sysdeps/unix/sysv/linux/clock_gettime.c

   1 /* clock_gettime -- Get current time from a POSIX clockid_t.  Linux version.
   2    Copyright (C) 2003-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdep.h>
  20 #include <kernel-features.h>
  21 #include <errno.h>
  22 #include <time.h>
  23 #include "kernel-posix-cpu-timers.h"
  24 #include <sysdep-vdso.h>
  25 #include <shlib-compat.h>
  26
  27 /* Get current value of CLOCK and store it in TP.  */
  28 int
  29 __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
  30 {
  31   int r;
  32
  33 #ifndef __NR_clock_gettime64
  34 # define __NR_clock_gettime64 __NR_clock_gettime
  35 #endif
  36
  37 #ifdef HAVE_CLOCK_GETTIME64_VSYSCALL
  38   int (*vdso_time64) (clockid_t clock_id, struct __timespec64 *tp)
  39     = GLRO(dl_vdso_clock_gettime64);
  40   if (vdso_time64 != NULL)
  41     {
  42       r = INTERNAL_VSYSCALL_CALL (vdso_time64, 2, clock_id, tp);
  43       if (r == 0)
  44         return 0;
  45       return INLINE_SYSCALL_ERROR_RETURN_VALUE (-r);
  46     }
  47 #endif
  48
  49 #ifdef HAVE_CLOCK_GETTIME_VSYSCALL
  50   int (*vdso_time) (clockid_t clock_id, struct timespec *tp)
  51     = GLRO(dl_vdso_clock_gettime);
  52   if (vdso_time != NULL)
  53     {
  54       struct timespec tp32;
  55       r = INTERNAL_VSYSCALL_CALL (vdso_time, 2, clock_id, &tp32);
  56       if (r == 0 && tp32.tv_sec >= 0)
  57         {
  58           *tp = valid_timespec_to_timespec64 (tp32);
  59           return 0;
  60         }
  61       else if (r != 0)
  62         return INLINE_SYSCALL_ERROR_RETURN_VALUE (-r);
  63
  64       /* Fallback to syscall if the 32-bit time_t vDSO returns overflows.  */
  65     }
  66 #endif
  67
  68   r = INTERNAL_SYSCALL_CALL (clock_gettime64, clock_id, tp);
  69   if (r == 0)
  70     return 0;
  71   if (r != -ENOSYS)
  72     return INLINE_SYSCALL_ERROR_RETURN_VALUE (-r);
  73
  74 #ifndef __ASSUME_TIME64_SYSCALLS
  75   /* Fallback code that uses 32-bit support.  */
  76   struct timespec tp32;
  77   r = INTERNAL_SYSCALL_CALL (clock_gettime, clock_id, &tp32);
  78   if (r == 0)
  79     {
  80       *tp = valid_timespec_to_timespec64 (tp32);
  81       return 0;
  82     }
  83 #endif
  84
  85   return INLINE_SYSCALL_ERROR_RETURN_VALUE (-r);
  86 }
  87
  88 #if __TIMESIZE != 64
  89 libc_hidden_def (__clock_gettime64)
  90
  91 int
  92 __clock_gettime (clockid_t clock_id, struct timespec *tp)
  93 {
  94   int ret;
  95   struct __timespec64 tp64;
  96
  97   ret = __clock_gettime64 (clock_id, &tp64);
  98
  99   if (ret == 0)
 100     {
 101       if (! in_time_t_range (tp64.tv_sec))
 102         {
 103           __set_errno (EOVERFLOW);
 104           return -1;
 105         }
 106
 107       *tp = valid_timespec64_to_timespec (tp64);
 108     }
 109
 110   return ret;
 111 }
 112 #endif
 113 libc_hidden_def (__clock_gettime)
 114
 115 versioned_symbol (libc, __clock_gettime, clock_gettime, GLIBC_2_17);
 116 /* clock_gettime moved to libc in version 2.17;
 117    old binaries may expect the symbol version it had in librt.  */
 118 #if SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_17)
 119 strong_alias (__clock_gettime, __clock_gettime_2);
 120 compat_symbol (libc, __clock_gettime_2, clock_gettime, GLIBC_2_2);
 121 #endif