sysdeps/unix/clock_nanosleep.c

   1 /* High-resolution sleep with the specified clock.
   2    Copyright (C) 2000-2019 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <errno.h>
  21 #include <time.h>
  22 #include <sysdep-cancel.h>
  23 #include <shlib-compat.h>
  24
  25 /* This implementation assumes that these is only a `nanosleep' system
  26    call.  So we have to remap all other activities.  */
  27 int
  28 __clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req,
  29                    struct timespec *rem)
  30 {
  31   struct timespec now;
  32
  33   if (__builtin_expect (req->tv_nsec, 0) < 0
  34       || __builtin_expect (req->tv_nsec, 0) >= 1000000000)
  35     return EINVAL;
  36
  37   if (clock_id == CLOCK_THREAD_CPUTIME_ID)
  38     return EINVAL;              /* POSIX specifies EINVAL for this case.  */
  39
  40   if (clock_id < CLOCK_REALTIME || clock_id > CLOCK_THREAD_CPUTIME_ID)
  41     return EINVAL;
  42
  43   /* If we got an absolute time, remap it.  */
  44   if (flags == TIMER_ABSTIME)
  45     {
  46       long int nsec;
  47       long int sec;
  48
  49       /* Make sure we use safe data types.  */
  50       assert (sizeof (sec) >= sizeof (now.tv_sec));
  51
  52       /* Get the current time for this clock.  */
  53       if (__clock_gettime (clock_id, &now) != 0)
  54         return errno;
  55
  56       /* Compute the difference.  */
  57       nsec = req->tv_nsec - now.tv_nsec;
  58       sec = req->tv_sec - now.tv_sec - (nsec < 0);
  59       if (sec < 0)
  60         /* The time has already elapsed.  */
  61         return 0;
  62
  63       now.tv_sec = sec;
  64       now.tv_nsec = nsec + (nsec < 0 ? 1000000000 : 0);
  65
  66       /* From now on this is our time.  */
  67       req = &now;
  68
  69       /* Make sure we are not modifying the struct pointed to by REM.  */
  70       rem = NULL;
  71     }
  72   else if (flags != 0)
  73     return EINVAL;
  74   else if (clock_id != CLOCK_REALTIME)
  75     /* Not supported.  */
  76     return ENOTSUP;
  77
  78   return __nanosleep (req, rem), 0 ? errno : 0;
  79 }
  80
  81 versioned_symbol (libc, __clock_nanosleep, clock_nanosleep, GLIBC_2_17);
  82 /* clock_nanosleep moved to libc in version 2.17;
  83    old binaries may expect the symbol version it had in librt.  */
  84 #if SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_17)
  85 strong_alias (__clock_nanosleep, __clock_nanosleep_2);
  86 compat_symbol (libc, __clock_nanosleep_2, clock_nanosleep, GLIBC_2_2);
  87 #endif