/*

 * Copyright (C) 2025 Versity, Inc.

 *

 * This file may be redistributed under the terms of the

 * GNU Lesser General Public License.

 */

#include <inttypes.h>

#include "superblocks.h"

#include "crc32c.h"

enum {

  SCOUTFS_TYPE_DATA,

  SCOUTFS_TYPE_METADATA,

};

#define SCOUTFS_UUID_BYTES 16

#define SCOUTFS_BLOCK_SM_SHIFT 12

#define SCOUTFS_BLOCK_SM_SIZE  (1 << SCOUTFS_BLOCK_SM_SHIFT)

#define SCOUTFS_BLOCK_LG_SHIFT 16

#define SCOUTFS_BLOCK_LG_SIZE  (1 << SCOUTFS_BLOCK_LG_SHIFT)

struct scoutfs_block_header {

  uint32_t crc;

  uint32_t magic;

  uint64_t fsid;

  uint64_t seq;

  uint64_t blkno;

};

#define SCOUTFS_FLAG_IS_META_BDEV 0x01

struct scoutfs_super_block {

  struct scoutfs_block_header hdr;

  uint64_t id;

  uint64_t fmt_vers;

  uint64_t flags;

  uint8_t uuid[SCOUTFS_UUID_BYTES];

  /* rest omitted */

};

static int probe_scoutfs(blkid_probe pr, const struct blkid_idmag *mag)

{

  const struct scoutfs_super_block *sb;

  const unsigned char *buf;

  uint32_t crc;

  /* scoutfs_super_block is always in a SCOUTFS_BLOCK_SM_SIZE block */

  buf = blkid_probe_get_sb_buffer(pr, mag, SCOUTFS_BLOCK_SM_SIZE);

  if (buf == NULL)

    return errno ? -errno : 1;

  sb = (struct scoutfs_super_block *)buf;

  crc = crc32c(~0, (char *)buf + sizeof(sb->hdr.crc), SCOUTFS_BLOCK_SM_SIZE - sizeof(sb->hdr.crc));

  if (!blkid_probe_verify_csum(pr, crc, le32_to_cpu(sb->hdr.crc)))

    return BLKID_PROBE_NONE;

  blkid_probe_sprintf_version(pr, "%"PRIu64, le64_to_cpu(sb->fmt_vers));

  blkid_probe_set_uuid(pr, sb->uuid);

  blkid_probe_sprintf_value(pr, "FSID", "%016"PRIx64, le64_to_cpu(sb->hdr.fsid));

  blkid_probe_set_wiper(pr, 0, 0x10000);

  if (mag->hint == SCOUTFS_TYPE_METADATA) {

    /* meta blocksize is 64k blocks */

    blkid_probe_set_fsblocksize(pr, SCOUTFS_BLOCK_LG_SIZE);

    blkid_probe_set_block_size(pr, SCOUTFS_BLOCK_LG_SIZE);

    if (!(le64_to_cpu(sb->flags) & SCOUTFS_FLAG_IS_META_BDEV))

      return BLKID_PROBE_NONE;

  } else {

    /* data blocksize is 4k blocks */

    blkid_probe_set_fsblocksize(pr, SCOUTFS_BLOCK_SM_SIZE);

    blkid_probe_set_block_size(pr, SCOUTFS_BLOCK_SM_SIZE);

    if (le64_to_cpu(sb->flags) & SCOUTFS_FLAG_IS_META_BDEV)

      return BLKID_PROBE_NONE;

  }

  return 0;

}

/*

 * Scoutfs has the same magic value for the data and the meta devices,

 * and the superblock format used in them is identical, except for the

 * flag used to indicate the meta device superblock.

 */

const struct blkid_idinfo scoutfs_meta_idinfo =

{

  .name   = "scoutfs_meta",

  .usage    = BLKID_USAGE_FILESYSTEM,

  .probefunc  = probe_scoutfs,

  .minsz    = 0x20000,

  .magics   = {

    {

      .magic  = "\x8b\x42\x3c\x10",

      .hint         = SCOUTFS_TYPE_METADATA,

      .kboff  = 64,

      .sboff  = 4,

      .len    = 4,

    },

    { NULL }

  }

};

const struct blkid_idinfo scoutfs_data_idinfo =

{

  .name   = "scoutfs_data",

  .usage    = BLKID_USAGE_FILESYSTEM,

  .probefunc  = probe_scoutfs,

  .minsz    = 0x20000,

  .magics   = {

    {

      .magic  = "\x8b\x42\x3c\x10",

      .hint         = SCOUTFS_TYPE_DATA,

      .kboff  = 64,

      .sboff  = 4,

      .len    = 4,

    },

    { NULL }

  }

};