libc/src/time/gettimeofday.cpp

   1 //===-- Implementation of gettimeofday function ---------------------------===//
   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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/time/gettimeofday.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/common.h"
  13
  14 #include <errno.h>
  15 #include <sys/syscall.h> // For syscall numbers.
  16
  17 namespace __llvm_libc {
  18
  19 LLVM_LIBC_FUNCTION(int, gettimeofday,
  20                    (struct timeval * tv, [[maybe_unused]] void *unused)) {
  21   if (tv == nullptr)
  22     return 0;
  23   struct timespec tp;
  24   long ret_val = __llvm_libc::syscall_impl(SYS_clock_gettime,
  25                                            static_cast<long>(CLOCK_REALTIME),
  26                                            reinterpret_cast<long>(&tp));
  27   // A negative return value indicates an error with the magnitude of the
  28   // value being the error code.
  29   if (ret_val < 0) {
  30     errno = -ret_val;
  31     return -1;
  32   }
  33   tv->tv_sec = tp.tv_sec;
  34   tv->tv_usec = tp.tv_nsec / 1000;
  35   return 0;
  36 }
  37
  38 } // namespace __llvm_libc