From aee7d69195e25fb9e7b250e85df0b50368ddc810 Mon Sep 17 00:00:00 2001
From: Uwe Hermann <uwe@hermann-uwe.de>
Date: Wed, 27 Jan 2016 08:19:38 +0100
Subject: [PATCH] Fix ERROR_SEM_TIMEOUT issue on Windows.

The sp_blocking_write() call was incorrectly returning an error upon
ERROR_SEM_TIMEOUT. It now returns 0 instead.
---
 serialport.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/serialport.c b/serialport.c
index fb603b3..d271478 100644
--- a/serialport.c
+++ b/serialport.c
@@ -764,8 +764,14 @@ SP_API enum sp_return sp_blocking_write(struct sp_port *port, const void *buf,
 		RETURN_INT(count);
 	} else if (GetLastError() == ERROR_IO_PENDING) {
 		DEBUG("Waiting for write to complete");
-		if (GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE) == 0)
-			RETURN_FAIL("GetOverlappedResult() failed");
+		if (GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE) == 0) {
+			if (GetLastError() == ERROR_SEM_TIMEOUT) {
+				DEBUG("Write timed out");
+				RETURN_INT(0);
+			} else {
+				RETURN_FAIL("GetOverlappedResult() failed");
+			}
+		}
 		DEBUG_FMT("Write completed, %d/%d bytes written", bytes_written, count);
 		RETURN_INT(bytes_written);
 	} else {