Incorrect slice() from fs.openAsBlob()

Version

v22.5.0

Platform

Linux penguin 6.6.32-02873-ge0e03a627715 #1 SMP PREEMPT Mon, 1 Jul 2024 20:29:42 +0000 aarch64 GNU/Linux

Subsystem

No response

What steps will reproduce the bug?

> await fs.promises.writeFile('a.txt', 'abcdefghij')
> blob = await fs.openAsBlob('a.txt')
Blob { size: 10, type: '' }
> await _.text()
'abcdefghij'
> blob.slice(3)
Blob { size: 7, type: '' }
> await _.text()
'defghij'
> blob.slice(3).slice()
Blob { size: 7, type: '' }
> await _.text()
'defg'

How often does it reproduce? Is there a required condition?

No response

What is the expected behavior? Why is that the expected behavior?

slice() with no arguments should be equivalent to slice(0, length) and return the entire blob; both of those are incorrectly returning something else.

What do you see instead?

The returned Blob object purports to have the expected size, but when it is read it has the wrong length.

Additional information

No response

Reproducible:

import fs from 'node:fs';

// await fs.writeFile('file.txt', '123456789')

const blob = await fs.openAsBlob('file.txt');
console.log(await blob.text());

console.log(await blob.slice(3).text());

console.log(await blob.slice(3).slice().text());

└─$ node index.mjs
123456789
456789
456

It however does not occur with non-fs blobs:

import { Blob } from 'node:buffer';

const blob = new Blob(['123456789']);

console.log(await blob.text());
console.log(await blob.slice(3).text());
console.log(await blob.slice(3).slice().text());

└─$ node index.mjs
123456789
456789
456789

Hey @redyetidev, could you assign me this issue? I'd like to work on it, if that's alright.

Feel free to work on it, but issues aren't typically assigned (except when they are self assigned).

If you have an improvement, feel free to submit a PR.

node/src/dataqueue/queue.cc

Line 854 in cf8e535

new_end = std::min(end.value(), end_);

Should be:

 new_end = std::min(end.value() + start_, end_);

Feel free to submit a PR with suggestions to the Conway.

src: fix slice of slice of file-backed Blob

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Incorrect slice() from fs.openAsBlob() #53908

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Platform

Subsystem

What steps will reproduce the bug?

How often does it reproduce? Is there a required condition?

What is the expected behavior? Why is that the expected behavior?

What do you see instead?

Additional information

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Incorrect slice() from fs.openAsBlob() #53908

Description

Version

Platform

Subsystem

What steps will reproduce the bug?

How often does it reproduce? Is there a required condition?

What is the expected behavior? Why is that the expected behavior?

What do you see instead?

Additional information

Activity

avivkeller commented on Jul 17, 2024

avivkeller commented on Jul 17, 2024

HardikGoyal2003 commented on Jul 17, 2024

avivkeller commented on Jul 17, 2024

jleedev commented on Jul 20, 2024

avivkeller commented on Jul 20, 2024

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