/* btrfs.c - B-tree file system.  */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2010  Free Software Foundation, Inc.
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB 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 a copy of the GNU General Public License
 *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <grub/err.h>
#include <grub/file.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/disk.h>
#include <grub/dl.h>
#include <grub/types.h>

#define BTRFS_SIGNATURE "_BHRfS_M"

struct btrfs_superblock
{ 
  grub_uint8_t dummy1[32];
  grub_uint16_t uuid[8];
  grub_uint8_t dummy2[16];
  grub_uint8_t signature[sizeof (BTRFS_SIGNATURE) - 1];
} __attribute__ ((packed));

struct grub_btrfs_data
{
  struct btrfs_superblock sblock;
};

static struct grub_btrfs_data *
grub_btrfs_mount (grub_disk_t disk)
{
  struct grub_btrfs_data *data = grub_malloc (sizeof (*data));
  if (! data)
    return NULL;

  if (grub_disk_read (disk, 128, 0, sizeof (data->sblock),
		      &data->sblock) != GRUB_ERR_NONE)
    goto fail;

  if (grub_memcmp ((char *) data->sblock.signature, BTRFS_SIGNATURE, sizeof (BTRFS_SIGNATURE) - 1))
    {
      grub_error (GRUB_ERR_BAD_FS, "not a Btrfs filesystem");
      goto fail;
    }

  return data;

 fail:
  if (grub_errno == GRUB_ERR_OUT_OF_RANGE)
    grub_error (GRUB_ERR_BAD_FS, "not a Btrfs filesystem");

  grub_free (data);
  return NULL;
}

static grub_err_t
grub_btrfs_open (struct grub_file *file __attribute__ ((unused)),
		 const char *name __attribute__ ((unused)))
{
  return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET, "only detection is supported for Btrfs");
}

static grub_err_t
grub_btrfs_dir (grub_device_t device,
                const char *path __attribute__ ((unused)),
                int (*hook) (const char *filename,
                             const struct grub_dirhook_info *info)
                __attribute__ ((unused)))
{
  struct grub_btrfs_data *data = grub_btrfs_mount (device->disk);
  if (grub_errno)
    return grub_errno;

  grub_free (data);

  return GRUB_ERR_NONE;
}

static grub_err_t
grub_btrfs_uuid (grub_device_t device, char **uuid)
{
  struct grub_btrfs_data *data;

  *uuid = NULL;

  data = grub_btrfs_mount (device->disk);
  if (! data)
    return grub_errno;

  *uuid = grub_xasprintf ("%04x%04x-%04x-%04x-%04x-%04x%04x%04x",
			  grub_be_to_cpu16 (data->sblock.uuid[0]),
			  grub_be_to_cpu16 (data->sblock.uuid[1]),
			  grub_be_to_cpu16 (data->sblock.uuid[2]),
			  grub_be_to_cpu16 (data->sblock.uuid[3]),
			  grub_be_to_cpu16 (data->sblock.uuid[4]),
			  grub_be_to_cpu16 (data->sblock.uuid[5]),
			  grub_be_to_cpu16 (data->sblock.uuid[6]),
			  grub_be_to_cpu16 (data->sblock.uuid[7]));

  grub_free (data);

  return grub_errno;
}

static struct grub_fs grub_btrfs_fs =
  {
    .name = "btrfs",
    .dir = grub_btrfs_dir,
    .open = grub_btrfs_open,
    .uuid = grub_btrfs_uuid,
  };

GRUB_MOD_INIT(btrfs)
{
  grub_fs_register (&grub_btrfs_fs);
}

GRUB_MOD_FINI(btrfs)
{
  grub_fs_unregister (&grub_btrfs_fs);
}