hurd/ctty-output.c

   1 /* _hurd_ctty_output -- Do an output RPC and generate SIGTTOU if necessary.
   2    Copyright (C) 1995-2023 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 <hurd.h>
  20 #include <hurd/signal.h>
  21
  22 /* Call *RPC on PORT and/or CTTY.  If a call on CTTY returns EBACKGROUND,
  23    generate SIGTTOU if appropriate.  */
  24
  25 error_t
  26 _hurd_ctty_output (io_t port, io_t ctty, error_t (*rpc) (io_t))
  27 {
  28   if (ctty == MACH_PORT_NULL)
  29     return (*rpc) (port);
  30   else
  31     {
  32       struct hurd_sigstate *ss = _hurd_self_sigstate ();
  33       error_t err;
  34
  35       do
  36         {
  37           struct sigaction *actions;
  38
  39           /* Don't use the ctty io port if we are blocking or ignoring
  40              SIGTTOU.  We redo this check at the top of the loop in case
  41              the signal handler changed the state.  */
  42           _hurd_sigstate_lock (ss);
  43           actions = _hurd_sigstate_actions (ss);
  44           if (__sigismember (&ss->blocked, SIGTTOU)
  45               || actions[SIGTTOU].sa_handler == SIG_IGN)
  46             err = EIO;
  47           else
  48             err = 0;
  49           _hurd_sigstate_unlock (ss);
  50
  51           if (err)
  52             return (*rpc) (port);
  53
  54           err = (*rpc) (ctty);
  55           if (err == EBACKGROUND)
  56             {
  57               if (_hurd_orphaned)
  58                 /* Our process group is orphaned, so we never generate a
  59                    signal; we just fail.  */
  60                 err = EIO;
  61               else
  62                 {
  63                   /* Send a SIGTTOU signal to our process group.
  64
  65                      We must remember here not to clobber ERR, since
  66                      the loop condition below uses it to recall that
  67                   we should retry after a stop.  */
  68
  69                   __USEPORT (CTTYID, _hurd_sig_post (0, SIGTTOU, port));
  70                   /* XXX what to do if error here? */
  71
  72                   /* At this point we should have just run the handler for
  73                      SIGTTOU or resumed after being stopped.  Now this is
  74                      still a "system call", so check to see if we should
  75                   restart it.  */
  76                   _hurd_sigstate_lock (ss);
  77                   actions = _hurd_sigstate_actions (ss);
  78                   if (!(actions[SIGTTOU].sa_flags & SA_RESTART))
  79                     err = EINTR;
  80                   _hurd_sigstate_unlock (ss);
  81                 }
  82             }
  83           /* If the last RPC generated a SIGTTOU, loop to try it again.  */
  84         } while (err == EBACKGROUND);
  85
  86       return err;
  87     }
  88 }