9P host and guest support

internal/commands/flag.go

@@ -14,6 +14,7 @@ import (
 	"unicode/utf8"
 	"unsafe"
 
+	"github.com/djdv/go-filesystem-utils/internal/filesystem"
 	"github.com/djdv/go-filesystem-utils/internal/generic"
 	"github.com/djdv/p9/p9"
 	"github.com/multiformats/go-multiaddr"
@@ -579,3 +580,13 @@ func parseMultiaddrList(parameter string) ([]multiaddr.Multiaddr, error) {
 	}
 	return maddrs, nil
 }
+
+func prefixIDFlag[
+	T interface {
+		~string
+		filesystem.Host | filesystem.ID
+	},
+](ID T,
+) string {
+	return strings.ToLower(string(ID)) + "-"
+}

internal/commands/mount.go

@@ -272,6 +272,7 @@ func makeHostCommands() []command.Command {
 	var (
 		commandMakers = []makeCommand{
 			makeFUSECommand,
+			makePlan9HostCommand,
 		}
 		commands = make([]command.Command, 0, len(commandMakers))
 	)
@@ -292,6 +293,7 @@ func makeGuestCommands[
 ](host filesystem.Host,
 ) []command.Command {
 	guests := makeIPFSCommands[HC, HM](host)
+	guests = append(guests, makePlan9GuestCommand[HC, HM](host))
 	sortCommands(guests)
 	return guests
 }

internal/commands/mountpoint.go

@@ -90,6 +90,7 @@ func makeMountPointHosts(path ninePath, autoUnlink bool) mountPointHosts {
 	var (
 		hostMakers = []makeHostsFunc{
 			makeFUSEHost,
+			makePlan9Host,
 		}
 		hosts = make(mountPointHosts, len(hostMakers))
 	)
@@ -142,6 +143,7 @@ func makeMountPointGuests[
 ) mountPointGuests {
 	guests := make(mountPointGuests)
 	makeIPFSGuests[HC](guests, path)
+	guests[p9fs.GuestID] = newMountPointFunc[HC, p9fs.Guest](path)
 	return guests
 }
 

internal/commands/mountpoint_9p.go

@@ -0,0 +1,121 @@
+package commands
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+
+	"github.com/djdv/go-filesystem-utils/internal/command"
+	"github.com/djdv/go-filesystem-utils/internal/filesystem"
+	p9fs "github.com/djdv/go-filesystem-utils/internal/filesystem/9p"
+	"github.com/djdv/go-filesystem-utils/internal/generic"
+	"github.com/multiformats/go-multiaddr"
+)
+
+type (
+	plan9GuestSettings p9fs.Guest
+	plan9GuestOption   func(*plan9GuestSettings) error
+	plan9GuestOptions  []plan9GuestOption
+
+	plan9HostSettings p9fs.Host
+	plan9HostOption   func(*plan9HostSettings) error
+	plan9HostOptions  []plan9HostOption
+)
+
+const p9ServerFlagName = "server"
+
+func makePlan9HostCommand() command.Command {
+	return makeMountSubcommand(
+		p9fs.HostID,
+		makeGuestCommands[plan9HostOptions, plan9HostSettings](p9fs.HostID),
+	)
+}
+
+func makePlan9Host(path ninePath, autoUnlink bool) (filesystem.Host, p9fs.MakeGuestFunc) {
+	guests := makeMountPointGuests[p9fs.Host](path)
+	return p9fs.HostID, newMakeGuestFunc(guests, path, autoUnlink)
+}
+
+func unmarshalPlan9() (filesystem.Host, decodeFunc) {
+	return p9fs.HostID, func(b []byte) (string, error) {
+		var host p9fs.Host
+		err := json.Unmarshal(b, &host)
+		return host.Maddr.String(), err
+	}
+}
+
+func (*plan9HostOptions) usage(guest filesystem.ID) string {
+	return string(p9fs.HostID) + " hosts " +
+		string(guest) + " as a 9P file server"
+}
+
+func (*plan9HostOptions) BindFlags(*flag.FlagSet) { /* NOOP */ }
+
+func (o9 plan9HostOptions) make() (plan9HostSettings, error) {
+	return makeWithOptions(o9...)
+}
+
+func (set plan9HostSettings) marshal(arg string) ([]byte, error) {
+	if arg == "" {
+		err := command.UsageError{
+			Err: generic.ConstError(
+				"expected server multiaddr",
+			),
+		}
+		return nil, err
+	}
+	maddr, err := multiaddr.NewMultiaddr(arg)
+	if err != nil {
+		return nil, err
+	}
+	set.Maddr = maddr
+	return json.Marshal(set)
+}
+
+func makePlan9GuestCommand[
+	HC mountCmdHost[HT, HM],
+	HM marshaller,
+	HT any,
+](host filesystem.Host,
+) command.Command {
+	return makeMountCommand[HC, HM, plan9GuestOptions, plan9GuestSettings](host, p9fs.GuestID)
+}
+
+func (*plan9GuestOptions) usage(filesystem.Host) string {
+	return string(p9fs.GuestID) + " attaches to a 9P file server"
+}
+
+func (o9 *plan9GuestOptions) BindFlags(flagSet *flag.FlagSet) {
+	var (
+		flagPrefix = prefixIDFlag(p9fs.GuestID)
+		srvUsage   = "9P2000.L file system server `maddr`"
+		srvName    = flagPrefix + p9ServerFlagName
+	)
+	flagSetFunc(flagSet, srvName, srvUsage, o9,
+		func(value multiaddr.Multiaddr, settings *plan9GuestSettings) error {
+			settings.Maddr = value
+			return nil
+		})
+}
+
+func (o9 plan9GuestOptions) make() (plan9GuestSettings, error) {
+	settings, err := makeWithOptions(o9...)
+	if err != nil {
+		return plan9GuestSettings{}, err
+	}
+	if settings.Maddr == nil {
+		var (
+			flagPrefix = prefixIDFlag(p9fs.GuestID)
+			srvName    = flagPrefix + p9ServerFlagName
+		)
+		return plan9GuestSettings{}, fmt.Errorf(
+			"flag `-%s` must be provided for 9P guests",
+			srvName,
+		)
+	}
+	return settings, nil
+}
+
+func (s9 plan9GuestSettings) marshal(string) ([]byte, error) {
+	return json.Marshal(s9)
+}

internal/commands/mountpoint_ipfs.go

@@ -71,10 +71,6 @@ func guestOverlayText(overlay, overlaid filesystem.ID) string {
 	return string(overlay) + " is an " + string(overlaid) + " overlay"
 }
 
-func prefixIDFlag(system filesystem.ID) string {
-	return strings.ToLower(string(system)) + "-"
-}
-
 func (*ipfsOptions) usage(filesystem.Host) string {
 	return string(ipfs.IPFSID) + " provides an empty root directory." +
 		"\nChild paths are forwarded to the IPFS API."

internal/commands/unmount.go

@@ -146,6 +146,7 @@ func newDecodeTargetFunc() p9fs.DecodeTargetFunc {
 	var (
 		decoderMakers = []makeDecoderFunc{
 			unmarshalFUSE,
+			unmarshalPlan9,
 		}
 		decoders = make(decoders, len(decoderMakers))
 	)