Struct JournalHeader 

pub struct JournalHeader {
    pub endian: JournalEndian,
    pub magic: u32,
    pub start: u64,
    pub end: u64,
    pub size: u64,
    pub blhdr_size: u32,
    pub checksum: u32,
    pub jhdr_size: u32,
    pub sequence_num: u32,
}

The journal header at JournalInfoBlock.offset (struct journal_header). All multi-byte fields use endian.

Fields

endian: JournalEndian

magic: u32

start: u64

Byte offset (relative to the journal device base = jib.offset) of the first live transaction.

end: u64

Byte offset of the first free byte. start == end means empty/clean.

size: u64

Journal size in bytes (matches JournalInfoBlock.size).

blhdr_size: u32

Size of each block_list_header region (data follows it).

checksum: u32

jhdr_size: u32

Journal header block size, and the unit binfo.bnum is multiplied by.

sequence_num: u32

Implementations

impl JournalHeader

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

Parse the journal header, auto-detecting byte order from endian.

pub fn is_empty(&self) -> bool

True when the journal has no pending transactions.

pub fn serialize(&self, original: Option<&[u8]>) -> Vec<u8>

Serialize the header back into a jhdr_size-byte block, recomputing the checksum. The bytes past the fixed header are preserved from original when supplied (so we don’t clobber any vendor padding macOS wrote).

Trait Implementations

impl Clone for JournalHeader

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for JournalHeader

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

Formats the value using the given formatter.