Path fetcher: Handle invalid paths

[edolstra]

Motivation

Fixes a regression caused by #312 when using a chroot store and a path:... input that refers to the host store.

Context

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Improved system stability by enhancing validation checks in file path handling, ensuring cache entries are only created when necessary information is available.

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[coderabbitai]

📝 Walkthrough

Walkthrough

Path fetcher cache prefill logic updated to use conditional querying. Instead of unconditionally querying path info via store.queryPathInfo, the code now uses store.maybeQueryPathInfo and only populates fingerprint and cache entry when path info is available, skipping the operation if info is absent.

Changes

Cohort / File(s)	Summary
Path Fetcher Cache Safety src/libfetchers/path.cc	Changed cache prefill from unconditional queryPathInfo to conditional maybeQueryPathInfo, writing cache entry only when path info is present

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 A safer path we now explore,
With queries gentle, not so brash,
Cache fills only when info's sure,
No empty writes in our stash! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Path fetcher: Handle invalid paths' directly aligns with the PR's objective of handling invalid paths in the path fetcher when using a chroot store, which is the primary change described in the summary and PR description.

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✨ Finishing touches

• 📝 Generate docstrings

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📜 Recent review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 322355f and 9a20bf5.

📒 Files selected for processing (1)

• src/libfetchers/path.cc

🧰 Additional context used

🧬 Code graph analysis (1)

src/libfetchers/path.cc (1)

src/libfetchers/fetch-to-store.cc (2)

• makeSourcePathToHashCacheKey (8-13)
• makeSourcePathToHashCacheKey (9-9)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (2)

• GitHub Check: build_x86_64-linux / build
• GitHub Check: build_aarch64-darwin / build

🔇 Additional comments (1)

src/libfetchers/path.cc (1)

159-165: LGTM! Graceful handling of invalid paths.

The change correctly addresses the regression by using maybeQueryPathInfo instead of queryPathInfo. When the path info is unavailable (e.g., host store path in a chroot store), the code now gracefully skips cache population rather than throwing, allowing fetchToStore() to proceed with the normal copy path.

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[github-actions]

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