/*

 * Copyright (C) 2014 Colin Walters <walters@verbum.org>

 *

 * SPDX-License-Identifier: LGPL-2.0+

 *

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

 *

 * This 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 this library; if not, write to the

 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 */

#include "config.h"

#include "ostree-linuxfsutil.h"

#include "otutil.h"

#include <fcntl.h>

#include <sys/ioctl.h>

#include <ext2fs/ext2_fs.h>

#include "otutil.h"

/**

 * _ostree_linuxfs_fd_alter_immutable_flag:

 * @fd: A file descriptor

 * @new_immutable_state: Set this to %TRUE to make the file immutable, %FALSE to unset the flag

 * @cancellable: Cancellable

 * @error: GError

 *

 * Alter the immutable flag of object referred to by @fd; may be a

 * regular file or a directory.

 *

 * If the operation is not supported by the underlying filesystem, or

 * we are running without sufficient privileges, this function will

 * silently do nothing.

 */

gboolean

_ostree_linuxfs_fd_alter_immutable_flag (int            fd,

                                         gboolean       new_immutable_state,

                                         GCancellable  *cancellable,

                                         GError       **error)

{

  static gint no_alter_immutable = 0;

  if (g_atomic_int_get (&no_alter_immutable))

    return TRUE;

  unsigned long flags;

  int r = ioctl (fd, EXT2_IOC_GETFLAGS, &flags);

  if (r == -1)

    {

      if (errno == EPERM)

        g_atomic_int_set (&no_alter_immutable, 1);

      else if (errno == EOPNOTSUPP || errno == ENOTTY)

        ;

      else

        return glnx_throw_errno_prefix (error, "ioctl(EXT2_IOC_GETFLAGS)");

    }

  else

    {

      gboolean prev_immutable_state = (flags & EXT2_IMMUTABLE_FL) > 0;

      if (prev_immutable_state == new_immutable_state)

        return TRUE;  /* Nothing to do */

      if (new_immutable_state)

        flags |= EXT2_IMMUTABLE_FL;

      else

        flags &= ~EXT2_IMMUTABLE_FL;

      r = ioctl (fd, EXT2_IOC_SETFLAGS, &flags);

      if (r == -1)

        {

          if (errno == EPERM)

            g_atomic_int_set (&no_alter_immutable, 1);

          else if (errno == EOPNOTSUPP || errno == ENOTTY)

            ;

          else

            return glnx_throw_errno_prefix (error, "ioctl(EXT2_IOC_SETFLAGS)");

        }

    }

  return TRUE;

}