sysdeps/generic/pselect.c

   1 /* Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <sys/time.h>
  22 #include <sys/select.h>
  23
  24 /* Check the first NFDS descriptors each in READFDS (if not NULL) for read
  25    readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
  26    (if not NULL) for exceptional conditions.  If TIMEOUT is not NULL, time out
  27    after waiting the interval specified therein.  Returns the number of ready
  28    descriptors, or -1 for errors.  */
  29 int
  30 __pselect (nfds, readfds, writefds, exceptfds, timeout)
  31      int nfds;
  32      fd_set *readfds;
  33      fd_set *writefds;
  34      fd_set *exceptfds;
  35      struct timespec *timeout;
  36 {
  37   struct timeval tval;
  38   int retval;
  39
  40   /* Change nanosecond number to microseconds.  This may loose
  41      precision and therefore the `pselect` should be available.  But
  42      for now it is hardly found.  */
  43   if (timeout != NULL)
  44     TIMESPEC_TO_TIMEVAL (&tval, timeout);
  45
  46   retval = __select (nfds, readfds, writefds, exceptfds,
  47                      timeout != NULL ? &tval : NULL);
  48
  49   /* Change the result back.  The remaining time must be made
  50      available to the caller.  */
  51   if (timeout != NULL)
  52     TIMEVAL_TO_TIMESPEC (&tval, timeout);
  53
  54   return retval;
  55 }
  56 weak_alias (__pselect, pselect)