gno.land/p/moul/x/plan9/memfs/v0

A RAM file server: Plan 9's ramfs, in a realm's heap. The reference implementation of ninep.File and ninep.Mutable.

1import memfs "gno.land/p/moul/x/plan9/memfs/v0"
2
3fs := memfs.New("g1...", runtime.ChainHeight())
4fs.MkdirAll("/usr/glenda/bin", height)
5fs.WriteFile("/tmp/greeting", "hello\n", height)
6root := fs.Root()   // a ninep.File, mountable into any namespace

Children live in an avl.Tree, so a directory listing is ordered by name and therefore identical on every validating node. A map would make Render a consensus bug.

Mutable is in-realm only. A non-crossing method runs in the caller's frame, so a foreign realm calling Create or Write here would be mutating objects it does not own. The read half is safe from anywhere, which is exactly what makes a memfs tree mountable into somebody else's namespace: they get reads, and only its owner gets writes.

The clock is a parameter, not an import. Every mutation takes the block height from the caller rather than reading chain state itself, so the same tree runs in a plain unit test.

9P behaviours reproduced rather than approximated:

• A directory reports Length 0, as 9P does.
• Qid.Version increments on every write, so a client holding a qid can tell "same file, changed" from "different file" without reading it.
• Writing past the end extends the file with NUL bytes.
• DMAPPEND pins every write to the end, whatever offset was asked for.
• Removing a non-empty directory is refused.

Design and analysis: moul/gno-contracts#136.

Not affiliated with Plan 9. Plan 9 from Bell Labs is the work of the Computing Science Research Center at Bell Labs; the name and the marks are theirs, and the copyright is held by the Plan 9 Foundation. This package borrows the vocabulary and none of the code: it is an independent homage, asking what that ecosystem's spirit looks like on a chain. Full attribution: NOTICE.

Part of moul/gno-contracts — moul's versioned gno.land contracts. See the repository for the full catalog, build/test tooling, and usage.

Dependency graph:

🧪 Highly experimental — potentially vibe-coded. Not audited; may break, change, or be removed at any time. Do not use with anything of value. Full disclaimer: DISCLAIMER.