1  /* Tests of signal delivery on an alternate stack (quick_exit).
       2     Copyright (C) 2019-2023 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     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <support/xsignal.h>
      20  #include <support/support.h>
      21  #include <support/check.h>
      22  #include <stdlib.h>
      23  
      24  /* C2011 7.4.1.1p5 specifies that only the following operations are
      25     guaranteed to be well-defined inside an asynchronous signal handler:
      26       * any operation on a lock-free atomic object
      27       * assigning a value to an object declared as volatile sig_atomic_t
      28       * calling abort, _Exit, quick_exit, or signal
      29         * signal may only be called with its first argument equal to the
      30           number of the signal that caused the handler to be called
      31  
      32     We use this list as a guideline for the set of operations that ought
      33     also to be safe in a _synchronous_ signal delivered on an alternate
      34     signal stack with only MINSIGSTKSZ bytes of space.
      35  
      36     This test program tests calls to quick_exit.  Note that this is only
      37     safe when there are no at_quick_exit callbacks.  */
      38  
      39  #define EXPECTED_STATUS 3
      40  
      41  static void
      42  handler (int unused)
      43  {
      44    quick_exit (EXPECTED_STATUS);
      45  }
      46  
      47  int
      48  do_test (void)
      49  {
      50    void *sstk = xalloc_sigstack (0);
      51    struct sigaction sa;
      52  
      53    sa.sa_handler = handler;
      54    sa.sa_flags   = SA_RESTART | SA_ONSTACK;
      55    sigfillset (&sa.sa_mask);
      56    if (sigaction (SIGUSR1, &sa, 0))
      57      FAIL_RET ("sigaction (SIGUSR1, handler): %m\n");
      58  
      59    raise (SIGUSR1);
      60  
      61    xfree_sigstack (sstk);
      62    FAIL_RET ("test process was not terminated by quick_exit in signal handler");
      63  }
      64  
      65  #include <support/test-driver.c>