qcow2

const (
	MAX_QCOW2_SIZE                     = 1 << 42 //single qcow2 file limit within 4TiB
	QCOW_EXTL2_SUBCLUSTERS_PER_CLUSTER = uint64(32)
	QCOW_L2_BITMAP_ALL_ALLOC           = uint64(1)<<32 - 1
	QCOW_L2_BITMAP_ALL_ZEROES          = QCOW_L2_BITMAP_ALL_ALLOC << 32
	QCOW_MAX_REFTABLE_SIZE             = (8 * 1024 * 1024)
)

const (
	L1E_OFFSET_MASK  = uint64(0x00fffffffffffe00)
	L2E_OFFSET_MASK  = uint64(0x00fffffffffffe00)
	REFT_OFFSET_MASK = uint64(0xfffffffffffffe00)
	INV_OFFSET       = uint64(0xff00000000000000)
)

const (
	DEFAULT_CLUSTER_SIZE = 65536
	DEFAULT_SECTOR_SIZE  = 512
	DEFAULT_CLUSTER_BITS = 16
	//1 refcount block can hold 2GiB data (64k * 32k),
	//1 refcount table holds 8k refcount blocks,
	//so 1 table can hold up to 16TiB data (including refcount blocks and l2 blocks and data blocks)
	DEFAULT_REFCOUNT_TABLE_CLUSTERS = 1
	QCOW2_VERSION2                  = 2
	QCOW2_VERSION3                  = 3
	QCOW2_REFCOUNT_ORDER            = 4
	QCOW2_CRYPT_METHOD              = 0
	//	DEFAULT_ALIGNMENT               = 4096    //align to 4k
	DEFAULT_ALIGNMENT    = DEFAULT_SECTOR_SIZE //align to sector
	DEFAULT_MAX_TRANSFER = 1 << 31             //2G
	DEFAULT_L2_CACHE     = 1024 * 1024         //default 1MiB for l2 cache
)

const (
	L1_TABLE_OFFSET = 65536 * 3
	L1_TABLE_SIZE   = 65536 >> 3
)

const (
	REFCOUNT_TABLE_OFFSET = 65536
	REFCOUNT_TABLE_SIZE   = 65536 >> 3
)

const (
	QCOW_OFLAG_COPIED     = 1 << 63
	QCOW_OFLAG_COMPRESSED = 1 << 62
	QCOW_OFLAG_ZERO       = 1 << 0
)

const (
	QCOW2_INCOMPAT_DIRTY_BITNR       = 0
	QCOW2_INCOMPAT_CORRUPT_BITNR     = 1
	QCOW2_INCOMPAT_DATA_FILE_BITNR   = 2
	QCOW2_INCOMPAT_COMPRESSION_BITNR = 3
	QCOW2_INCOMPAT_EXTL2_BITNR       = 4
	QCOW2_INCOMPAT_DIRTY             = 1 << QCOW2_INCOMPAT_DIRTY_BITNR
	QCOW2_INCOMPAT_CORRUPT           = 1 << QCOW2_INCOMPAT_CORRUPT_BITNR
	QCOW2_INCOMPAT_DATA_FILE         = 1 << QCOW2_INCOMPAT_DATA_FILE_BITNR
	QCOW2_INCOMPAT_COMPRESSION       = 1 << QCOW2_INCOMPAT_COMPRESSION_BITNR
	QCOW2_INCOMPAT_EXTL2             = 1 << QCOW2_INCOMPAT_EXTL2_BITNR
	QCOW2_INCOMPAT_MASK              = QCOW2_INCOMPAT_DIRTY | QCOW2_INCOMPAT_CORRUPT | QCOW2_INCOMPAT_DATA_FILE | QCOW2_INCOMPAT_COMPRESSION | QCOW2_INCOMPAT_EXTL2
)

const (
	QCOW2_AUTOCLEAR_BITMAPS_BITNR       = 0
	QCOW2_AUTOCLEAR_DATA_FILE_RAW_BITNR = 1
	QCOW2_AUTOCLEAR_BITMAPS             = 1 << QCOW2_AUTOCLEAR_BITMAPS_BITNR
	QCOW2_AUTOCLEAR_DATA_FILE_RAW       = 1 << QCOW2_AUTOCLEAR_DATA_FILE_RAW_BITNR
	QCOW2_AUTOCLEAR_MASK                = QCOW2_AUTOCLEAR_BITMAPS | QCOW2_AUTOCLEAR_DATA_FILE_RAW
)

const (
	QCOW2_CLUSTER_UNALLOCATED = iota
	QCOW2_CLUSTER_ZERO_PLAIN
	QCOW2_CLUSTER_ZERO_ALLOC
	QCOW2_CLUSTER_NORMAL
	QCOW2_CLUSTER_COMPRESSED
)

const (
	//used features
	BDRV_O_RDWR   = 0x0002
	BDRV_O_UNMAP  = 0x4000  /* execute guest UNMAP/TRIM operations */
	BDRV_O_CREATE = 0x80000 /* create of non-exist */

	//unused feratures
	BDRV_O_NO_SHARE     = 0x0001 /* don't share permissions */
	BDRV_O_RESIZE       = 0x0004 /* request permission for resizing the node */
	BDRV_O_SNAPSHOT     = 0x0008 /* open the file read only and save writes in a snapshot */
	BDRV_O_TEMPORARY    = 0x0010 /* delete the file after use */
	BDRV_O_NOCACHE      = 0x0020 /* do not use the host page cache */
	BDRV_O_NATIVE_AIO   = 0x0080 /* use native AIO instead of the thread pool */
	BDRV_O_NO_BACKING   = 0x0100 /* don't open the backing file */
	BDRV_O_NO_FLUSH     = 0x0200 /* disable flushing on this disk */
	BDRV_O_COPY_ON_READ = 0x0400 /* copy read backing sectors into image */
	BDRV_O_INACTIVE     = 0x0800 /* consistency hint for migration handoff */
	BDRV_O_CHECK        = 0x1000 /* open solely for consistency check */
	BDRV_O_ALLOW_RDWR   = 0x2000 /* allow reopen to change from r/o to r/w */
	BDRV_O_PROTOCOL     = 0x8000
	BDRV_O_NO_IO        = 0x10000 /* don't initialize for I/O */
	BDRV_O_AUTO_RDONLY  = 0x20000 /* degrade to read-only if opening read-write fails */
	BDRV_O_IO_URING     = 0x40000 /* use io_uring instead of the thread pool */

	BDRV_O_CACHE_MASK = (BDRV_O_NOCACHE | BDRV_O_NO_FLUSH)
)

const (
	BDRV_SECTOR_BITS = 9
	BDRV_SECTOR_SIZE = (1 << BDRV_SECTOR_BITS)
)

const (
	BDRV_BLOCK_DATA         = 0x01
	BDRV_BLOCK_ZERO         = 0x02
	BDRV_BLOCK_OFFSET_VALID = 0x04
	BDRV_BLOCK_RAW          = 0x08
	BDRV_BLOCK_ALLOCATED    = 0x10
	BDRV_BLOCK_EOF          = 0x20
	BDRV_BLOCK_RECURSE      = 0x40
)

const (
	OPT_FMT         = "fmt"
	OPT_SIZE        = "size"
	OPT_FILENAME    = "filename"
	OPT_BACKING     = "backing"
	OPT_SUBCLUSTER  = "enable-subcluster"
	OPT_L2CACHESIZE = "l2-cache-size"
	OPT_DATAFILE    = "datafile"
)

const (
	PERM_READ     = 0x01
	PERM_WRITE    = 0x02
	PERM_RESIZE   = 0x04
	PERM_ALL      = PERM_READ | PERM_WRITE | PERM_RESIZE
	PERM_READABLE = PERM_READ
	PERM_WRITABLE = PERM_WRITE | PERM_RESIZE
)

const (
	TYPE_RAW = iota
	TYPE_QCOW2
)

const (
	TYPE_RAW_NAME   = "raw"
	TYPE_QCOW2_NAME = "qcow2"
)

const (
	/* Size of L1 table entries */
	L1E_SIZE = 8
	/* Size of reftable entries */
	REFTABLE_ENTRY_SIZE = 8
	/* Size of normal and extended L2 entries */
	L2E_SIZE_NORMAL   = 8
	L2E_SIZE_EXTENDED = 8 * 2
	SIZE_UINT64       = uint64(unsafe.Sizeof(uint64(0)))
	SIZE_UINT32       = uint32(unsafe.Sizeof(uint32(0)))
	SIZE_INT          = int(unsafe.Sizeof(int(0)))
)

const (
	QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN = iota
	QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC
	QCOW2_SUBCLUSTER_ZERO_PLAIN
	QCOW2_SUBCLUSTER_ZERO_ALLOC
	QCOW2_SUBCLUSTER_NORMAL
	QCOW2_SUBCLUSTER_COMPRESSED
	QCOW2_SUBCLUSTER_INVALID
)

const (
	BDRV_REQ_COPY_ON_READ     = 0x1
	BDRV_REQ_ZERO_WRITE       = 0x2
	BDRV_REQ_MAY_UNMAP        = 0x4
	BDRV_REQ_FUA              = 0x10
	BDRV_REQ_WRITE_COMPRESSED = 0x20
	BDRV_REQ_WRITE_UNCHANGED  = 0x40
	BDRV_REQ_SERIALISING      = 0x80
	BDRV_REQ_NO_FALLBACK      = 0x100
	BDRV_REQ_PREFETCH         = 0x200
	BDRV_REQ_NO_WAIT          = 0x400
	BDRV_REQ_MASK             = 0x7ff
)

const (
	QCOW2_DISCARD_NEVER = iota
	QCOW2_DISCARD_ALWAYS
	QCOW2_DISCARD_REQUEST
	QCOW2_DISCARD_SNAPSHOT
	QCOW2_DISCARD_OTHER
	QCOW2_DISCARD_MAX
)

const (
	BACKING_FILE_OFFSET = 32768
)

const (
	IOV_MAX = 1024
)

const MAX_BOUNCE_BUFFER = uint64(32768 << 9)

const Max_WRITE_ZEROS = uint64(65536)

const QCOW2_EXT_MAGIC_DATA_FILE = uint32(0x44415441)