1  /* Copyright (C) 1992-2023 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 <hurd.h>
      20  #include <hurd/signal.h>
      21  
      22  /* Run signals handlers on the stack specified by SS (if not NULL).
      23     If OSS is not NULL, it is filled in with the old signal stack status.  */
      24  int
      25  __sigaltstack (const stack_t *argss, stack_t *oss)
      26  {
      27    struct hurd_sigstate *s;
      28    stack_t ss, old;
      29  
      30    /* Fault before taking any locks.  */
      31    if (argss != NULL)
      32      ss = *argss;
      33    if (oss != NULL)
      34      *(volatile stack_t *) oss = *oss;
      35  
      36    s = _hurd_self_sigstate ();
      37    __spin_lock (&s->lock);
      38  
      39    if (argss != NULL
      40        && (ss.ss_flags & SS_DISABLE)
      41        && (s->sigaltstack.ss_flags & SS_ONSTACK))
      42      {
      43        /* Can't disable a stack that is in use.  */
      44        __spin_unlock (&s->lock);
      45        return __hurd_fail (EINVAL);
      46      }
      47  
      48    old = s->sigaltstack;
      49  
      50    if (argss != NULL)
      51      s->sigaltstack = ss;
      52  
      53    __spin_unlock (&s->lock);
      54  
      55    if (oss != NULL)
      56      *oss = old;
      57  
      58    return 0;
      59  }
      60  libc_hidden_def (__sigaltstack)
      61  weak_alias (__sigaltstack, sigaltstack)