fs: guard against undefined behavior

[ronag]

Calling close on a file description which is currently in use is
undefined behavior due to implementation details in libuv. Add
a guard against this when using FileHandle.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/32749/

[ronag]

@nodejs/fs

[jasnell]

@addaleax ... This brought an edge case to mind that I'm not sure how we're handling...

What should happen in the following case

'use strict';constfs=require('fs');const{ Worker, workerData, isMainThread }=require('worker_threads');if(isMainThread){asyncfunctionfoo(){constfh=awaitfs.promises.open(__filename);constbuffer=Buffer.alloc(1000);// Not awaiting...constp=fh.read(buffer,0,1000);// Transferring the FileHandle while there's potentially// an outstanding async operation on it.constw=newWorker(__filename,{workerData: fh,transferList: [fh]});// Then awaiting...awaitp;returnbuffer.toString();}foo().then(console.log);}else{workerData.close();}

First immediate thought is that we should throw if attempting to transfer a FileHandle that has pending operations.

[addaleax]

First immediate thought is that we should throw if attempting to transfer a FileHandle that has pending operations.

Yeah, I agree – that sounds like the best approach to me 👍

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/32762/

[jasnell]

It would likely be good to add a comment to the fs.md documentation for FileHandle.close() that pending operations will be completed.

[ronag]

It would likely be good to add a comment to the fs.md documentation for FileHandle.close() that pending operations will be completed.

Fixed

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/32767/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/32768/ ✅

[ronag]

Landed in a0f87aa