こんにちは TAG-さん!

I'm requesting a TAG review of Multiple Readers and Writers in File System Access API.

Currently, only one FileSystemSyncAccessHandle may be open at a time per file, preventing an origin from reading the same file from multiple tabs easily. Conversely, multiple FileSystemWritableFileStream can be simultaneously open, letting multiple writers clobber each other.

Introducing new “create” modes for FileSystemSyncAccessHandle and FileSystemWritableFileStream allows opening either multiple readers/writers or an exclusive writer to a file entry, depending on the application's use case.

handle.createSyncAccessHandle({ mode: 'read-only' });
handle.createWritable({ mode: ‘exclusive’ });

• Explainer: https://github.com/whatwg/fs/blob/main/proposals/MultipleReadersWriters.md
• Security and Privacy self-review: No changes introduced to the existing review (WICG/file-system-access/security-privacy-questionnaire.md)
• GitHub repo: whatwg/fs
• Primary contacts:
  • Austin Sullivan (@a-sully), Google Chrome
  • Daseul Lee (@dslee414), Google Chrome
• Organization/project driving the design: Google/Chromium
• External status/issue trackers for this feature: https://bugs.chromium.org/p/chromium/issues/detail?id=1382215

Further details:

• I have reviewed the TAG's Web Platform Design Principles
• The group where the incubation/design work on this is being done: whatwg/fs and WICG/file-system-access
• The group where standardization of this work is intended to be done: whatwg/fs
• Existing major pieces of multi-stakeholder review or discussion of this design: https://github.com/whatwg/fs/issues/34
• Major unresolved issues with or opposition to this design: Webkit is positive in regards to allowing multiple read-only FileSystemSyncAccessHandles, but the stance for multiple writers is not yet known.
• This work is being funded by: Google

You should also know that…

• FileSystemSyncAccessHandle is available only on Bucket File System (a.k.a. Origin Private File System), while FileSystemWritableFileStream is available on both Bucket File System (implemented in Blink, Gecko, WebKit) and local file system (Chromium-only).
• We think that adding an optional dictionary is probably not controversial, and adding modes like shared read-only, exclusive readwrite, and (unsafe) shared readwrite are common across native file system APIs, but feedback on the specific enum strings would be especially welcome.
• Also, we think that preventing modification of a parent directory via shared lock would be desired, as a file entry is represented by a file path; however, native file system behavior on this varies, and feedback on this is welcome.

We'd prefer the TAG provide feedback as:

🐛 open issues in our GitHub repo for each point of feedback