lib/nanosleep.c

   1 /* Provide a replacement for the POSIX nanosleep function.
   2    Copyright (C) 1999, 2000 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 <stdio.h>
  27 #include <sys/types.h>
  28 #include <signal.h>
  29
  30 #include <errno.h>
  31 #ifndef errno
  32 extern int errno;
  33 #endif
  34
  35 #if HAVE_UNISTD_H
  36 # include <unistd.h>
  37 #endif
  38
  39 /* Some systems (MSDOS) don't have SIGCONT.
  40    Using SIGTERM here turns the signal-handling code below
  41    into a no-op on such systems. */
  42 #ifndef SIGCONT
  43 # define SIGCONT SIGTERM
  44 #endif
  45
  46 #include "nanosleep.h"
  47
  48 static int suspended;
  49 int first_call = 1;
  50
  51 /* Handle SIGCONT. */
  52
  53 static void
  54 sighandler (int sig)
  55 {
  56   suspended = 1;
  57 }
  58
  59 /* FIXME: comment */
  60
  61 static void
  62 my_usleep (const struct timespec *ts_delay)
  63 {
  64   struct timeval tv_delay;
  65   tv_delay.tv_sec = ts_delay->tv_sec;
  66   tv_delay.tv_usec = ts_delay->tv_nsec / 1000;
  67   select (0, (void *) 0, (void *) 0, (void *) 0, &tv_delay);
  68 }
  69
  70 /* FIXME: comment */
  71
  72 int
  73 rpl_nanosleep (const struct timespec *requested_delay,
  74                struct timespec *remaining_delay)
  75 {
  76 #ifdef SA_NOCLDSTOP
  77   struct sigaction oldact, newact;
  78 #endif
  79
  80   suspended = 0;
  81
  82   /* set up sig handler */
  83   if (first_call)
  84     {
  85 #ifdef SA_NOCLDSTOP
  86       newact.sa_handler = sighandler;
  87       sigemptyset (&newact.sa_mask);
  88       newact.sa_flags = 0;
  89
  90       sigaction (SIGCONT, NULL, &oldact);
  91       if (oldact.sa_handler != SIG_IGN)
  92         sigaction (SIGCONT, &newact, NULL);
  93 #else
  94       if (signal (SIGCONT, SIG_IGN) != SIG_IGN)
  95         signal (SIGCONT, sighandler);
  96 #endif
  97       first_call = 0;
  98     }
  99
 100   my_usleep (requested_delay);
 101
 102   if (suspended)
 103     {
 104       /* Calculate time remaining.  */
 105       /* FIXME: the code in sleep doesn't use this, so there's no
 106          rush to implement it.  */
 107
 108       errno = EINTR;
 109     }
 110
 111   /* FIXME: Restore sig handler?  */
 112
 113   return suspended;
 114 }