dropbox: make setting mod time on existing files work properly

This is a fix left over from the v2 conversion.  Dropbox ignores the
client modification on an incoming file if it was identical to the
existing file.  This change deletes the existing file first before
re-uploading the new one.

cmd/mountlib/file.go

@@ -125,7 +125,7 @@ func (f *File) applyPendingModTime() error {
 	switch err {
 	case nil:
 		fs.Debugf(f.o, "File.applyPendingModTime OK")
-	case fs.ErrorCantSetModTime:
+	case fs.ErrorCantSetModTime, fs.ErrorCantSetModTimeWithoutDelete:
 		// do nothing, in order to not break "touch somefile" if it exists already
 	default:
 		fs.Errorf(f.o, "File.applyPendingModTime error: %v", err)

dropbox/dropbox.go

@@ -810,9 +810,9 @@ func (o *Object) ModTime() time.Time {
 // Commits the datastore
 func (o *Object) SetModTime(modTime time.Time) error {
 	// Dropbox doesn't have a way of doing this so returning this
-	// error will cause the file to be re-uploaded to set the
+	// error will cause the file to be deleted first then
-	// time.
+	// re-uploaded to set the time.
-	return fs.ErrorCantSetModTime
+	return fs.ErrorCantSetModTimeWithoutDelete
 }
 
 // Storable returns whether this object is storable

fs/fs.go

@@ -36,6 +36,7 @@ var (
 	ErrorCantDirMove                 = errors.New("can't move directory - incompatible remotes")
 	ErrorDirExists                   = errors.New("can't copy directory - destination already exists")
 	ErrorCantSetModTime              = errors.New("can't set modified time")
+	ErrorCantSetModTimeWithoutDelete = errors.New("can't set modified time without deleting existing object")
 	ErrorDirNotFound                 = errors.New("directory not found")
 	ErrorObjectNotFound              = errors.New("object not found")
 	ErrorLevelNotSupported           = errors.New("level value not supported")

fs/operations.go

@@ -183,7 +183,14 @@ func equal(src, dst Object, sizeOnly, checkSum bool) bool {
 			// mtime of the dst object here
 			err := dst.SetModTime(srcModTime)
 			if err == ErrorCantSetModTime {
-				Debugf(src, "src and dst identical but can't set mod time without re-uploading")
+				Debugf(dst, "src and dst identical but can't set mod time without re-uploading")
+				return false
+			} else if err == ErrorCantSetModTimeWithoutDelete {
+				Debugf(dst, "src and dst identical but can't set mod time without deleting and re-uploading")
+				err = dst.Remove()
+				if err != nil {
+					Errorf(dst, "failed to delete before re-upload: %v", err)
+				}
 				return false
 			} else if err != nil {
 				Stats.Error()

fstest/fstests/fstests.go

@@ -672,7 +672,7 @@ func TestObjectSetModTime(t *testing.T) {
 	newModTime := fstest.Time("2011-12-13T14:15:16.999999999Z")
 	obj := findObject(t, file1.Path)
 	err := obj.SetModTime(newModTime)
-	if err == fs.ErrorCantSetModTime {
+	if err == fs.ErrorCantSetModTime || err == fs.ErrorCantSetModTimeWithoutDelete {
 		t.Log(err)
 		return
 	}