fix(ext/node/fs): position argument not applied (#24009)

We didn't honour the `position` options of `fd.read` and `fd.write`
because we checked if the buffer is of type `Buffer` instead of just
`Uint8Array`. Node does the latter. In doing so I noticed that the file
handle id was written to a public property which it definitely shouldn't
be. This was probably a typo.

Fixes #23707

ext/node/polyfills/internal/fs/handle.ts

@@ -28,27 +28,27 @@ export class FileHandle extends EventEmitter {
  #rid: number;
  constructor(rid: number) {
  super();
- this.rid = rid;
+ this.#rid = rid;
  }
 
  get fd() {
- return this.rid;
+ return this.#rid;
  }
 
  read(
- buffer: Buffer,
+ buffer: Uint8Array,
  offset?: number,
  length?: number,
  position?: number | null,
  ): Promise<ReadResult>;
  read(options?: ReadOptions): Promise<ReadResult>;
  read(
- bufferOrOpt: Buffer | ReadOptions,
+ bufferOrOpt: Uint8Array | ReadOptions,
  offset?: number,
  length?: number,
  position?: number | null,
  ): Promise<ReadResult> {
- if (bufferOrOpt instanceof Buffer) {
+ if (bufferOrOpt instanceof Uint8Array) {
  return new Promise((resolve, reject) => {
  read(
  this.fd,
@@ -90,12 +90,12 @@ export class FileHandle extends EventEmitter {
  encoding: string,
  ): Promise<WriteResult>;
  write(
- bufferOrStr: Buffer | string,
+ bufferOrStr: Uint8Array | string,
  offsetOrPosition: number,
  lengthOrEncoding: number | string,
  position?: number,
  ): Promise<WriteResult> {
- if (bufferOrStr instanceof Buffer) {
+ if (bufferOrStr instanceof Uint8Array) {
  const buffer = bufferOrStr;
  const offset = offsetOrPosition;
  const length = lengthOrEncoding;

tests/unit_node/_fs/_fs_write_test.ts

@@ -49,3 +49,27 @@ Deno.test({
  assertEquals(decoder.decode(data), "hello");
  },
 });
+
+Deno.test({
+ name: "Data is padded if position > length",
+ async fn() {
+ const tempFile: string = Deno.makeTempFileSync();
+
+ using file = await Deno.open(tempFile, {
+ create: true,
+ write: true,
+ read: true,
+ });
+
+ const str = "hello world";
+ const buffer = Buffer.from(str);
+ const bytesWritten = writeSync(file.rid, buffer, 0, str.length, 4);
+
+ const data = Deno.readFileSync(tempFile);
+ Deno.removeSync(tempFile);
+
+ assertEquals(bytesWritten, str.length);
+ // Check if result is padded
+ assertEquals(decoder.decode(data), "\x00\x00\x00\x00hello world");
+ },
+});

tests/unit_node/fs_test.ts

@@ -15,7 +15,13 @@ import {
  statSync,
  writeFileSync,
 } from "node:fs";
-import { constants as fsPromiseConstants, cp } from "node:fs/promises";
+import {
+ constants as fsPromiseConstants,
+ cp,
+ FileHandle,
+ open,
+ writeFile,
+} from "node:fs/promises";
 import process from "node:process";
 import { pathToAbsoluteFileUrl } from "../unit/test_util.ts";
 
@@ -165,3 +171,33 @@ Deno.test(
  assertEquals(result, undefined);
  },
 );
+
+// Test for https://github.com/denoland/deno/issues/23707
+Deno.test(
+ "[node/fs/promises read] respect position argument",
+ async () => {
+ const file = mkdtempSync(join(tmpdir(), "foo-")) + "/test.bin";
+ await writeFile(file, "");
+
+ const res: number[] = [];
+ let fd: FileHandle | undefined;
+ try {
+ fd = await open(file, "r+");
+
+ for (let i = 0; i <= 5; i++) {
+ const buffer = new Uint8Array([i]);
+ await fd.write(buffer, 0, 1, i + 10);
+ }
+
+ for (let i = 10; i <= 15; i++) {
+ const buffer = new Uint8Array(1);
+ await fd.read(buffer, 0, 1, i);
+ res.push(Number(buffer.toString()));
+ }
+ } finally {
+ await fd?.close();
+ }
+
+ assertEquals(res, [0, 1, 2, 3, 4, 5]);
+ },
+);