std: sys: uefi: os: Implement join_paths #150993

Ayush1325 · 2026-01-12T07:36:29Z

Tested using OVMF using QEMU.

@rustbot label +O-UEFI

rustbot · 2026-01-12T07:36:34Z

rustbot has assigned @Mark-Simulacrum.
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rust-bors · 2026-01-14T16:53:45Z

☔ The latest upstream changes (presumably #151107) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot · 2026-01-15T05:31:47Z

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.

Ayush1325 · 2026-01-24T05:36:29Z

cc @nicholasbishop

nicholasbishop

LGTM.

Only thought I have is that this is basically the same implementation as the Windows join_paths, so they could share code. But I don't see a good existing place to put that shared code, and it's not a large amount of duplicated code, so I don't feel strongly about avoiding the duplication.

View changes since this review

library/std/src/sys/pal/uefi/os.rs

Mark-Simulacrum · 2026-01-24T19:26:44Z

library/std/src/sys/pal/uefi/os.rs

+        if v.contains(&(b'"' as u16)) {
+            return Err(JoinPathsError);
+        } else if v.contains(&PATHS_SEP) {
+            joined.push(b'"' as u16);


Can you point to documentation suggesting it's valid to quote elements of the PATH? I'm not seeing anything to that effect in the linked specification.

I tested on OVMF just now and indeed, while file names can contain ;, the path variable does not seem to support those paths. Using " does not seem to do anything (although it does not cause any error either).

So I have made ; an invalid character.

rustbot · 2026-01-24T19:27:16Z

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

Ayush1325 · 2026-01-25T06:43:01Z

@rustbot ready

Mark-Simulacrum · 2026-01-25T13:18:22Z

library/std/src/sys/pal/uefi/os.rs

+            joined.push(PATHS_SEP)
+        }
+        let v = path.encode_wide().collect::<Vec<u16>>();
+        if v.contains(&QUOTE) || v.contains(&PATHS_SEP) {


I don't think a path containing " is invalid (why do you think it is?) -- it just means that the file path has that character in it? The reason we need to forbid PATHS_SEP is that there's no way to escape that, so including it actually includes two paths (likely non-existent ones, though that's not guaranteed).

I don't think a path containing " is invalid (why do you think it is?) -- it just means that the file path has that character in it? The reason we need to forbid PATHS_SEP is that there's no way to escape that, so including it actually includes two paths (likely non-existent ones, though that's not guaranteed).

Well, according to UEFI shell spec, file name has the following rules: one or more ASCII characters, excluding * ? < > \ / ” : ). So from the perspective of path variable (which is specific to UEFI shell), a path cannot have ".

With that said, the reason of course is different.

; will give us an incorrect (i.e. something user might not have expected) path variable.

" will give us an invalid path.

So not sure if we need to throw error for " (and other invalid characters).

My sense is that it doesn't make sense to attempt to validate that the components are valid paths in join_paths, we should only validate that the paths are accurately joined (i.e., each path on input is present in the output or an error is returned).

Ok, I have removed the " check.

Mark-Simulacrum · 2026-01-25T20:21:23Z

library/std/src/sys/pal/uefi/os.rs

 }

 impl fmt::Display for JoinPathsError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "not supported on this platform yet".fmt(f)
+        "path segment contains `\"` or `;`".fmt(f)


This is stale.

Mark-Simulacrum · 2026-01-25T20:21:47Z

library/std/src/env.rs

@@ -518,8 +518,8 @@ pub struct JoinPathsError {
 ///
 /// Returns an [`Err`] (containing an error message) if one of the input
 /// [`Path`]s contains an invalid character for constructing the `PATH`
-/// variable (a double quote on Windows or a colon on Unix), or if the system
-/// does not have a `PATH`-like variable (e.g. UEFI or WASI).
+/// variable (a double quote on Windows or a colon on Unix and UEFI), or if


I think it's a semicolon on UEFI?

- PATHS_SEP is defined as global const since I will implement split_paths in the future. - Tested using OVMF using QEMU. Signed-off-by: Ayush Singh <ayush@beagleboard.org>

rustbot assigned Mark-Simulacrum Jan 12, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jan 12, 2026

rustbot added the O-UEFI UEFI label Jan 12, 2026

Ayush1325 mentioned this pull request Jan 12, 2026

Tracking Issue for uefi-std #100499

Open

Ayush1325 force-pushed the uefi-join-path branch from 723e209 to e50d7bb Compare January 12, 2026 17:46

Ayush1325 force-pushed the uefi-join-path branch from e50d7bb to 988e7e2 Compare January 15, 2026 05:31

Ayush1325 force-pushed the uefi-join-path branch from 988e7e2 to 0750de6 Compare January 15, 2026 05:37

nicholasbishop approved these changes Jan 24, 2026

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Mark-Simulacrum requested changes Jan 24, 2026

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 24, 2026

Ayush1325 force-pushed the uefi-join-path branch from 0750de6 to 845f848 Compare January 25, 2026 06:40

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 25, 2026

Ayush1325 force-pushed the uefi-join-path branch from 845f848 to 85647ca Compare January 25, 2026 06:44

Ayush1325 requested a review from Mark-Simulacrum January 25, 2026 10:09

Mark-Simulacrum reviewed Jan 25, 2026

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Ayush1325 force-pushed the uefi-join-path branch from 85647ca to a7d25a7 Compare January 25, 2026 20:00

Mark-Simulacrum reviewed Jan 25, 2026

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Ayush1325 force-pushed the uefi-join-path branch from a7d25a7 to d7b193f Compare January 26, 2026 04:11

std: sys: uefi: os: Implement join_paths

3df2fa4

- PATHS_SEP is defined as global const since I will implement split_paths in the future. - Tested using OVMF using QEMU. Signed-off-by: Ayush Singh <ayush@beagleboard.org>

Ayush1325 force-pushed the uefi-join-path branch from d7b193f to 3df2fa4 Compare January 26, 2026 04:13

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std: sys: uefi: os: Implement join_paths #150993

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std: sys: uefi: os: Implement join_paths #150993

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