path: root/libelf/version_xlate.h

/* Conversion functions for versioning information.
   Copyright (C) 1998, 1999, 2000, 2002, 2003, 2015 Red Hat, Inc.
   Copyright (C) 2022 Mark J. Wielaard <mark@klomp.org>
   This file is part of elfutils.
   Written by Ulrich Drepper <drepper@redhat.com>, 1998.

   This file is free software; you can redistribute it and/or modify
   it under the terms of either

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at
       your option) any later version

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at
       your option) any later version

   or both in parallel, as here.

   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 copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see <http://www.gnu.org/licenses/>.  */

#include <assert.h>
#include <gelf.h>

#include "libelfP.h"


static void
elf_cvt_Verdef (void *dest, const void *src, size_t len, int encode)
{
  /* We have two different record types: ElfXX_Verndef and ElfXX_Verdaux.
     To recognize them we have to walk the data structure and convert
     them one after the other.  The ENCODE parameter specifies whether
     we are encoding or decoding.  When we are encoding we can immediately
     use the data in the buffer; if not, we have to decode the data before
     using it.  */
  size_t def_offset = 0;
  GElf_Verdef *ddest;
  GElf_Verdef *dsrc;

  /* We rely on the types being all the same size.  */
  assert (sizeof (GElf_Verdef) == sizeof (Elf32_Verdef));
  assert (sizeof (GElf_Verdaux) == sizeof (Elf32_Verdaux));
  assert (sizeof (GElf_Verdef) == sizeof (Elf64_Verdef));
  assert (sizeof (GElf_Verdaux) == sizeof (Elf64_Verdaux));

  if (len == 0)
    return;

  /* Below we rely on the next field offsets to be correct, start by
     copying over all data as is in case some data isn't translated.
     We don't want to leave (undefined) garbage in the dest buffer.  */
  memmove (dest, src, len);

  do
    {
      size_t aux_offset;
      GElf_Verdaux *asrc;

      /* Test for correct offset.  */
      if (def_offset > len
	  || len - def_offset < sizeof (GElf_Verdef)
	  || (def_offset & (__alignof__ (GElf_Verdef) - 1)) != 0)
	return;

      /* Work the tree from the first record.  */
      ddest = (GElf_Verdef *) ((char *) dest + def_offset);
      dsrc = (GElf_Verdef *) ((char *) src + def_offset);

      /* Decode first if necessary.  */
      if (! encode)
	{
	  ddest->vd_version = bswap_16 (dsrc->vd_version);
	  ddest->vd_flags = bswap_16 (dsrc->vd_flags);
	  ddest->vd_ndx = bswap_16 (dsrc->vd_ndx);
	  ddest->vd_cnt = bswap_16 (dsrc->vd_cnt);
	  ddest->vd_hash = bswap_32 (dsrc->vd_hash);
	  ddest->vd_aux = bswap_32 (dsrc->vd_aux);
	  ddest->vd_next = bswap_32 (dsrc->vd_next);

	  if (ddest->vd_aux > len - def_offset)
	    return;
	  aux_offset = def_offset + ddest->vd_aux;
	}
      else
	{
	  if (dsrc->vd_aux > len - def_offset)
	    return;
	  aux_offset = def_offset + dsrc->vd_aux;
	}

      /* Handle all the auxiliary records belonging to this definition.  */
      do
	{
	  GElf_Verdaux *adest;

	  /* Test for correct offset.  */
	  if (aux_offset > len
	      || len - aux_offset < sizeof (GElf_Verdaux)
	      || (aux_offset & (__alignof__ (GElf_Verdaux) - 1)) != 0)
	    return;

	  adest = (GElf_Verdaux *) ((char *) dest + aux_offset);
	  asrc = (GElf_Verdaux *) ((char *) src + aux_offset);

	  if (encode)
	    {
	      if (asrc->vda_next > len - aux_offset)
		return;
	      aux_offset += asrc->vda_next;
	    }

	  adest->vda_name = bswap_32 (asrc->vda_name);
	  adest->vda_next = bswap_32 (asrc->vda_next);

	  if (! encode)
	    {
	      if (adest->vda_next > len - aux_offset)
		return;
	      aux_offset += adest->vda_next;
	    }
	}
      while (asrc->vda_next != 0);

      /* Encode now if necessary.  */
      if (encode)
	{
	  if (dsrc->vd_next > len - def_offset)
	    return;
	  def_offset += dsrc->vd_next;

	  ddest->vd_version = bswap_16 (dsrc->vd_version);
	  ddest->vd_flags = bswap_16 (dsrc->vd_flags);
	  ddest->vd_ndx = bswap_16 (dsrc->vd_ndx);
	  ddest->vd_cnt = bswap_16 (dsrc->vd_cnt);
	  ddest->vd_hash = bswap_32 (dsrc->vd_hash);
	  ddest->vd_aux = bswap_32 (dsrc->vd_aux);
	  ddest->vd_next = bswap_32 (dsrc->vd_next);
	}
      else
	{
	  if (ddest->vd_next > len - def_offset)
	    return;
	  def_offset += ddest->vd_next;
	}
    }
  while (dsrc->vd_next != 0);
}


static void
elf_cvt_Verneed (void *dest, const void *src, size_t len, int encode)
{
  /* We have two different record types: ElfXX_Verndef and ElfXX_Verdaux.
     To recognize them we have to walk the data structure and convert
     them one after the other.  The ENCODE parameter specifies whether
     we are encoding or decoding.  When we are encoding we can immediately
     use the data in the buffer; if not, we have to decode the data before
     using it.  */
  size_t need_offset = 0;
  GElf_Verneed *ndest;
  GElf_Verneed *nsrc;

  /* We rely on the types being all the same size.  */
  assert (sizeof (GElf_Verneed) == sizeof (Elf32_Verneed));
  assert (sizeof (GElf_Vernaux) == sizeof (Elf32_Vernaux));
  assert (sizeof (GElf_Verneed) == sizeof (Elf64_Verneed));
  assert (sizeof (GElf_Vernaux) == sizeof (Elf64_Vernaux));

  if (len == 0)
    return;

  /* Below we rely on the next field offsets to be correct, start by
     copying over all data as is in case some data isn't translated.
     We don't want to leave (undefined) garbage in the dest buffer.  */
  memmove (dest, src, len);

  do
    {
      size_t aux_offset;
      GElf_Vernaux *asrc;

      /* Test for correct offset.  */
      if (need_offset > len
	  || len - need_offset < sizeof (GElf_Verneed)
	  || (need_offset & (__alignof__ (GElf_Verneed) - 1)) != 0)
	return;

      /* Work the tree from the first record.  */
      ndest = (GElf_Verneed *) ((char *) dest + need_offset);
      nsrc = (GElf_Verneed *) ((char *) src + need_offset);

      /* Decode first if necessary.  */
      if (! encode)
	{
	  ndest->vn_version = bswap_16 (nsrc->vn_version);
	  ndest->vn_cnt = bswap_16 (nsrc->vn_cnt);
	  ndest->vn_file = bswap_32 (nsrc->vn_file);
	  ndest->vn_aux = bswap_32 (nsrc->vn_aux);
	  ndest->vn_next = bswap_32 (nsrc->vn_next);

	  if (ndest->vn_aux > len - need_offset)
	    return;
	  aux_offset = need_offset + ndest->vn_aux;
	}
      else
	{
	  if (nsrc->vn_aux > len - need_offset)
	    return;
	  aux_offset = need_offset + nsrc->vn_aux;
	}

      /* Handle all the auxiliary records belonging to this requirement.  */
      do
	{
	  GElf_Vernaux *adest;

	  /* Test for correct offset.  */
	  if (aux_offset > len
	      || len - aux_offset < sizeof (GElf_Vernaux)
	      || (aux_offset & (__alignof__ (GElf_Vernaux) - 1)) != 0)
	    return;

	  adest = (GElf_Vernaux *) ((char *) dest + aux_offset);
	  asrc = (GElf_Vernaux *) ((char *) src + aux_offset);

	  if (encode)
	    {
	      if (asrc->vna_next > len - aux_offset)
		return;
	      aux_offset += asrc->vna_next;
	    }

	  adest->vna_hash = bswap_32 (asrc->vna_hash);
	  adest->vna_flags = bswap_16 (asrc->vna_flags);
	  adest->vna_other = bswap_16 (asrc->vna_other);
	  adest->vna_name = bswap_32 (asrc->vna_name);
	  adest->vna_next = bswap_32 (asrc->vna_next);

	  if (! encode)
	    {
	      if (adest->vna_next > len - aux_offset)
		return;
	      aux_offset += adest->vna_next;
	    }
	}
      while (asrc->vna_next != 0);

      /* Encode now if necessary.  */
      if (encode)
	{
	  if (nsrc->vn_next > len - need_offset)
	    return;
	  need_offset += nsrc->vn_next;

	  ndest->vn_version = bswap_16 (nsrc->vn_version);
	  ndest->vn_cnt = bswap_16 (nsrc->vn_cnt);
	  ndest->vn_file = bswap_32 (nsrc->vn_file);
	  ndest->vn_aux = bswap_32 (nsrc->vn_aux);
	  ndest->vn_next = bswap_32 (nsrc->vn_next);
	}
      else
	{
	  if (ndest->vn_next > len - need_offset)
	    return;
	  need_offset += ndest->vn_next;
	}
    }
  while (nsrc->vn_next != 0);
}