library/std/src/sys/pal/unix/time.rs - toolchain/rustc - Git at Google

 use crate::time::Duration;
 use crate::{fmt, io};

 const NSEC_PER_SEC: u64 = 1_000_000_000;
 pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() };
 #[allow(dead_code)] // Used for pthread condvar timeouts
 pub const TIMESPEC_MAX: libc::timespec =
     libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 };

 // This additional constant is only used when calling
 // `libc::pthread_cond_timedwait`.
 #[cfg(target_os = "nto")]
 pub(in crate::sys) const TIMESPEC_MAX_CAPPED: libc::timespec = libc::timespec {
     tv_sec: (u64::MAX / NSEC_PER_SEC) as i64,
     tv_nsec: (u64::MAX % NSEC_PER_SEC) as i64,
 };

 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 #[repr(transparent)]
 #[rustc_layout_scalar_valid_range_start(0)]
 #[rustc_layout_scalar_valid_range_end(999_999_999)]
 struct Nanoseconds(u32);

 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct SystemTime {
     pub(crate) t: Timespec,
 }

 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub(crate) struct Timespec {
     tv_sec: i64,
     tv_nsec: Nanoseconds,
 }

 impl SystemTime {
     #[cfg_attr(any(target_os = "horizon", target_os = "hurd"), allow(unused))]
     pub fn new(tv_sec: i64, tv_nsec: i64) -> Result<SystemTime, io::Error> {
         Ok(SystemTime { t: Timespec::new(tv_sec, tv_nsec)? })
     }

     pub fn now() -> SystemTime {
         SystemTime { t: Timespec::now(libc::CLOCK_REALTIME) }
     }

     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)? })
     }
 }

 impl fmt::Debug for SystemTime {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("SystemTime")
             .field("tv_sec", &self.t.tv_sec)
             .field("tv_nsec", &self.t.tv_nsec.0)
             .finish()
     }
 }

 impl Timespec {
     const unsafe fn new_unchecked(tv_sec: i64, tv_nsec: i64) -> Timespec {
         Timespec { tv_sec, tv_nsec: unsafe { Nanoseconds(tv_nsec as u32) } }
     }

     pub const fn zero() -> Timespec {
         unsafe { Self::new_unchecked(0, 0) }
     }

     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(any(
             target_os = "macos",
             target_os = "ios",
             target_os = "tvos",
             target_os = "watchos"
         ))]
         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_io_error!(io::ErrorKind::InvalidData, "Invalid timestamp"))
         }
     }

     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::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(libc::clockid_t, *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> {
         if self >= other {
             // NOTE(eddyb) two aspects of this `if`-`else` are required for LLVM
             // to optimize it into a branchless form (see also #75545):
             //
             // 1. `self.tv_sec - other.tv_sec` shows up as a common expression
             //    in both branches, i.e. the `else` must have its `- 1`
             //    subtraction after the common one, not interleaved with it
             //    (it used to be `self.tv_sec - 1 - other.tv_sec`)
             //
             // 2. the `Duration::new` call (or any other additional complexity)
             //    is outside of the `if`-`else`, not duplicated in both branches
             //
             // Ideally this code could be rearranged such that it more
             // directly expresses the lower-cost behavior we want from it.
             let (secs, nsec) = if self.tv_nsec.0 >= other.tv_nsec.0 {
                 ((self.tv_sec - other.tv_sec) as u64, self.tv_nsec.0 - other.tv_nsec.0)
             } else {
                 (
                     (self.tv_sec - other.tv_sec - 1) as u64,
                     self.tv_nsec.0 + (NSEC_PER_SEC as u32) - other.tv_nsec.0,
                 )
             };

             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.0;
         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.0 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)]
     pub fn to_timespec(&self) -> Option<libc::timespec> {
         Some(libc::timespec {
             tv_sec: self.tv_sec.try_into().ok()?,
             tv_nsec: self.tv_nsec.0.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.0 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) -> __timespec64 {
         __timespec64::new(self.tv_sec, self.tv_nsec.0 as _)
     }
 }

 #[cfg(all(
     target_os = "linux",
     target_env = "gnu",
     target_pointer_width = "32",
     not(target_arch = "riscv32")
 ))]
 #[repr(C)]
 pub(crate) struct __timespec64 {
     pub(crate) tv_sec: i64,
     #[cfg(target_endian = "big")]
     _padding: i32,
     pub(crate) tv_nsec: i32,
     #[cfg(target_endian = "little")]
     _padding: i32,
 }

 #[cfg(all(
     target_os = "linux",
     target_env = "gnu",
     target_pointer_width = "32",
     not(target_arch = "riscv32")
 ))]
 impl __timespec64 {
     pub(crate) fn new(tv_sec: i64, tv_nsec: i32) -> Self {
         Self { tv_sec, tv_nsec, _padding: 0 }
     }
 }

 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Instant {
     t: Timespec,
 }

 impl Instant {
     pub fn now() -> Instant {
         // https://www.manpagez.com/man/3/clock_gettime/
         //
         // CLOCK_UPTIME_RAW   clock that increments monotonically, in the same man-
         //                    ner as CLOCK_MONOTONIC_RAW, but that does not incre-
         //                    ment while the system is asleep.  The returned value
         //                    is identical to the result of mach_absolute_time()
         //                    after the appropriate mach_timebase conversion is
         //                    applied.
         //
         // Instant on macos was historically implemented using mach_absolute_time;
         // we preserve this value domain out of an abundance of caution.
         #[cfg(any(
             target_os = "macos",
             target_os = "ios",
             target_os = "watchos",
             target_os = "tvos"
         ))]
         const clock_id: libc::clockid_t = libc::CLOCK_UPTIME_RAW;
         #[cfg(not(any(
             target_os = "macos",
             target_os = "ios",
             target_os = "watchos",
             target_os = "tvos"
         )))]
         const clock_id: libc::clockid_t = libc::CLOCK_MONOTONIC;
         Instant { t: Timespec::now(clock_id) }
     }

     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)? })
     }
 }

 impl fmt::Debug for Instant {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("Instant")
             .field("tv_sec", &self.t.tv_sec)
             .field("tv_nsec", &self.t.tv_nsec.0)
             .finish()
     }
 }
	use crate::time::Duration;
	use crate::{fmt, io};

	const NSEC_PER_SEC: u64 = 1_000_000_000;
	pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() };
	#[allow(dead_code)] // Used for pthread condvar timeouts
	pub const TIMESPEC_MAX: libc::timespec =
	libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 };

	// This additional constant is only used when calling
	// `libc::pthread_cond_timedwait`.
	#[cfg(target_os = "nto")]
	pub(in crate::sys) const TIMESPEC_MAX_CAPPED: libc::timespec = libc::timespec {
	tv_sec: (u64::MAX / NSEC_PER_SEC) as i64,
	tv_nsec: (u64::MAX % NSEC_PER_SEC) as i64,
	};

	#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
	#[repr(transparent)]
	#[rustc_layout_scalar_valid_range_start(0)]
	#[rustc_layout_scalar_valid_range_end(999_999_999)]
	struct Nanoseconds(u32);

	#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
	pub struct SystemTime {
	pub(crate) t: Timespec,
	}

	#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
	pub(crate) struct Timespec {
	tv_sec: i64,
	tv_nsec: Nanoseconds,
	}

	impl SystemTime {
	#[cfg_attr(any(target_os = "horizon", target_os = "hurd"), allow(unused))]
	pub fn new(tv_sec: i64, tv_nsec: i64) -> Result<SystemTime, io::Error> {
	Ok(SystemTime { t: Timespec::new(tv_sec, tv_nsec)? })
	}

	pub fn now() -> SystemTime {
	SystemTime { t: Timespec::now(libc::CLOCK_REALTIME) }
	}

	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)? })
	}
	}

	impl fmt::Debug for SystemTime {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	f.debug_struct("SystemTime")
	.field("tv_sec", &self.t.tv_sec)
	.field("tv_nsec", &self.t.tv_nsec.0)
	.finish()
	}
	}

	impl Timespec {
	const unsafe fn new_unchecked(tv_sec: i64, tv_nsec: i64) -> Timespec {
	Timespec { tv_sec, tv_nsec: unsafe { Nanoseconds(tv_nsec as u32) } }
	}

	pub const fn zero() -> Timespec {
	unsafe { Self::new_unchecked(0, 0) }
	}

	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(any(
	target_os = "macos",
	target_os = "ios",
	target_os = "tvos",
	target_os = "watchos"
	))]
	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_io_error!(io::ErrorKind::InvalidData, "Invalid timestamp"))
	}
	}

	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::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(libc::clockid_t, *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> {
	if self >= other {
	// NOTE(eddyb) two aspects of this `if`-`else` are required for LLVM
	// to optimize it into a branchless form (see also #75545):
	//
	// 1. `self.tv_sec - other.tv_sec` shows up as a common expression
	// in both branches, i.e. the `else` must have its `- 1`
	// subtraction after the common one, not interleaved with it
	// (it used to be `self.tv_sec - 1 - other.tv_sec`)
	//
	// 2. the `Duration::new` call (or any other additional complexity)
	// is outside of the `if`-`else`, not duplicated in both branches
	//
	// Ideally this code could be rearranged such that it more
	// directly expresses the lower-cost behavior we want from it.
	let (secs, nsec) = if self.tv_nsec.0 >= other.tv_nsec.0 {
	((self.tv_sec - other.tv_sec) as u64, self.tv_nsec.0 - other.tv_nsec.0)
	} else {
	(
	(self.tv_sec - other.tv_sec - 1) as u64,
	self.tv_nsec.0 + (NSEC_PER_SEC as u32) - other.tv_nsec.0,
	)
	};

	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.0;
	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.0 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)]
	pub fn to_timespec(&self) -> Option<libc::timespec> {
	Some(libc::timespec {
	tv_sec: self.tv_sec.try_into().ok()?,
	tv_nsec: self.tv_nsec.0.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.0 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) -> __timespec64 {
	__timespec64::new(self.tv_sec, self.tv_nsec.0 as _)
	}
	}

	#[cfg(all(
	target_os = "linux",
	target_env = "gnu",
	target_pointer_width = "32",
	not(target_arch = "riscv32")
	))]
	#[repr(C)]
	pub(crate) struct __timespec64 {
	pub(crate) tv_sec: i64,
	#[cfg(target_endian = "big")]
	_padding: i32,
	pub(crate) tv_nsec: i32,
	#[cfg(target_endian = "little")]
	_padding: i32,
	}

	#[cfg(all(
	target_os = "linux",
	target_env = "gnu",
	target_pointer_width = "32",
	not(target_arch = "riscv32")
	))]
	impl __timespec64 {
	pub(crate) fn new(tv_sec: i64, tv_nsec: i32) -> Self {
	Self { tv_sec, tv_nsec, _padding: 0 }
	}
	}

	#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
	pub struct Instant {
	t: Timespec,
	}

	impl Instant {
	pub fn now() -> Instant {
	// https://www.manpagez.com/man/3/clock_gettime/
	//
	// CLOCK_UPTIME_RAW clock that increments monotonically, in the same man-
	// ner as CLOCK_MONOTONIC_RAW, but that does not incre-
	// ment while the system is asleep. The returned value
	// is identical to the result of mach_absolute_time()
	// after the appropriate mach_timebase conversion is
	// applied.
	//
	// Instant on macos was historically implemented using mach_absolute_time;
	// we preserve this value domain out of an abundance of caution.
	#[cfg(any(
	target_os = "macos",
	target_os = "ios",
	target_os = "watchos",
	target_os = "tvos"
	))]
	const clock_id: libc::clockid_t = libc::CLOCK_UPTIME_RAW;
	#[cfg(not(any(
	target_os = "macos",
	target_os = "ios",
	target_os = "watchos",
	target_os = "tvos"
	)))]
	const clock_id: libc::clockid_t = libc::CLOCK_MONOTONIC;
	Instant { t: Timespec::now(clock_id) }
	}

	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)? })
	}
	}

	impl fmt::Debug for Instant {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	f.debug_struct("Instant")
	.field("tv_sec", &self.t.tv_sec)
	.field("tv_nsec", &self.t.tv_nsec.0)
	.finish()
	}
	}