sysdeps/i386/backtrace.c

   1 /* Return backtrace of current program state.
   2    Copyright (C) 1998 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <execinfo.h>
  22
  23
  24 /* This is a global variable set at program start time.  It marks the
  25    highest used stack address.  */
  26 extern void *__libc_stack_end;
  27
  28
  29 /* This is the stack alyout we see with every stack frame.
  30
  31             +-----------------+        +-----------------+
  32     %ebp -> | %ebp last frame--------> | %ebp last frame--->...
  33             |                 |        |                 |
  34             | return address  |        | return address  |
  35             +-----------------+        +-----------------+
  36 */
  37 struct layout
  38 {
  39   struct layout *next;
  40   void *return_address;
  41 };
  42
  43 int
  44 __backtrace (array, size)
  45      void **array;
  46      int size;
  47 {
  48   /* We assume that all the code is generated with frame pointers set.  */
  49   register void *ebp __asm__ ("ebp");
  50   register void *esp __asm__ ("esp");
  51   struct layout *current;
  52   int cnt = 0;
  53
  54   /* We skip the call to this function, it makes no sense to record it.  */
  55   current = (struct layout *) ebp;
  56   while (cnt < size)
  57     {
  58       if ((void *) current < esp || (void *) current > __libc_stack_end)
  59         /* This means the address is out of range.  Note that for the
  60            toplevel we see a frame pointer with value NULL which clearly is
  61            out of range.  */
  62         break;
  63
  64       array[cnt++] = current->return_address;
  65
  66       current = current->next;
  67     }
  68
  69   return cnt;
  70 }
  71 weak_alias (__backtrace, backtrace)