libdwarf/dwarf_offdie.c

/* Return die at given offset.
   Copyright (C) 2000, 2002 Red Hat, Inc.
   This file is part of Red Hat elfutils.
   Written by Ulrich Drepper <drepper@redhat.com>, 2000.

   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.

   Red Hat elfutils 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
   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.

   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
   license is granted, either expressly or impliedly, by designation as an
   included package.  Should you wish to participate in the Open Invention
   Network licensing program, please visit www.openinventionnetwork.com
   <http://www.openinventionnetwork.com>.  */

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

#include <dwarf.h>
#include <stdlib.h>

#include <libdwarfP.h>


/* XXX This function will have to be optimized.  The search is too linear
   to be performed too often -> O(n²).  */
static Dwarf_CU_Info
find_cu (Dwarf_Debug dbg, Dwarf_Off offset, Dwarf_Error *error)
{
  Dwarf_CU_Info cu;
  Dwarf_Word cu_offset;

  /* Search in the CUs already known.  */
  for (cu = dbg->cu_list; cu != NULL; cu = cu->next)
    if (cu->offset <= offset
	&& cu->offset + 2 * cu->offset_size - 4 + cu->length > offset)
      return cu;

  /* The CU is not yet loaded.  Do this now.  */
  if (dbg->cu_list_tail == NULL)
    cu_offset = 0;
  else
    cu_offset = (dbg->cu_list_tail->offset
		 + 2 * dbg->cu_list_tail->offset_size - 4
		 + dbg->cu_list_tail->length);

  while (1)
    {
      /* Get next CU and add it to the end of the list.  */
      if (__libdwarf_get_cu_at_offset (dbg, cu_offset, &cu, error)
	  != DW_DLV_OK)
	return NULL;

      /* Offset of next CU.  */
      cu_offset += 2 * cu->offset_size - 4 + cu->length;

      /* If this the CU we are looking for?  */
      if (offset < cu_offset)
	return cu;
    }
}


int
dwarf_offdie (dbg, offset, return_die, error)
     Dwarf_Debug dbg;
     Dwarf_Off offset;
     Dwarf_Die *return_die;
     Dwarf_Error *error;
{
  Dwarf_CU_Info cu;
  Dwarf_Die new_die;
  Dwarf_Small *die_addr;
  Dwarf_Word u128;

  if (offset >= dbg->sections[IDX_debug_info].size)
    {
      /* Completely out of bounds.  */
      __libdwarf_error (dbg, error, DW_E_INVALID_OFFSET);
      return DW_DLV_ERROR;
    }

  /* Find the compile unit this address belongs to.  */
  cu = find_cu (dbg, offset, error);
  if (cu == NULL)
    return DW_DLV_ERROR;

  /* Creata a new die.  */
  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.  */
  die_addr = (Dwarf_Small *) dbg->sections[IDX_debug_info].addr + offset;
  new_die->addr = die_addr;

  /* And the compile unit.  */
  new_die->cu = 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, cu, u128, error);
  if (new_die->abbrev == NULL)
    {
      free (new_die);
      return DW_DLV_ERROR;
    }

  *return_die = new_die;
  return DW_DLV_OK;
}