Don't drop buffered input data in findOffset() (#1392)

src/tui/light.go

@@ -27,7 +27,7 @@ const (
 
 const consoleDevice string = "/dev/tty"
 
-var offsetRegexp *regexp.Regexp = regexp.MustCompile("\x1b\\[([0-9]+);([0-9]+)R")
+var offsetRegexp *regexp.Regexp = regexp.MustCompile("(.*)\x1b\\[([0-9]+);([0-9]+)R")
 
 func openTtyIn() *os.File {
 	in, err := os.OpenFile(consoleDevice, syscall.O_RDONLY, 0)
@@ -154,8 +154,10 @@ func (r *LightRenderer) findOffset() (row int, col int) {
 	for tries := 0; tries < offsetPollTries; tries++ {
 		bytes = r.getBytesInternal(bytes, tries > 0)
 		offsets := offsetRegexp.FindSubmatch(bytes)
-		if len(offsets) > 2 {
-			return atoi(string(offsets[1]), 0) - 1, atoi(string(offsets[2]), 0) - 1
+		if len(offsets) > 3 {
+			// add anything we skipped over to the input buffer
+			r.buffer = append(r.buffer, offsets[1]...)
+			return atoi(string(offsets[2]), 0) - 1, atoi(string(offsets[3]), 0) - 1
 		}
 	}
 	return -1, -1