/* Get section at specific index.

   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2015 Red Hat, Inc.

   This file is part of elfutils.

   Contributed 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/>.  */

#ifdef HAVE_CONFIG_H

# include <config.h>

#endif

#include <assert.h>

#include <stddef.h>

#include <stdlib.h>

#include "libelfP.h"

Elf_Scn *

elf_getscn (Elf *elf, size_t idx)

{

  if (elf == NULL)

    return NULL;

  if (unlikely (elf->kind != ELF_K_ELF))

    {

      __libelf_seterrno (ELF_E_INVALID_HANDLE);

      return NULL;

    }

  rwlock_rdlock (elf->lock);

  Elf_Scn *result = NULL;

  /* Find the section in the list.  */

  Elf_ScnList *runp = (elf->class == ELFCLASS32

		       || (offsetof (struct Elf, state.elf32.scns)

			   == offsetof (struct Elf, state.elf64.scns))

		       ? &elf->state.elf32.scns : &elf->state.elf64.scns);

  /* Section zero is special.  It always exists even if there is no

     "first" section.  And it is needed to store "overflow" values

     from the Elf header.  */

  if (idx == 0 && runp->cnt == 0 && runp->max > 0)

    {

      Elf_Scn *scn0 = &runp->data[0];

      if (elf->class == ELFCLASS32)

	{

	  scn0->shdr.e32 = (Elf32_Shdr *) calloc (1, sizeof (Elf32_Shdr));

	  if (scn0->shdr.e32 == NULL)

	    {

	      __libelf_seterrno (ELF_E_NOMEM);

	      goto out;

	    }

	}

      else

	{

	  scn0->shdr.e64 = (Elf64_Shdr *) calloc (1, sizeof (Elf64_Shdr));

	  if (scn0->shdr.e64 == NULL)

	    {

	      __libelf_seterrno (ELF_E_NOMEM);

	      goto out;

	    }

	}

      scn0->elf = elf;

      scn0->shdr_flags = ELF_F_DIRTY | ELF_F_MALLOCED;

      scn0->list = elf->state.elf.scns_last;

      scn0->data_read = 1;

      runp->cnt = 1;

    }

  while (1)

    {

      if (idx < runp->max)

	{

	  if (idx < runp->cnt)

	    result = &runp->data[idx];

	  else

	    __libelf_seterrno (ELF_E_INVALID_INDEX);

	  break;

	}

      idx -= runp->max;

      runp = runp->next;

      if (runp == NULL)

	{

	  __libelf_seterrno (ELF_E_INVALID_INDEX);

	  break;

	}

    }

 out:

  rwlock_unlock (elf->lock);

  return result;

}

INTDEF(elf_getscn)