src/libdw/dwarf_getattrs.c

/* Get attributes of the DIE.
   Copyright (C) 2004, 2005, 2008, 2009 Red Hat, Inc.
   This file is part of Red Hat elfutils.
   Written by Ulrich Drepper <drepper@redhat.com>, 2004.

   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.

   In addition, as a special exception, Red Hat, Inc. gives You the
   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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   code used in conjunction with Red Hat elfutils except the Non-GPL Code
   covered by this exception.  If you modify this file, you may extend this
   exception to your version of the file, but you are not obligated to do
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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
   license is granted, either expressly or impliedly, by designation as an
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   <http://www.openinventionnetwork.com>.  */

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

#include "libdwP.h"


ptrdiff_t
dwarf_getattrs (Dwarf_Die *die, int (*callback) (Dwarf_Attribute *, void *),
		void *arg, ptrdiff_t offset)
{
  if (die == NULL)
    return -1l;

  if (unlikely (offset == 1))
    return 1;

  const unsigned char *die_addr = die->addr;

  /* Get the abbreviation code.  */
  unsigned int u128;
  get_uleb128 (u128, die_addr);

  if (die->abbrev == NULL)
    /* Find the abbreviation.  */
    die->abbrev = __libdw_findabbrev (die->cu, u128);

  if (unlikely (die->abbrev == DWARF_END_ABBREV))
    {
    invalid_dwarf:
      __libdw_seterrno (DWARF_E_INVALID_DWARF);
      return -1l;
    }

  /* This is where the attributes start.  */
  const unsigned char *attrp = die->abbrev->attrp;
  const unsigned char *const offset_attrp = die->abbrev->attrp + offset;

  /* Go over the list of attributes.  */
  Dwarf *dbg = die->cu->dbg;
  while (1)
    {
      /* Are we still in bounds?  */
      if (unlikely (attrp
		    >= ((unsigned char *) dbg->sectiondata[IDX_debug_abbrev]->d_buf
			+ dbg->sectiondata[IDX_debug_abbrev]->d_size)))
	goto invalid_dwarf;

      /* Get attribute name and form.  */
      Dwarf_Attribute attr;
      const unsigned char *remembered_attrp = attrp;

      // XXX Fix bound checks
      get_uleb128 (attr.code, attrp);
      get_uleb128 (attr.form, attrp);

      /* We can stop if we found the attribute with value zero.  */
      if (attr.code == 0 && attr.form == 0)
	/* Do not return 0 here - there would be no way to
	   distinguish this value from the attribute at offset 0.
	   Instead we return +1 which would never be a valid
	   offset of an attribute.  */
        return 1l;

      /* If we are not to OFFSET_ATTRP yet, we just have to skip
	 the values of the intervening attributes.  */
      if (remembered_attrp >= offset_attrp)
	{
	  /* Fill in the rest.  */
	  attr.valp = (unsigned char *) die_addr;
	  attr.cu = die->cu;

	  /* Now call the callback function.  */
	  if (callback (&attr, arg) != DWARF_CB_OK)
	    /* Return the offset of the start of the attribute, so that
	       dwarf_getattrs() can be restarted from this point if the
	       caller so desires.  */
	    return remembered_attrp - die->abbrev->attrp;
	}

      /* Skip over the rest of this attribute (if there is any).  */
      if (attr.form != 0)
	{
	  size_t len = __libdw_form_val_len (dbg, die->cu, attr.form,
					     die_addr);

	  if (unlikely (len == (size_t) -1l))
	    /* Something wrong with the file.  */
	    return -1l;

	  // XXX We need better boundary checks.
	  die_addr += len;
	}
    }
  /* NOTREACHED */
}