uefi-raw: time feature with conversions to/from OffsetDateTime by phip1611 · Pull Request #1899 · rust-osdev/uefi-rs

phip1611 · 2026-02-22T11:12:06Z

This PR introduces a new time feature that enables interoperability between our EFI Time struct and the time crate's OffsetDateTime type. The goal is to make it easier to work with standard Rust time types while maintaining the safety and validation guarantees of the Time struct.

The PR only focuses on uefi-raw, uefi follows in a next step.

This replaces #1896 as it is clearly a better strategy to move as much of the time handling as possible into a bulletproof crate. I decided to go with time as it is the defacto standard of the ecosystem.

Highlights

New conversions
- Time::to_offset_date_time() -> converts a valid Time into an OffsetDateTime in UTC or using a provided default local timezone.
- Time::to_offset_date_time_with_default_timezone(local: UtcOffset) -> handles UNSPECIFIED_TIMEZONE safely with an optional local offset.
- TryFrom<OffsetDateTime> for Time -> allows converting standard Rust times into EFI Time, with proper error handling for unrepresentable years or offsets with non-zero seconds.
Error handling
- Introduced ToOffsetDateTimeError and FromOffsetDateTimeError for detailed conversion errors.
- Covers invalid years, invalid components, unspecified timezone in no_std, and offsets with seconds.
Comprehensive unit tests
- Tests for all public methods, including boundary cases (nanoseconds, offsets, years).
- Conversion round-trips validated where possible.
- I used an LLM (ChatGPT) as sparring partner - very helpful!

Benefits

Makes Time more ergonomic to use with standard Rust time APIs.
More bulletproof than uefi: improve handling of Time #1896

Checklist

Sensible git history (for example, squash "typo" or "fix" commits). See the Rewriting History guide for help.
Update the changelog (if necessary)

This makes it clearer that this value can be any of those three. Reference: https://github.com/tianocore/edk2/blob/b7a715f7c03c45c6b4575bf88596bfd79658b8ce/EmbeddedPkg/Library/TimeBaseLib/TimeBaseLib.c#L253

By adding a convenient integration with `OffsetDateTime` of the `time` crate, we make `Time` much more usable. This commit adds the helpers `to_offset_date_time()` and `to_offset_date_time_with_default_timezone()`: the latter helps to better cope with Time::UNSPECIFIED_TIMEZONE.

This helps to better keep an overview.

phip1611 · 2026-02-22T13:00:32Z


 //! Date and time types.

-use bitflags::bitflags;


Hint: this looks quite invasive in github UI. I just moved everything feature( = "time") related into mod time_crate_integration

phip1611 · 2026-02-22T13:00:36Z

    /// Indicates the time should be interpreted as local time.
    pub const UNSPECIFIED_TIMEZONE: i16 = 0x07ff;

-    #[cfg(feature = "time")]


Hint: this looks quite invasive in github UI. I just moved everything feature( = "time") related into mod time_crate_integration

phip1611 · 2026-02-22T13:00:43Z

 }

 #[cfg(feature = "time")]
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]


Hint: this looks quite invasive in github UI. I just moved everything feature( = "time") related into mod time_crate_integration

nicholasbishop · 2026-03-08T17:40:03Z

    pub struct Daylight: u8 {
+        /// Daylight information not available or not applicable to the time
+        /// zone.
+        const NONE = 0;


The bitflags docs recommend against defining a zero flag.

ah, that's good to know. How about using newtype_enum!() then?

nicholasbishop · 2026-03-08T17:42:40Z


+[features]
+default = ["time"]
+time = ["dep:time"]


A convention I've seen recommended for crates where the major version can be expected to change (which is the case here; I think time is planning on a 1.0 transition at some point), is to include the version in the feature name. Something like time03.

makes sense - thanks

nicholasbishop · 2026-03-08T17:43:08Z

 uguid.workspace = true

+[features]
+default = ["time"]


I think we should remove this, uefi-raw should not enable optional deps by default.

nicholasbishop · 2026-03-08T17:43:42Z

 bitflags = "2.0.0"
 log = { version = "0.4.5", default-features = false }
 ptr_meta = { version = "0.3.0", default-features = false, features = ["derive"] }
+time = { version = "0.3", default-features = false, features = [] }


nit:

Suggested change

time = { version = "0.3", default-features = false, features = [] }

time = { version = "0.3", default-features = false }

Oh good catch, thanks!

nicholasbishop · 2026-03-08T17:45:56Z

 }

+#[cfg(feature = "time")]
+mod time_crate_integration {


Can we move this module (and the tests below) to a separate file? I think that'd be a little easier to read.

sure, makes sense

nicholasbishop · 2026-03-08T17:51:50Z

+    }
+
+    impl Time {
+        fn _to_offset_date_time(


nit: we should avoid underscore-prefixed functions as that turns off unused function warnings. example

nicholasbishop · 2026-03-08T17:54:58Z

+        /// let odt: OffsetDateTime = t.to_offset_date_time_with_default_timezone(default_offset).unwrap();
+        /// assert_eq!(odt.offset(), default_offset);
+        /// ```
+        pub fn to_offset_date_time_with_default_timezone(


Rather than providing this, I think we should have a conversion to PrimitiveDateTime. The caller can then choose to convert that to an OffsetDateTime with assume_offset.

Oh that's a better design. Thanks!

nicholasbishop · 2026-03-08T17:58:43Z

+
+    /// Errors that can happen when converting a [`Time`] to a [`OffsetDateTime`].
+    #[derive(Debug, Copy, Clone, PartialEq, Eq)]
+    pub enum ToOffsetDateTimeError {


I'm not convinced that having detailed error enums is going to be useful to end users, and it potentially makes the API harder to evolve later without a major version bump. The jiff crate for example opted for a mostly-opaque error type: https://docs.rs/jiff/latest/jiff/struct.Error.html.

What do you think about having just one public type like pub struct TimeError(InternalTimeError)? InternalTimeError would not be public, and would be an enum allowing us to provide the detailed error info via Display, but not make it programmatically acessible.

I think having a single time error type is fine. thanks for the pointer!

phip1611 · 2026-03-15T16:06:07Z

Closing this in favor of a new PR with a new design to keep the discussion clean and focused

phip1611 requested a review from nicholasbishop February 22, 2026 11:12

phip1611 self-assigned this Feb 22, 2026

phip1611 mentioned this pull request Feb 22, 2026

uefi: improve handling of Time #1896

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phip1611 force-pushed the uefi-raw-time-v2 branch from 7b5985f to 9fe899b Compare February 22, 2026 11:15

phip1611 requested a review from Copilot February 22, 2026 11:16

Copilot started reviewing on behalf of phip1611 February 22, 2026 11:16 View session

phip1611 force-pushed the uefi-raw-time-v2 branch from 9fe899b to e8b000e Compare February 22, 2026 11:17

phip1611 changed the title ~~uefi-raw: time feature with conversions to/from OffsetDateTime~~ time feature with conversions to/from OffsetDateTime Feb 22, 2026

phip1611 mentioned this pull request Feb 22, 2026

Release Plan: v0.37, v0.38, and beyond #1878

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phip1611 force-pushed the uefi-raw-time-v2 branch from e8b000e to 710b3d4 Compare February 22, 2026 12:29

uefi-raw: time: add missing valid daytime option

d16cfdf

This makes it clearer that this value can be any of those three. Reference: https://github.com/tianocore/edk2/blob/b7a715f7c03c45c6b4575bf88596bfd79658b8ce/EmbeddedPkg/Library/TimeBaseLib/TimeBaseLib.c#L253

phip1611 force-pushed the uefi-raw-time-v2 branch 2 times, most recently from 53f2bbd to 3b96089 Compare February 22, 2026 12:41

phip1611 changed the title ~~time feature with conversions to/from OffsetDateTime~~ uefi-raw: time feature with conversions to/from OffsetDateTime Feb 22, 2026

phip1611 force-pushed the uefi-raw-time-v2 branch 2 times, most recently from ba4f75b to 730cd38 Compare February 22, 2026 12:48

phip1611 added 2 commits February 22, 2026 13:49

uefi-raw: impl TryFrom for OffsetDateTime to Time

59ae1af

phip1611 force-pushed the uefi-raw-time-v2 branch from 730cd38 to 59ae1af Compare February 22, 2026 12:49

uefi-raw: add time integration into module

dbbf96e

This helps to better keep an overview.

phip1611 commented Feb 22, 2026

View reviewed changes

nicholasbishop reviewed Mar 8, 2026

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phip1611 closed this Mar 15, 2026

phip1611 mentioned this pull request Mar 15, 2026

uefi: Add integration with crates jiff and time for struct Time #1911

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	time = { version = "0.3", default-features = false, features = [] }
	time = { version = "0.3", default-features = false }

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phip1611 Mar 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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phip1611 commented Mar 15, 2026

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phip1611 commented Feb 22, 2026 •

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