sysdeps/unix/sysv/linux/microblaze/pselect32.c

   1 /* Synchronous I/O multiplexing.  Linux/microblaze version.
   2    Copyright (C) 2019-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <signal.h>
  21 #include <time.h>
  22 #include <sys/poll.h>
  23 #include <sysdep-cancel.h>
  24
  25 #ifndef __ASSUME_PSELECT
  26 int
  27 __pselect32 (int nfds, fd_set *readfds, fd_set *writefds,
  28              fd_set *exceptfds, const struct __timespec64 *timeout,
  29              const sigset_t *sigmask)
  30 {
  31   /* The fallback uses 'select' which shows the race condition regarding
  32      signal mask set/restore, requires two additional syscalls, and has
  33      a worse timeout precision (microseconds instead of nanoseconds).  */
  34
  35   struct timeval tv32, *ptv32 = NULL;
  36   if (timeout != NULL)
  37     {
  38       if (! in_time_t_range (timeout->tv_sec)
  39           || ! valid_nanoseconds (timeout->tv_nsec))
  40         {
  41           __set_errno (EINVAL);
  42           return -1;
  43         }
  44
  45       tv32 = valid_timespec64_to_timeval (*timeout);
  46       ptv32 = &tv32;
  47     }
  48
  49   sigset_t savemask;
  50   if (sigmask != NULL)
  51     __sigprocmask (SIG_SETMASK, sigmask, &savemask);
  52
  53   /* select itself is a cancellation entrypoint.  */
  54   int ret = __select (nfds, readfds, writefds, exceptfds, ptv32);
  55
  56   if (sigmask != NULL)
  57     __sigprocmask (SIG_SETMASK, &savemask, NULL);
  58
  59   return ret;
  60 }
  61 #endif /* __ASSUME_PSELECT  */