libc/src/time/linux/time.cpp

   1 //===-- Linux implementation of the time 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/time_func.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/common.h"
  13 #include "src/errno/libc_errno.h"
  14
  15 #include <sys/syscall.h> // For syscall numbers.
  16 #include <time.h>
  17
  18 namespace __llvm_libc {
  19
  20 LLVM_LIBC_FUNCTION(time_t, time, (time_t * tp)) {
  21   // TODO: Use the Linux VDSO to fetch the time and avoid the syscall.
  22   struct timespec ts;
  23   long ret_val = __llvm_libc::syscall_impl(SYS_clock_gettime, CLOCK_REALTIME,
  24                                            reinterpret_cast<long>(&ts));
  25   if (ret_val < 0) {
  26     libc_errno = -ret_val;
  27     return -1;
  28   }
  29
  30   if (tp != nullptr)
  31     *tp = time_t(ts.tv_sec);
  32   return time_t(ts.tv_sec);
  33 }
  34
  35 } // namespace __llvm_libc