hurd/msgportdemux.c

   1 /* Demux messages sent on the signal port.
   2    Copyright (C) 1991-2017 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <hurd.h>
  20 #include <hurd/signal.h>
  21 #include <stddef.h>
  22
  23 struct demux
  24   {
  25     struct demux *next;
  26     boolean_t (*demux) (mach_msg_header_t *inp,
  27                         mach_msg_header_t *outp);
  28   };
  29
  30 struct demux *_hurd_msgport_demuxers = NULL;
  31
  32 extern boolean_t __msg_server (mach_msg_header_t *inp,
  33                                mach_msg_header_t *outp);
  34
  35 static boolean_t
  36 msgport_server (mach_msg_header_t *inp,
  37                 mach_msg_header_t *outp)
  38 {
  39   extern boolean_t _S_msg_server (mach_msg_header_t *inp,
  40                                   mach_msg_header_t *outp);
  41   extern boolean_t _S_exc_server (mach_msg_header_t *inp,
  42                                   mach_msg_header_t *outp);
  43   struct demux *d;
  44
  45   for (d = _hurd_msgport_demuxers; d != NULL; d = d->next)
  46     if ((*d->demux) (inp, outp))
  47       return 1;
  48
  49   return (_S_exc_server (inp, outp) ||
  50           _S_msg_server (inp, outp));
  51 }
  52
  53 /* This is the code that the signal thread runs.  */
  54 void
  55 _hurd_msgport_receive (void)
  56 {
  57   /* Get our own sigstate cached so we never again have to take a lock to
  58      fetch it.  There is much code in hurdsig.c that operates with some
  59      sigstate lock held, which will deadlock with _hurd_thread_sigstate.
  60
  61      Furthermore, in the cthreads case this is the convenient spot
  62      to initialize _hurd_msgport_thread (see hurdsig.c:_hurdsig_init).  */
  63
  64   _hurd_msgport_thread = _hurd_self_sigstate ()->thread;
  65
  66   while (1)
  67     (void) __mach_msg_server (msgport_server, __vm_page_size, _hurd_msgport);
  68 }