vfs: add symlink support to VFS

This is somewhat limited in that it only resolves symlinks when files
are opened. This will work fine for the intended use in rclone mount,
but is inadequate for the other servers probably.

vfs/dir.go

@@ -459,7 +459,8 @@ func (d *Dir) addObject(node Node) {
 // This will be replaced with a real object when it is read back from the
 // remote.
 //
-// This is used to add directory entries while things are uploading
+// This is used by the vfs cache to insert objects that are uploading
+// into the directory tree.
 func (d *Dir) AddVirtual(leaf string, size int64, isDir bool) {
 	var node Node
 	d.mu.RLock()
@@ -475,7 +476,16 @@ func (d *Dir) AddVirtual(leaf string, size int64, isDir bool) {
 		entry := fs.NewDir(remote, time.Now())
 		node = newDir(d.vfs, d.f, d, entry)
 	} else {
+		isLink := false
+		if d.vfs.Opt.Links {
+			// since the path came from the cache it may have fs.LinkSuffix,
+			// so remove it and mark the *File accordingly
+			leaf, isLink = strings.CutSuffix(leaf, fs.LinkSuffix)
+		}
 		f := newFile(d, dPath, nil, leaf)
+		if isLink {
+			f.setSymlink()
+		}
 		f.setSize(size)
 		node = f
 	}
@@ -628,7 +638,7 @@ func (d *Dir) _purgeVirtual() {
 				// if writing in progress then leave virtual
 				continue
 			}
-			if d.vfs.Opt.CacheMode >= vfscommon.CacheModeMinimal && d.vfs.cache.InUse(f.Path()) {
+			if d.vfs.Opt.CacheMode >= vfscommon.CacheModeMinimal && d.vfs.cache.InUse(f.CachePath()) {
 				// if object in use or dirty then leave virtual
 				continue
 			}
@@ -718,6 +728,9 @@ func (d *Dir) _readDirFromEntries(entries fs.DirEntries, dirTree dirtree.DirTree
 		if name == "." || name == ".." {
 			continue
 		}
+		if d.vfs.Opt.Links {
+			name, _ = strings.CutSuffix(name, fs.LinkSuffix)
+		}
 		node := d.items[name]
 		if mv.add(d, name) {
 			continue