libjava/posix.cc

   1 // posix.cc -- Helper functions for POSIX-flavored OSs.
   2
   3 /* Copyright (C) 2000  Free Software Foundation
   4
   5    This file is part of libgcj.
   6
   7 This software is copyrighted work licensed under the terms of the
   8 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   9 details.  */
  10
  11 #include <config.h>
  12
  13 #include "posix.h"
  14
  15 #include <errno.h>
  16
  17 #if defined (ECOS)
  18 extern "C" unsigned long long _clock (void);
  19 #endif
  20
  21 // gettimeofday implementation.
  22 void
  23 _Jv_gettimeofday (struct timeval *tv)
  24 {
  25 #if defined (HAVE_GETTIMEOFDAY)
  26   gettimeofday (tv, NULL);
  27 #elif defined (HAVE_TIME)
  28   tv->tv_sec = time (NULL);
  29   tv->tv_usec = 0;
  30 #elif defined (HAVE_FTIME)
  31   struct timeb t;
  32   ftime (&t);
  33   tv->tv_sec = t.time;
  34   tv->tv_usec = t.millitm * 1000;
  35 #elif defined (ECOS)
  36   // FIXME.
  37   tv->tv_sec = _clock () / 1000;
  38   tv->tv_usec = 0;
  39 #else
  40   // In the absence of any function, time remains forever fixed.
  41   tv->tv_sec = 23;
  42   tv->tv_usec = 0;
  43 #endif
  44 }
  45
  46 // A wrapper for select() which ignores EINTR.
  47 int
  48 _Jv_select (int n, fd_set *readfds, fd_set  *writefds,
  49             fd_set *exceptfds, struct timeval *timeout)
  50 {
  51 #ifdef HAVE_SELECT
  52   // If we have a timeout, compute the absolute ending time.
  53   struct timeval end, delay;
  54   if (timeout)
  55     {
  56       _Jv_gettimeofday (&end);
  57       end.tv_usec += timeout->tv_usec;
  58       if (end.tv_usec >= 1000000)
  59         {
  60           ++end.tv_sec;
  61           end.tv_usec -= 1000000;
  62         }
  63       end.tv_sec += timeout->tv_sec;
  64       delay = *timeout;
  65     }
  66   else
  67     {
  68       // Placate compiler.
  69       delay.tv_sec = delay.tv_usec = 0;
  70     }
  71
  72   while (1)
  73     {
  74       int r = select (n, readfds, writefds, exceptfds,
  75                       timeout ? &delay : NULL);
  76       if (r != -1 || errno != EINTR)
  77         return r;
  78
  79       struct timeval after;
  80       if (timeout)
  81         {
  82           _Jv_gettimeofday (&after);
  83           // Now compute new timeout argument.
  84           delay.tv_usec = end.tv_usec - after.tv_usec;
  85           delay.tv_sec = end.tv_sec - after.tv_sec;
  86           if (delay.tv_usec < 0)
  87             {
  88               --delay.tv_sec;
  89               delay.tv_usec += 1000000;
  90             }
  91           if (delay.tv_sec < 0)
  92             {
  93               // We assume that the user wants a valid select() call
  94               // more than precise timing.  So if we get a series of
  95               // EINTR we just keep trying with delay 0 until we get a
  96               // valid result.
  97               delay.tv_sec = 0;
  98             }
  99         }
 100     }
 101 #else /* HAVE_SELECT */
 102   return 0;
 103 #endif
 104 }