sysdeps/generic/pselect.c

   1 /* Copyright (C) 1996, 1997, 1998 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 <signal.h>
  22 #include <sys/time.h>
  23 #include <sys/select.h>
  24
  25 /* Check the first NFDS descriptors each in READFDS (if not NULL) for read
  26    readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
  27    (if not NULL) for exceptional conditions.  If TIMEOUT is not NULL, time out
  28    after waiting the interval specified therein.  Additionally set the sigmask
  29    SIGMASK for this call.  Returns the number of ready descriptors, or -1 for
  30    errors.  */
  31 int
  32 __pselect (nfds, readfds, writefds, exceptfds, timeout, sigmask)
  33      int nfds;
  34      fd_set *readfds;
  35      fd_set *writefds;
  36      fd_set *exceptfds;
  37      const struct timespec *timeout;
  38      const sigset_t *sigmask;
  39 {
  40   struct timeval tval;
  41   int retval;
  42   sigset_t savemask;
  43
  44   /* Change nanosecond number to microseconds.  This may loose
  45      precision and therefore the `pselect` should be available.  But
  46      for now it is hardly found.  */
  47   if (timeout != NULL)
  48     TIMESPEC_TO_TIMEVAL (&tval, timeout);
  49
  50   /* The setting and restoring of the signal mask and the select call
  51      should be an atomic operation.  This can't be done without kernel
  52      help.  */
  53   __sigprocmask (SIG_SETMASK, sigmask, &savemask);
  54   retval = __select (nfds, readfds, writefds, exceptfds,
  55                      timeout != NULL ? &tval : NULL);
  56   __sigprocmask (SIG_SETMASK, &savemask, NULL);
  57
  58   return retval;
  59 }
  60 weak_alias (__pselect, pselect)