uutils/coreutils

chmod: behavioral divergence from coreutils when the target file is not accessible

Open

#9789 opened on Dec 23, 2025

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U - chmodgood first issue

Description

Component

chmod

Description

In Chmoder::chmod()

if !file.exists() {
    // .........
}

Path::exists() is used to determine whether a file is existed. Because Path::exists() will return false when there is a metadata access errors, including PermissionDenied, it can misclassify existing but inaccessible paths as non-existent, producing incorrect result.

Test / Reproduction Steps

core_sbx$ sudo mkdir locked
core_sbx$ sudo touch locked/file
core_sbx$ sudo chmod 000 locked
core_sbx$ ../../coreutils/target/release/chmod 000 locked/file
../../coreutils/target/release/chmod: cannot access 'locked/file': No such file or directory
core_sbx$ chmod 000 locked/file
chmod: cannot access 'locked/file': Permission denied

Impact

Behavioral divergence from GNU coreutils: scripts and tooling may treat No such file differently from Permission denied.

Contributor guide

Tech stack
rust
Domain
cli
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
RustFile permissionsPath::exists() behavior
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85
Research direction
Examine the `chmod` implementation in the repository, particularly the `Chmoder::chmod()` method. Replace the `Path::exists()` call with `File::open()` or `metadata()` to properly handle permission errors. Ensure the error message matches GNU coreutils when the file exists but is inaccessible. Update any relevant tests to cover this case.