commands: mount - add NFS guest support

Author: djdv

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"
@@ -585,3 +586,7 @@ func parseMultiaddrList(parameter string) ([]multiaddr.Multiaddr, error) {
 	}
 	return maddrs, nil
 }
+
+func prefixIDFlag(system filesystem.ID) string {
+	return strings.ToLower(string(system)) + "-"
+}

internal/commands/mount.go

@@ -294,6 +294,9 @@ func makeGuestCommands[
 ](host filesystem.Host,
 ) []command.Command {
 	guests := makeIPFSCommands[HC, HM](host)
+	if nfsGuest := makeNFSGuestCommand[HC, HM](host); nfsGuest != nil {
+		guests = append(guests, nfsGuest)
+	}
 	sortCommands(guests)
 	return guests
 }

internal/commands/mountpoint.go

@@ -143,6 +143,7 @@ func makeMountPointGuests[
 ) mountPointGuests {
 	guests := make(mountPointGuests)
 	makeIPFSGuests[HC](guests, path)
+	makeNFSGuest[HC](guests, path)
 	return guests
 }
 

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/mountpoint_nfs.go

@@ -6,6 +6,8 @@ import (
 	"encoding/json"
 	"errors"
 	"flag"
+	"fmt"
+	"os"
 
 	"github.com/djdv/go-filesystem-utils/internal/command"
 	"github.com/djdv/go-filesystem-utils/internal/filesystem"
@@ -16,11 +18,24 @@ import (
 )
 
 type (
-	nfsHostSettings nfs.Host
-	nfsHostOption   func(*nfsHostSettings) error
-	nfsHostOptions  []nfsHostOption
+	nfsHostSettings  nfs.Host
+	nfsHostOption    func(*nfsHostSettings) error
+	nfsHostOptions   []nfsHostOption
+	nfsGuestSettings struct {
+		nfs.Guest
+		defaultUID, defaultGID,
+		defaultHostname, defaultDirpath bool
+	}
+	nfsGuestOption  func(*nfsGuestSettings) error
+	nfsGuestOptions []nfsGuestOption
 )
 
+const nfsServerFlagName = "server"
+
+func (ns nfsGuestSettings) marshal(string) ([]byte, error) {
+	return json.Marshal(ns.Guest)
+}
+
 func makeNFSCommand() command.Command {
 	return makeMountSubcommand(
 		nfs.HostID,
@@ -73,3 +88,121 @@ func unmarshalNFS() (filesystem.Host, decodeFunc) {
 		return "", errors.New("NFS host address was not present in the mountpoint data")
 	}
 }
+
+func makeNFSGuestCommand[
+	HC mountCmdHost[HT, HM],
+	HM marshaller,
+	HT any,
+](host filesystem.Host,
+) command.Command {
+	return makeMountCommand[HC, HM, nfsGuestOptions, nfsGuestSettings](host, nfs.GuestID)
+}
+
+func makeNFSGuest[
+	HC mountPointHost[T],
+	T any,
+](guests mountPointGuests, path ninePath,
+) {
+	guests[nfs.GuestID] = newMountPointFunc[HC, nfs.Guest](path)
+}
+
+func (*nfsGuestOptions) usage(filesystem.Host) string {
+	return string(nfs.GuestID) + " attaches to an NFS file server"
+}
+
+func (no *nfsGuestOptions) BindFlags(flagSet *flag.FlagSet) {
+	var (
+		flagPrefix = prefixIDFlag(nfs.GuestID)
+		srvName    = flagPrefix + nfsServerFlagName
+	)
+	const srvUsage = "NFS server `maddr`"
+	flagSetFunc(flagSet, srvName, srvUsage, no,
+		func(value multiaddr.Multiaddr, settings *nfsGuestSettings) error {
+			settings.Maddr = value
+			return nil
+		})
+	hostnameName := flagPrefix + "hostname"
+	const hostnameUsage = "client's `hostname`"
+	flagSetFunc(flagSet, hostnameName, hostnameUsage, no,
+		func(value string, settings *nfsGuestSettings) error {
+			settings.Hostname = value
+			return nil
+		})
+	flagSet.Lookup(hostnameName).
+		DefValue = "caller's hostname"
+	dirpathName := flagPrefix + "dirpath"
+	const dirpathUsage = "`dirpath` used when mounting the server"
+	flagSetFunc(flagSet, dirpathName, dirpathUsage, no,
+		func(value string, settings *nfsGuestSettings) error {
+			settings.Dirpath = value
+			return nil
+		})
+	flagSet.Lookup(dirpathName).
+		DefValue = "/"
+	linkSepName := flagPrefix + "link-separator"
+	const linkSepUsage = "`separator` character to replace with `/` when parsing relative symlinks"
+	flagSetFunc(flagSet, linkSepName, linkSepUsage, no,
+		func(value string, settings *nfsGuestSettings) error {
+			settings.LinkSeparator = value
+			return nil
+		})
+	linkLimitName := flagPrefix + "link-limit"
+	const linkLimitUsage = "sets the maximum amount of times a symbolic link will be resolved in a link chain"
+	flagSetFunc(flagSet, linkLimitName, linkLimitUsage, no,
+		func(value uint, settings *nfsGuestSettings) error {
+			settings.LinkLimit = value
+			return nil
+		})
+	uidName := flagPrefix + "uid"
+	const uidUsage = "client's `uid`"
+	flagSetFunc(flagSet, uidName, uidUsage, no,
+		func(value uint32, settings *nfsGuestSettings) error {
+			settings.UID = value
+			return nil
+		})
+	flagSet.Lookup(uidName).
+		DefValue = "caller's uid"
+	gidName := flagPrefix + "gid"
+	const gidUsage = "client's `gid`"
+	flagSetFunc(flagSet, gidName, gidUsage, no,
+		func(value uint32, settings *nfsGuestSettings) error {
+			settings.GID = value
+			return nil
+		})
+	flagSet.Lookup(gidName).
+		DefValue = "caller's gid"
+}
+
+func (no nfsGuestOptions) make() (nfsGuestSettings, error) {
+	settings, err := makeWithOptions(no...)
+	if err != nil {
+		return nfsGuestSettings{}, err
+	}
+	if settings.Maddr == nil {
+		var (
+			flagPrefix = prefixIDFlag(nfs.GuestID)
+			srvName    = flagPrefix + nfsServerFlagName
+		)
+		return nfsGuestSettings{}, fmt.Errorf(
+			"flag `-%s` must be provided for NFS guests",
+			srvName,
+		)
+	}
+	if settings.Hostname == "" {
+		hostname, err := os.Hostname()
+		if err != nil {
+			return nfsGuestSettings{}, err
+		}
+		settings.Hostname = hostname
+	}
+	if settings.defaultUID {
+		settings.UID = uint32(os.Getuid())
+	}
+	if settings.defaultGID {
+		settings.GID = uint32(os.Getgid())
+	}
+	if settings.Dirpath == "" {
+		settings.Dirpath = "/"
+	}
+	return settings, nil
+}

internal/commands/mountpoint_nonfs.go

@@ -21,3 +21,18 @@ func makeNFSHost(ninePath, bool) (filesystem.Host, p9fs.MakeGuestFunc) {
 func unmarshalNFS() (filesystem.Host, decodeFunc) {
 	return nfsHost, nil
 }
+
+func makeNFSGuestCommand[
+	HC mountCmdHost[HT, HM],
+	HM marshaller,
+	HT any,
+](host filesystem.Host,
+) command.Command {
+	return nil
+}
+
+func makeNFSGuest[
+	HC mountPointHost[T],
+	T any,
+](mountPointGuests, ninePath,
+) { /*NOOP*/ }