1  /* Copyright (C) 1993-2023 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, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <errno.h>
      19  #include <unistd.h>
      20  #include <hurd.h>
      21  #include <hurd/port.h>
      22  #include <hurd/fd.h>
      23  #include <hurd/ioctl.h>
      24  #include <lowlevellock.h>
      25  
      26  /* Create a new session with the calling process as its leader.
      27     The process group IDs of the session and the calling process
      28     are set to the process ID of the calling process, which is returned.  */
      29  pid_t
      30  __setsid (void)
      31  {
      32    error_t err;
      33    unsigned int stamp;
      34  
      35  retry:
      36    HURD_CRITICAL_BEGIN;
      37    __mutex_lock (&_hurd_dtable_lock);
      38  
      39    stamp = _hurd_pids_changed_stamp; /* Atomic fetch.  */
      40  
      41    /* Tell the proc server we want to start a new session.  */
      42    err = __USEPORT (PROC, __proc_setsid (port));
      43    if (err)
      44      __mutex_unlock (&_hurd_dtable_lock);
      45    else
      46      {
      47        /* Punt our current ctty, and update the dtable accordingly.  We hold
      48  	 the dtable lock from before the proc_setsid call through clearing
      49  	 the cttyid port and processing the dtable, so that we can be sure
      50  	 that it's all done by the time the signal thread processes the
      51  	 pgrp change notification.  */
      52        _hurd_locked_install_cttyid (MACH_PORT_NULL);
      53  
      54        /* Synchronize with the signal thread to make sure we have received
      55  	 and processed proc_newids before returning to the user.
      56  	 This is necessary to ensure that _hurd_pgrp (and thus the value
      57  	 returned by `getpgrp ()' in other threads) has been updated before
      58  	 we return.  */
      59        while (_hurd_pids_changed_stamp == stamp)
      60          lll_wait (_hurd_pids_changed_stamp, stamp, 0);
      61      }
      62  
      63    HURD_CRITICAL_END;
      64    if (err == EINTR)
      65      /* Got a signal while inside an RPC of the critical section, retry again */
      66      goto retry;
      67  
      68    return err ? __hurd_fail (err) : _hurd_pgrp;
      69  }
      70  
      71  weak_alias (__setsid, setsid)