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

rustbot has assigned @clarfonthey.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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Owners of files modified in this PR: @ChrisDenton, libs
@ChrisDenton, libs expanded to 12 candidates
Random selection from Darksonn, Mark-Simulacrum, clarfonthey, jhpratt

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.

…=<try> Added implementation on `set_permissions_nofollow` for all primary platforms try-job: dist-various-* try-job: test-various try-job: aarch64-apple

rust-bors · 2026-07-20T21:46:05Z

☀️ Try build successful (CI)
Build commit: b256fe7 (b256fe740cb5430fa284e90b785c776d2cf5e193)
Base parent: 9e71b3b (9e71b3bc704eea68d39bd0f6a46703c7d22f5d3b)

clarfonthey · 2026-07-20T22:24:37Z

@rustbot review

I'll do another pass on review later and then we should be good to merge this, hopefully.

clarfonthey · 2026-07-24T02:23:06Z

+            #[cfg(not(any(target_os = "espidf", target_os = "horizon")))]
+            {
+                use crate::os::wasi::fs::OpenOptionsExt;
+                options.custom_flags(libc::O_NOFOLLOW);
+            }
+


This is just dead code, yeah?

View changes since the review

Sorry, rephrase: the code in this block is unconditionally included because the cfg should be redundant.

clarfonthey · 2026-07-24T02:24:05Z

Code looks good, r=me minus one comment.

…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 · 2026-07-24T14:10:41Z

⚠️ Warning ⚠️

This PR is based on an upstream commit that is older than 28 days.

It's recommended to update your branch according to the rustc-dev-guide.

asder8215 · 2026-07-24T16:25:16Z

@bors r=clarfonthey

rust-bors · 2026-07-24T16:25:21Z

@asder8215: 🔑 Insufficient privileges: not in review users

asder8215 · 2026-07-24T16:27:58Z

Is that not how it works?

clarfonthey · 2026-07-24T16:48:02Z

(delegate try only allows try commands, not r+)

@bors r+ rollup=iffy

Failed before, tests passed now, still cautious.

rust-bors · 2026-07-24T16:48:06Z

📌 Commit cdad583 has been approved by clarfonthey

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 1. This pull request will be tested once the tree is reopened.

Reason for tree closure: spurious CI failures

asder8215 · 2026-07-24T16:59:14Z

(delegate try only allows try commands, not r+)

Oh got you. I think I just noticed in other PRs in the past with reviewers saying r=me and then the PR author run bors command with r=<person who gave r=me>.

I don't know if that's what r=me means, but that's what I thought it allowed unprivileged users to do.

@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

@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

Rollup of 17 pull requests Successful merges: - #158168 (Added implementation on `set_permissions_nofollow` for all primary platforms) - #138618 (Support using const pointers in asm `const` operand) - #157962 (Function item should not be used as const arg) - #158404 (trait_solver: normalize next-gen region constraints) - #158709 (rustdoc: warn on improperly interleaved HTML/MD) - #159720 (document #[global_allocator] constraints) - #159732 (optimization: don't look for diagnostic/canonical items without rustc_attrs enabled) - #159740 (reuse regular exported_non_generic_symbols logic in Miri) - #159780 (check `extern "custom"` function pointers) - #159786 (rustdoc-js: ignore editor temp files in test folder discovery) - #159819 (std::sync::poison: disable auto_cfg on PoisonError::new) - #155388 (stepping into where-clauses during normalization may be productive) - #155914 (when bailing on ambiguity, don't force other results to ambig) - #159411 ([rustdoc] Correctly handle output options with --show-coverage) - #159439 (Fix(lib/fs/win): Fall back on Win32 delete for `Dir::remove_file`) - #159809 (Avoid `#[target_features]`) - #159826 (Remove redundant `#[rustc_paren_sugar]` feature gate)

clarfonthey · 2026-07-24T23:54:23Z

I don't know if that's what r=me means, but that's what I thought it allowed unprivileged users to do.

Yeah, bors only responds to @ mentions, so, this is just a syntax that folks use to clarify that it's okay to merge with the review on their behalf. It's all confusing and being a relatively new team member myself I'm also just working off of things I've noticed, so, you're not too far off.

Either way, hopefully merge succeeds this time, and thank you for putting the work in!

jhpratt · 2026-07-25T01:08:56Z

@bors r- #159872 (comment)

failures:

---- fs::tests::set_get_permissions_nofollows_symlink stdout ----

thread 'fs::tests::set_get_permissions_nofollows_symlink' (10416) panicked at library/std/src/fs/tests.rs:674:37:
called `Result::unwrap_err()` on an `Ok` value: ()
---- fs::tests::set_get_permissions_nofollows_symlink stdout end ----

failures:
    fs::tests::set_get_permissions_nofollows_symlink

test result: FAILED. 534 passed; 1 failed; 28 ignored; 0 measured; 0 filtered out; finished in 311.70s

rust-bors · 2026-07-25T01:09:03Z

This pull request was unapproved.

This PR was contained in a rollup (#159872), which was unapproved.

View changes since this unapproval

clarfonthey · 2026-07-25T02:13:55Z

Kind of incredible how every platform seems to handle this differently, somehow.

rustbot assigned clarfonthey Jun 20, 2026

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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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Rollup of 18 pull requests #159871

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Rollup of 17 pull requests #159872

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