fs: use byteLength to handle ArrayBuffer views

lib/fs.js

@@ -531,7 +531,7 @@ function read(fd, buffer, offset, length, position, callback) {
     ({
       buffer = Buffer.alloc(16384),
       offset = 0,
-      length = buffer.length,
+      length = buffer.byteLength,
       position
     } = options);
   }
@@ -586,15 +586,15 @@ ObjectDefineProperty(read, internalUtil.customPromisifyArgs,
 function readSync(fd, buffer, offset, length, position) {
   fd = getValidatedFd(fd);
 
+  validateBuffer(buffer);
+
   if (arguments.length <= 3) {
     // Assume fs.read(fd, buffer, options)
     const options = offset || {};
 
-    ({ offset = 0, length = buffer.length, position } = options);
+    ({ offset = 0, length = buffer.byteLength, position } = options);
   }
 
-  validateBuffer(buffer);
-
   if (offset == null) {
     offset = 0;
   } else {
@@ -681,7 +681,7 @@ function write(fd, buffer, offset, length, position, callback) {
       validateInteger(offset, 'offset');
     }
     if (typeof length !== 'number')
-      length = buffer.length - offset;
+      length = buffer.byteLength - offset;
     if (typeof position !== 'number')
       position = null;
     validateOffsetLengthWrite(offset, length, buffer.byteLength);

lib/internal/fs/promises.js

@@ -279,19 +279,19 @@ async function writeFileHandle(filehandle, data, signal, encoding) {
       checkAborted(signal);
       await write(
         filehandle, buf, undefined,
-        isArrayBufferView(buf) ? buf.length : encoding);
+        isArrayBufferView(buf) ? buf.byteLength : encoding);
       checkAborted(signal);
     }
     return;
   }
   data = new Uint8Array(data.buffer, data.byteOffset, data.byteLength);
-  let remaining = data.length;
+  let remaining = data.byteLength;
   if (remaining === 0) return;
   do {
     checkAborted(signal);
     const { bytesWritten } =
       await write(filehandle, data, 0,
-                  MathMin(kWriteFileMaxChunkSize, data.length));
+                  MathMin(kWriteFileMaxChunkSize, data.byteLength));
     remaining -= bytesWritten;
     data = new Uint8Array(
       data.buffer,
@@ -403,7 +403,7 @@ async function read(handle, bufferOrOptions, offset, length, position) {
       buffer = Buffer.alloc(16384);
     }
     offset = bufferOrOptions.offset || 0;
-    length = buffer.length;
+    length = buffer.byteLength;
     position = bufferOrOptions.position || null;
   }
 
@@ -418,12 +418,12 @@ async function read(handle, bufferOrOptions, offset, length, position) {
   if (length === 0)
     return { bytesRead: length, buffer };
 
-  if (buffer.length === 0) {
+  if (buffer.byteLength === 0) {
     throw new ERR_INVALID_ARG_VALUE('buffer', buffer,
                                     'is empty and cannot be written');
   }
 
-  validateOffsetLengthRead(offset, length, buffer.length);
+  validateOffsetLengthRead(offset, length, buffer.byteLength);
 
   if (!NumberIsSafeInteger(position))
     position = -1;
@@ -446,7 +446,7 @@ async function readv(handle, buffers, position) {
 }
 
 async function write(handle, buffer, offset, length, position) {
-  if (buffer?.length === 0)
+  if (buffer?.byteLength === 0)
     return { bytesWritten: 0, buffer };
 
   if (isArrayBufferView(buffer)) {
@@ -456,7 +456,7 @@ async function write(handle, buffer, offset, length, position) {
       validateInteger(offset, 'offset');
     }
     if (typeof length !== 'number')
-      length = buffer.length - offset;
+      length = buffer.byteLength - offset;
     if (typeof position !== 'number')
       position = null;
     validateOffsetLengthWrite(offset, length, buffer.byteLength);

test/parallel/test-fs-write-buffer.js

@@ -146,3 +146,20 @@ tmpdir.refresh();
     fs.closeSync(fd);
   }));
 }
+
+// fs.write with a DataView, without the offset and length parameters:
+{
+  const filename = path.join(tmpdir.path, 'write8.txt');
+  fs.open(filename, 'w', 0o644, common.mustSucceed((fd) => {
+    const cb = common.mustSucceed((written) => {
+      assert.strictEqual(written, expected.length);
+      fs.closeSync(fd);
+
+      const found = fs.readFileSync(filename, 'utf8');
+      assert.strictEqual(found, expected.toString());
+    });
+
+    const uint8 = Uint8Array.from(expected);
+    fs.write(fd, new DataView(uint8.buffer), cb);
+  }));
+}