chore(proto): change symlinktarget to be byte sequence (fixes #9913) (#9914)

lib/model/fakeconns_test.go

@@ -97,7 +97,7 @@ func (f *fakeConnection) addFileLocked(name string, flags uint32, ftype protocol
 		file.Name = name
 		file.Type = ftype
 		file.Version = version
-		file.SymlinkTarget = string(data)
+		file.SymlinkTarget = data
 		file.NoPermissions = true
 	}
 	f.files = append(f.files, file)

lib/model/folder_sendrecv.go

@@ -743,7 +743,7 @@ func (f *sendReceiveFolder) handleSymlink(file protocol.FileInfo, snap *db.Snaps
 		l.Debugf("need symlink\n\t%v\n\t%v", file, curFile)
 	}
 
-	if file.SymlinkTarget == "" {
+	if len(file.SymlinkTarget) == 0 {
 		// Index entry from a Syncthing predating the support for including
 		// the link target in the index entry. We log this as an error.
 		f.newPullError(file.Name, errIncompatibleSymlink)
@@ -758,7 +758,7 @@ func (f *sendReceiveFolder) handleSymlink(file protocol.FileInfo, snap *db.Snaps
 	// We declare a function that acts on only the path name, so
 	// we can pass it to InWritableDir.
 	createLink := func(path string) error {
-		if err := f.mtimefs.CreateSymlink(file.SymlinkTarget, path); err != nil {
+		if err := f.mtimefs.CreateSymlink(string(file.SymlinkTarget), path); err != nil {
 			return err
 		}
 		return f.setPlatformData(&file, path)

lib/model/folder_sendrecv_test.go

@@ -891,7 +891,7 @@ func TestCopyOwner(t *testing.T) {
 		Name:          "foo/bar/sym",
 		Type:          protocol.FileInfoTypeSymlink,
 		Permissions:   0o644,
-		SymlinkTarget: "over the rainbow",
+		SymlinkTarget: []byte("over the rainbow"),
 	}
 
 	f.handleSymlink(symlink, snap, dbUpdateChan, scanChan)
@@ -958,7 +958,7 @@ func TestSRConflictReplaceFileByLink(t *testing.T) {
 
 	// Simulate remote creating a symlink with the same name
 	file.Type = protocol.FileInfoTypeSymlink
-	file.SymlinkTarget = "bar"
+	file.SymlinkTarget = []byte("bar")
 	rem := device1.Short()
 	file.Version = protocol.Vector{}.Update(rem)
 	file.ModifiedBy = rem