contrib/tar/lib/msleep.c

   1 /* Sleep a given number of milliseconds.
   2    Copyright (C) 1992, 1993, 1994, 1997 Free Software Foundation, Inc.
   3    François Pinard <pinard@iro.umontreal.ca>, 1992.
   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 2, or (at your option)
   8    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, write to the Free Software Foundation,
  17    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 /* This code is heavily borrowed from Taylor UUCP 1.03.  Ian picks one of
  24    usleep, nap, napms, poll, select and sleep, in decreasing order of
  25    preference.  The sleep function is always available.  */
  26
  27 /* In many cases, we will sleep if the wanted number of milliseconds
  28    is higher than this value.  */
  29 #define THRESHOLD_FOR_SLEEP 30000
  30
  31 /* Include some header files.  */
  32
  33 #if HAVE_UNISTD_H
  34 # include <unistd.h>
  35 #endif
  36
  37 #if HAVE_POLL
  38 # if HAVE_STROPTS_H
  39 #  include <stropts.h>
  40 # endif
  41 # if HAVE_POLL_H
  42 #  include <sys/types.h>
  43 #  include <poll.h>
  44 # endif
  45 # if !HAVE_STROPTS_H && !HAVE_POLL_H
  46 /* We need a definition for struct pollfd, although it doesn't matter
  47    what it contains.  */
  48 struct pollfd
  49 {
  50   int idummy;
  51 };
  52 # endif
  53 #else
  54 # if HAVE_SELECT
  55 #  include <sys/time.h>
  56 # endif
  57 #endif
  58
  59 /*---------------------------------------.
  60 | Sleep a given number of milliseconds.  |
  61 `---------------------------------------*/
  62
  63 void
  64 msleep (milliseconds)
  65      int milliseconds;
  66 {
  67 #if HAVE_USLEEP
  68
  69   if (milliseconds > 0)
  70     usleep (milliseconds * (long) 1000);
  71
  72 #else
  73 # if HAVE_NAP
  74
  75   if (milliseconds > 0)
  76     nap ((long) milliseconds);
  77
  78 # else
  79 #  if HAVE_NAPMS
  80
  81   if (milliseconds >= THRESHOLD_FOR_SLEEP)
  82     {
  83       sleep (milliseconds / 1000);
  84       milliseconds %= 1000;
  85     }
  86   if (milliseconds > 0)
  87     napms (milliseconds);
  88
  89 #  else
  90 #   if HAVE_POLL
  91
  92   struct pollfd sdummy;         /* poll(2) checks this address */
  93
  94   if (milliseconds >= THRESHOLD_FOR_SLEEP)
  95     {
  96       sleep (milliseconds / 1000);
  97       milliseconds %= 1000;
  98     }
  99   if (milliseconds > 0)
 100     poll (&sdummy, 0, milliseconds);
 101
 102 #   else
 103 #    if HAVE_SELECT
 104
 105   struct timeval s;
 106
 107   if (milliseconds >= THRESHOLD_FOR_SLEEP)
 108     {
 109       sleep (milliseconds / 1000);
 110       milliseconds %= 1000;
 111     }
 112   if (milliseconds > 0)
 113     {
 114       s.tv_sec = milliseconds / 1000;
 115       s.tv_usec = (milliseconds % 1000) * (long) 1000;
 116       select (0, NULL, NULL, NULL, &s);
 117     }
 118
 119 #    else
 120
 121   /* Round the time up to the next full second.  */
 122
 123   if (milliseconds > 0)
 124     sleep ((milliseconds + 999) / 1000);
 125
 126 #    endif
 127 #   endif
 128 #  endif
 129 # endif
 130 #endif
 131 }