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v0 source pure

Package rc is a small shell over a Plan 9 namespace.

Readme View source

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

A small shell over a Plan 9 namespace: ls, cat, stat, ns, bind, mount, unmount, mkdir, rm, echo, cd, pwd, walk, help.

1import rc "gno.land/p/moul/x/plan9/rc/v0"
2
3sh, fs := rc.NewMemShell("g1...", rc.ReadWrite, runtime.ChainHeight)
4out, err := sh.Run("bind -ac /srv/dev /dev; echo hello > /tmp/greeting; ls -l /")

A namespace you cannot inspect is a namespace you cannot trust. Everything here operates on an ns.Ns and returns text, so one realm's Render becomes a file browser and one transaction becomes a shell command.

The mode split is the security model. A shell in ReadOnly mode refuses every mutating command, which is what lets a realm expose it through Render, where mutating anything would be a bug, while the same code backs a crossing Exec that may write.

On the first error the run stops and returns it. A realm should let that error panic, so a half-applied command line reverts with its transaction rather than leaving a namespace nobody asked for.

Two commands exist to make a namespace legible rather than to do work:

  • ns prints the mount table in ns(1) format.
  • walk /bin/rc prints how each element resolves, with the union width per step. It is where a bind stops being magic: the width column says exactly where one took effect, and that a union is top level only.

Quoting follows rc: single quotes, with '' inside a quoted string standing for one literal quote. Commands are separated by ; or newlines, and quoting is respected when splitting them. MaxCommands (32) bounds one run.

Live demo: r/moul/x/plan9/ns renders it. 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:

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

Overview

Package rc is a small shell over a Plan 9 namespace.

It exists because a namespace you cannot inspect is a namespace you cannot trust. Everything here operates on a gno.land/p/moul/x/plan9/ns namespace and returns text, so one realm's Render becomes a file browser and one transaction becomes a shell command:

Example
1Exec("bind -a /srv/dev /dev; echo hello > /tmp/greeting")

The mode split is the security model. A Shell in ReadOnly mode refuses every mutating command, which is what lets a realm expose the shell through Render, where mutating anything would be a bug, while the same code backs a crossing Exec that may write.

Quoting follows rc: single quotes, with ” inside a quoted string standing for one literal quote. Commands are separated by ';' or newlines, and quoting is respected when splitting them.

On the first error the run STOPS and returns it. A realm should let that error panic, so a half-applied command line reverts with the transaction rather than leaving the namespace in a state nobody asked for.

NOTICE. 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 (https://p9f.org). This package is not affiliated with, endorsed by, or sponsored by them, and contains no Plan 9 code: it borrows the vocabulary so that the design reads without a glossary, and it is an homage, asking what that ecosystem's spirit looks like on a chain. Full attribution: NOTICE.md at the root of moul/gno-contracts.

Constants 2

const MaxCommands 

1const MaxCommands = 32
source

MaxCommands bounds one run, so a single call cannot loop the VM.

Variables 1

var ErrReadOnly, ErrUsage, ErrUnknown, ErrQuote 

 1var (
 2	// ErrReadOnly is returned when a mutating command runs in ReadOnly mode.
 3	ErrReadOnly = errors.New("read-only shell")
 4	// ErrUsage reports a malformed command line.
 5	ErrUsage = errors.New("usage")
 6	// ErrUnknown reports a command this shell does not have.
 7	ErrUnknown = errors.New("command not found")
 8	// ErrQuote reports an unterminated quoted string.
 9	ErrQuote = errors.New("unterminated '")
10)
source

Functions 2

func New 

1func New(n *ns.Ns, mode Mode, now func() int64) *Shell
source

New returns a shell over n. now supplies the block height stamped on writes and may be nil in ReadOnly mode.

func NewMemShell 

1func NewMemShell(uid string, mode Mode, now func() int64) (*Shell, *memfs.FS)
source

NewMemShell is the convenience a realm or a test wants: a fresh ram root, a namespace over it, and a shell. It exists here rather than in ns so that ns keeps no dependency on a particular file server.

Types 2

type Mode

ident 
1type Mode uint8
source

Mode decides whether mutating commands are allowed.

type Shell

struct 
1type Shell struct {
2	ns   *ns.Ns
3	mode Mode
4	now  func() int64
5}
source

Shell runs commands against one namespace.

Methods on Shell

func Ns

method on Shell 
1func (s *Shell) Ns() *ns.Ns
source

Ns returns the namespace the shell operates on.

func Run

method on Shell 
1func (s *Shell) Run(line string) (string, error)
source

Run executes a command line and returns its output. Execution stops at the first error.

Imports 6

Source Files 4