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/* dwarf2-backtrac.cc - backtrace implementation driven by the dwarf2

 exception unwinder.  */

/* Copyright (C) 2003  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the

Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for

details.  */

/* Written by David Daney <ddaney@avtrex.com> */

/*

  Although this in theory could be 'C' instead of C++, saying that it

  is C++ and including jvm.h makes it easier to insure that the proper

  compiler options are used.  There must be unwind tables for

  backtrace because it is on the stack when _Unwind_Backtrace is

  called.  Compiling as C++ insures this.

*/

#include <config.h>

#include <unwind.h>

#include <jvm.h>

extern "C"

{

  int backtrace (void **, int);

}

struct backtrace_state

{

  int skip_count;

  int current_level;

  int max_level;

  void **locations;

};

static _Unwind_Reason_Code

my_trace_fn (struct _Unwind_Context *uc, void *arg)

{

  struct backtrace_state *bs = (struct backtrace_state *) arg;

  if (bs->skip_count)

    {

      bs->skip_count--;

      return _URC_NO_REASON;

    }

  _Unwind_Ptr loc = _Unwind_GetIP (uc);

  if (bs->current_level < bs->max_level)

    bs->locations[bs->current_level++] = (void *) loc;

  if (bs->current_level >= bs->max_level)

    return _URC_END_OF_STACK;

  else

    return _URC_NO_REASON;

}

/*

 * backtrace is defined in (some versions of) libc.  This definition

 * must match so that it can replace the libc version at link time.

 *

 * Fill the locations array with at most len back trace locations.

 *

 * Returns the number of locations actually filled in.

 *

 */

int

backtrace (void **locations, int len)

{

  struct backtrace_state bs;

  bs.skip_count = 1;            /* Don't log the call to backtrace itself. */

  bs.current_level = 0;

  bs.max_level = len;

  bs.locations = locations;

  _Unwind_Backtrace (my_trace_fn, &bs);

  return bs.current_level;

}