From d160ec2364fc0613b2966815ddb6b0e945e1225e Mon Sep 17 00:00:00 2001
From: Nicholas Bishop <nbishop@nbishop.net>
Date: Fri, 19 Jul 2024 11:50:36 -0400
Subject: [PATCH] Add uefi::runtime module

The initial version here just provides functions for getting and setting the
system time. Later commits will add functions to get/set variables, handle
update capsules, etc.

Also added some tests for the new code in the test runner (note that there were
no existing tests for the time-related functions of `RuntimeServices`).
---
 uefi-test-runner/src/runtime/mod.rs | 32 +++++++++++++++-
 uefi/CHANGELOG.md                   |  2 +
 uefi/src/lib.rs                     |  1 +
 uefi/src/runtime.rs                 | 57 +++++++++++++++++++++++++++++
 4 files changed, 91 insertions(+), 1 deletion(-)
 create mode 100644 uefi/src/runtime.rs

diff --git a/uefi-test-runner/src/runtime/mod.rs b/uefi-test-runner/src/runtime/mod.rs
index 9babae774..41c6d6344 100644
--- a/uefi-test-runner/src/runtime/mod.rs
+++ b/uefi-test-runner/src/runtime/mod.rs
@@ -1,8 +1,38 @@
+mod vars;
+
+use uefi::runtime::{self, Daylight, Time, TimeParams};
 use uefi::table::runtime::RuntimeServices;
 
 pub fn test(rt: &RuntimeServices) {
     info!("Testing runtime services");
     vars::test(rt);
+    test_time();
 }
 
-mod vars;
+fn test_time() {
+    // Print the current time and time capabilities.
+    info!(
+        "Time with caps: {:?}",
+        runtime::get_time_and_caps().unwrap()
+    );
+
+    // Set the time.
+    let time = Time::new(TimeParams {
+        year: 2020,
+        month: 1,
+        day: 2,
+        hour: 3,
+        minute: 4,
+        second: 5,
+        nanosecond: 6,
+        time_zone: None,
+        daylight: Daylight::IN_DAYLIGHT,
+    })
+    .unwrap();
+    unsafe { runtime::set_time(&time).unwrap() };
+
+    // Print the new time and check that the year was successfully changed.
+    let now = runtime::get_time().unwrap();
+    info!("After setting time: {}", now);
+    assert_eq!(now.year(), 2020);
+}
diff --git a/uefi/CHANGELOG.md b/uefi/CHANGELOG.md
index c00f2a651..c757db4fb 100644
--- a/uefi/CHANGELOG.md
+++ b/uefi/CHANGELOG.md
@@ -3,6 +3,8 @@
 ## Added
 - `uefi::system` is a new module that provides freestanding functions for
   accessing fields of the global system table.
+- `uefi::runtime` is a new module that provides freestanding functions for
+  runtime services using the global system table.
 - Add standard derives for `ConfigTableEntry`.
 - `PcrEvent`/`PcrEventInputs` impl `Align`, `Eq`, and `PartialEq`.
 - Added `PcrEvent::new_in_box` and `PcrEventInputs::new_in_box`.
diff --git a/uefi/src/lib.rs b/uefi/src/lib.rs
index a40d4edac..52ff54cbb 100644
--- a/uefi/src/lib.rs
+++ b/uefi/src/lib.rs
@@ -119,6 +119,7 @@ pub use uguid::guid;
 mod result;
 pub use result::{Error, Result, ResultExt, Status, StatusExt};
 
+pub mod runtime;
 pub mod system;
 pub mod table;
 
diff --git a/uefi/src/runtime.rs b/uefi/src/runtime.rs
new file mode 100644
index 000000000..56015bc60
--- /dev/null
+++ b/uefi/src/runtime.rs
@@ -0,0 +1,57 @@
+//! UEFI runtime services.
+//!
+//! These services are available both before and after exiting boot
+//! services. Note that various restrictions apply when calling runtime services
+//! functions after exiting boot services; see the "Calling Convention" section
+//! of the UEFI specification for details.
+
+use crate::table::{self};
+use crate::{Result, StatusExt};
+use core::ptr::{self, NonNull};
+
+pub use crate::table::runtime::{Daylight, Time, TimeCapabilities, TimeError, TimeParams};
+
+fn runtime_services_raw_panicking() -> NonNull<uefi_raw::table::runtime::RuntimeServices> {
+    let st = table::system_table_raw_panicking();
+    // SAFETY: valid per requirements of `set_system_table`.
+    let st = unsafe { st.as_ref() };
+    NonNull::new(st.runtime_services).expect("runtime services are not active")
+}
+
+/// Query the current time and date information.
+pub fn get_time() -> Result<Time> {
+    let rt = runtime_services_raw_panicking();
+    let rt = unsafe { rt.as_ref() };
+
+    let mut time = Time::invalid();
+    let time_ptr: *mut Time = &mut time;
+    unsafe { (rt.get_time)(time_ptr.cast(), ptr::null_mut()) }.to_result_with_val(|| time)
+}
+
+/// Query the current time and date information and the RTC capabilities.
+pub fn get_time_and_caps() -> Result<(Time, TimeCapabilities)> {
+    let rt = runtime_services_raw_panicking();
+    let rt = unsafe { rt.as_ref() };
+
+    let mut time = Time::invalid();
+    let time_ptr: *mut Time = &mut time;
+    let mut caps = TimeCapabilities::default();
+    unsafe { (rt.get_time)(time_ptr.cast(), &mut caps) }.to_result_with_val(|| (time, caps))
+}
+
+/// Sets the current local time and date information
+///
+/// During runtime, if a PC-AT CMOS device is present in the platform, the
+/// caller must synchronize access to the device before calling `set_time`.
+///
+/// # Safety
+///
+/// Undefined behavior could happen if multiple tasks try to
+/// use this function at the same time without synchronisation.
+pub unsafe fn set_time(time: &Time) -> Result {
+    let rt = runtime_services_raw_panicking();
+    let rt = unsafe { rt.as_ref() };
+
+    let time: *const Time = time;
+    (rt.set_time)(time.cast()).to_result()
+}