1 files changed, 165 insertions, 0 deletions
diff --git a/library/std/src/sys/hermit/time.rs b/library/std/src/sys/hermit/time.rs
new file mode 100644
index 00000000000..c02de17c1fc
--- /dev/null
+++ b/library/std/src/sys/hermit/time.rs
@@ -0,0 +1,165 @@
+#![allow(dead_code)]
+
+use crate::cmp::Ordering;
+use crate::convert::TryInto;
+use crate::sys::hermit::abi;
+use crate::sys::hermit::abi::timespec;
+use crate::sys::hermit::abi::{CLOCK_MONOTONIC, CLOCK_REALTIME, NSEC_PER_SEC};
+use crate::time::Duration;
+use core::hash::{Hash, Hasher};
+
+#[derive(Copy, Clone, Debug)]
+struct Timespec {
+    t: timespec,
+}
+
+impl Timespec {
+    const fn zero() -> Timespec {
+        Timespec { t: timespec { tv_sec: 0, tv_nsec: 0 } }
+    }
+
+    fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
+        if self >= other {
+            Ok(if self.t.tv_nsec >= other.t.tv_nsec {
+                Duration::new(
+                    (self.t.tv_sec - other.t.tv_sec) as u64,
+                    (self.t.tv_nsec - other.t.tv_nsec) as u32,
+                )
+            } else {
+                Duration::new(
+                    (self.t.tv_sec - 1 - other.t.tv_sec) as u64,
+                    self.t.tv_nsec as u32 + (NSEC_PER_SEC as u32) - other.t.tv_nsec as u32,
+                )
+            })
+        } else {
+            match other.sub_timespec(self) {
+                Ok(d) => Err(d),
+                Err(d) => Ok(d),
+            }
+        }
+    }
+
+    fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
+        let mut secs = other
+            .as_secs()
+            .try_into() // <- target type would be `libc::time_t`
+            .ok()
+            .and_then(|secs| self.t.tv_sec.checked_add(secs))?;
+
+        // Nano calculations can't overflow because nanos are <1B which fit
+        // in a u32.
+        let mut nsec = other.subsec_nanos() + self.t.tv_nsec as u32;
+        if nsec >= NSEC_PER_SEC as u32 {
+            nsec -= NSEC_PER_SEC as u32;
+            secs = secs.checked_add(1)?;
+        }
+        Some(Timespec { t: timespec { tv_sec: secs, tv_nsec: nsec as _ } })
+    }
+
+    fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
+        let mut secs = other
+            .as_secs()
+            .try_into() // <- target type would be `libc::time_t`
+            .ok()
+            .and_then(|secs| self.t.tv_sec.checked_sub(secs))?;
+
+        // Similar to above, nanos can't overflow.
+        let mut nsec = self.t.tv_nsec as i32 - other.subsec_nanos() as i32;
+        if nsec < 0 {
+            nsec += NSEC_PER_SEC as i32;
+            secs = secs.checked_sub(1)?;
+        }
+        Some(Timespec { t: timespec { tv_sec: secs, tv_nsec: nsec as _ } })
+    }
+}
+
+impl PartialEq for Timespec {
+    fn eq(&self, other: &Timespec) -> bool {
+        self.t.tv_sec == other.t.tv_sec && self.t.tv_nsec == other.t.tv_nsec
+    }
+}
+
+impl Eq for Timespec {}
+
+impl PartialOrd for Timespec {
+    fn partial_cmp(&self, other: &Timespec) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Timespec {
+    fn cmp(&self, other: &Timespec) -> Ordering {
+        let me = (self.t.tv_sec, self.t.tv_nsec);
+        let other = (other.t.tv_sec, other.t.tv_nsec);
+        me.cmp(&other)
+    }
+}
+
+impl Hash for Timespec {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.t.tv_sec.hash(state);
+        self.t.tv_nsec.hash(state);
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
+pub struct Instant {
+    t: Timespec,
+}
+
+impl Instant {
+    pub fn now() -> Instant {
+        let mut time: Timespec = Timespec::zero();
+        let _ = unsafe { abi::clock_gettime(CLOCK_MONOTONIC, &mut time.t as *mut timespec) };
+
+        Instant { t: time }
+    }
+
+    pub const fn zero() -> Instant {
+        Instant { t: Timespec::zero() }
+    }
+
+    pub fn actually_monotonic() -> bool {
+        true
+    }
+
+    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
+        self.t.sub_timespec(&other.t).ok()
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
+        Some(Instant { t: self.t.checked_add_duration(other)? })
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
+        Some(Instant { t: self.t.checked_sub_duration(other)? })
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub struct SystemTime {
+    t: Timespec,
+}
+
+pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() };
+
+impl SystemTime {
+    pub fn now() -> SystemTime {
+        let mut time: Timespec = Timespec::zero();
+        let _ = unsafe { abi::clock_gettime(CLOCK_REALTIME, &mut time.t as *mut timespec) };
+
+        SystemTime { t: time }
+    }
+
+    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
+        self.t.sub_timespec(&other.t)
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
+        Some(SystemTime { t: self.t.checked_add_duration(other)? })
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
+        Some(SystemTime { t: self.t.checked_sub_duration(other)? })
+    }
+}