/* Copyright (C) 2001-2024 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
   <https://www.gnu.org/licenses/>.  */

#include <dirent.h>
#include <stddef.h>
#include <hurd.h>
#include <hurd/fs.h>
#include <hurd/fd.h>
#include "dirstream.h"

/* Read a directory entry from DIRP.  */
struct dirent64 *
__readdir64 (DIR *dirp)
{
  struct dirent64 *dp;

  if (dirp == NULL)
    return __hurd_fail (EINVAL), NULL;

  __libc_lock_lock (dirp->__lock);

  do
    {
      if (dirp->__ptr - dirp->__data >= dirp->__size)
	{
	  /* We've emptied out our buffer.  Refill it.  */

	  char *data = dirp->__data;
	  mach_msg_type_number_t data_size = dirp->__size;
	  int nentries;
	  error_t err;

	  if (err = HURD_FD_PORT_USE (dirp->__fd,
				      __dir_readdir (port,
						     &data, &data_size,
						     dirp->__entry_ptr,
						     -1, 0, &nentries)))
	    {
	      __hurd_fail (err);
	      dp = NULL;
	      break;
	    }

	  dirp->__size = data_size;
	  /* DATA now corresponds to entry index DIRP->__entry_ptr.  */
	  dirp->__entry_data = dirp->__entry_ptr;

	  if (data != dirp->__data)
	    {
	      /* The data was passed out of line, so our old buffer is no
		 longer useful.  Deallocate the old buffer and reset our
		 information for the new buffer.  */
	      if (dirp->__data != NULL)
		{
		  err = __vm_deallocate (__mach_task_self (),
					 (vm_address_t) dirp->__data,
					 dirp->__allocation);
		  assert_perror (err);
		}
	      dirp->__data = data;
	      dirp->__allocation = round_page (dirp->__size);
	    }

	  /* Reset the pointer into the buffer.  */
	  dirp->__ptr = dirp->__data;

	  if (nentries == 0)
	    {
	      /* End of file.  */
	      dp = NULL;
	      break;
	    }

	  /* We trust the filesystem to return correct data and so we
	     ignore NENTRIES.  */
	}

      dp = (struct dirent64 *) dirp->__ptr;
      dirp->__ptr += dp->d_reclen;
      ++dirp->__entry_ptr;

      /* Loop to ignore deleted files.  */
    } while (dp->d_fileno == 0);

  __libc_lock_unlock (dirp->__lock);

  return dp;
}

libc_hidden_def (__readdir64)
weak_alias (__readdir64, readdir64)