lib/nanosleep.c

   1 /* Provide a replacement for the POSIX nanosleep function.
   2    Copyright (C) 1999, 2000, 2002, 2004 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* written by Jim Meyering */
  19
  20 #include <config.h>
  21
  22 /* Undefine nanosleep here so any prototype is not redefined to be a
  23    prototype for rpl_nanosleep. (they'd conflict e.g., on alpha-dec-osf3.2)  */
  24 #undef nanosleep
  25
  26 #include <stdbool.h>
  27 #include <stdio.h>
  28 #include <sys/types.h>
  29 #include <signal.h>
  30
  31 #include <errno.h>
  32
  33 #if HAVE_UNISTD_H
  34 # include <unistd.h>
  35 #endif
  36
  37 /* Some systems (MSDOS) don't have SIGCONT.
  38    Using SIGTERM here turns the signal-handling code below
  39    into a no-op on such systems. */
  40 #ifndef SIGCONT
  41 # define SIGCONT SIGTERM
  42 #endif
  43
  44 #include "timespec.h"
  45
  46 static sig_atomic_t volatile suspended;
  47
  48 /* Handle SIGCONT. */
  49
  50 static void
  51 sighandler (int sig)
  52 {
  53   suspended = 1;
  54 }
  55
  56 /* FIXME: comment */
  57
  58 static void
  59 my_usleep (const struct timespec *ts_delay)
  60 {
  61   struct timeval tv_delay;
  62   tv_delay.tv_sec = ts_delay->tv_sec;
  63   tv_delay.tv_usec = (ts_delay->tv_nsec + 999) / 1000;
  64   if (tv_delay.tv_usec == 1000000)
  65     {
  66       tv_delay.tv_sec++;
  67       tv_delay.tv_usec = 0;
  68     }
  69   select (0, (void *) 0, (void *) 0, (void *) 0, &tv_delay);
  70 }
  71
  72 /* FIXME: comment */
  73
  74 int
  75 rpl_nanosleep (const struct timespec *requested_delay,
  76                struct timespec *remaining_delay)
  77 {
  78   static bool initialized;
  79
  80 #ifdef SA_NOCLDSTOP
  81   struct sigaction oldact, newact;
  82 #endif
  83
  84   suspended = 0;
  85
  86   /* set up sig handler */
  87   if (! initialized)
  88     {
  89 #ifdef SA_NOCLDSTOP
  90       newact.sa_handler = sighandler;
  91       sigemptyset (&newact.sa_mask);
  92       newact.sa_flags = 0;
  93
  94       sigaction (SIGCONT, NULL, &oldact);
  95       if (oldact.sa_handler != SIG_IGN)
  96         sigaction (SIGCONT, &newact, NULL);
  97 #else
  98       if (signal (SIGCONT, SIG_IGN) != SIG_IGN)
  99         signal (SIGCONT, sighandler);
 100 #endif
 101       initialized = true;
 102     }
 103
 104   my_usleep (requested_delay);
 105
 106   if (suspended)
 107     {
 108       /* Calculate time remaining.  */
 109       /* FIXME: the code in sleep doesn't use this, so there's no
 110          rush to implement it.  */
 111
 112       errno = EINTR;
 113     }
 114
 115   /* FIXME: Restore sig handler?  */
 116
 117   return suspended;
 118 }