fix: handle ENOTDIR in FileDataAccessor.getStats to prevent 500 on duplicate slug POST - #2152

📁 Related issues

#2021

✍️ Description

Patch fix (I don't have permissions to add the label)

Posting a file to a container twice with the same Slug header causes a 500 InternalServerError on file-system-backed deployments (e.g. solidcommunity.net). The second POST succeeds on in-memory servers but crashes on disk-based ones.

Root cause: DataAccessorBasedStore.createSafeUri checks whether a resource already exists at the slug path by calling hasResource with both test.json and its container equivalent test.json/. On Linux/macOS, stat('test.json/') on a regular file returns the POSIX error ENOTDIR instead of ENOENT. FileDataAccessor.getStats only caught ENOENT and converted it to NotFoundHttpError; ENOTDIR escaped as a raw OS error, which ParsingHttpHandler then wrapped into a 500.

Call trace (before fix):

1. POST /container/ with Slug: test.json (file already exists on disk)
2. DataAccessorBasedStore.addResource → createSafeUri
3. createSafeUri builds candidate path test.json, then checks hasResource({ path: 'test.json/' }) first (the container-equivalent check)
4. hasResource calls FileDataAccessor.getMetadata({ path: 'test.json/' })
5. getMetadata maps the URL to a filesystem path …/test.json/ and calls getStats
6. getStats calls stat('…/test.json/') — Linux sees the trailing slash, tries to treat test.json as a directory, and throws ENOTDIR
7. getStats only handles ENOENT; ENOTDIR is re-thrown as a raw OS error
8. hasResource only catches NotFoundHttpError; raw ENOTDIR propagates out — the || short-circuits and the second check (test.json without slash) is never reached
9. ParsingHttpHandler.handleError sees a non-HttpError and returns a 500

Fix: Also catch ENOTDIR in getStats and convert it to NotFoundHttpError. ENOTDIR on a trailing-slash path means "no container exists here" — semantically identical to not-found. With the fix:

• hasResource({ path: 'test.json/' }) catches NotFoundHttpError → returns false
• false || continues to hasResource({ path: 'test.json' }) → file exists → returns true
• Condition is met → UUID fallback name is generated → 201

Result after fix:

• First POST Slug: test.json → 201 at .../test.json
• Second POST same slug → 201 at .../cb0ccbd8-f25a-... (UUID fallback)

✅ PR check list

Before this pull request can be merged, a core maintainer will check whether

• this PR is labeled with the correct semver label
  • semver.patch: Backwards compatible bug fixes.
  • semver.minor: Backwards compatible feature additions.
  • semver.major: Breaking changes. This includes changing interfaces or configuration behaviour.
• the correct branch is targeted. Patch updates can target main, other changes should target the latest versions/* branch.
• the RELEASE_NOTES.md document in case of relevant feature or config changes.
• any relevant documentation was updated to reflect the changes in this PR.