Added implementation on `set_permissions_nofollow` for all primary platforms by asder8215 · Pull Request #158168 · rust-lang/rust

asder8215 · 2026-06-20T06:51:38Z

For context, this PR is related to the tracking issue for std::fs::set_permissions_nofollow. This PR does a few different things:

Windows support is provided for std::fs::set_permissions_nofollow. On Windows, it uses OpenOptions::open with the custom flag FILE_FLAG_OPEN_REPARSE_POINT enabled and then sets the permissions on the reparse point directly. All other platforms (hermit, motor, solid, uefi, etc.) defer to what fs::set_permissions does since symlinks aren't supported on those platforms, so they effectively do the same thing.
The implementation for Unix was modified to use fchmodat instead of doing two separate calls (open and then fchmod via OpenOptions).
Because the previous implementations actually used fchmod instead of chmod underneath the hood (as that's what File::set_permissions, which is not to be confused with fs::set_permissions as that does use chmod, does underneath the hood), it actually had some incorrect documentation about the error returned by fchmod on symlinks. Instead of io::ErrorKind::FilesystemLoop, it returns io::ErrorKind::InvalidInput. You can read the documentation for fchmod. fchmodat does effectively the same thing as the open + fchmod combo, but it does return a different error, io::ErrorKind::Unsupported, that makes more sense. Regardless, I corrected the documentation for std::fs::set_permissions_nofollow and added a lot more clarifying information.
A test case has been added to verify if set_permissions_nofollow is operating correctly.

cc @ChrisDenton and @lolbinarycat

rustbot · 2026-06-20T06:51:42Z

r? @clarfonthey

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clarfonthey · 2026-06-20T12:09:10Z

 }

+pub fn set_perm_nofollow(path: &Path, perm: FilePermissions) -> io::Result<()> {
+    set_perm(path, perm)


Similar to UEFI, I would swap the method bodies here, so that set_perm defers to set_perm_nofollow plus a comment that says symlinks aren't supported.

View changes since the review

clarfonthey · 2026-06-20T12:15:58Z

@rustbot author

CI failure appears to be a simple typo but I also left some feedback on other stuff to fix. Otherwise, implementation looks good, although I would add an extra comment on the tracking issue once this is merged to have some Windows folks double-check that opening all reparse points in this method doesn't do anything we don't want, since that technically includes more than just symlinks. It should work in pretty much all normal use cases, just want to double-check the edge cases before stabilisation.

rustbot · 2026-06-20T12:16:02Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

clarfonthey · 2026-06-22T00:56:50Z

    check!(file.set_permissions(p));
 }

+#[test]


I assume you didn't mean to keep this in?

View changes since the review

No, I did mean to keep this in. I templated this test off the two tests before this chmod_works()/fchmod_works() (it's before this test). But to be honest, this test is using both fchmod/fchmodat depending on platform.

Which reminds me that I need to update documentation to mention that it uses open + fchmodon wasi platforms.

I guess that the main confusion here is that aren't there platforms where this will just fail, e.g. ones without any permissions, like VexOS?

Now that you ask that, does CI run these tests on platforms like VexOS/UEFI? I know it checks if the code compiles on those platforms, but I haven't noticed if CI actually runs these tests on those platforms.

This should definitely panic on certain lines like 1413.

clarfonthey · 2026-06-22T01:00:01Z

r=me minus one small mistake, plus figuring out why the tests aren't running atm.

asder8215 · 2026-06-23T04:06:05Z

This is the same error as #156269. I'm not sure what the CI error is for.

…pported (windows, unix, uefi, etc.); modified the Unix implementation to use fchmodat instead of open + fchmod; clarified documentations for set_permissions_nofollow; added a test case for set_permissions_nofollow

rustbot · 2026-06-23T14:38:54Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

asder8215 · 2026-06-23T16:24:34Z

@clarfonthey Finally got this to work with CI (sorry about the many force pushes!).

Let me know if you want me to remove the fchmodat_works test or not.

clarfonthey · 2026-06-23T16:36:58Z

Force-pushes are totally fine; I can deal. Will try and take a look later today.

clarfonthey · 2026-06-23T16:51:22Z

Just kidding, had some extra time to check this out and it looks good to me.

@bors r+ rollup=iffy

(touches multiple targets that might not be tested in PR CI. if rollup fails, we can do a dedicated try job first.)

rust-bors · 2026-06-23T16:51:25Z

📌 Commit 4804060 has been approved by clarfonthey

It is now in the queue for this repository.

@ChrisDenton

…nofollow, r=clarfonthey Added implementation on `set_permissions_nofollow` for all primary platforms For context, this PR is related to the tracking issue for [`std::fs::set_permissions_nofollow`](rust-lang#141607). This PR does a few different things: * Windows support is provided for `std::fs::set_permissions_nofollow`. On Windows, it uses `OpenOptions::open` with the custom flag `FILE_FLAG_OPEN_REPARSE_POINT` enabled and then sets the permissions on the reparse point directly. All other platforms (hermit, motor, solid, uefi, etc.) defer to what `fs::set_permissions` does since symlinks aren't supported on those platforms, so they effectively do the same thing. * The implementation for Unix was modified to use [`fchmodat`](https://linux.die.net/man/2/fchmodat) instead of doing two separate calls (`open` and then `fchmod` via `OpenOptions`). * Because the previous implementations actually used `fchmod` instead of `chmod` underneath the hood (as that's what `File::set_permissions`, which is not to be confused with `fs::set_permissions` as that does use `chmod`, does underneath the hood), it actually had some incorrect documentation about the error returned by `fchmod` on symlinks. Instead of `io::ErrorKind::FilesystemLoop`, it returns `io::ErrorKind::InvalidInput`. You can read the documentation for [`fchmod`](https://pubs.opengroup.org/onlinepubs/009696699/functions/fchmod.html). `fchmodat` does effectively the same thing as the `open` + `fchmod` combo, but it does return a different error, `io::ErrorKind::Unsupported`, that makes more sense. Regardless, I corrected the documentation for `std::fs::set_permissions_nofollow` and added a lot more clarifying information. * A test case has been added to verify if `set_permissions_nofollow` is operating correctly. cc @ChrisDenton and @lolbinarycat

rustbot assigned clarfonthey Jun 20, 2026

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clarfonthey mentioned this pull request Jun 20, 2026

Missing variables/fields give confusing error when name is the same as a built-in attribute like start or path #86290

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mkroening mentioned this pull request Jun 22, 2026

hermit/fs: Return unsupported() instead of from_raw_os_error(22) #158247

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asder8215 mentioned this pull request Jun 23, 2026

Implement Metadata:from_statx for Linux MetadataExt trait #156269

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JonathanBrouwer mentioned this pull request Jun 23, 2026

Rollup of 23 pull requests #158316

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