microsoft / microsoft/VFSForGit

Mac: Include placeholder mtime in xattrs and check it when updating placeholders

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affects: reliability domain: user-mode platform: macOS
Dominant language
C#
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Merged PRs (30d)
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Description

Reduce the likelihood that PrjFS_UpdatePlaceholderFileIfNeeded deletes a user-modified file by:

  • Storing the placeholder mtime (i.e. when it was created or hydrated) in the placeholder's xattrs.
  • Checking the mtime in the xattrs against the mtime on the file in PrjFS_UpdatePlaceholderFileIfNeeded before deleting the file
  • Returning PrjFS_UpdateFailureCause_FullFile from PrjFS_UpdatePlaceholderFileIfNeeded if the mtimes do not match.

TBD: Does updating our custom xattrs change the file's mtime? If so, this approach might not work.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the Mac implementation of PrjFS_UpdatePlaceholderFileIfNeeded and the placeholder xattr handling. Determine whether updating custom xattrs changes the file mtime, then compare the stored placeholder mtime with the file mtime before deletion. Done means mismatches return PrjFS_UpdateFailureCause_FullFile and user-modified files are preserved.

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp
Domain
operating-systems
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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