windows: Fix restart of RX/error wait operation after reads.

This fixes bug #421.

diff --git a/serialport.c b/serialport.c
index 2ec2c2f19225f9a526f6438f7b6144a5a6270351..f74fea7bc82e6e2ef5d3d4e67b48095571c9ca7e 100644 (file)
--- a/serialport.c
+++ b/serialport.c
@@ -888,6 +888,7 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
 
 #ifdef _WIN32
        DWORD bytes_read = 0;
+       DWORD wait_result = 0;
 
        /* Set timeout. */
        port->timeouts.ReadIntervalTimeout = 0;
@@ -909,10 +910,15 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
                bytes_read = count;
        }
 
-       /* Start background operation for subsequent events. */
-       if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
-               if (GetLastError() != ERROR_IO_PENDING)
-                       RETURN_FAIL("WaitCommEvent() failed");
+       /* Restart wait operation if needed. */
+       if (GetOverlappedResult(port->hdl, &port->wait_ovl, &wait_result, FALSE)) {
+               /* Previous wait completed, start a new one. */
+               if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
+                       if (GetLastError() != ERROR_IO_PENDING)
+                               RETURN_FAIL("WaitCommEvent() failed");
+               }
+       } else if (GetLastError() != ERROR_IO_INCOMPLETE) {
+               RETURN_FAIL("GetOverlappedResult() failed");
        }
 
        RETURN_INT(bytes_read);
@@ -994,6 +1000,7 @@ SP_API enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf,
 
 #ifdef _WIN32
        DWORD bytes_read;
+       DWORD wait_result;
 
        /* Set timeout. */
        port->timeouts.ReadIntervalTimeout = MAXDWORD;
@@ -1009,12 +1016,15 @@ SP_API enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf,
        if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE) == 0)
                RETURN_FAIL("GetOverlappedResult() failed");
 
-       if (bytes_read > 0) {
-               /* Start background operation for subsequent events. */
+       /* Restart wait operation if needed. */
+       if (GetOverlappedResult(port->hdl, &port->wait_ovl, &wait_result, FALSE)) {
+               /* Previous wait completed, start a new one. */
                if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
                        if (GetLastError() != ERROR_IO_PENDING)
                                RETURN_FAIL("WaitCommEvent() failed");
                }
+       } else if (GetLastError() != ERROR_IO_INCOMPLETE) {
+               RETURN_FAIL("GetOverlappedResult() failed");
        }
 
        RETURN_INT(bytes_read);