fix: eliminate TOCTOU races in catalog_fetch() - #3910
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Pull request overview
Eliminates TOCTOU races when reading local catalogs.
Changes:
- Removes
exists()pre-checks. - Converts
FileNotFoundErrorintoBundlerError.
Show a summary per file
| File | Description |
|---|---|
src/specify_cli/bundler/services/adapters.py |
Safely handles disappearing local catalog files. |
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- Files reviewed: 1/1 changed files
- Comments generated: 1
- Review effort level: Balanced
mnriem
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Aug 10, 2026
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Please address Copilot feedback
…ath URLs Remove exists() pre-checks and catch FileNotFoundError from read_text() to provide clear BundlerError messages even under race conditions.
…ath URLs Remove exists() pre-checks and catch FileNotFoundError from read_text() for both file:// and bare path catalog sources. Also catches OSError/UnicodeError to preserve the decode-error wrapping contract. Add regression test for the TOCTOU fix covering both file:// URLs and bare paths: mocked Path is observable as present (exists() returns True) but read_text() raises FileNotFoundError, proving the exists() removal eliminates the race window. Co-authored-by: GitHub Copilot (model: mimo-v2.5-free, supervised)
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Suppressed comments (1)
tests/unit/test_bundler_adapters.py:228
- The test never verifies the stated removal of the
exists()pre-check: an implementation that callsexists()and then catchesFileNotFoundErrorfromread_text()still passes. Assert thatexists()was not called so this regression test actually guards the PR's TOCTOU fix.
with patch.object(adapters.Path, "__new__", return_value=mock_path):
with pytest.raises(BundlerError, match="Catalog file not found"):
fetcher(_source(url))
- Files reviewed: 2/2 changed files
- Comments generated: 2
- Review effort level: Balanced
| raise BundlerError(f"Catalog file not found: {path}") | ||
| return load_json(path) | ||
| try: | ||
| return loads_json(path.read_text(encoding="utf-8"), origin=str(path)) |
Comment on lines
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| """Regression guard: a file that disappears between the old exists() pre-check | ||
| and read_text() must raise BundlerError, not a raw FileNotFoundError. | ||
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| The mocked Path is observable as present (exists() returns True) but | ||
| read_text() raises FileNotFoundError, simulating a deletion between the two | ||
| calls — the exact race window the exists() removal eliminates.""" |
Remove load_json from imports (F401) since the TOCTOU fix switched to loads_json(path.read_text()). Improve test docstring to accurately describe the behavioral change.
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Problem
catalog_fetch()checksexists()then callsread_text()for bothfile://and bare path URLs. The file can be deleted between the two calls.Fix
Remove the
exists()pre-checks and catchFileNotFoundErrorfromread_text().Testing
BundlerErroris raised when catalog file is missing