touch: use write-open + futimens on Unix to trigger IN_CLOSE_WRITE #9813
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…inux - Add `try_futimens_via_write_fd` function for Unix systems to open files write-only and set times using `futimens`, ensuring inotify watchers detect file closure after touch. - Modify `update_times` to attempt this method before falling back to `set_file_times`, improving compatibility with file monitoring tools on Linux. - Include necessary imports for Unix-specific operations.
- Updated the spell-checker comment to include 'futimens', likely a system call or function name, to avoid false positives in code spell-checking.
sylvestre
reviewed
Dec 24, 2025
sylvestre
reviewed
Dec 24, 2025
Contributor
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is it possible to add tests ? thanks |
…time setting - Add nix and tempfile dependencies to Cargo.toml and Cargo.lock - Replace unsafe libc::futimens calls with nix::sys::stat::futimens for better safety and portability - Introduce try_futimens_via_write_fd function using nix abstractions - Add unit tests to verify futimens functionality on Unix systems This change reduces unsafe code usage and leverages a Rust-friendly library for Unix-specific operations.
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add |
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sorry, it needs to be rebased |
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GNU testsuite comparison: |
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GNU testsuite comparison: |
Merging this PR will not alter performance
Comparing 
Footnotes
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GNU testsuite comparison: |
sylvestre
reviewed
Feb 10, 2026
src/uu/touch/src/touch.rs
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| let mtime_spec = TimeSpec::new(mtime.unix_seconds() as _, mtime.nanoseconds() as _); | ||
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| futimens(&file, &atime_spec, &mtime_spec) | ||
| .map_err(|err| std::io::Error::from_raw_os_error(err as i32)) |
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he conversion from nix::Error to std::io::Error is incorrect
sylvestre
reviewed
Feb 10, 2026
src/uu/touch/src/touch.rs
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| #[cfg(unix)] | ||
| { | ||
| // Open write-only and use futimens to trigger IN_CLOSE_WRITE on Linux. | ||
| if !is_stdout && try_futimens_via_write_fd(path, atime, mtime).is_ok() { |
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Silent error swallowing with is_ok() loses information about why futimens failed.
sylvestre
reviewed
Feb 10, 2026
src/uu/touch/src/touch.rs
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| /// access and modification times on the open FD (not by path), which also | ||
| /// triggers `IN_CLOSE_WRITE` on Linux when the FD is closed. | ||
| fn try_futimens_via_write_fd(path: &Path, atime: FileTime, mtime: FileTime) -> std::io::Result<()> { | ||
| let metadata = fs::metadata(path)?; |
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Unnecessary metadata check before open. Opens file twice (metadata + open). Should check metadata after opening via file.metadata() to avoid TOCTOU and reduce syscalls.
sylvestre
reviewed
Feb 10, 2026
src/uu/touch/src/touch.rs
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| fn try_futimens_via_write_fd(path: &Path, atime: FileTime, mtime: FileTime) -> std::io::Result<()> { | ||
| let metadata = fs::metadata(path)?; | ||
| if !metadata.is_file() { | ||
| return Err(Error::other("not a regular file")); |
sylvestre
reviewed
Feb 10, 2026
src/uu/touch/src/touch.rs
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| } | ||
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| let file = OpenOptions::new().write(true).open(path)?; | ||
| let atime_spec = TimeSpec::new(atime.unix_seconds() as _, atime.nanoseconds() as _); |
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Unsafe type cast 'as _' for nanoseconds. Should explicitly cast to i32: atime.nanoseconds() as i32
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GNU testsuite comparison: |
sylvestre
reviewed
Feb 10, 2026
src/uu/touch/src/touch.rs
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| uu_app, | ||
| }; | ||
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| #[cfg(unix)] |
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Redundant import - std::fs is already imported unconditionally at line 26
… fallback Enhanced error handling in the touch utility by: - Adding proper error message translation for non-regular files - Implementing fallback mechanism when futimens fails - Improving error context and messaging for better user experience - Adding proper handling for special files like FIFOs and directories - Ensuring consistent error reporting across different platforms
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GNU testsuite comparison: |
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Summary
Make
touchopen regular files for write and callfutimenson the fd (Unix only). This matches GNU touch behavior and ensures inotify emitsIN_CLOSE_WRITEwhen timestamps are updated.Motivation
Some inotify-based reloaders watch only
IN_CLOSE_WRITE. With the current path-based timestamp update,touchemits onlyIN_ATTRIB, so those watchers miss the change. This caused infinite loops in downstream tests (e.g., 0 A.D. hotload tests on Ubuntu Questing).Changes
OpenOptions::new().write(true)and callfutimenson the fd for regular files.set_file_timespath-based update when open/futimens fails or the target is not a regular file.Testing
cargo test -p uu_touchNotes
related
#9812