libdw/dwarf_siblingof.c

/* Return sibling of given DIE.
   Copyright (C) 2003, 2004, 2005, 2007, 2008 Red Hat, Inc.
   This file is part of Red Hat elfutils.
   Written by Ulrich Drepper <drepper@redhat.com>, 2003.

   Red Hat elfutils is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by the
   Free Software Foundation; version 2 of the License.

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   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License along
   with Red Hat elfutils; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

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   additional right to link the code of Red Hat elfutils with code licensed
   under any Open Source Initiative certified open source license
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   this file solely under the GPL without exception.

   Red Hat elfutils is an included package of the Open Invention Network.
   An included package of the Open Invention Network is a package for which
   Open Invention Network licensees cross-license their patents.  No patent
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#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include "libdwP.h"
#include <dwarf.h>
#include <string.h>


int
dwarf_siblingof (die, result)
     Dwarf_Die *die;
     Dwarf_Die *result;
{
  /* Ignore previous errors.  */
  if (die == NULL)
    return -1;

  if (result == NULL)
    return -1;

  if (result != die)
    result->addr = NULL;

  unsigned int level = 0;

  /* Copy of the current DIE.  */
  Dwarf_Die this_die = *die;
  /* Temporary attributes we create.  */
  Dwarf_Attribute sibattr;
  /* Copy of the CU in the request.  */
  sibattr.cu = this_die.cu;
  /* That's the address we start looking.  */
  unsigned char *addr = this_die.addr;
  /* End of the buffer.  */
  unsigned char *endp
    = ((unsigned char *) sibattr.cu->dbg->sectiondata[IDX_debug_info]->d_buf
       + sibattr.cu->end);

  /* Search for the beginning of the next die on this level.  We
     must not return the dies for children of the given die.  */
  do
    {
      /* Find the end of the DIE or the sibling attribute.  */
      addr = __libdw_find_attr (&this_die, DW_AT_sibling, &sibattr.code,
				&sibattr.form);
      if (sibattr.code == DW_AT_sibling)
	{
	  Dwarf_Off offset;
	  sibattr.valp = addr;
	  if (unlikely (__libdw_formref (&sibattr, &offset) != 0))
	    /* Something went wrong.  */
	    return -1;

	  /* Compute the next address.  */
	  addr = ((unsigned char *)
		  sibattr.cu->dbg->sectiondata[IDX_debug_info]->d_buf
		  + sibattr.cu->start + offset);
	}
      else if (unlikely (addr == NULL)
	       || unlikely (this_die.abbrev == DWARF_END_ABBREV))
	return -1;
      else if (this_die.abbrev->has_children)
	/* This abbreviation has children.  */
	++level;


      while (1)
	{
	  /* Make sure we are still in range.  Some producers might skip
	     the trailing NUL bytes.  */
	  if (addr >= endp)
	    return 1;

	  if (*addr != '\0')
	    break;

	  if (level-- == 0)
	    {
	      if (result != die)
		result->addr = addr;
	      /* No more sibling at all.  */
	      return 1;
	    }

	  ++addr;
	}

      /* Initialize the 'current DIE'.  */
      this_die.addr = addr;
      this_die.abbrev = NULL;
    }
  while (level > 0);

  /* Maybe we reached the end of the CU.  */
  if (addr >= endp)
    return 1;

  /* Clear the entire DIE structure.  This signals we have not yet
     determined any of the information.  */
  memset (result, '\0', sizeof (Dwarf_Die));

  /* We have the address.  */
  result->addr = addr;

  /* Same CU as the parent.  */
  result->cu = sibattr.cu;

  return 0;
}
INTDEF(dwarf_siblingof)