std/sys/pal/unix/
time.rs

1use core::num::niche_types::Nanoseconds;
2
3use crate::time::Duration;
4use crate::{fmt, io};
5
6const NSEC_PER_SEC: u64 = 1_000_000_000;
7pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() };
8#[allow(dead_code)] // Used for pthread condvar timeouts
9pub const TIMESPEC_MAX: libc::timespec =
10    libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 };
11
12// This additional constant is only used when calling
13// `libc::pthread_cond_timedwait`.
14#[cfg(target_os = "nto")]
15pub(in crate::sys) const TIMESPEC_MAX_CAPPED: libc::timespec = libc::timespec {
16    tv_sec: (u64::MAX / NSEC_PER_SEC) as i64,
17    tv_nsec: (u64::MAX % NSEC_PER_SEC) as i64,
18};
19
20#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
21pub struct SystemTime {
22    pub(crate) t: Timespec,
23}
24
25#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
26pub(crate) struct Timespec {
27    tv_sec: i64,
28    tv_nsec: Nanoseconds,
29}
30
31impl SystemTime {
32    #[cfg_attr(any(target_os = "horizon", target_os = "hurd"), allow(unused))]
33    pub fn new(tv_sec: i64, tv_nsec: i64) -> Result<SystemTime, io::Error> {
34        Ok(SystemTime { t: Timespec::new(tv_sec, tv_nsec)? })
35    }
36
37    pub fn now() -> SystemTime {
38        SystemTime { t: Timespec::now(libc::CLOCK_REALTIME) }
39    }
40
41    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
42        self.t.sub_timespec(&other.t)
43    }
44
45    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
46        Some(SystemTime { t: self.t.checked_add_duration(other)? })
47    }
48
49    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
50        Some(SystemTime { t: self.t.checked_sub_duration(other)? })
51    }
52}
53
54impl fmt::Debug for SystemTime {
55    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
56        f.debug_struct("SystemTime")
57            .field("tv_sec", &self.t.tv_sec)
58            .field("tv_nsec", &self.t.tv_nsec)
59            .finish()
60    }
61}
62
63impl Timespec {
64    const unsafe fn new_unchecked(tv_sec: i64, tv_nsec: i64) -> Timespec {
65        Timespec { tv_sec, tv_nsec: unsafe { Nanoseconds::new_unchecked(tv_nsec as u32) } }
66    }
67
68    pub const fn zero() -> Timespec {
69        unsafe { Self::new_unchecked(0, 0) }
70    }
71
72    const fn new(tv_sec: i64, tv_nsec: i64) -> Result<Timespec, io::Error> {
73        // On Apple OS, dates before epoch are represented differently than on other
74        // Unix platforms: e.g. 1/10th of a second before epoch is represented as `seconds=-1`
75        // and `nanoseconds=100_000_000` on other platforms, but is `seconds=0` and
76        // `nanoseconds=-900_000_000` on Apple OS.
77        //
78        // To compensate, we first detect this special case by checking if both
79        // seconds and nanoseconds are in range, and then correct the value for seconds
80        // and nanoseconds to match the common unix representation.
81        //
82        // Please note that Apple OS nonetheless accepts the standard unix format when
83        // setting file times, which makes this compensation round-trippable and generally
84        // transparent.
85        #[cfg(target_vendor = "apple")]
86        let (tv_sec, tv_nsec) =
87            if (tv_sec <= 0 && tv_sec > i64::MIN) && (tv_nsec < 0 && tv_nsec > -1_000_000_000) {
88                (tv_sec - 1, tv_nsec + 1_000_000_000)
89            } else {
90                (tv_sec, tv_nsec)
91            };
92        if tv_nsec >= 0 && tv_nsec < NSEC_PER_SEC as i64 {
93            Ok(unsafe { Self::new_unchecked(tv_sec, tv_nsec) })
94        } else {
95            Err(io::const_error!(io::ErrorKind::InvalidData, "invalid timestamp"))
96        }
97    }
98
99    pub fn now(clock: libc::clockid_t) -> Timespec {
100        use crate::mem::MaybeUninit;
101        use crate::sys::cvt;
102
103        // Try to use 64-bit time in preparation for Y2038.
104        #[cfg(all(
105            target_os = "linux",
106            target_env = "gnu",
107            target_pointer_width = "32",
108            not(target_arch = "riscv32")
109        ))]
110        {
111            use crate::sys::weak::weak;
112
113            // __clock_gettime64 was added to 32-bit arches in glibc 2.34,
114            // and it handles both vDSO calls and ENOSYS fallbacks itself.
115            weak!(
116                fn __clock_gettime64(
117                    clockid: libc::clockid_t,
118                    tp: *mut __timespec64,
119                ) -> libc::c_int;
120            );
121
122            if let Some(clock_gettime64) = __clock_gettime64.get() {
123                let mut t = MaybeUninit::uninit();
124                cvt(unsafe { clock_gettime64(clock, t.as_mut_ptr()) }).unwrap();
125                let t = unsafe { t.assume_init() };
126                return Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap();
127            }
128        }
129
130        let mut t = MaybeUninit::uninit();
131        cvt(unsafe { libc::clock_gettime(clock, t.as_mut_ptr()) }).unwrap();
132        let t = unsafe { t.assume_init() };
133        Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap()
134    }
135
136    pub fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
137        // When a >= b, the difference fits in u64.
138        fn sub_ge_to_unsigned(a: i64, b: i64) -> u64 {
139            debug_assert!(a >= b);
140            a.wrapping_sub(b).cast_unsigned()
141        }
142
143        if self >= other {
144            let (secs, nsec) = if self.tv_nsec.as_inner() >= other.tv_nsec.as_inner() {
145                (
146                    sub_ge_to_unsigned(self.tv_sec, other.tv_sec),
147                    self.tv_nsec.as_inner() - other.tv_nsec.as_inner(),
148                )
149            } else {
150                // Following sequence of assertions explain why `self.tv_sec - 1` does not underflow.
151                debug_assert!(self.tv_nsec < other.tv_nsec);
152                debug_assert!(self.tv_sec > other.tv_sec);
153                debug_assert!(self.tv_sec > i64::MIN);
154                (
155                    sub_ge_to_unsigned(self.tv_sec - 1, other.tv_sec),
156                    self.tv_nsec.as_inner() + (NSEC_PER_SEC as u32) - other.tv_nsec.as_inner(),
157                )
158            };
159
160            Ok(Duration::new(secs, nsec))
161        } else {
162            match other.sub_timespec(self) {
163                Ok(d) => Err(d),
164                Err(d) => Ok(d),
165            }
166        }
167    }
168
169    pub fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
170        let mut secs = self.tv_sec.checked_add_unsigned(other.as_secs())?;
171
172        // Nano calculations can't overflow because nanos are <1B which fit
173        // in a u32.
174        let mut nsec = other.subsec_nanos() + self.tv_nsec.as_inner();
175        if nsec >= NSEC_PER_SEC as u32 {
176            nsec -= NSEC_PER_SEC as u32;
177            secs = secs.checked_add(1)?;
178        }
179        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
180    }
181
182    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
183        let mut secs = self.tv_sec.checked_sub_unsigned(other.as_secs())?;
184
185        // Similar to above, nanos can't overflow.
186        let mut nsec = self.tv_nsec.as_inner() as i32 - other.subsec_nanos() as i32;
187        if nsec < 0 {
188            nsec += NSEC_PER_SEC as i32;
189            secs = secs.checked_sub(1)?;
190        }
191        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
192    }
193
194    #[allow(dead_code)]
195    pub fn to_timespec(&self) -> Option<libc::timespec> {
196        Some(libc::timespec {
197            tv_sec: self.tv_sec.try_into().ok()?,
198            tv_nsec: self.tv_nsec.as_inner().try_into().ok()?,
199        })
200    }
201
202    // On QNX Neutrino, the maximum timespec for e.g. pthread_cond_timedwait
203    // is 2^64 nanoseconds
204    #[cfg(target_os = "nto")]
205    pub(in crate::sys) fn to_timespec_capped(&self) -> Option<libc::timespec> {
206        // Check if timeout in nanoseconds would fit into an u64
207        if (self.tv_nsec.as_inner() as u64)
208            .checked_add((self.tv_sec as u64).checked_mul(NSEC_PER_SEC)?)
209            .is_none()
210        {
211            return None;
212        }
213        self.to_timespec()
214    }
215
216    #[cfg(all(
217        target_os = "linux",
218        target_env = "gnu",
219        target_pointer_width = "32",
220        not(target_arch = "riscv32")
221    ))]
222    pub fn to_timespec64(&self) -> __timespec64 {
223        __timespec64::new(self.tv_sec, self.tv_nsec.as_inner() as _)
224    }
225}
226
227#[cfg(all(
228    target_os = "linux",
229    target_env = "gnu",
230    target_pointer_width = "32",
231    not(target_arch = "riscv32")
232))]
233#[repr(C)]
234pub(crate) struct __timespec64 {
235    pub(crate) tv_sec: i64,
236    #[cfg(target_endian = "big")]
237    _padding: i32,
238    pub(crate) tv_nsec: i32,
239    #[cfg(target_endian = "little")]
240    _padding: i32,
241}
242
243#[cfg(all(
244    target_os = "linux",
245    target_env = "gnu",
246    target_pointer_width = "32",
247    not(target_arch = "riscv32")
248))]
249impl __timespec64 {
250    pub(crate) fn new(tv_sec: i64, tv_nsec: i32) -> Self {
251        Self { tv_sec, tv_nsec, _padding: 0 }
252    }
253}
254
255#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
256pub struct Instant {
257    t: Timespec,
258}
259
260impl Instant {
261    #[cfg(target_vendor = "apple")]
262    pub(crate) const CLOCK_ID: libc::clockid_t = libc::CLOCK_UPTIME_RAW;
263    #[cfg(not(target_vendor = "apple"))]
264    pub(crate) const CLOCK_ID: libc::clockid_t = libc::CLOCK_MONOTONIC;
265    pub fn now() -> Instant {
266        // https://www.manpagez.com/man/3/clock_gettime/
267        //
268        // CLOCK_UPTIME_RAW   clock that increments monotonically, in the same man-
269        //                    ner as CLOCK_MONOTONIC_RAW, but that does not incre-
270        //                    ment while the system is asleep.  The returned value
271        //                    is identical to the result of mach_absolute_time()
272        //                    after the appropriate mach_timebase conversion is
273        //                    applied.
274        //
275        // Instant on macos was historically implemented using mach_absolute_time;
276        // we preserve this value domain out of an abundance of caution.
277        Instant { t: Timespec::now(Self::CLOCK_ID) }
278    }
279
280    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
281        self.t.sub_timespec(&other.t).ok()
282    }
283
284    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
285        Some(Instant { t: self.t.checked_add_duration(other)? })
286    }
287
288    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
289        Some(Instant { t: self.t.checked_sub_duration(other)? })
290    }
291
292    #[cfg_attr(
293        not(target_os = "linux"),
294        allow(unused, reason = "needed by the `sleep_until` on some unix platforms")
295    )]
296    pub(crate) fn into_timespec(self) -> Timespec {
297        self.t
298    }
299}
300
301impl fmt::Debug for Instant {
302    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
303        f.debug_struct("Instant")
304            .field("tv_sec", &self.t.tv_sec)
305            .field("tv_nsec", &self.t.tv_nsec)
306            .finish()
307    }
308}
std/sys/pal/unix/time.rs

std/sys/pal/unix/
time.rs
