std/sys/pal/unix/
time.rs

1use core::num::niche_types::Nanoseconds;
2
3use crate::sys_common::AsInner;
4use crate::time::Duration;
5use crate::{fmt, io};
6
7const NSEC_PER_SEC: u64 = 1_000_000_000;
8pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() };
9#[allow(dead_code)] // Used for pthread condvar timeouts
10pub const TIMESPEC_MAX: libc::timespec =
11    libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 };
12
13// This additional constant is only used when calling
14// `libc::pthread_cond_timedwait`.
15#[cfg(target_os = "nto")]
16pub(in crate::sys) const TIMESPEC_MAX_CAPPED: libc::timespec = libc::timespec {
17    tv_sec: (u64::MAX / NSEC_PER_SEC) as i64,
18    tv_nsec: (u64::MAX % NSEC_PER_SEC) as i64,
19};
20
21#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
22pub struct SystemTime {
23    pub(crate) t: Timespec,
24}
25
26#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
27pub(crate) struct Timespec {
28    tv_sec: i64,
29    tv_nsec: Nanoseconds,
30}
31
32impl SystemTime {
33    #[cfg_attr(any(target_os = "horizon", target_os = "hurd"), allow(unused))]
34    pub fn new(tv_sec: i64, tv_nsec: i64) -> Result<SystemTime, io::Error> {
35        Ok(SystemTime { t: Timespec::new(tv_sec, tv_nsec)? })
36    }
37
38    pub fn now() -> SystemTime {
39        SystemTime { t: Timespec::now(libc::CLOCK_REALTIME) }
40    }
41
42    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
43        self.t.sub_timespec(&other.t)
44    }
45
46    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
47        Some(SystemTime { t: self.t.checked_add_duration(other)? })
48    }
49
50    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
51        Some(SystemTime { t: self.t.checked_sub_duration(other)? })
52    }
53}
54
55impl fmt::Debug for SystemTime {
56    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
57        f.debug_struct("SystemTime")
58            .field("tv_sec", &self.t.tv_sec)
59            .field("tv_nsec", &self.t.tv_nsec)
60            .finish()
61    }
62}
63
64impl Timespec {
65    const unsafe fn new_unchecked(tv_sec: i64, tv_nsec: i64) -> Timespec {
66        Timespec { tv_sec, tv_nsec: unsafe { Nanoseconds::new_unchecked(tv_nsec as u32) } }
67    }
68
69    pub const fn zero() -> Timespec {
70        unsafe { Self::new_unchecked(0, 0) }
71    }
72
73    const fn new(tv_sec: i64, tv_nsec: i64) -> Result<Timespec, io::Error> {
74        // On Apple OS, dates before epoch are represented differently than on other
75        // Unix platforms: e.g. 1/10th of a second before epoch is represented as `seconds=-1`
76        // and `nanoseconds=100_000_000` on other platforms, but is `seconds=0` and
77        // `nanoseconds=-900_000_000` on Apple OS.
78        //
79        // To compensate, we first detect this special case by checking if both
80        // seconds and nanoseconds are in range, and then correct the value for seconds
81        // and nanoseconds to match the common unix representation.
82        //
83        // Please note that Apple OS nonetheless accepts the standard unix format when
84        // setting file times, which makes this compensation round-trippable and generally
85        // transparent.
86        #[cfg(target_vendor = "apple")]
87        let (tv_sec, tv_nsec) =
88            if (tv_sec <= 0 && tv_sec > i64::MIN) && (tv_nsec < 0 && tv_nsec > -1_000_000_000) {
89                (tv_sec - 1, tv_nsec + 1_000_000_000)
90            } else {
91                (tv_sec, tv_nsec)
92            };
93        if tv_nsec >= 0 && tv_nsec < NSEC_PER_SEC as i64 {
94            Ok(unsafe { Self::new_unchecked(tv_sec, tv_nsec) })
95        } else {
96            Err(io::const_error!(io::ErrorKind::InvalidData, "invalid timestamp"))
97        }
98    }
99
100    pub fn now(clock: libc::clockid_t) -> Timespec {
101        use crate::mem::MaybeUninit;
102        use crate::sys::cvt;
103
104        // Try to use 64-bit time in preparation for Y2038.
105        #[cfg(all(
106            target_os = "linux",
107            target_env = "gnu",
108            target_pointer_width = "32",
109            not(target_arch = "riscv32")
110        ))]
111        {
112            use crate::sys::weak::weak;
113
114            // __clock_gettime64 was added to 32-bit arches in glibc 2.34,
115            // and it handles both vDSO calls and ENOSYS fallbacks itself.
116            weak!(
117                fn __clock_gettime64(
118                    clockid: libc::clockid_t,
119                    tp: *mut __timespec64,
120                ) -> libc::c_int;
121            );
122
123            if let Some(clock_gettime64) = __clock_gettime64.get() {
124                let mut t = MaybeUninit::uninit();
125                cvt(unsafe { clock_gettime64(clock, t.as_mut_ptr()) }).unwrap();
126                let t = unsafe { t.assume_init() };
127                return Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap();
128            }
129        }
130
131        let mut t = MaybeUninit::uninit();
132        cvt(unsafe { libc::clock_gettime(clock, t.as_mut_ptr()) }).unwrap();
133        let t = unsafe { t.assume_init() };
134        Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap()
135    }
136
137    pub fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
138        // When a >= b, the difference fits in u64.
139        fn sub_ge_to_unsigned(a: i64, b: i64) -> u64 {
140            debug_assert!(a >= b);
141            a.wrapping_sub(b).cast_unsigned()
142        }
143
144        if self >= other {
145            let (secs, nsec) = if self.tv_nsec.as_inner() >= other.tv_nsec.as_inner() {
146                (
147                    sub_ge_to_unsigned(self.tv_sec, other.tv_sec),
148                    self.tv_nsec.as_inner() - other.tv_nsec.as_inner(),
149                )
150            } else {
151                // Following sequence of assertions explain why `self.tv_sec - 1` does not underflow.
152                debug_assert!(self.tv_nsec < other.tv_nsec);
153                debug_assert!(self.tv_sec > other.tv_sec);
154                debug_assert!(self.tv_sec > i64::MIN);
155                (
156                    sub_ge_to_unsigned(self.tv_sec - 1, other.tv_sec),
157                    self.tv_nsec.as_inner() + (NSEC_PER_SEC as u32) - other.tv_nsec.as_inner(),
158                )
159            };
160
161            Ok(Duration::new(secs, nsec))
162        } else {
163            match other.sub_timespec(self) {
164                Ok(d) => Err(d),
165                Err(d) => Ok(d),
166            }
167        }
168    }
169
170    pub fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
171        let mut secs = self.tv_sec.checked_add_unsigned(other.as_secs())?;
172
173        // Nano calculations can't overflow because nanos are <1B which fit
174        // in a u32.
175        let mut nsec = other.subsec_nanos() + self.tv_nsec.as_inner();
176        if nsec >= NSEC_PER_SEC as u32 {
177            nsec -= NSEC_PER_SEC as u32;
178            secs = secs.checked_add(1)?;
179        }
180        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
181    }
182
183    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
184        let mut secs = self.tv_sec.checked_sub_unsigned(other.as_secs())?;
185
186        // Similar to above, nanos can't overflow.
187        let mut nsec = self.tv_nsec.as_inner() as i32 - other.subsec_nanos() as i32;
188        if nsec < 0 {
189            nsec += NSEC_PER_SEC as i32;
190            secs = secs.checked_sub(1)?;
191        }
192        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
193    }
194
195    #[allow(dead_code)]
196    pub fn to_timespec(&self) -> Option<libc::timespec> {
197        Some(libc::timespec {
198            tv_sec: self.tv_sec.try_into().ok()?,
199            tv_nsec: self.tv_nsec.as_inner().try_into().ok()?,
200        })
201    }
202
203    // On QNX Neutrino, the maximum timespec for e.g. pthread_cond_timedwait
204    // is 2^64 nanoseconds
205    #[cfg(target_os = "nto")]
206    pub(in crate::sys) fn to_timespec_capped(&self) -> Option<libc::timespec> {
207        // Check if timeout in nanoseconds would fit into an u64
208        if (self.tv_nsec.as_inner() as u64)
209            .checked_add((self.tv_sec as u64).checked_mul(NSEC_PER_SEC)?)
210            .is_none()
211        {
212            return None;
213        }
214        self.to_timespec()
215    }
216
217    #[cfg(all(
218        target_os = "linux",
219        target_env = "gnu",
220        target_pointer_width = "32",
221        not(target_arch = "riscv32")
222    ))]
223    pub fn to_timespec64(&self) -> __timespec64 {
224        __timespec64::new(self.tv_sec, self.tv_nsec.as_inner() as _)
225    }
226}
227
228#[cfg(all(
229    target_os = "linux",
230    target_env = "gnu",
231    target_pointer_width = "32",
232    not(target_arch = "riscv32")
233))]
234#[repr(C)]
235pub(crate) struct __timespec64 {
236    pub(crate) tv_sec: i64,
237    #[cfg(target_endian = "big")]
238    _padding: i32,
239    pub(crate) tv_nsec: i32,
240    #[cfg(target_endian = "little")]
241    _padding: i32,
242}
243
244#[cfg(all(
245    target_os = "linux",
246    target_env = "gnu",
247    target_pointer_width = "32",
248    not(target_arch = "riscv32")
249))]
250impl __timespec64 {
251    pub(crate) fn new(tv_sec: i64, tv_nsec: i32) -> Self {
252        Self { tv_sec, tv_nsec, _padding: 0 }
253    }
254}
255
256#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
257pub struct Instant {
258    t: Timespec,
259}
260
261impl Instant {
262    #[cfg(target_vendor = "apple")]
263    pub(crate) const CLOCK_ID: libc::clockid_t = libc::CLOCK_UPTIME_RAW;
264    #[cfg(not(target_vendor = "apple"))]
265    pub(crate) const CLOCK_ID: libc::clockid_t = libc::CLOCK_MONOTONIC;
266    pub fn now() -> Instant {
267        // https://www.manpagez.com/man/3/clock_gettime/
268        //
269        // CLOCK_UPTIME_RAW   clock that increments monotonically, in the same man-
270        //                    ner as CLOCK_MONOTONIC_RAW, but that does not incre-
271        //                    ment while the system is asleep.  The returned value
272        //                    is identical to the result of mach_absolute_time()
273        //                    after the appropriate mach_timebase conversion is
274        //                    applied.
275        //
276        // Instant on macos was historically implemented using mach_absolute_time;
277        // we preserve this value domain out of an abundance of caution.
278        Instant { t: Timespec::now(Self::CLOCK_ID) }
279    }
280
281    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
282        self.t.sub_timespec(&other.t).ok()
283    }
284
285    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
286        Some(Instant { t: self.t.checked_add_duration(other)? })
287    }
288
289    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
290        Some(Instant { t: self.t.checked_sub_duration(other)? })
291    }
292
293    #[cfg_attr(
294        not(target_os = "linux"),
295        allow(unused, reason = "needed by the `sleep_until` on some unix platforms")
296    )]
297    pub(crate) fn into_timespec(self) -> Timespec {
298        self.t
299    }
300}
301
302impl AsInner<Timespec> for Instant {
303    fn as_inner(&self) -> &Timespec {
304        &self.t
305    }
306}
307
308impl fmt::Debug for Instant {
309    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
310        f.debug_struct("Instant")
311            .field("tv_sec", &self.t.tv_sec)
312            .field("tv_nsec", &self.t.tv_nsec)
313            .finish()
314    }
315}
std/sys/pal/unix/time.rs

std/sys/pal/unix/
time.rs
