lib/cmake: check for libusb_handle_events_timeout_completed()

libusb < 1.0.9 doesn't have libusb_handle_events_timeout_completed(),
but libusb <= 1.0.8 doesn't have version.h, so we need to check
for the function.

The cmake-code was borrowed from UHD, which also checks
for libusb_error_name(), we add that as well since it might come
handy later on.

Signed-off-by: Steve Markgraf <steve@steve-m.de>

cmake/Modules/FindLibUSB.cmake

@@ -24,6 +24,24 @@ endif()
     /usr/local/lib
   )
 
+include(CheckFunctionExists)
+if(LIBUSB_INCLUDE_DIRS)
+    set(CMAKE_REQUIRED_INCLUDES ${LIBUSB_INCLUDE_DIRS})
+endif()
+if(LIBUSB_LIBRARIES)
+    set(CMAKE_REQUIRED_LIBRARIES ${LIBUSB_LIBRARIES})
+endif()
+
+CHECK_FUNCTION_EXISTS("libusb_handle_events_timeout_completed" HAVE_LIBUSB_HANDLE_EVENTS_TIMEOUT_COMPLETED)
+if(HAVE_LIBUSB_HANDLE_EVENTS_TIMEOUT_COMPLETED)
+    add_definitions(-DHAVE_LIBUSB_HANDLE_EVENTS_TIMEOUT_COMPLETED=1)
+endif(HAVE_LIBUSB_HANDLE_EVENTS_TIMEOUT_COMPLETED)
+
+CHECK_FUNCTION_EXISTS("libusb_error_name" HAVE_LIBUSB_ERROR_NAME)
+if(HAVE_LIBUSB_ERROR_NAME)
+    add_definitions(-DHAVE_LIBUSB_ERROR_NAME=1)
+endif(HAVE_LIBUSB_ERROR_NAME)
+
 if(LIBUSB_INCLUDE_DIR AND LIBUSB_LIBRARIES)
   set(LIBUSB_FOUND TRUE CACHE INTERNAL "libusb-1.0 found")
   message(STATUS "Found libusb-1.0: ${LIBUSB_INCLUDE_DIR}, ${LIBUSB_LIBRARIES}")

src/librtlsdr.c

@@ -1775,7 +1775,11 @@ int rtlsdr_read_async(rtlsdr_dev_t *dev, rtlsdr_read_async_cb_t cb, void *ctx,
 	}
 
 	while (RTLSDR_INACTIVE != dev->async_status) {
+#ifdef HAVE_LIBUSB_HANDLE_EVENTS_TIMEOUT_COMPLETED
 		r = libusb_handle_events_timeout_completed(dev->ctx, &tv, &dev->async_cancel);
+#else
+		r = libusb_handle_events_timeout(dev->ctx, &tv);
+#endif
 		if (r < 0) {
 			/*fprintf(stderr, "handle_events returned: %d\n", r);*/
 			if (r == LIBUSB_ERROR_INTERRUPTED) /* stray signal */
@@ -1807,7 +1811,11 @@ int rtlsdr_read_async(rtlsdr_dev_t *dev, rtlsdr_read_async_cb_t cb, void *ctx,
 				/* handle any events that still need to
 				 * be handled before exiting after we
 				 * just cancelled all transfers */
+#ifdef HAVE_LIBUSB_HANDLE_EVENTS_TIMEOUT_COMPLETED
 				libusb_handle_events_timeout_completed(dev->ctx, &zerotv, NULL);
+#else
+				libusb_handle_events_timeout(dev->ctx, &zerotv);
+#endif
 				break;
 			}
 		}