Delete file after createWriteStream raises no error when stream.write('whatever')

[ghost]

I'm on a mac, Node v8.6.0.
Briefly, if I do this in mocha :

import  fs from 'fs-extra'

const stream = fse.createWriteStream(
                path.normalize('./myfile.txt'),
                {flags: 'a', encoding: 'utf8', mode: 0o0666}
            )
stream.on('error', err => {
    // this is never called
    console.log(err)
})
fs.unlinkSync('./myfile.txt')

try{
    stream.write('whatever', () => {
                console.log('All is well.')
            })
}
catch (err) {
   assert.isUndefined(err)
}
const stream = fse.createWriteStream(
                path.normalize('./myfile.txt'),
                {flags: 'a', encoding: UTF8, mode: FILE_MODE}
            )
stream.on('error', err => {
    assert.isNotOk(err)
})
// !!! I delete the stream`s file
fs.unlinkSync('./myfile.txt')

try{
    stream.write('whatever')
}
catch (err) {
   assert.isUndefined(err)
}

the test passes.
I don't thimk this has anything to do with importing fs-extra. It's just a wrapper for fs.
Is this a normal behaviour? Shouldn't there be some way to prevent this kind of error?
Thank you for your time.

[addaleax]

Hi! A few things:

• If you have an issue and you think it is a problem with Node, try to provide a test file that doesn’t use external modules (like fs-extra) or requires transpilation to work.
• fs.createWriteStream() is not a synchronous operation – it’s possible that the fs.unlinkSync() call would always be run before the file is actually opened.

And even if it does run while the stream is open, then no, at least on non-Windows systems (don’t know about others) this is the expected behavior.

There’s a reason the operation is called unlink() and not delete() or something like that: “Removing” a file on a POSIX operating system means decreasing a reference count, not actually deleting it right away. The file is only removed once all references to it on the hard drive are gone and all programs that access the file have released their handles to them, see e.g. https://linux.die.net/man/2/unlink

[addaleax]

@vladblindu I’m closing this in the hope that the question is answered for you. If not, please feel free to comment again (here or, if you have more questions, on the https://github.com/nodejs/help repository)

[ghost]

Thank you again for your time and your explanation. I’ll modify my code accordingly. Sorry for the ES6 syntax. I am quite unexperienced with this kind of issue reporting. Also please excuse me I replied so late. Thanks again I also apologise for the late reply

…

On 24 Jan 2018, at 21:03, Anna Henningsen ***@***.***> wrote: Closed #18274 <#18274>. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#18274 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AH1F_mjEUSZl9t7qWt6ivxmye04qgDQiks5tN36EgaJpZM4RllYx>.

[leodutra]

I can confirm this is still happening on Windows, when using https://github.com/sindresorhus/got
This is using Node stream package (https://github.com/sindresorhus/got/blob/master/source/as-stream.ts).

Whenever I start downloading and streaming to the opened file, and hard delete the file, no error is thrown.

[amitzur]

This is happening to me as well. To reproduce:

const fs = require('fs')
const os = require('os')
const filepath = 'x.log'
const writer = fs.createWriteStream(filepath, {flags: 'a', encoding: 'utf8'})
setInterval(() => {
        writer.write(`${Date.now()}${os.EOL}`, err => {
            console.log('err', err);
        });
}, 1000)

setTimeout(() => {
    fs.unlinkSync(filepath)    
}, 3000)

I'm running on Linux Ubuntu 20.04 and getting this output:

err undefined
err undefined
err undefined
err undefined
err undefined
err undefined
err undefined
...

Even though I would expect to see an exception from the writer.write after the file was deleted.

[rejetto]

@amitzur if this is not reopened, would you consider opening another issue with your example?

[amitzur]

@rejetto makes sense. I will, thanks!