/* Get information from dynamic table at the given index.

   Copyright (C) 2000, 2001, 2002, 2005, 2009, 2014, 2015 Red Hat, Inc.

   This file is part of elfutils.

   Written by Ulrich Drepper <drepper@redhat.com>, 2000.

   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/>.  */

#ifdef HAVE_CONFIG_H

# include <config.h>

#endif

#include <assert.h>

#include <gelf.h>

#include <string.h>

#include "libelfP.h"

GElf_Dyn *

gelf_getdyn (Elf_Data *data, int ndx, GElf_Dyn *dst)

{

  Elf_Data_Scn *data_scn = (Elf_Data_Scn *) data;

  GElf_Dyn *result = NULL;

  Elf *elf;

  if (data_scn == NULL)

    return NULL;

  if (unlikely (data_scn->d.d_type != ELF_T_DYN))

    {

      __libelf_seterrno (ELF_E_INVALID_HANDLE);

      return NULL;

    }

  elf = data_scn->s->elf;

  rwlock_rdlock (elf->lock);

  /* This is the one place where we have to take advantage of the fact

     that an `Elf_Data' pointer is also a pointer to `Elf_Data_Scn'.

     The interface is broken so that it requires this hack.  */

  if (elf->class == ELFCLASS32)

    {

      Elf32_Dyn *src;

      /* Here it gets a bit more complicated.  The format of the symbol

	 table entries has to be adopted.  The user better has provided

	 a buffer where we can store the information.  While copying the

	 data we are converting the format.  */

      if (INVALID_NDX (ndx, Elf32_Dyn, &data_scn->d))

	{

	  __libelf_seterrno (ELF_E_INVALID_INDEX);

	  goto out;

	}

      src = &((Elf32_Dyn *) data_scn->d.d_buf)[ndx];

      /* This might look like a simple copy operation but it's

	 not.  There are zero- and sign-extensions going on.  */

      dst->d_tag = src->d_tag;

      /* It OK to copy `d_val' since `d_ptr' has the same size.  */

      dst->d_un.d_val = src->d_un.d_val;

    }

  else

    {

      /* If this is a 64 bit object it's easy.  */

      assert (sizeof (GElf_Dyn) == sizeof (Elf64_Dyn));

      /* The data is already in the correct form.  Just make sure the

	 index is OK.  */

      if (INVALID_NDX (ndx, GElf_Dyn, &data_scn->d))

	{

	  __libelf_seterrno (ELF_E_INVALID_INDEX);

	  goto out;

	}

      *dst = ((GElf_Dyn *) data_scn->d.d_buf)[ndx];

    }

  result = dst;

 out:

  rwlock_unlock (elf->lock);

  return result;

}