Struct qcow::Version3Header

pub struct Version3Header {
    pub incompatible_features: IncompatibleFeatures,
    pub compatible_features: CompatibleFeatures,
    pub autoclear_features: AutoClearFeatures,
    pub refcount_order: u32,
    pub compression_type: CompressionType,
}

Part of header only present in Qcow version 3

Fields

incompatible_features: IncompatibleFeatures

Bitmask of incompatible features. An implementation must fail to open an image if an unknown bit is set.

compatible_features: CompatibleFeatures

Bitmask of compatible features. An implementation can safely ignore any unknown bits that are set.

autoclear_features: AutoClearFeatures

Bitmask of auto-clear features. An implementation may only write to an image with unknown auto-clear features if it clears the respective bits from this field first.

refcount_order: u32

Describes the width of a reference count block entry (width in bits: refcount_bits = 1 << refcount_order). For version 2 images, the order is always assumed to be 4 (i.e. refcount_bits = 16). This value may not exceed 6 (i.e. refcount_bits = 64).

compression_type: CompressionType

Defines the compression method used for compressed clusters.

All compressed clusters in an image use the same compression type.

If the incompatible bit “Compression type” is set: the field must be present and non-zero (which means non-zlib compression type). Otherwise, this field must not be present or must be zero (which means zlib).

Trait Implementations

impl BinRead for Version3Header

type Args = ()

The type of arguments needed to be supplied in order to read this type, usually a tuple.

fn read_options<R: Read + Seek>(
    __binread_generated_var_reader: &mut R,
    __binread_generated_var_options: &ReadOptions,
    __binread_generated_var_arguments: Self::Args
) -> BinResult<Self>

Read the type from the reader

fn read<R>(reader: &mut R) -> Result<Self, Error> where
    R: Read + Seek, 

Read the type from the reader while assuming no arguments have been passed

fn read_args<R>(reader: &mut R, args: Self::Args) -> Result<Self, Error> where
    R: Read + Seek, 

Read the type from the reader using the specified arguments

fn after_parse<R>(
    &mut self,
    &mut R,
    &ReadOptions,
    Self::Args
) -> Result<(), Error> where
    R: Read + Seek, 

fn args_default() -> Option<Self::Args>

The default arguments to be used when using the read shortcut method. Override this for any type that optionally requries arguments

impl Debug for Version3Header

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.