From: Martin Ling <redacted>
Date: Wed, 27 Nov 2013 14:31:54 +0000 (+0000)
Subject: Handle EINTR from tcdrain() in sp_drain().
X-Git-Tag: libserialport-0.1.0~31
X-Git-Url: https://sigrok.org/gitaction?a=commitdiff_plain;h=2c827b218813f2663fc3fb09d2ad61f50c4ec1ff;p=libserialport.git

Handle EINTR from tcdrain() in sp_drain().
---

diff --git a/libserialport.h.in b/libserialport.h.in
index 46e2fda..41948c1 100644
--- a/libserialport.h.in
+++ b/libserialport.h.in
@@ -878,6 +878,13 @@ enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers);
 /**
  * Wait for buffered data to be transmitted.
  *
+ * @warning If your program runs on Unix, defines its own signal handlers, and
+ *          needs to abort draining the output buffer when when these are
+ *          called, then you should not use this function. It repeats system
+ *          calls that return with EINTR. To be able to abort a drain from a
+ *          signal handler, you would need to implement your own blocking
+ *          drain by polling the result of sp_output_waiting().
+ *
  * @param port Pointer to port structure.
  *
  * @return SP_OK upon success, a negative error code otherwise.
diff --git a/serialport.c b/serialport.c
index 51eda87..bbb53bd 100644
--- a/serialport.c
+++ b/serialport.c
@@ -799,13 +799,23 @@ enum sp_return sp_drain(struct sp_port *port)
 	/* Returns non-zero upon success, 0 upon failure. */
 	if (FlushFileBuffers(port->hdl) == 0)
 		RETURN_FAIL("FlushFileBuffers() failed");
+	RETURN_OK();
 #else
-	/* Returns 0 upon success, -1 upon failure. */
-	if (tcdrain(port->fd) < 0)
-		RETURN_FAIL("tcdrain() failed");
+	int result;
+	while (1) {
+		result = tcdrain(port->fd);
+		if (result < 0) {
+			if (errno == EINTR) {
+				DEBUG("tcdrain() was interrupted");
+				continue;
+			} else {
+				RETURN_FAIL("tcdrain() failed");
+			}
+		} else {
+			RETURN_OK();
+		}
+	}
 #endif
-
-	RETURN_OK();
 }
 
 enum sp_return sp_blocking_write(struct sp_port *port, const void *buf, size_t count, unsigned int timeout)