Constant BACKUP_HEADER_SIZE 

pub const BACKUP_HEADER_SIZE: usize = 32;

Header for an incremental backup file.

[magic: 4 bytes "GBAK"]
[version: u32 LE]
[start_epoch: u64 LE]
[end_epoch: u64 LE]
[record_count: u64 LE]
... WAL frames ...