Share Timespec between Unix and Hermit

library/std/src/sys/pal/common/mod.rs

@@ -11,6 +11,7 @@
 #![allow(dead_code)]
 
 pub mod small_c_string;
+pub(crate) mod timespec;
 
 #[cfg(test)]
 mod tests;

library/std/src/sys/pal/common/timespec.rs

@@ -0,0 +1,179 @@
+use core::num::niche_types::Nanoseconds;
+
+use crate::io;
+use crate::time::Duration;
+
+const NSEC_PER_SEC: u64 = 1_000_000_000;
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub(crate) struct Timespec {
+    pub(crate) tv_sec: i64,
+    pub(crate) tv_nsec: Nanoseconds,
+}
+
+impl Timespec {
+    const unsafe fn new_unchecked(tv_sec: i64, tv_nsec: i64) -> Timespec {
+        Timespec { tv_sec, tv_nsec: unsafe { Nanoseconds::new_unchecked(tv_nsec as u32) } }
+    }
+
+    pub const fn zero() -> Timespec {
+        unsafe { Self::new_unchecked(0, 0) }
+    }
+
+    pub(crate) const fn new(tv_sec: i64, tv_nsec: i64) -> Result<Timespec, io::Error> {
+        // On Apple OS, dates before epoch are represented differently than on other
+        // Unix platforms: e.g. 1/10th of a second before epoch is represented as `seconds=-1`
+        // and `nanoseconds=100_000_000` on other platforms, but is `seconds=0` and
+        // `nanoseconds=-900_000_000` on Apple OS.
+        //
+        // To compensate, we first detect this special case by checking if both
+        // seconds and nanoseconds are in range, and then correct the value for seconds
+        // and nanoseconds to match the common unix representation.
+        //
+        // Please note that Apple OS nonetheless accepts the standard unix format when
+        // setting file times, which makes this compensation round-trippable and generally
+        // transparent.
+        #[cfg(target_vendor = "apple")]
+        let (tv_sec, tv_nsec) =
+            if (tv_sec <= 0 && tv_sec > i64::MIN) && (tv_nsec < 0 && tv_nsec > -1_000_000_000) {
+                (tv_sec - 1, tv_nsec + 1_000_000_000)
+            } else {
+                (tv_sec, tv_nsec)
+            };
+        if tv_nsec >= 0 && tv_nsec < NSEC_PER_SEC as i64 {
+            Ok(unsafe { Self::new_unchecked(tv_sec, tv_nsec) })
+        } else {
+            Err(io::const_error!(io::ErrorKind::InvalidData, "invalid timestamp"))
+        }
+    }
+
+    #[cfg(unix)]
+    pub fn now(clock: libc::clockid_t) -> Timespec {
+        use crate::mem::MaybeUninit;
+        use crate::sys::cvt;
+
+        // Try to use 64-bit time in preparation for Y2038.
+        #[cfg(all(
+            target_os = "linux",
+            target_env = "gnu",
+            target_pointer_width = "32",
+            not(target_arch = "riscv32")
+        ))]
+        {
+            use crate::sys::time::__timespec64;
+            use crate::sys::weak::weak;
+
+            // __clock_gettime64 was added to 32-bit arches in glibc 2.34,
+            // and it handles both vDSO calls and ENOSYS fallbacks itself.
+            weak!(
+                fn __clock_gettime64(
+                    clockid: libc::clockid_t,
+                    tp: *mut __timespec64,
+                ) -> libc::c_int;
+            );
+
+            if let Some(clock_gettime64) = __clock_gettime64.get() {
+                let mut t = MaybeUninit::uninit();
+                cvt(unsafe { clock_gettime64(clock, t.as_mut_ptr()) }).unwrap();
+                let t = unsafe { t.assume_init() };
+                return Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap();
+            }
+        }
+
+        let mut t = MaybeUninit::uninit();
+        cvt(unsafe { libc::clock_gettime(clock, t.as_mut_ptr()) }).unwrap();
+        let t = unsafe { t.assume_init() };
+        Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap()
+    }
+
+    pub fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
+        // When a >= b, the difference fits in u64.
+        fn sub_ge_to_unsigned(a: i64, b: i64) -> u64 {
+            debug_assert!(a >= b);
+            a.wrapping_sub(b).cast_unsigned()
+        }
+
+        if self >= other {
+            let (secs, nsec) = if self.tv_nsec.as_inner() >= other.tv_nsec.as_inner() {
+                (
+                    sub_ge_to_unsigned(self.tv_sec, other.tv_sec),
+                    self.tv_nsec.as_inner() - other.tv_nsec.as_inner(),
+                )
+            } else {
+                // Following sequence of assertions explain why `self.tv_sec - 1` does not underflow.
+                debug_assert!(self.tv_nsec < other.tv_nsec);
+                debug_assert!(self.tv_sec > other.tv_sec);
+                debug_assert!(self.tv_sec > i64::MIN);
+                (
+                    sub_ge_to_unsigned(self.tv_sec - 1, other.tv_sec),
+                    self.tv_nsec.as_inner() + (NSEC_PER_SEC as u32) - other.tv_nsec.as_inner(),
+                )
+            };
+
+            Ok(Duration::new(secs, nsec))
+        } else {
+            match other.sub_timespec(self) {
+                Ok(d) => Err(d),
+                Err(d) => Ok(d),
+            }
+        }
+    }
+
+    pub fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
+        let mut secs = self.tv_sec.checked_add_unsigned(other.as_secs())?;
+
+        // Nano calculations can't overflow because nanos are <1B which fit
+        // in a u32.
+        let mut nsec = other.subsec_nanos() + self.tv_nsec.as_inner();
+        if nsec >= NSEC_PER_SEC as u32 {
+            nsec -= NSEC_PER_SEC as u32;
+            secs = secs.checked_add(1)?;
+        }
+        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
+    }
+
+    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
+        let mut secs = self.tv_sec.checked_sub_unsigned(other.as_secs())?;
+
+        // Similar to above, nanos can't overflow.
+        let mut nsec = self.tv_nsec.as_inner() as i32 - other.subsec_nanos() as i32;
+        if nsec < 0 {
+            nsec += NSEC_PER_SEC as i32;
+            secs = secs.checked_sub(1)?;
+        }
+        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
+    }
+
+    #[allow(dead_code)]
+    #[cfg(unix)]
+    pub fn to_timespec(&self) -> Option<libc::timespec> {
+        Some(libc::timespec {
+            tv_sec: self.tv_sec.try_into().ok()?,
+            tv_nsec: self.tv_nsec.as_inner().try_into().ok()?,
+        })
+    }
+
+    // On QNX Neutrino, the maximum timespec for e.g. pthread_cond_timedwait
+    // is 2^64 nanoseconds
+    #[cfg(target_os = "nto")]
+    pub(in crate::sys) fn to_timespec_capped(&self) -> Option<libc::timespec> {
+        // Check if timeout in nanoseconds would fit into an u64
+        if (self.tv_nsec.as_inner() as u64)
+            .checked_add((self.tv_sec as u64).checked_mul(NSEC_PER_SEC)?)
+            .is_none()
+        {
+            return None;
+        }
+        self.to_timespec()
+    }
+
+    #[cfg(all(
+        target_os = "linux",
+        target_env = "gnu",
+        target_pointer_width = "32",
+        not(target_arch = "riscv32")
+    ))]
+    pub fn to_timespec64(&self) -> crate::sys::time::__timespec64 {
+        crate::sys::time::__timespec64::new(self.tv_sec, self.tv_nsec.as_inner() as _)
+    }
+}

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

@@ -1,122 +1,23 @@
 #![allow(dead_code)]
 
-use core::hash::{Hash, Hasher};
+use core::hash::Hash;
 
 use super::hermit_abi::{self, CLOCK_MONOTONIC, CLOCK_REALTIME, timespec};
-use crate::cmp::Ordering;
 use crate::ops::{Add, AddAssign, Sub, SubAssign};
+use crate::sys::common::timespec::Timespec;
 use crate::time::Duration;
 
 const NSEC_PER_SEC: i32 = 1_000_000_000;
 
-#[derive(Copy, Clone, Debug)]
-struct Timespec {
-    t: timespec,
-}
-
-impl Timespec {
-    const fn zero() -> Timespec {
-        Timespec { t: timespec { tv_sec: 0, tv_nsec: 0 } }
-    }
-
-    const fn new(tv_sec: i64, tv_nsec: i32) -> Timespec {
-        assert!(tv_nsec >= 0 && tv_nsec < NSEC_PER_SEC);
-        // SAFETY: The assert above checks tv_nsec is within the valid range
-        Timespec { t: timespec { tv_sec, tv_nsec } }
-    }
-
-    fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
-        fn sub_ge_to_unsigned(a: i64, b: i64) -> u64 {
-            debug_assert!(a >= b);
-            a.wrapping_sub(b).cast_unsigned()
-        }
-
-        if self >= other {
-            // Logic here is identical to Unix version of `Timestamp::sub_timespec`,
-            // check comments there why operations do not overflow.
-            Ok(if self.t.tv_nsec >= other.t.tv_nsec {
-                Duration::new(
-                    sub_ge_to_unsigned(self.t.tv_sec, other.t.tv_sec),
-                    (self.t.tv_nsec - other.t.tv_nsec) as u32,
-                )
-            } else {
-                Duration::new(
-                    sub_ge_to_unsigned(self.t.tv_sec - 1, other.t.tv_sec),
-                    (self.t.tv_nsec + NSEC_PER_SEC - 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 = self.t.tv_sec.checked_add_unsigned(other.as_secs())?;
-
-        // Nano calculations can't overflow because nanos are <1B which fit
-        // in a u32.
-        let mut nsec = other.subsec_nanos() + u32::try_from(self.t.tv_nsec).unwrap();
-        if nsec >= NSEC_PER_SEC.try_into().unwrap() {
-            nsec -= u32::try_from(NSEC_PER_SEC).unwrap();
-            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 = self.t.tv_sec.checked_sub_unsigned(other.as_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(Timespec);
 
 impl Instant {
     pub fn now() -> Instant {
-        let mut time: Timespec = Timespec::zero();
-        let _ = unsafe { hermit_abi::clock_gettime(CLOCK_MONOTONIC, &raw mut time.t) };
+        let mut time: timespec = timespec { tv_sec: 0, tv_nsec: 0 };
+        let _ = unsafe { hermit_abi::clock_gettime(CLOCK_MONOTONIC, &raw mut time) };
 
-        Instant(time)
+        Instant(Timespec::new(time.tv_sec, time.tv_nsec as i64).unwrap())
     }
 
     #[stable(feature = "time2", since = "1.8.0")]
@@ -210,14 +111,13 @@ pub const UNIX_EPOCH: SystemTime = SystemTime(Timespec::zero());
 
 impl SystemTime {
     pub fn new(tv_sec: i64, tv_nsec: i32) -> SystemTime {
-        SystemTime(Timespec::new(tv_sec, tv_nsec))
+        SystemTime(Timespec::new(tv_sec, tv_nsec as i64).unwrap())
     }
 
     pub fn now() -> SystemTime {
-        let mut time: Timespec = Timespec::zero();
-        let _ = unsafe { hermit_abi::clock_gettime(CLOCK_REALTIME, &raw mut time.t) };
-
-        SystemTime(time)
+        let mut time: timespec = timespec { tv_sec: 0, tv_nsec: 0 };
+        let _ = unsafe { hermit_abi::clock_gettime(CLOCK_REALTIME, &raw mut time) };
+        SystemTime::new(time.tv_sec, time.tv_nsec)
     }
 
     pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {

library/std/src/sys/pal/unix/futex.rs

@@ -28,9 +28,9 @@ pub type SmallPrimitive = u32;
 /// Returns false on timeout, and true in all other cases.
 #[cfg(any(target_os = "linux", target_os = "android", target_os = "freebsd"))]
 pub fn futex_wait(futex: &Atomic<u32>, expected: u32, timeout: Option<Duration>) -> bool {
-    use super::time::Timespec;
     use crate::ptr::null;
     use crate::sync::atomic::Ordering::Relaxed;
+    use crate::sys::common::timespec::Timespec;
 
     // Calculate the timeout as an absolute timespec.
     //