sysdeps/mach/hurd/setsid.c

   1 /* Copyright (C) 1993,94,95,97,99 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <unistd.h>
  21 #include <hurd.h>
  22 #include <hurd/port.h>
  23 #include <hurd/fd.h>
  24
  25 /* Create a new session with the calling process as its leader.
  26    The process group IDs of the session and the calling process
  27    are set to the process ID of the calling process, which is returned.  */
  28 pid_t
  29 __setsid (void)
  30 {
  31   error_t err;
  32   unsigned int stamp;
  33
  34   HURD_CRITICAL_BEGIN;
  35   __mutex_lock (&_hurd_dtable_lock);
  36
  37   stamp = _hurd_pids_changed_stamp; /* Atomic fetch.  */
  38
  39   /* Tell the proc server we want to start a new session.  */
  40   err = __USEPORT (PROC, __proc_setsid (port));
  41   if (err)
  42     __mutex_unlock (&_hurd_dtable_lock);
  43   else
  44     {
  45       /* Punt our current ctty, and update the dtable accordingly.  We hold
  46          the dtable lock from before the proc_setsid call through clearing
  47          the cttyid port and processing the dtable, so that we can be sure
  48          that it's all done by the time the signal thread processes the
  49          pgrp change notification.  */
  50       _hurd_locked_install_cttyid (MACH_PORT_NULL);
  51
  52       /* Synchronize with the signal thread to make sure we have received
  53          and processed proc_newids before returning to the user.
  54          This is necessary to ensure that _hurd_pgrp (and thus the value
  55          returned by `getpgrp ()' in other threads) has been updated before
  56          we return.  */
  57       while (_hurd_pids_changed_stamp == stamp)
  58         {
  59 #ifdef noteven
  60           /* XXX we have no need for a mutex, but cthreads demands one.  */
  61           __condition_wait (&_hurd_pids_changed_sync, NULL);
  62 #else
  63           __swtch_pri (0);
  64 #endif
  65         }
  66     }
  67
  68   HURD_CRITICAL_END;
  69
  70   return err ? __hurd_fail (err) : _hurd_pgrp;
  71 }
  72
  73 weak_alias (__setsid, setsid)