text: /* Return backtrace of current program state.  Generic version.
     Copyright (C) 1998-2015 Free Software Foundation, Inc.
     This file is part of the GNU C Library.
     Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; if not, see
     <http://www.gnu.org/licenses/>.  */
  
  #include <execinfo.h>
  #include <signal.h>
  #include <frame.h>
  #include <sigcontextinfo.h>
  #include <ldsodefs.h>
  
  /* This implementation assumes a stack layout that matches the defaults
     used by gcc's `__builtin_frame_address' and `__builtin_return_address'
     (FP is the frame pointer register):
  
  	  +-----------------+     +-----------------+
      FP -> | previous FP --------> | previous FP ------>...
  	  |                 |     |                 |
  	  | return address  |     | return address  |
  	  +-----------------+     +-----------------+
  
    */
  
  /* Get some notion of the current stack.  Need not be exactly the top
     of the stack, just something somewhere in the current frame.  */
  #ifndef CURRENT_STACK_FRAME
  # define CURRENT_STACK_FRAME  ({ char __csf; &__csf; })
  #endif
  
  /* By default we assume that the stack grows downward.  */
  #ifndef INNER_THAN
  # define INNER_THAN <
  #endif
  
  /* By default assume the `next' pointer in struct layout points to the
     next struct layout.  */
  #ifndef ADVANCE_STACK_FRAME
  # define ADVANCE_STACK_FRAME(next) ((struct layout *) (next))
  #endif
  
  /* By default, the frame pointer is just what we get from gcc.  */
  #ifndef FIRST_FRAME_POINTER
  # define FIRST_FRAME_POINTER  __builtin_frame_address (0)
  #endif
  
  int
  __backtrace (array, size)
       void **array;
       int size;
  {
    struct layout *current;
    void *top_frame;
    void *top_stack;
    int cnt = 0;
  
    top_frame = FIRST_FRAME_POINTER;
    top_stack = CURRENT_STACK_FRAME;
  
    /* We skip the call to this function, it makes no sense to record it.  */
    current = ((struct layout *) top_frame);
    while (cnt < size)
      {
        if ((void *) current INNER_THAN top_stack
  	  || !((void *) current INNER_THAN __libc_stack_end))
         /* This means the address is out of range.  Note that for the
  	  toplevel we see a frame pointer with value NULL which clearly is
  	  out of range.  */
  	break;
  
        array[cnt++] = current->return_address;
  
        current = ADVANCE_STACK_FRAME (current->next);
      }
  
    return cnt;
  }
  weak_alias (__backtrace, backtrace)
  libc_hidden_def (__backtrace)
  