1  /* Copyright (C) 1991-2023 Free Software Foundation, Inc.
       2  
       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 <hurd.h>
      21  #include <hurd/signal.h>
      22  #include <hurd/msg.h>
      23  #include <sysdep-cancel.h>
      24  
      25  /* Change the set of blocked signals to SET,
      26     wait until a signal arrives, and restore the set of blocked signals.  */
      27  int
      28  __sigsuspend (const sigset_t *set)
      29  {
      30    struct hurd_sigstate *ss;
      31    sigset_t newmask, oldmask, pending;
      32    mach_port_t wait;
      33    mach_msg_header_t msg;
      34    int cancel_oldtype;
      35  
      36    if (set != NULL)
      37      /* Crash before locking.  */
      38      newmask = *set;
      39  
      40    /* Get a fresh port we will wait on.  */
      41    wait = __mach_reply_port ();
      42  
      43    ss = _hurd_self_sigstate ();
      44  
      45    _hurd_sigstate_lock (ss);
      46  
      47    oldmask = ss->blocked;
      48    if (set != NULL)
      49      /* Change to the new blocked signal mask.  */
      50      ss->blocked = newmask & ~_SIG_CANT_MASK;
      51  
      52    /* Notice if any pending signals just became unblocked.  */
      53    pending = _hurd_sigstate_pending (ss) & ~ss->blocked;
      54  
      55    /* Tell the signal thread to message us when a signal arrives.  */
      56    ss->suspended = wait;
      57    _hurd_sigstate_unlock (ss);
      58  
      59    if (pending)
      60      /* Tell the signal thread to check for pending signals.  */
      61      __msg_sig_post (_hurd_msgport, 0, 0, __mach_task_self ());
      62  
      63    /* Wait for the signal thread's message.  */
      64  
      65    cancel_oldtype = LIBC_CANCEL_ASYNC();
      66    __mach_msg (&msg, MACH_RCV_MSG, 0, sizeof (msg), wait,
      67  	      MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
      68    LIBC_CANCEL_RESET (cancel_oldtype);
      69    __mach_port_destroy (__mach_task_self (), wait);
      70  
      71    /* Restore the old mask and check for pending signals again.  */
      72    _hurd_sigstate_lock (ss);
      73    ss->blocked = oldmask;
      74    pending = _hurd_sigstate_pending(ss) & ~ss->blocked;
      75    _hurd_sigstate_unlock (ss);
      76  
      77    if (pending)
      78      /* Tell the signal thread to check for pending signals.  */
      79      __msg_sig_post (_hurd_msgport, 0, 0, __mach_task_self ());
      80  
      81    /* We've been interrupted!  And a good thing, too.
      82       Otherwise we'd never return.
      83       That's right; this function always returns an error.  */
      84    return __hurd_fail (EINTR);
      85  }
      86  libc_hidden_def (__sigsuspend)
      87  weak_alias (__sigsuspend, sigsuspend)