Module container 

The container: 32-byte file header, 32-byte chunk descriptors, the directory at the end of the file, and the 8-byte trailer ([spec/02-file-structure.md]).

Structs

ChunkDescriptor

One 32-byte chunk directory entry.

ChunkType

A four-byte chunk type tag.

Directory

The chunk directory: one descriptor per chunk, in file order.

FileHeader

The fixed 32-byte file header at offset 0.

Constants

CHUNK_DESCRIPTOR_SIZE

Size of one chunk descriptor.

CHUNK_FLAG_ENCRYPTED

Chunk descriptor bit 4: this payload is sealed.

FILE_HEADER_RESERVED_MASK

Bits a conforming v1 writer must leave clear: 0, 2, 4 and 5-31.

FILE_HEADER_SIZE

Size of the fixed file header at offset 0.

FLAG_ENCRYPTED

header.flags bit 3: an AUTH chunk is present and content chunks are sealed.

FLAG_MULTI_SECTOR

header.flags bit 1: the file uses sector-based layer encoding.

MAGIC

File magic, LUMN.

TRAILER_MAGIC

Trailer magic, LEND.

TRAILER_SIZE

Size of the directory trailer.

Functions

crc32c

CRC-32C (Castagnoli) as the container and the LTBL/trailer use it.

first_chunk_type

The chunk type of the first chunk, or None if the directory is all null.

parse_directory

Parse the chunk directory.

parse_trailer

Read and verify the directory trailer, returning its CRC-32C.

verify_trailer_crc

Verify the trailer CRC-32C covers every preceding byte.