winapi: add hid_winapi_set_write_timeout (#700)

Add API function to control hid_write timeout on WinAPI backend.

Resolves: #686

Author: Youw

hidtest/test.c

@@ -198,6 +198,10 @@ int main(int argc, char* argv[])
  		return 1;
 	}
 
+#if defined(_WIN32) && HID_API_VERSION >= HID_API_MAKE_VERSION(0, 15, 0)
+	hid_winapi_set_write_timeout(handle, 5000);
+#endif
+
 	// Read the Manufacturer String
 	wstr[0] = 0x0000;
 	res = hid_get_manufacturer_string(handle, wstr, MAX_STR);

windows/hid.c

@@ -194,6 +194,7 @@ struct hid_device_ {
 		OVERLAPPED ol;
 		OVERLAPPED write_ol;
 		struct hid_device_info* device_info;
+		DWORD write_timeout_ms;
 };
 
 static hid_device *new_hid_device()
@@ -219,6 +220,7 @@ static hid_device *new_hid_device()
 	memset(&dev->write_ol, 0, sizeof(dev->write_ol));
 	dev->write_ol.hEvent = CreateEvent(NULL, FALSE, FALSE /*initial state f=nonsignaled*/, NULL);
 	dev->device_info = NULL;
+	dev->write_timeout_ms = 1000;
 
 	return dev;
 }
@@ -1052,6 +1054,11 @@ HID_API_EXPORT hid_device * HID_API_CALL hid_open_path(const char *path)
 	return dev;
 }
 
+void HID_API_EXPORT_CALL hid_winapi_set_write_timeout(hid_device *dev, unsigned long timeout)
+{
+	dev->write_timeout_ms = timeout;
+}
+
 int HID_API_EXPORT HID_API_CALL hid_write(hid_device *dev, const unsigned char *data, size_t length)
 {
 	DWORD bytes_written = 0;
@@ -1103,7 +1110,7 @@ int HID_API_EXPORT HID_API_CALL hid_write(hid_device *dev, const unsigned char *
 	if (overlapped) {
 		/* Wait for the transaction to complete. This makes
 		   hid_write() synchronous. */
-		res = WaitForSingleObject(dev->write_ol.hEvent, 1000);
+		res = WaitForSingleObject(dev->write_ol.hEvent, dev->write_timeout_ms);
 		if (res != WAIT_OBJECT_0) {
 			/* There was a Timeout. */
 			register_winapi_error(dev, L"hid_write/WaitForSingleObject");

windows/hidapi_winapi.h

@@ -67,6 +67,26 @@ extern "C" {
 		 */
 		int HID_API_EXPORT_CALL hid_winapi_descriptor_reconstruct_pp_data(void *hidp_preparsed_data, unsigned char *buf, size_t buf_size);
 
+		/**
+		 * @brief Sets the timeout for hid_write operation.
+		 *
+		 * Since version 0.15.0, @ref HID_API_VERSION >= HID_API_MAKE_VERSION(0, 15, 0)
+		 *
+		 * The default timeout is 1sec for winapi backend.
+		 *
+		 * In case if 1sec is not enough, on in case of multi-platform development,
+		 * the recommended value is 5sec, e.g. to match (unconfigurable) 5sec timeout
+		 * set for hidraw (linux kernel) implementation.
+		 *
+		 * When the timeout is set to 0, hid_write function becomes non-blocking and would exit immediately.
+		 * When the timeout is set to INFINITE ((DWORD)-1), the function will not exit,
+		 * until the write operation is performed or an error occured.
+		 * See dwMilliseconds parameter documentation of WaitForSingleObject function.
+		 *
+		 * @param timeout New timeout value in milliseconds.
+		 */
+		void HID_API_EXPORT_CALL hid_winapi_set_write_timeout(hid_device *dev, unsigned long timeout);
+
 #ifdef __cplusplus
 }
 #endif