[hermes] Harden against weird symlink layout

[joshlf]

---

This PR is on branch hermes.

• 　  [WIP] Agent #3050
• 　  [WIP] #3049
• 　  [hermes] Invoke Aeneas #3048
• 　  [hermes] More aggressively test hidden item rejection #3047
• 　  [hermes] Reject annotated items in blocks #3046
• 　  [hermes] Warn on #[cfg_attr(..., path = "...")] #3045
• 　  [hermes] Don't pass overly-long arguments to Charon #3044
• 👉 [hermes] Harden against weird symlink layout #3043
• 　  [hermes] Clean up after removing shadow crate support #3038
• 　  [hermes] Finalize removal of shadow crate code #3037
• 　  [hermes] Remove diagnostic path mapping from shadow copy #3036
• 　  [hermes] Stop copying shadow crate; run in-place #3035
• 　  [hermes] Disable unsafe redaction #3034
• 　  [hermes] Take responsibility for all terminal UI #3019
• 　  [hermes] Get tests passing again #3018
• 　  [hermes] Add some tests for Charon invocation #3015
• 　  [hermes] Add Charon step #3014
• 　  [hermes] Isolate shadow crate from other artifacts #3013
• 　  [hermes] Add some trace/debug logging #3012
• 　  [hermes] Add one more UI test #3011
• 　  [hermes] Add fixture testing #3010
• 　  [hermes] Finish shadow crate creation #3009
• 　  [hermes] Discover mod foo; declarations #3008
• 　  [hermes] Resolve Cargo and Hermes target dirs #3007
• 　  [hermes] Add shadow copy creation #3006
• 　  [hermes] Add package/target/root resolution #3005
• 　  [hermes] Add source code transformation #3004
• 　  [hermes] Add UI testing #3003
• 　  [hermes] Initial commit of parser #3002

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git fetch origin refs/heads/Gtu5rhuk5rjkrhhqpfwbmniejgf57ogzn && git checkout FETCH_HEAD

Cherry Pick

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Pull

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[gemini-code-assist]

Summary of Changes

Hello @joshlf, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the hermes tool's ability to correctly process Rust projects, particularly those with complex file system layouts involving symlinks or non-standard module structures. By introducing robust path canonicalization and refining module resolution logic, the changes prevent issues like infinite loops during file scanning and ensure accurate dependency checks. The update also improves error handling for file operations, making the tool more stable.

Highlights

• Robust Error Handling: Updated file reading operations in parse.rs to propagate errors using the ? operator instead of panicking, improving the tool's resilience to file system issues.
• Symlink Resolution for Workspace Dependencies: Implemented path canonicalization for the workspace root and package paths in resolve.rs to accurately determine if dependencies are within the workspace, even when symlinks are involved.
• Preventing Cyclic Module Processing: Introduced path canonicalization in scanner.rs when processing files recursively, ensuring that the same file is not processed multiple times due to symlinks or varied relative paths, and added graceful handling for missing or unreachable files.
• Enhanced Module Path Resolution Logic: Refined the logic in scanner.rs for determining the base directory when resolving child modules, differentiating between mod.rs, lib.rs, main.rs, and other module files to correctly locate nested modules.
• Comprehensive Test Coverage: Added several new test fixtures (canonicalized_workspace, cyclic_paths, missing_cfg_file, nested_file_mod) to validate the improved symlink handling, error propagation, and module resolution logic.

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Changelog

• tools/hermes/src/parse.rs
  • Changed fs::read_to_string to propagate errors instead of panicking.
• tools/hermes/src/resolve.rs
  • Imported the fs module.
  • Canonicalized the workspace_root path to correctly handle symlinks.
  • Canonicalized package paths before checking if they are within the workspace.
• tools/hermes/src/scanner.rs
  • Imported the OsStr module.
  • Canonicalized src_path at the beginning of process_file_recursive to prevent reprocessing files via symlinks.
  • Added error handling for canonicalize to skip unreachable or missing files gracefully.
  • Updated the logic for determining the base_dir for child modules, distinguishing between mod.rs/lib.rs/main.rs and other *.rs files.
  • Passed references to src_path and base_dir to relevant functions.
• tools/hermes/tests/fixtures/canonicalized_workspace/expected_status.txt
  • Added expected status for canonicalized workspace test.
• tools/hermes/tests/fixtures/canonicalized_workspace/source/Cargo.toml
  • Added workspace definition for test fixture.
• tools/hermes/tests/fixtures/canonicalized_workspace/source/crates/app/Cargo.toml
  • Added app package definition with a relative path dependency for test fixture.
• tools/hermes/tests/fixtures/canonicalized_workspace/source/crates/app/src/lib.rs
  • Added main_proof function for test fixture.
• tools/hermes/tests/fixtures/canonicalized_workspace/source/crates/lib/Cargo.toml
  • Added library package definition for test fixture.
• tools/hermes/tests/fixtures/canonicalized_workspace/source/crates/lib/src/lib.rs
  • Added shared function for test fixture.
• tools/hermes/tests/fixtures/cyclic_paths/expected_status.txt
  • Added expected status for cyclic paths test.
• tools/hermes/tests/fixtures/cyclic_paths/source/Cargo.toml
  • Added package definition for cyclic paths test fixture.
• tools/hermes/tests/fixtures/cyclic_paths/source/src/lib.rs
  • Added self_loop module and valid function for cyclic paths test fixture.
• tools/hermes/tests/fixtures/missing_cfg_file/expected_status.txt
  • Added expected status for missing cfg file test.
• tools/hermes/tests/fixtures/missing_cfg_file/source/Cargo.toml
  • Added package definition for missing cfg file test fixture.
• tools/hermes/tests/fixtures/missing_cfg_file/source/src/lib.rs
  • Added conditional windows_sys module and demo function for missing cfg file test fixture.
• tools/hermes/tests/fixtures/nested_file_mod/expected_config.toml
  • Added command configuration for nested file module test.
• tools/hermes/tests/fixtures/nested_file_mod/expected_status.txt
  • Added expected status for nested file module test.
• tools/hermes/tests/fixtures/nested_file_mod/source/Cargo.toml
  • Added package definition for nested file module test fixture.
• tools/hermes/tests/fixtures/nested_file_mod/source/src/foo.rs
  • Added bar module declaration for nested file module test fixture.
• tools/hermes/tests/fixtures/nested_file_mod/source/src/foo/bar.rs
  • Added deep_proof function for nested file module test fixture.
• tools/hermes/tests/fixtures/nested_file_mod/source/src/lib.rs
  • Added foo module declaration for nested file module test fixture.

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[gemini-code-assist]

Code Review

The pull request significantly improves the path resolution logic within the hermes tool, specifically hardening it against issues arising from symlinks and complex module layouts. By introducing fs::canonicalize at critical points in resolve.rs and scanner.rs, the tool now correctly handles workspace roots and package paths, preventing incorrect comparisons and potential infinite loops (as demonstrated by the new cyclic_paths test fixture). Additionally, the module resolution logic in scanner.rs has been refined to correctly determine base directories for child modules based on Rust's mod.rs and file-named module conventions. The changes are well-implemented and include appropriate error handling and logging. The addition of new test fixtures thoroughly validates these improvements.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.87%. Comparing base (0556c73) to head (f1646ac).

Additional details and impacted files

@@                        Coverage Diff                         @@
##           Gldfbyjdbfd3uolcvhjysepgbx472jv5a    #3043   +/-   ##
==================================================================
  Coverage                              91.87%   91.87%           
==================================================================
  Files                                     20       20           
  Lines                                   6057     6057           
==================================================================
  Hits                                    5565     5565           
  Misses                                   492      492           

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