')
     position = null;