`mv`: `-n` (`--no-clobber`) is racy, unlike GNU `mv`
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- Dominant language
- Rust
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Description
GNU mv makes its best attempt to use renameat2 with the RENAME_NOREPLACE flag, falling back via gnulib to the accessat + renameat (or via glibc to access + rename on even older kernels) if that isn't possible. uutils mv does not use renameat2, performing a racy check which is essentially equivalent to the access + rename construction. This introduces a low but non-zero risk of data loss when -n is relied upon. (For reference, BusyBox mv has the same deficiency, and, like uutils, does not bother with renameat and accessat, only making use of access and rename instead.)
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by locating uutils mv and its -n/--no-clobber implementation, then review how it performs the existence check and rename. Compare the available platform APIs with GNU mv's renameat2 and fallback approaches; done means eliminating the identified race without breaking supported platforms and validating the behavior with relevant tests.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- cli, operating-systems
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100