/* Copyright (C) 1993-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <stddef.h>

#include <dirent.h>

#include <unistd.h>

#include <endian.h>

#include <assert.h>

/* Read a directory entry from DIRP.  */

struct dirent *

__readdir (DIR *dirp)

{

  struct dirent64 *entry64 = __readdir64 (dirp);

  if (sizeof (struct dirent64) == sizeof (struct dirent))

    /* We should in fact just be an alias to readdir64 on this machine.  */

    return (struct dirent *) entry64;

  /* These are all compile-time constants.  We know that d_ino is the first

     member and that the layout of the following members matches exactly in

     both structures.  */

  assert (offsetof (struct dirent, d_ino) == 0);

  assert (offsetof (struct dirent64, d_ino) == 0);

# define MATCH(memb)							      \

  assert (offsetof (struct dirent64, memb) - sizeof (entry64->d_ino)	      \

	  == offsetof (struct dirent, memb) - sizeof (ino_t))

  MATCH (d_reclen);

  MATCH (d_type);

  MATCH (d_namlen);

# undef MATCH

  if (entry64 == NULL)

    return NULL;

  struct dirent *const entry = ((void *) (&entry64->d_ino + 1)

				- sizeof entry->d_ino);

  const ino_t d_ino = entry64->d_ino;

  if (d_ino != entry64->d_ino)

    {

      __set_errno (EOVERFLOW);

      return NULL;

    }

# if BYTE_ORDER != BIG_ENDIAN	/* We just skipped over the zero high word.  */

  entry->d_ino = d_ino;	/* ... or the nonzero low word, swap it.  */

# endif

  entry->d_reclen -= sizeof entry64->d_ino - sizeof entry->d_ino;

  return entry;

}

weak_alias (__readdir, readdir)