libdwarf/dwarf_child.c

/* Return child of die.
   Copyright (C) 2000, 2001, 2002 Red Hat, Inc.
   Written by Ulrich Drepper <drepper@redhat.com>, 2000.

   This program is Open Source software; you can redistribute it and/or
   modify it under the terms of the Open Software License version 1.0 as
   published by the Open Source Initiative.

   You should have received a copy of the Open Software License along
   with this program; if not, you may obtain a copy of the Open Software
   License version 1.0 from http://www.opensource.org/licenses/osl.php or
   by writing the Open Source Initiative c/o Lawrence Rosen, Esq.,
   3001 King Ranch Road, Ukiah, CA 95482.   */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdlib.h>

#include <libdwarfP.h>


int
dwarf_child (die, return_kid, error)
     Dwarf_Die die;
     Dwarf_Die *return_kid;
     Dwarf_Error *error;
{
  Dwarf_Debug dbg = die->cu->dbg;
  Dwarf_Abbrev abbrev;
  Dwarf_Small *attrp;
  Dwarf_Small *die_addr;
  Dwarf_Word u128;
  Dwarf_Die new_die;

  if (! die->abbrev->has_children)
    return DW_DLV_NO_ENTRY;

  /* Address of the given die.  */
  die_addr = die->addr;

  /* Get abbrev code.  */
  get_uleb128 (u128, die_addr);
  /*  And get the abbreviation itself.  */
  abbrev = __libdwarf_get_abbrev (dbg, die->cu, u128, error);
  if (abbrev == NULL)
    return DW_DLV_ERROR;

  /* This is where the attributes start.  */
  attrp = abbrev->attrp;

  /* Skip over the attributes of the given die.  */
  while (1)
    {
      Dwarf_Word attr_name;
      Dwarf_Word attr_form;

      /* Are we still in bounds?  */
      if (unlikely (attrp
		    >= ((Dwarf_Small *)dbg->sections[IDX_debug_abbrev].addr
			+ dbg->sections[IDX_debug_abbrev].size)))
	{
	  __libdwarf_error (dbg, error, DW_E_INVALID_DWARF);
	  return DW_DLV_ERROR;
	}

      /* Get attribute name and form.

	 XXX We don't check whether this reads beyond the end of the
	 section.  */
      get_uleb128 (attr_name, attrp);
      get_uleb128 (attr_form, attrp);

      /* We can stop if we found the attribute with value zero.  */
      if (attr_name == 0 && attr_form == 0)
	break;

      /* Skip over the rest of this attribute (if there is any).  */
      if (attr_form != 0)
	{
	  size_t len;

	  if (unlikely (__libdwarf_form_val_len (dbg, die->cu, attr_form,
						 die_addr, &len, error)
			!= DW_DLV_OK))
	    return DW_DLV_ERROR;

	  die_addr += len;
	}
    }

  /* Allocate the die structure for the result.  */
  new_die = (Dwarf_Die) malloc (sizeof (struct Dwarf_Die_s));
  if (new_die == NULL)
    {
      __libdwarf_error (dbg, error, DW_E_NOMEM);
      return DW_DLV_ERROR;
    }
#ifdef DWARF_DEBUG
  new_die->memtag = DW_DLA_DIE;
#endif

  /* Remember the address.  */
  new_die->addr = die_addr;

  /* And the compile unit.  */
  new_die->cu = die->cu;

  /* 7.5.2  Debugging Information Entry

     Each debugging information entry begins with an unsigned LEB128
     number containing the abbreviation code for the entry.  */
  get_uleb128 (u128, die_addr);

  /* Find the abbreviation.  */
  new_die->abbrev = __libdwarf_get_abbrev (dbg, die->cu, u128, error);
  if (new_die->abbrev == NULL)
    return DW_DLV_ERROR;

  *return_kid = new_die;
  return DW_DLV_OK;
}