63 lines · cpp
1//===--- clock_gettime linux implementation ---------------------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "src/__support/time/clock_gettime.h"10#include "hdr/types/clockid_t.h"11#include "hdr/types/struct_timespec.h"12#include "src/__support/OSUtil/linux/vdso.h"13#include "src/__support/OSUtil/syscall.h"14#include "src/__support/common.h"15#include "src/__support/error_or.h"16#include "src/__support/macros/config.h"17#include <sys/syscall.h>18 19#if defined(SYS_clock_gettime64)20#include <linux/time_types.h>21#endif22 23namespace LIBC_NAMESPACE_DECL {24namespace internal {25ErrorOr<int> clock_gettime(clockid_t clockid, timespec *ts) {26 using namespace vdso;27 int ret;28#if defined(SYS_clock_gettime)29 TypedSymbol<VDSOSym::ClockGetTime> clock_gettime;30 if (LIBC_LIKELY(clock_gettime != nullptr))31 ret = clock_gettime(clockid, ts);32 else33 ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_clock_gettime,34 static_cast<long>(clockid),35 reinterpret_cast<long>(ts));36#elif defined(SYS_clock_gettime64)37 static_assert(38 sizeof(time_t) == sizeof(int64_t),39 "SYS_clock_gettime64 requires struct timespec with 64-bit members.");40 41 TypedSymbol<VDSOSym::ClockGetTime64> clock_gettime64;42 __kernel_timespec ts64{};43 if (LIBC_LIKELY(clock_gettime64 != nullptr))44 ret = clock_gettime64(clockid, &ts64);45 else46 ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_clock_gettime64,47 static_cast<long>(clockid),48 reinterpret_cast<long>(&ts64));49 if (ret == 0) {50 ts->tv_sec = static_cast<decltype(ts->tv_sec)>(ts64.tv_sec);51 ts->tv_nsec = static_cast<decltype(ts->tv_nsec)>(ts64.tv_nsec);52 }53#else54#error "SYS_clock_gettime and SYS_clock_gettime64 syscalls not available."55#endif56 if (ret < 0)57 return Error(-ret);58 return ret;59}60 61} // namespace internal62} // namespace LIBC_NAMESPACE_DECL63