libelf/elf_newdata.c

/* Create new, empty section data.
   Copyright (C) 1998, 1999, 2000, 2001, 2002 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 <stddef.h>
#include <stdlib.h>

#include "libelfP.h"


Elf_Data *
elf_newdata (Elf_Scn *scn)
{
  Elf_Data_List *result = NULL;

  if (scn == NULL)
    return NULL;

  if (unlikely (scn->index == 0))
    {
      /* It is not allowed to add something to the 0th section.  */
      __libelf_seterrno (ELF_E_NOT_NUL_SECTION);
      return NULL;
    }

  if (scn->elf->class == ELFCLASS32
      || (offsetof (struct Elf, state.elf32.ehdr)
	  == offsetof (struct Elf, state.elf64.ehdr))
      ? scn->elf->state.elf32.ehdr == NULL
      : scn->elf->state.elf64.ehdr == NULL)
    {
      __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
      return NULL;
    }

  rwlock_wrlock (scn->elf->lock);

  if (scn->data_read && scn->data_list_rear == NULL)
    {
      /* This means the section was created by the user and this is the
	 first data.  */
      result = &scn->data_list;
      result->flags = ELF_F_DIRTY;
    }
  else
    {
      /* Create a new, empty data descriptor.  */
      result = (Elf_Data_List *) calloc (1, sizeof (Elf_Data_List));
      if (result == NULL)
	{
	  __libelf_seterrno (ELF_E_NOMEM);
	  goto out;
	}

      result->flags = ELF_F_DIRTY | ELF_F_MALLOCED;

      if (scn->data_list_rear == NULL)
	/* We create new data without reading/converting the data from the
	   file.  That is fine but we have to remember this.  */
	scn->data_list_rear = &scn->data_list;
    }

  /* Set the predefined values.  */
  result->data.d.d_version = __libelf_version;

  result->data.s = scn;

  /* Add to the end of the list.  */
  if (scn->data_list_rear != NULL)
    scn->data_list_rear->next = result;

  scn->data_list_rear = result;

 out:
  rwlock_unlock (scn->elf->lock);

  /* Please note that the following is thread safe and is also defined
     for RESULT == NULL since it still return NULL.  */
  return &result->data.d;
}