external/gpl2/xcvs/dist/lib/nanosleep.c

   1 /* Provide a replacement for the POSIX nanosleep function.
   2    Copyright (C) 1999, 2000, 2002, 2004, 2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 /* written by Jim Meyering */
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 /* Undefine nanosleep here so any prototype is not redefined to be a
  25    prototype for rpl_nanosleep. (they'd conflict e.g., on alpha-dec-osf3.2)  */
  26 #undef nanosleep
  27
  28 #include <stdbool.h>
  29 #include <stdio.h>
  30 #include <sys/types.h>
  31 #include <signal.h>
  32
  33 #include <errno.h>
  34
  35 #if HAVE_UNISTD_H
  36 # include <unistd.h>
  37 #endif
  38
  39 #include "timespec.h"
  40
  41 /* Some systems (MSDOS) don't have SIGCONT.
  42    Using SIGTERM here turns the signal-handling code below
  43    into a no-op on such systems. */
  44 #ifndef SIGCONT
  45 # define SIGCONT SIGTERM
  46 #endif
  47
  48 #if ! HAVE_SIGINTERRUPT
  49 # define siginterrupt(sig, flag) /* empty */
  50 #endif
  51
  52 static sig_atomic_t volatile suspended;
  53
  54 /* Handle SIGCONT. */
  55
  56 static void
  57 sighandler (int sig)
  58 {
  59   suspended = 1;
  60 }
  61
  62 /* FIXME: comment */
  63
  64 static void
  65 my_usleep (const struct timespec *ts_delay)
  66 {
  67   struct timeval tv_delay;
  68   tv_delay.tv_sec = ts_delay->tv_sec;
  69   tv_delay.tv_usec = (ts_delay->tv_nsec + 999) / 1000;
  70   if (tv_delay.tv_usec == 1000000)
  71     {
  72       tv_delay.tv_sec++;
  73       tv_delay.tv_usec = 0;
  74     }
  75   select (0, NULL, NULL, NULL, &tv_delay);
  76 }
  77
  78 /* FIXME: comment */
  79
  80 int
  81 rpl_nanosleep (const struct timespec *requested_delay,
  82                struct timespec *remaining_delay)
  83 {
  84   static bool initialized;
  85
  86   /* set up sig handler */
  87   if (! initialized)
  88     {
  89 #ifdef SA_NOCLDSTOP
  90       struct sigaction oldact, newact;
  91       newact.sa_handler = sighandler;
  92       sigemptyset (&newact.sa_mask);
  93       newact.sa_flags = 0;
  94
  95       sigaction (SIGCONT, NULL, &oldact);
  96       if (oldact.sa_handler != SIG_IGN)
  97         sigaction (SIGCONT, &newact, NULL);
  98 #else
  99       if (signal (SIGCONT, SIG_IGN) != SIG_IGN)
 100         {
 101           signal (SIGCONT, sighandler);
 102           siginterrupt (SIGCONT, 1);
 103         }
 104 #endif
 105       initialized = true;
 106     }
 107
 108   suspended = 0;
 109
 110   my_usleep (requested_delay);
 111
 112   if (suspended)
 113     {
 114       /* Calculate time remaining.  */
 115       /* FIXME: the code in sleep doesn't use this, so there's no
 116          rush to implement it.  */
 117
 118       errno = EINTR;
 119     }
 120
 121   /* FIXME: Restore sig handler?  */
 122
 123   return suspended;
 124 }