mirror of
https://github.com/jart/cosmopolitan.git
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165 lines
8.2 KiB
C
165 lines
8.2 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=8 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/struct/timespec.h"
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#include "libc/calls/struct/timespec.internal.h"
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#include "libc/calls/syscall_support-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.h"
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#include "libc/intrin/strace.h"
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#include "libc/runtime/syslib.internal.h"
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#include "libc/sysv/consts/clock.h"
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#ifdef __aarch64__
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#define CGT_VDSO __vdsosym("LINUX_2.6.39", "__kernel_clock_gettime")
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#else
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#define CGT_VDSO __vdsosym("LINUX_2.6", "__vdso_clock_gettime")
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#endif
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typedef int clock_gettime_f(int, struct timespec *);
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static clock_gettime_f *__clock_gettime_get(void) {
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clock_gettime_f *cgt;
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if (IsLinux() && (cgt = CGT_VDSO)) {
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return cgt;
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} else if (__syslib) {
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return (void *)__syslib->__clock_gettime;
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#ifdef __x86_64__
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} else if (IsWindows()) {
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return sys_clock_gettime_nt;
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} else if (IsXnu()) {
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return sys_clock_gettime_xnu;
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#endif
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} else {
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return sys_clock_gettime;
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}
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}
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static int __clock_gettime_init(int, struct timespec *);
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static clock_gettime_f *__clock_gettime = __clock_gettime_init;
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static int __clock_gettime_init(int clockid, struct timespec *ts) {
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clock_gettime_f *cgt;
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__clock_gettime = cgt = __clock_gettime_get();
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return cgt(clockid, ts);
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}
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static int clock_gettime_impl(int clock, struct timespec *ts) {
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// BSDs and sometimes Linux too will crash when `ts` is NULL
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// it's also nice to not have to check for null in polyfills
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struct timespec memory;
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if (!ts)
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ts = &memory;
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return __clock_gettime(clock, ts);
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}
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/**
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* Returns nanosecond time.
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*
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* The `clock` parameter may bo set to:
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*
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* - `CLOCK_REALTIME` returns a wall clock timestamp represented in
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* nanoseconds since the UNIX epoch (~1970). It'll count time in the
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* suspend state. This clock is subject to being smeared by various
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* adjustments made by NTP. These timestamps can have unpredictable
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* discontinuous jumps when clock_settime() is used. Therefore this
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* clock is the default clock for everything, even pthread condition
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* variables. Cosmopoiltan guarantees this clock will never raise
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* `EINVAL` and also guarantees `CLOCK_REALTIME == 0` will always be
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* the case. On Windows this maps to GetSystemTimePreciseAsFileTime().
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* On platforms with vDSOs like Linux, Windows, and MacOS ARM64 this
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* should take about 20 nanoseconds.
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*
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* - `CLOCK_MONOTONIC` returns a timestamp with an unspecified epoch,
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* that should be when the system was powered on. These timestamps
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* shouldn't go backwards. Timestamps shouldn't count time spent in
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* the sleep, suspend, and hibernation states. These timestamps won't
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* be impacted by clock_settime(). These timestamps may be impacted by
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* frequency adjustments made by NTP. Cosmopoiltan guarantees this
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* clock will never raise `EINVAL`. MacOS and BSDs use the word
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* "uptime" to describe this clock. On Windows this maps to
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* QueryUnbiasedInterruptTimePrecise().
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*
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* - `CLOCK_BOOTTIME` is a monotonic clock returning a timestamp with an
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* unspecified epoch, that should be relative to when the host system
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* was powered on. These timestamps shouldn't go backwards. Timestamps
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* should also include time spent in a sleep, suspend, or hibernation
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* state. These timestamps aren't impacted by clock_settime(), but
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* they may be impacted by frequency adjustments made by NTP. This
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* clock will raise an `EINVAL` error on extremely old Linux distros
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* like RHEL5. MacOS and BSDs use the word "monotonic" to describe
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* this clock. On Windows this maps to QueryInterruptTimePrecise().
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*
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* - `CLOCK_MONOTONIC_RAW` returns a timestamp from an unspecified
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* epoch. These timestamps don't count time spent in the sleep,
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* suspend, and hibernation states. This clock is not impacted by
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* clock_settime(). Unlike `CLOCK_MONOTONIC` this clock is guaranteed
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* to not be impacted by frequency adjustments. Providing this level
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* of assurances may make this clock 10x slower than the monotonic
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* clock. Furthermore this clock may cause `EINVAL` to be raised if
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* running on a host system that doesn't provide those guarantees,
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* e.g. OpenBSD and MacOS on AMD64.
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*
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* - `CLOCK_REALTIME_COARSE` is the same as `CLOCK_REALTIME` except
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* it'll go faster if the host OS provides a cheaper way to read the
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* wall time. Please be warned that coarse can be really coarse.
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* Rather than nano precision, you're looking at `CLK_TCK` precision,
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* which can lag as far as 30 milliseconds behind or possibly more.
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* Cosmopolitan may fallback to `CLOCK_REALTIME` if a faster less
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* accurate clock isn't provided by the system. This clock will raise
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* an `EINVAL` error on extremely old Linux distros like RHEL5. On
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* platforms with vDSOs like Linux, Windows, and MacOS ARM64 this
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* should take about 5 nanoseconds.
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*
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* - `CLOCK_MONOTONIC_COARSE` is the same as `CLOCK_MONOTONIC` except
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* it'll go faster if the host OS provides a cheaper way to read the
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* unbiased time. Please be warned that coarse can be really coarse.
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* Rather than nano precision, you're looking at `CLK_TCK` precision,
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* which can lag as far as 30 milliseconds behind or possibly more.
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* Cosmopolitan may fallback to `CLOCK_REALTIME` if a faster less
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* accurate clock isn't provided by the system. This clock will raise
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* an `EINVAL` error on extremely old Linux distros like RHEL5. On
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* platforms with vDSOs like Linux, Windows, and MacOS ARM64 this
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* should take about 5 nanoseconds.
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*
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* - `CLOCK_PROCESS_CPUTIME_ID` returns the amount of time this process
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* was actively scheduled. This is similar to getrusage() and clock().
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*
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* - `CLOCK_THREAD_CPUTIME_ID` returns the amount of time this thread
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* was actively scheduled. This is similar to getrusage() and clock().
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*
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* @param ts is where the result is stored (or null to do clock check)
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* @return 0 on success, or -1 w/ errno
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* @raise EFAULT if `ts` points to invalid memory
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* @error EINVAL if `clock` isn't supported on this system
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* @error EPERM if pledge() is in play without stdio promise
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* @error ESRCH on NetBSD if PID/TID OR'd into `clock` wasn't found
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* @see strftime(), gettimeofday()
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* @asyncsignalsafe
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* @vforksafe
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*/
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int clock_gettime(int clock, struct timespec *ts) {
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int rc = clock_gettime_impl(clock, ts);
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if (rc) {
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errno = -rc;
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rc = -1;
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}
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TIMETRACE("clock_gettime(%s, [%s]) → %d% m", DescribeClockName(clock),
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DescribeTimespec(rc, ts), rc);
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return rc;
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}
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