Module tar_split 

Tar-split integration for reading container layers without full tar serialization.

This module provides the TarSplitFdStream which reads tar-split metadata files and returns file descriptors for the actual file content, enabling zero-copy access to layer data.

Overview

The tar-split format stores tar header metadata separately from file content, allowing reconstruction of tar archives without duplicating the actual file data. This implementation uses that metadata to provide file descriptors directly to the files in the overlay diff directory.

Architecture

The tar-split format is NDJSON (newline-delimited JSON), gzip-compressed:

• Type 1 (FileType): File/directory references with name, optional size, optional CRC64
• Type 2 (SegmentType): Raw TAR header bytes and padding (base64-encoded)
• CRC64-ISO algorithm for checksums

Structs

TarHeader

Tar header information extracted from tar-split metadata.

TarSplitFdStream

Stream that reads tar-split metadata and provides file descriptors for file content.

Enums

TarSplitItem

Item returned from tar-split stream iteration.