lamfold-cpio 0.0.2

no_std initramfs/newc cpio frontend for lamfold — a FoldFrontend tree over the permissive cpio_reader
Documentation

lamfold-cpio

The initramfs/cpio frontend of the lamfold read-only media stack — a FoldFrontend tree over the permissive cpio_reader.

Reads over a lamfold::BlockSource and implements lamfold::FoldFrontend. cpio is the Linux initramfs/initrd archive format — a flat (header, path, data) stream, not a block filesystem. Spec: the lamfold design spec §4.

Reuse, not clean-room

cpio's record parsing is trivial and a permissive no_std reader already exists, so — per the SDS "reuse where licensing does not hinder" rule — this frontend reuses cpio_reader (MIT OR Apache-2.0) for record parsing and contributes only what lamfold needs: fold the flat path list into a directory tree (creating intermediate directories a nested path implies) and present it through FoldFrontend, so an initramfs reads through the same dispatch_fs_over_source path as a real filesystem.

Status

Layer State
Record parsing (newc / CRC / portable-ASCII / old-binary, via cpio_reader) ✅ reused
Tree construction (explicit + path-implied directories) ✅ done + tested
Regular files (zero-copy (offset, len) views into the archive) ✅ done + tested
Symlinks via read_link ✅ done + tested

Complete. Verified against a real cpio -H newc archive: probe, tree build (including a directory implied by sub/inner.txt), files (full + partial + EOF), and a symlink. The archive is read into memory once (read-capped) — appropriate for an initramfs, which is resident anyway. #![forbid(unsafe_code)].

Build / test

cargo build
cargo test                                   # walks tests/fixtures/initramfs.newc
cargo build --no-default-features            # no_std check

MIT OR Apache-2.0.