Struct BlockHeader 

pub struct BlockHeader {
    pub header_size: u16,
    pub flags: u32,
    pub compression: [u8; 4],
    pub allocated_size: u64,
    pub used_size: u64,
    pub data_size: u64,
    pub checksum: [u8; 16],
}

A decoded block header.

Fields

header_size: u16

The header size as recorded in the file, excluding the magic and this field. Preserved so a re-emitted block keeps any padding it had.

flags: u32

Flag bits; see FLAG_STREAMED.

compression: [u8; 4]

The compression name, \0-padded to four bytes in the file.

allocated_size: u64

Space reserved for the block’s data, excluding the header.

used_size: u64

Bytes actually used on disk, excluding the header.

data_size: u64

Size of the data once decoded. Equal to used_size when uncompressed.

checksum: [u8; 16]

MD5 of the used data. All-zero means “do not verify”.

Implementations

impl BlockHeader

pub fn parse(buf: &[u8]) -> Result<(Self, usize)>

Decode a header from a buffer positioned at the block magic.

Returns the header and the number of bytes it occupied, so the caller can find the data that follows.

pub fn write(&self, out: &mut Vec<u8>)

Encode the header, including magic, into out.

Any header_size beyond the fields is written as zero padding, so a block that was read with an enlarged header re-emits at the same size.

pub fn on_disk_size(&self) -> usize

The number of bytes this header occupies in the file.

pub fn is_streamed(&self) -> bool

Whether the streamed flag is set.

pub fn compression_name(&self) -> &str

The compression name with its \0 padding removed.

An empty name means the block is uncompressed.

pub fn set_compression(&mut self, name: &str) -> Result<()>

Set the compression name, which must fit in four bytes.

pub fn has_checksum(&self) -> bool

Whether a checksum is recorded. All-zero means “do not verify”.

Trait Implementations

impl Clone for BlockHeader

fn clone(&self) -> BlockHeader

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BlockHeader

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

Formats the value using the given formatter.

impl Default for BlockHeader

fn default() -> Self

Returns the “default value” for a type.

impl Eq for BlockHeader

impl PartialEq for BlockHeader

fn eq(&self, other: &BlockHeader) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for BlockHeader