lib/xnanosleep.c

   1 /* xnanosleep.c -- a more convenient interface to nanosleep
   2
   3    Copyright (C) 2002-2007, 2009-2019 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Mostly written (for sleep.c) by Paul Eggert.
  19    Factored out (creating this file) by Jim Meyering.  */
  20
  21 #include <config.h>
  22
  23 #include "xnanosleep.h"
  24
  25 #include <timespec.h>
  26
  27 #include <errno.h>
  28 #include <time.h>
  29
  30 /* Sleep until the time (call it WAKE_UP_TIME) specified as
  31    SECONDS seconds after the time this function is called.
  32    SECONDS must be non-negative.  If SECONDS is so large that
  33    it is not representable as a 'struct timespec', then use
  34    the maximum value for that interval.  Return -1 on failure
  35    (setting errno), 0 on success.  */
  36
  37 int
  38 xnanosleep (double seconds)
  39 {
  40   struct timespec ts_sleep = dtotimespec (seconds);
  41
  42   for (;;)
  43     {
  44       /* Linux-2.6.8.1's nanosleep returns -1, but doesn't set errno
  45          when resumed after being suspended.  Earlier versions would
  46          set errno to EINTR.  nanosleep from linux-2.6.10, as well as
  47          implementations by (all?) other vendors, doesn't return -1
  48          in that case;  either it continues sleeping (if time remains)
  49          or it returns zero (if the wake-up time has passed).  */
  50       errno = 0;
  51       if (nanosleep (&ts_sleep, NULL) == 0)
  52         break;
  53       if (errno != EINTR && errno != 0)
  54         return -1;
  55     }
  56
  57   return 0;
  58 }