uefi: fs: Add file times plumbing

- Add FileTimes implementation.

Signed-off-by: Ayush Singh <ayush@beagleboard.org>

Author: Ayush1325

library/std/src/sys/fs/uefi.rs

@@ -7,7 +7,7 @@ use crate::hash::Hash;
 use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut, SeekFrom};
 use crate::path::{Path, PathBuf};
 use crate::sys::time::SystemTime;
-use crate::sys::unsupported;
+use crate::sys::{unsupported, unsupported_err};
 
 #[expect(dead_code)]
 const FILE_PERMISSIONS_MASK: u64 = r_efi::protocols::file::READ_ONLY;
@@ -18,6 +18,7 @@ pub struct File(!);
 pub struct FileAttr {
     attr: u64,
     size: u64,
+    times: FileTimes,
 }
 
 pub struct ReadDir(!);
@@ -33,7 +34,11 @@ pub struct OpenOptions {
 }
 
 #[derive(Copy, Clone, Debug, Default)]
-pub struct FileTimes {}
+pub struct FileTimes {
+    accessed: Option<SystemTime>,
+    modified: Option<SystemTime>,
+    created: Option<SystemTime>,
+}
 
 #[derive(Clone, PartialEq, Eq, Debug)]
 // Bool indicates if file is readonly
@@ -60,15 +65,15 @@ impl FileAttr {
     }
 
     pub fn modified(&self) -> io::Result<SystemTime> {
-        unsupported()
+        self.times.modified.ok_or(unsupported_err())
     }
 
     pub fn accessed(&self) -> io::Result<SystemTime> {
-        unsupported()
+        self.times.accessed.ok_or(unsupported_err())
     }
 
     pub fn created(&self) -> io::Result<SystemTime> {
-        unsupported()
+        self.times.created.ok_or(unsupported_err())
     }
 }
 
@@ -92,8 +97,13 @@ impl FilePermissions {
 }
 
 impl FileTimes {
-    pub fn set_accessed(&mut self, _t: SystemTime) {}
-    pub fn set_modified(&mut self, _t: SystemTime) {}
+    pub fn set_accessed(&mut self, t: SystemTime) {
+        self.accessed = Some(t);
+    }
+
+    pub fn set_modified(&mut self, t: SystemTime) {
+        self.modified = Some(t);
+    }
 }
 
 impl FileType {
@@ -386,6 +396,7 @@ mod uefi_fs {
     use crate::path::Path;
     use crate::ptr::NonNull;
     use crate::sys::helpers;
+    use crate::sys::time::{self, SystemTime};
 
     pub(crate) struct File(NonNull<file::Protocol>);
 
@@ -533,4 +544,23 @@ mod uefi_fs {
 
         Ok(())
     }
+
+    /// EDK2 FAT driver uses EFI_UNSPECIFIED_TIMEZONE to represent localtime. So for proper
+    /// conversion to SystemTime, we use the current time to get the timezone in such cases.
+    #[expect(dead_code)]
+    fn uefi_to_systemtime(mut time: r_efi::efi::Time) -> SystemTime {
+        time.timezone = if time.timezone == r_efi::efi::UNSPECIFIED_TIMEZONE {
+            time::system_time_internal::now().unwrap().timezone
+        } else {
+            time.timezone
+        };
+        SystemTime::from_uefi(time)
+    }
+
+    /// Convert to UEFI Time with the current timezone.
+    #[expect(dead_code)]
+    fn systemtime_to_uefi(time: SystemTime) -> r_efi::efi::Time {
+        let now = time::system_time_internal::now().unwrap();
+        time.to_uefi_loose(now.timezone, now.daylight)
+    }
 }

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

@@ -8,6 +8,20 @@ use crate::time::Duration;
 
 const SECS_IN_MINUTE: u64 = 60;
 
+const MAX_UEFI_TIME: Duration = from_uefi(r_efi::efi::Time {
+    year: 9999,
+    month: 12,
+    day: 31,
+    hour: 23,
+    minute: 59,
+    second: 59,
+    nanosecond: 999_999_999,
+    timezone: 1440,
+    daylight: 0,
+    pad1: 0,
+    pad2: 0,
+});
+
 #[test]
 fn align() {
     // UEFI ABI specifies that allocation alignment minimum is always 8. So this can be
@@ -44,7 +58,7 @@ fn systemtime_start() {
     };
     assert_eq!(from_uefi(&t), Duration::new(0, 0));
     assert_eq!(t, to_uefi(&from_uefi(&t), -1440, 0).unwrap());
-    assert!(to_uefi(&from_uefi(&t), 0, 0).is_none());
+    assert!(to_uefi(&from_uefi(&t), 0, 0).is_err());
 }
 
 #[test]
@@ -64,7 +78,7 @@ fn systemtime_utc_start() {
     };
     assert_eq!(from_uefi(&t), Duration::new(1440 * SECS_IN_MINUTE, 0));
     assert_eq!(t, to_uefi(&from_uefi(&t), 0, 0).unwrap());
-    assert!(to_uefi(&from_uefi(&t), -1440, 0).is_some());
+    assert!(to_uefi(&from_uefi(&t), -1440, 0).is_err());
 }
 
 #[test]
@@ -82,8 +96,44 @@ fn systemtime_end() {
         daylight: 0,
         pad2: 0,
     };
-    assert!(to_uefi(&from_uefi(&t), 1440, 0).is_some());
-    assert!(to_uefi(&from_uefi(&t), 1439, 0).is_none());
+    assert!(to_uefi(&from_uefi(&t), 1440, 0).is_ok());
+    assert!(to_uefi(&from_uefi(&t), 1439, 0).is_err());
+}
+
+#[test]
+fn min_time() {
+    let inp = Duration::from_secs(1440 * SECS_IN_MINUTE);
+    let new_tz = to_uefi(&inp, 1440, 0).err().unwrap();
+    assert_eq!(new_tz, 0);
+    assert!(to_uefi(&inp, new_tz, 0).is_ok());
+
+    let inp = Duration::from_secs(1450 * SECS_IN_MINUTE);
+    let new_tz = to_uefi(&inp, 1440, 0).err().unwrap();
+    assert_eq!(new_tz, 10);
+    assert!(to_uefi(&inp, new_tz, 0).is_ok());
+
+    let inp = Duration::from_secs(1450 * SECS_IN_MINUTE + 10);
+    let new_tz = to_uefi(&inp, 1440, 0).err().unwrap();
+    assert_eq!(new_tz, 9);
+    assert!(to_uefi(&inp, new_tz, 0).is_ok());
+}
+
+#[test]
+fn max_time() {
+    let inp = MAX_UEFI_TIME;
+    let new_tz = to_uefi(&inp, -1440, 0).err().unwrap();
+    assert_eq!(new_tz, 1440);
+    assert!(to_uefi(&inp, new_tz, 0).is_ok());
+
+    let inp = MAX_UEFI_TIME - Duration::from_secs(1440 * SECS_IN_MINUTE);
+    let new_tz = to_uefi(&inp, -1440, 0).err().unwrap();
+    assert_eq!(new_tz, 0);
+    assert!(to_uefi(&inp, new_tz, 0).is_ok());
+
+    let inp = MAX_UEFI_TIME - Duration::from_secs(1440 * SECS_IN_MINUTE + 10);
+    let new_tz = to_uefi(&inp, -1440, 0).err().unwrap();
+    assert_eq!(new_tz, 0);
+    assert!(to_uefi(&inp, new_tz, 0).is_ok());
 }
 
 // UEFI IoSlice and IoSliceMut Tests

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

@@ -1,5 +1,7 @@
 use crate::time::Duration;
 
+const SECS_IN_MINUTE: u64 = 60;
+
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
 pub struct Instant(Duration);
 
@@ -70,13 +72,32 @@ impl SystemTime {
         Self(system_time_internal::from_uefi(&t))
     }
 
-    #[expect(dead_code)]
-    pub(crate) const fn to_uefi(self, timezone: i16, daylight: u8) -> Option<r_efi::efi::Time> {
-        system_time_internal::to_uefi(&self.0, timezone, daylight)
+    pub(crate) const fn to_uefi(
+        self,
+        timezone: i16,
+        daylight: u8,
+    ) -> Result<r_efi::efi::Time, i16> {
+        // system_time_internal::to_uefi requires a valid timezone. In case of unspecified timezone,
+        // we just pass 0 since it is assumed that no timezone related adjustments are required.
+        if timezone == r_efi::efi::UNSPECIFIED_TIMEZONE {
+            system_time_internal::to_uefi(&self.0, 0, daylight)
+        } else {
+            system_time_internal::to_uefi(&self.0, timezone, daylight)
+        }
+    }
+
+    /// Create UEFI Time with the closest timezone (minute offset) that still allows the time to be
+    /// represented.
+    pub(crate) fn to_uefi_loose(self, timezone: i16, daylight: u8) -> r_efi::efi::Time {
+        match self.to_uefi(timezone, daylight) {
+            Ok(x) => x,
+            Err(tz) => self.to_uefi(tz, daylight).unwrap(),
+        }
     }
 
     pub fn now() -> SystemTime {
         system_time_internal::now()
+            .map(Self::from_uefi)
             .unwrap_or_else(|| panic!("time not implemented on this platform"))
     }
 
@@ -117,12 +138,11 @@ pub(crate) mod system_time_internal {
     use crate::mem::MaybeUninit;
     use crate::ptr::NonNull;
 
-    const SECS_IN_MINUTE: u64 = 60;
     const SECS_IN_HOUR: u64 = SECS_IN_MINUTE * 60;
     const SECS_IN_DAY: u64 = SECS_IN_HOUR * 24;
-    const TIMEZONE_DELTA: u64 = 1440 * SECS_IN_MINUTE;
+    const SYSTEMTIME_TIMEZONE: u64 = 1440 * SECS_IN_MINUTE;
 
-    pub fn now() -> Option<SystemTime> {
+    pub(crate) fn now() -> Option<Time> {
         let runtime_services: NonNull<RuntimeServices> = helpers::runtime_services()?;
         let mut t: MaybeUninit<Time> = MaybeUninit::uninit();
         let r = unsafe {
@@ -132,9 +152,7 @@ pub(crate) mod system_time_internal {
             return None;
         }
 
-        let t = unsafe { t.assume_init() };
-
-        Some(SystemTime::from_uefi(t))
+        Some(unsafe { t.assume_init() })
     }
 
     /// This algorithm is a modified form of the one described in the post
@@ -175,7 +193,7 @@ pub(crate) mod system_time_internal {
             + (t.hour as u64) * SECS_IN_HOUR;
 
         // Calculate the offset from 1/1/1900 at timezone -1440 min
-        let adjusted_localtime_epoc: u64 = localtime_epoch + TIMEZONE_DELTA;
+        let adjusted_localtime_epoc: u64 = localtime_epoch + SYSTEMTIME_TIMEZONE;
 
         let epoch: u64 = if t.timezone == r_efi::efi::UNSPECIFIED_TIMEZONE {
             adjusted_localtime_epoc
@@ -193,16 +211,24 @@ pub(crate) mod system_time_internal {
     ///
     /// The changes are to use 1900-01-01-00:00:00 with timezone -1440 as anchor instead of UNIX
     /// epoch used in the original algorithm.
-    pub(crate) const fn to_uefi(dur: &Duration, timezone: i16, daylight: u8) -> Option<Time> {
+    pub(crate) const fn to_uefi(dur: &Duration, timezone: i16, daylight: u8) -> Result<Time, i16> {
+        const MIN_IN_HOUR: u64 = 60;
+        const MIN_IN_DAY: u64 = MIN_IN_HOUR * 24;
+
         // Check timzone validity
         assert!(timezone <= 1440 && timezone >= -1440);
 
         // FIXME(#126043): use checked_sub_signed once stabilized
+        // This cannot fail for valid SystemTime due to SYSTEMTIME_TIMEZONE
         let secs =
             dur.as_secs().checked_add_signed((-timezone as i64) * SECS_IN_MINUTE as i64).unwrap();
 
         // Convert to seconds since 1900-01-01-00:00:00 in timezone.
-        let Some(secs) = secs.checked_sub(TIMEZONE_DELTA) else { return None };
+        let Some(secs) = secs.checked_sub(SYSTEMTIME_TIMEZONE) else {
+            let new_tz =
+                (secs / SECS_IN_MINUTE - if secs % SECS_IN_MINUTE == 0 { 0 } else { 1 }) as i16;
+            return Err(new_tz);
+        };
 
         let days = secs / SECS_IN_DAY;
         let remaining_secs = secs % SECS_IN_DAY;
@@ -225,9 +251,10 @@ pub(crate) mod system_time_internal {
         let minute = ((remaining_secs % SECS_IN_HOUR) / SECS_IN_MINUTE) as u8;
         let second = (remaining_secs % SECS_IN_MINUTE) as u8;
 
-        // Check Bounds
-        if y >= 1900 && y <= 9999 {
-            Some(Time {
+        // At this point, invalid time will be greater than MAX representable time. It cannot be less
+        // than minimum time since we already take care of that case above.
+        if y <= 9999 {
+            Ok(Time {
                 year: y as u16,
                 month: m as u8,
                 day: d as u8,
@@ -241,7 +268,17 @@ pub(crate) mod system_time_internal {
                 pad2: 0,
             })
         } else {
-            None
+            assert!(y == 10000);
+            assert!(m == 1);
+
+            let delta = ((d - 1) as u64 * MIN_IN_DAY
+                + hour as u64 * MIN_IN_HOUR
+                + minute as u64
+                + if second == 0 { 0 } else { 1 }) as i16;
+            let new_tz = timezone + delta;
+
+            assert!(new_tz <= 1440 && new_tz >= -1440);
+            Err(new_tz)
         }
     }
 }