1  /* Stack overflow handling.
       2  
       3     Copyright (C) 2002, 2004, 2008-2021 Free Software Foundation, Inc.
       4  
       5     This program is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU General Public License as published by
       7     the Free Software Foundation; either version 3 of the License, or
       8     (at your option) any later version.
       9  
      10     This program 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
      13     GNU General Public License for more details.
      14  
      15     You should have received a copy of the GNU General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  
      19  /* Set up ACTION so that it is invoked on C stack overflow and on other,
      20     stack-unrelated, segmentation violation.
      21     Return -1 (setting errno) if this cannot be done.
      22  
      23     When a stack overflow or segmentation violation occurs:
      24     1) ACTION is called.  It is passed an argument equal to
      25          - 0, for a stack overflow,
      26          - SIGSEGV, for a segmentation violation that does not appear related
      27            to stack overflow.
      28        On many platforms the two cases are hard to distinguish; when in doubt,
      29        zero is passed.
      30     2) If ACTION returns, a message is written to standard error, and the
      31        program is terminated: in the case of stack overflow, with exit code
      32        exit_failure (see "exitfail.h"), otherwise through a signal SIGSEGV.
      33  
      34     A null ACTION acts like an action that does nothing.
      35  
      36     Restrictions:
      37     - ACTION must be async-signal-safe.
      38     - ACTION together with its callees must not require more than 64 KiB of
      39       stack space.
      40     - ACTION must not create and then invoke nested functions
      41       <https://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html>, because
      42       this implementation does not guarantee an executable stack.
      43     - ACTION should not call longjmp, because this implementation does not
      44       guarantee that it is safe to return to the original stack.
      45  
      46     This function may install a handler for the SIGSEGV signal or for the SIGBUS
      47     signal or exercise other system dependent exception handling APIs.  */
      48  
      49  extern int c_stack_action (_GL_ASYNC_SAFE void (* /*action*/) (int));