windows: Revise management of WaitCommEvent() operations.

This fixes (at least parts of) bug #341.

diff --git a/libserialport_internal.h b/libserialport_internal.h
index 55108240be0ab6219884701b9589c9ed24be111f..329c3786305df950a9eed0e3ab62d07ecb8847ea 100644 (file)
--- a/libserialport_internal.h
+++ b/libserialport_internal.h
@@ -109,6 +109,7 @@ struct sp_port {
        DWORD events;
        BYTE pending_byte;
        BOOL writing;
+       BOOL wait_running;
 #else
        int fd;
 #endif

diff --git a/serialport.c b/serialport.c
index ae108ae4bc2f606ea0cd7f20976abbb1a2ddbd8e..a9b88e656ea49e7bf6a37e7ad1bc01f3eec44642 100644 (file)
--- a/serialport.c
+++ b/serialport.c
@@ -399,6 +399,43 @@ SP_API void sp_free_port_list(struct sp_port **list)
        CHECK_PORT_HANDLE(); \
 } while (0)
 
+#ifdef WIN32
+/** To be called after port receive buffer is emptied. */
+static enum sp_return restart_wait(struct sp_port *port)
+{
+       DWORD wait_result;
+
+       if (port->wait_running) {
+               /* Check status of running wait operation. */
+               if (GetOverlappedResult(port->hdl, &port->wait_ovl,
+                               &wait_result, FALSE)) {
+                       DEBUG("Previous wait completed");
+                       port->wait_running = FALSE;
+               } else if (GetLastError() == ERROR_IO_INCOMPLETE) {
+                       DEBUG("Previous wait still running");
+                       RETURN_OK();
+               } else {
+                       RETURN_FAIL("GetOverlappedResult() failed");
+               }
+       }
+
+       if (!port->wait_running) {
+               /* Start new wait operation. */
+               if (WaitCommEvent(port->hdl, &port->events,
+                               &port->wait_ovl)) {
+                       DEBUG("New wait returned, events already pending");
+               } else if (GetLastError() == ERROR_IO_PENDING) {
+                       DEBUG("New wait running in background");
+                       port->wait_running = TRUE;
+               } else {
+                       RETURN_FAIL("WaitCommEvent() failed");
+               }
+       }
+
+       RETURN_OK();
+}
+#endif
+
 SP_API enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 {
        struct port_data data;
@@ -472,16 +509,15 @@ SP_API enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
                RETURN_FAIL("SetCommMask() failed");
        }
 
-       /* Start background operation for RX and error events. */
-       if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
-               if (GetLastError() != ERROR_IO_PENDING) {
-                       sp_close(port);
-                       RETURN_FAIL("WaitCommEvent() failed");
-               }
-       }
-
        port->writing = FALSE;
+       port->wait_running = FALSE;
 
+       ret = restart_wait(port);
+
+       if (ret < 0) {
+               sp_close(port);
+               RETURN_CODEVAL(ret);
+       }
 #else
        int flags_local = O_NONBLOCK | O_NOCTTY;
 
@@ -623,6 +659,9 @@ SP_API enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
        /* Returns non-zero upon success, 0 upon failure. */
        if (PurgeComm(port->hdl, flags) == 0)
                RETURN_FAIL("PurgeComm() failed");
+
+       if (buffers & SP_BUF_INPUT)
+               TRY(restart_wait(port));
 #else
        int flags = 0;
        if (buffers == SP_BUF_BOTH)
@@ -894,7 +933,8 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
 
 #ifdef _WIN32
        DWORD bytes_read = 0;
-       DWORD wait_result = 0;
+       DWORD bytes_remaining;
+       int ret;
 
        /* Set timeout. */
        port->timeouts.ReadIntervalTimeout = 0;
@@ -916,16 +956,16 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
                bytes_read = count;
        }
 
-       /* 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");
-       }
+       ret = sp_input_waiting(port);
+
+       if (ret < 0)
+               RETURN_CODEVAL(ret);
+
+       bytes_remaining = ret;
+
+       /* Restart wait operation if buffer was emptied. */
+       if (bytes_read > 0 && bytes_remaining == 0)
+               TRY(restart_wait(port));
 
        RETURN_INT(bytes_read);
 
@@ -1005,7 +1045,8 @@ SP_API enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf,
 
 #ifdef _WIN32
        DWORD bytes_read;
-       DWORD wait_result;
+       DWORD bytes_remaining;
+       int ret;
 
        /* Set timeout. */
        port->timeouts.ReadIntervalTimeout = MAXDWORD;
@@ -1021,16 +1062,16 @@ 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");
 
-       /* 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");
-       }
+       ret = sp_input_waiting(port);
+
+       if (ret < 0)
+               RETURN_CODEVAL(ret);
+
+       bytes_remaining = ret;
+
+       /* Restart wait operation if buffer was emptied. */
+       if (bytes_read > 0 && bytes_remaining == 0)
+               TRY(restart_wait(port));
 
        RETURN_INT(bytes_read);
 #else