EXPERIMENT vhost server for virtioFS

example/virtiofs/main.go

@@ -0,0 +1,51 @@
+// Copyright 2024 the Go-FUSE Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"flag"
+	"log"
+	"net"
+
+	"github.com/hanwen/go-fuse/v2/fs"
+	"github.com/hanwen/go-fuse/v2/fuse"
+	"github.com/hanwen/go-fuse/v2/vhostuser"
+)
+
+func main() {
+	log.SetFlags(log.Lmicroseconds)
+	flag.Parse()
+
+	sockpath := flag.Arg(0)
+	orig := flag.Arg(1)
+	l, err := net.ListenUnix("unix", &net.UnixAddr{sockpath, "unix"})
+	if err != nil {
+		log.Fatal("Listen", err)
+	}
+
+	root, err := fs.NewLoopbackRoot(orig)
+	if err != nil {
+		log.Fatal(err)
+	}
+	opts := &fs.Options{}
+	opts.Debug = true
+	opts.Logger = log.Default()
+	opts.MountOptions.Logger = opts.Logger
+	rawFS := fs.NewNodeFS(root, opts)
+	ps := fuse.NewProtocolServer(rawFS, &opts.MountOptions)
+
+	for {
+		conn, err := l.AcceptUnix()
+		if err != nil {
+			break
+		}
+
+		dev := vhostuser.NewFSDevice(ps)
+		srv := vhostuser.NewServer(conn, dev)
+		if err := srv.Serve(); err != nil {
+			log.Printf("Serve: %v %T", err, err)
+		}
+	}
+}

fuse/protocol-server_test.go

@@ -0,0 +1,21 @@
+package fuse
+
+import (
+	"log"
+	"testing"
+)
+
+func TestProtocolServerParse(t *testing.T) {
+	in := [][]byte{
+		[]byte("A\x00\x00\x00\x16\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00.\x04\x00\x00\x00\x00\x00\x00"),
+		[]byte("\x00\x00\x00\x00\x00\x00\x00\x00security.selinux\x00"),
+	}
+	out := [][]byte{make([]byte, 16), make([]byte, 16)}
+
+	opts := MountOptions{}
+	opts.Debug = true
+	opts.Logger = log.Default()
+	ps := NewProtocolServer(NewDefaultRawFileSystem(), &opts)
+	n, status := ps.HandleRequest(in, out)
+	log.Println(n, status)
+}

fuse/request.go

@@ -108,7 +108,7 @@ func (r *request) InputDebug() string {
 	if h != nil && h.InType != nil {
 		val = Print(asType(r.inData(), h.InType))
 	}
-
+	log.Println(val)
 	names := ""
 	if h.FileNames == 1 {
 		names = fmt.Sprintf(" %q", r.filename())

fuse/server.go

@@ -74,17 +74,16 @@ func (ps *ProtocolServer) HandleRequest(in [][]byte,
 	inTogether := make([]byte, len(in[0])+len(in[1]))
 	copy(inTogether, in[0])
 	copy(inTogether[len(in[0]):], in[1])
-	h, inSize, outSize, payloadSize, errno := parseRequest(inTogether, nil)
+	h, inSize, outSize, outPayloadSize, errno := parseRequest(inTogether, nil)
 	if errno != 0 {
 		return 0, errno
 	}
-
-	log.Printf("h: %v %d %d %d %v", h, inSize, outSize, payloadSize, errno)
+	log.Printf("%d %d payloadSize %d", inSize, outSize, outPayloadSize)
 	req := request{
 		cancel:    make(chan struct{}),
 		inputBuf:  inTogether[:inSize],
-		outputBuf: make([]byte, outSize+int(sizeOfOutHeader)),
-		inPayload: make([]byte, payloadSize),
+		outputBuf: make([]byte, outSize+int(sizeOfOutHeader)+outPayloadSize),
+		inPayload: inTogether[inSize:],
 	}
 
 	ps.protocolServer.handleRequest(h, &req)
@@ -93,7 +92,7 @@ func (ps *ProtocolServer) HandleRequest(in [][]byte,
 	if len(req.outputBuf) > len(out[0]) {
 		copy(out[1], req.outputBuf[len(out[0]):])
 	}
-	if payloadSize > 0 {
+	if outPayloadSize > 0 {
 		copy(out[len(out)-1], req.outPayload)
 	}
 	return len(req.outPayload) + len(req.outputBuf), 0

vhostuser/fs_test.go

@@ -0,0 +1,81 @@
+package vhostuser
+
+import (
+	"log"
+	"net"
+	"os"
+	"os/exec"
+	"testing"
+
+	"github.com/hanwen/go-fuse/v2/fs"
+	"github.com/hanwen/go-fuse/v2/fuse"
+)
+
+func listenVFS(sockpath string, rawFS fuse.RawFileSystem, opts *fuse.MountOptions) {
+	os.Remove(sockpath)
+	l, err := net.ListenUnix("unix", &net.UnixAddr{sockpath, "unix"})
+	if err != nil {
+		log.Fatal("Listen", err)
+	}
+	for {
+		conn, err := l.AcceptUnix()
+		if err != nil {
+			break
+		}
+
+		ps := fuse.NewProtocolServer(rawFS, opts)
+		dev := NewFSDevice(ps)
+		srv := NewServer(conn, dev)
+		if err := srv.Serve(); err != nil {
+			log.Printf("Serve: %v %T", err, err)
+		}
+	}
+}
+
+func TestBasic(t *testing.T) {
+	orig := t.TempDir()
+	if err := os.WriteFile(orig+"/file.txt", []byte("hello world\n"), 0666); err != nil {
+		t.Errorf("WriteFile: %v", err)
+	}
+	root, err := fs.NewLoopbackRoot(orig)
+	if err != nil {
+		t.Fatal(err)
+	}
+	opts := &fs.Options{}
+	opts.Debug = true
+	opts.Logger = log.Default()
+	opts.MountOptions.Logger = opts.Logger
+	rawFS := fs.NewNodeFS(root, opts)
+
+	bindir := os.Getenv("HOME") + "/.cache/go-fuse-virtiofs"
+	sockpath := "/tmp/vhostqemu"
+	go listenVFS(sockpath, rawFS, &opts.MountOptions)
+
+	cmd := exec.Command("qemu-system-x86_64",
+		"-M", "pc", "-m", "4G", "-cpu", "host", "-smp", "2",
+		"-enable-kvm",
+
+		// to create the communications socket
+		"-chardev", "socket,id=char0,path="+sockpath,
+
+		// instantiate the device
+		"-device", "vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs",
+
+		// force use of memory sharable with virtiofsd.
+		"-object", "memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on", "-numa", "node,memdev=mem",
+
+		"-kernel", bindir+"/bzImage",
+		"-initrd", bindir+"/initramfs.cpio.gz",
+		"-nographic",
+		"-append",
+		"console=ttyS0",
+	)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Start(); err != nil {
+		t.Fatal(err)
+	}
+	if err := cmd.Wait(); err != nil {
+		t.Fatal(err)
+	}
+}