nodefs: symlink/readlink.

nodefs/README.md

@@ -60,4 +60,8 @@ To decide
    * cancellation through context.Context (standard, more GC overhead)
      or a custom context (could reuse across requests.)?
 
+   * Readlink return: []byte or string ?
 
+   * Should Operations.Lookup return *Inode or Operations ?
+
+   * Should bridge.Lookup() add the child, bridge.Unlink remove the child, etc.?

nodefs/api.go

@@ -105,7 +105,8 @@ type Operations interface {
 	Unlink(ctx context.Context, name string) fuse.Status
 	Rename(ctx context.Context, name string, newParent Operations, newName string, flags uint32) fuse.Status
 	Create(ctx context.Context, name string, flags uint32, mode uint32) (node *Inode, fh FileHandle, fuseFlags uint32, code fuse.Status)
-
+	Symlink(ctx context.Context, target, name string, out *fuse.EntryOut) (node *Inode, code fuse.Status)
+	Readlink(ctx context.Context) (string, fuse.Status)
 	Open(ctx context.Context, flags uint32) (fh FileHandle, fuseFlags uint32, code fuse.Status)
 
 	Read(ctx context.Context, f FileHandle, dest []byte, off int64) (fuse.ReadResult, fuse.Status)

nodefs/bridge.go

@@ -374,12 +374,27 @@ func (b *rawBridge) Link(input *fuse.LinkIn, filename string, out *fuse.EntryOut
 	return fuse.ENOSYS
 }
 
-func (b *rawBridge) Symlink(header *fuse.InHeader, pointedTo string, linkName string, out *fuse.EntryOut) (code fuse.Status) {
-	return fuse.ENOSYS
+func (b *rawBridge) Symlink(header *fuse.InHeader, target string, name string, out *fuse.EntryOut) (code fuse.Status) {
+	log.Println("symlink1")
+	parent, _ := b.inode(header.NodeId, 0)
+	child, code := parent.node.Symlink(context.TODO(), target, name, out)
+	if !code.Ok() {
+		return code
+	}
+
+	b.addNewChild(parent, name, child, nil, out)
+	b.setEntryOutTimeout(out)
+	return fuse.OK
 }
 
 func (b *rawBridge) Readlink(header *fuse.InHeader) (out []byte, code fuse.Status) {
-	return nil, fuse.ENOSYS
+	n, _ := b.inode(header.NodeId, 0)
+	result, code := n.node.Readlink(context.TODO())
+	if !code.Ok() {
+		return nil, code
+	}
+
+	return []byte(result), fuse.OK
 }
 
 func (b *rawBridge) Access(input *fuse.AccessIn) (code fuse.Status) {

nodefs/default.go

@@ -6,6 +6,7 @@ package nodefs
 
 import (
 	"context"
+	"log"
 	"time"
 
 	"github.com/hanwen/go-fuse/fuse"
@@ -57,6 +58,15 @@ func (n *DefaultOperations) Read(ctx context.Context, f FileHandle, dest []byte,
 	return nil, fuse.ENOSYS
 }
 
+func (n *DefaultOperations) Symlink(ctx context.Context, target, name string, out *fuse.EntryOut) (node *Inode, code fuse.Status) {
+	log.Println("defsyml")
+	return nil, fuse.ENOSYS
+}
+
+func (n *DefaultOperations) Readlink(ctx context.Context) (string, fuse.Status) {
+	return "", fuse.ENOSYS
+}
+
 func (n *DefaultOperations) Fsync(ctx context.Context, f FileHandle, flags uint32) fuse.Status {
 	if f != nil {
 		return f.Fsync(ctx, flags)

nodefs/loopback.go

@@ -6,6 +6,7 @@ package nodefs
 
 import (
 	"context"
+	"log"
 	"os"
 	"path/filepath"
 	"sync"
@@ -14,6 +15,8 @@ import (
 	"github.com/hanwen/go-fuse/fuse"
 )
 
+var _ = log.Printf
+
 type loopbackRoot struct {
 	loopbackNode
 
@@ -183,6 +186,40 @@ func (n *loopbackNode) Create(ctx context.Context, name string, flags uint32, mo
 	return ch, lf, 0, fuse.OK
 }
 
+func (n *loopbackNode) Symlink(ctx context.Context, target, name string, out *fuse.EntryOut) (*Inode, fuse.Status) {
+	p := filepath.Join(n.path(), name)
+	err := syscall.Symlink(target, p)
+	if err != nil {
+		return nil, fuse.ToStatus(err)
+	}
+	st := syscall.Stat_t{}
+	if syscall.Lstat(p, &st); err != nil {
+		syscall.Unlink(p)
+		return nil, fuse.ToStatus(err)
+	}
+	node := n.rootNode.newLoopbackNode()
+	ch := n.inode().NewInode(node, st.Mode, idFromStat(&st))
+
+	out.Attr.FromStat(&st)
+	return ch, fuse.OK
+}
+
+func (n *loopbackNode) Readlink(ctx context.Context) (string, fuse.Status) {
+	p := n.path()
+
+	for l := 256; ; l *= 2 {
+		buf := make([]byte, l)
+		sz, err := syscall.Readlink(p, buf)
+		if err != nil {
+			return "", fuse.ToStatus(err)
+		}
+
+		if sz < len(buf) {
+			return string(buf[:sz]), fuse.OK
+		}
+	}
+}
+
 func (n *loopbackNode) Open(ctx context.Context, flags uint32) (fh FileHandle, fuseFlags uint32, code fuse.Status) {
 	p := n.path()
 	f, err := os.OpenFile(p, int(flags), 0)

nodefs/simple_test.go

@@ -407,3 +407,20 @@ func TestParallelFileOpen(t *testing.T) {
 	}
 	wg.Wait()
 }
+
+func TestSymlink(t *testing.T) {
+	tc := newTestCase(t)
+	defer tc.Clean()
+
+	fn := tc.mntDir + "/link"
+	target := "target"
+	if err := os.Symlink(target, fn); err != nil {
+		t.Fatalf("Symlink: %v", err)
+	}
+
+	if got, err := os.Readlink(fn); err != nil {
+		t.Fatalf("Readlink: %v", err)
+	} else if got != target {
+		t.Errorf("Readlink: got %q, want %q", got, target)
+	}
+}