FileHandle.read does not respect length parameter with Uint8Array

[acrois]

Version: Deno 1.45.5

Code:

import { assert } from "https://deno.land/std@0.224.0/assert/assert.ts";
import { open, unlink, writeFile } from "node:fs/promises";

Deno.test("fs: FileHandle.read() respects length parameter with Uint8Array", async () => {
  // Create a file with some sample data
  const filename = "example.bin";
  const array = new Uint8Array(256);
  for (let i = 0; i < 256; i++) {
    array[i] = i;
  }
  await writeFile(filename, array);

  // Open the file for reading
  const fileHandle = await open(filename, "r");

  // Test reading a portion of the file
  // NOTE: it is important that the array we are reading into is greater than our read length
  //       as it will often be larger in the case of reading a file in chunks.
  const readArray = new Uint8Array(2048);

  const readLength = 20;
  const readOffset = 100;
  const writeOffset = 0;

  const { bytesRead } = await fileHandle.read(
    readArray,
    writeOffset,
    readLength,
    readOffset,
  );

  assert(
    bytesRead === readLength,
    `Expected ${readLength} but got ${bytesRead}`,
  );

  for (let i = writeOffset; i < readLength; i++) {
    assert(readArray[i] === readOffset + i, "Correct data");
  }

  // Close the file handle
  await fileHandle.close();

  // Remove the test file
  await unlink(filename);
});

Test:

deno test --allow-read --allow-write

Result:

error: AssertionError: Expected 20 but got 156

Problematic:
https://github.com/denoland/deno/blob/main/ext/node/polyfills/internal/fs/handle.ts#L51-L64

[marvinhagemeister]

I can reproduce it with 1.45.5 but not in main anymore. Doing a git bisect it looks like #25049 fixed it.

You can try out the latest deno canary release by running deno upgrade --canary. We'll likely cut a patch or minor release later this week.

[dsherret]

Going to close because it seems like it's fixed in canary (deno upgrade --canary). Let us know if not.