sysdeps/unix/sysv/linux/clock_getcpuclockid.c

   1 /* clock_getcpuclockid -- Get a clockid_t for process CPU time.  Linux version.
   2    Copyright (C) 2004-2024 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 <errno.h>
  20 #include <time.h>
  21 #include <unistd.h>
  22 #include "kernel-posix-cpu-timers.h"
  23 #include <sysdep.h>
  24 #include <shlib-compat.h>
  25
  26 int
  27 __clock_getcpuclockid (pid_t pid, clockid_t *clock_id)
  28 {
  29   /* The clockid_t value is a simple computation from the PID.
  30      But we do a clock_getres call to validate it.  */
  31
  32   const clockid_t pidclock = make_process_cpuclock (pid, CPUCLOCK_SCHED);
  33
  34 #ifndef __NR_clock_getres_time64
  35 # define __NR_clock_getres_time64 __NR_clock_getres
  36 #endif
  37   int r = INTERNAL_SYSCALL_CALL (clock_getres_time64, pidclock, NULL);
  38
  39 #ifndef __ASSUME_TIME64_SYSCALLS
  40   if (r != 0 && r == -ENOSYS)
  41     r = INTERNAL_SYSCALL_CALL (clock_getres, pidclock, NULL);
  42 #endif
  43
  44   if (r == 0)
  45     {
  46       *clock_id = pidclock;
  47       return 0;
  48     }
  49   if (r == -EINVAL)
  50     /* The clock_getres system call checked the PID for us.  */
  51     return ESRCH;
  52   return -r;
  53 }
  54
  55 versioned_symbol (libc, __clock_getcpuclockid, clock_getcpuclockid, GLIBC_2_17);
  56 /* clock_getcpuclockid moved to libc in version 2.17;
  57    old binaries may expect the symbol version it had in librt.  */
  58 #if SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_17)
  59 strong_alias (__clock_getcpuclockid, __clock_getcpuclockid_2);
  60 compat_symbol (libc, __clock_getcpuclockid_2, clock_getcpuclockid, GLIBC_2_2);
  61 #endif