There's another check for EOF which needs to be enclosed inside the number of characters read check...

mandrav · mandrav · commit d973f99e550f · 2014-08-23T12:44:14.000+03:00
Former-commit-id: 6107fe4e8071f8bdece2f323a2ca6a7f1b773c29 [formerly 224a2ad7872efa21efdf36ee9aef429424a55a38]
Former-commit-id: 8a9267e3820dae4d2a85fbfb0a13caaf96113404
diff --git a/serialport.go.REMOVED.git-id b/serialport.go.REMOVED.git-id
@@ -1 +1 @@
-7fb064c5acccf8f336f2ecb53219018144da9058
+353672d9d2343442b3dea6ef3a1f77ad925d73f2

Original file line number	Diff line number	Diff line change
`@@ -1 +1 @@`
`1`		`-7fb064c5acccf8f336f2ecb53219018144da9058`
	`1`	`+353672d9d2343442b3dea6ef3a1f77ad925d73f2`