1  /* clock_getcpuclockid -- Get a clockid_t for process CPU time.  Linux version.
       2     Copyright (C) 2004-2023 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