GUACAMOLE-249: Remove CLIPRDR callback typecasts, relying instead on configure tests to check need for const.

configure.ac

@@ -597,6 +597,36 @@ then
 
 fi
 
+# CLIPRDR callback variants
+if test "x${have_freerdp2}" = "xyes"
+then
+
+    # FreeRDP 2.0.0-rc3 and older did not use const for CLIPRDR callbacks
+    AC_MSG_CHECKING([whether CLIPRDR callbacks require const for their final parameter])
+    AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+
+        #include <freerdp/client/cliprdr.h>
+        #include <winpr/wtypes.h>
+
+        UINT test_monitor_ready(CliprdrClientContext* cliprdr,
+                const CLIPRDR_MONITOR_READY* monitor_ready);
+
+        CliprdrClientContext context = {
+            .MonitorReady = test_monitor_ready
+        };
+
+        int main() {
+            return (int) context.MonitorReady(NULL, NULL);
+        }
+
+    ]])],
+    [AC_MSG_RESULT([yes])]
+    [AC_DEFINE([FREERDP_CLIPRDR_CALLBACKS_REQUIRE_CONST],,
+               [Whether CLIPRDR callbacks require const for the final parameter])],
+    [AC_MSG_RESULT([no])])
+
+fi
+
 AM_CONDITIONAL([ENABLE_RDP], [test "x${have_freerdp2}" = "xyes"])
 
 #

src/protocols/rdp/channels/cliprdr.c

@@ -21,6 +21,7 @@
 #include "client.h"
 #include "common/clipboard.h"
 #include "common/iconv.h"
+#include "config.h"
 #include "plugins/channels.h"
 #include "rdp.h"
 
@@ -37,6 +38,20 @@
 #include <stdlib.h>
 #include <string.h>
 
+#ifdef FREERDP_CLIPRDR_CALLBACKS_REQUIRE_CONST
+/**
+ * FreeRDP 2.0.0-rc4 and newer requires the final argument for all CLIPRDR
+ * callbacks to be const.
+ */
+#define CLIPRDR_CONST const
+#else
+/**
+ * FreeRDP 2.0.0-rc3 and older requires the final argument for all CLIPRDR
+ * callbacks to NOT be const.
+ */
+#define CLIPRDR_CONST
+#endif
+
 /**
  * Sends a Format List PDU to the RDP server containing the formats of
  * clipboard data supported. This PDU is used both to indicate the general
@@ -127,7 +142,7 @@ static UINT guac_rdp_cliprdr_send_capabilities(CliprdrClientContext* cliprdr) {
  *     (non-zero) otherwise.
  */
 static UINT guac_rdp_cliprdr_monitor_ready(CliprdrClientContext* cliprdr,
-        const CLIPRDR_MONITOR_READY* monitor_ready) {
+        CLIPRDR_CONST CLIPRDR_MONITOR_READY* monitor_ready) {
 
     /* FreeRDP-specific handlers for CLIPRDR are not assigned, and thus not
      * callable, until after the relevant guac_rdp_clipboard structure is
@@ -241,7 +256,7 @@ static int guac_rdp_cliprdr_format_supported(const CLIPRDR_FORMAT_LIST* format_l
  *     (non-zero) otherwise.
  */
 static UINT guac_rdp_cliprdr_format_list(CliprdrClientContext* cliprdr,
-        const CLIPRDR_FORMAT_LIST* format_list) {
+        CLIPRDR_CONST CLIPRDR_FORMAT_LIST* format_list) {
 
     /* FreeRDP-specific handlers for CLIPRDR are not assigned, and thus not
      * callable, until after the relevant guac_rdp_clipboard structure is
@@ -296,7 +311,7 @@ static UINT guac_rdp_cliprdr_format_list(CliprdrClientContext* cliprdr,
  *     (non-zero) otherwise.
  */
 static UINT guac_rdp_cliprdr_format_data_request(CliprdrClientContext* cliprdr,
-        const CLIPRDR_FORMAT_DATA_REQUEST* format_data_request) {
+        CLIPRDR_CONST CLIPRDR_FORMAT_DATA_REQUEST* format_data_request) {
 
     /* FreeRDP-specific handlers for CLIPRDR are not assigned, and thus not
      * callable, until after the relevant guac_rdp_clipboard structure is
@@ -373,7 +388,7 @@ static UINT guac_rdp_cliprdr_format_data_request(CliprdrClientContext* cliprdr,
  *     (non-zero) otherwise.
  */
 static UINT guac_rdp_cliprdr_format_data_response(CliprdrClientContext* cliprdr,
-        const CLIPRDR_FORMAT_DATA_RESPONSE* format_data_response) {
+        CLIPRDR_CONST CLIPRDR_FORMAT_DATA_RESPONSE* format_data_response) {
 
     /* FreeRDP-specific handlers for CLIPRDR are not assigned, and thus not
      * callable, until after the relevant guac_rdp_clipboard structure is
@@ -474,10 +489,10 @@ static void guac_rdp_cliprdr_channel_connected(rdpContext* context,
     cliprdr->custom = clipboard;
     clipboard->cliprdr = cliprdr;
 
-    cliprdr->MonitorReady = (pcCliprdrMonitorReady) guac_rdp_cliprdr_monitor_ready;
+    cliprdr->MonitorReady = guac_rdp_cliprdr_monitor_ready;
-    cliprdr->ServerFormatList = (pcCliprdrServerFormatList) guac_rdp_cliprdr_format_list;
+    cliprdr->ServerFormatList = guac_rdp_cliprdr_format_list;
-    cliprdr->ServerFormatDataRequest = (pcCliprdrServerFormatDataRequest) guac_rdp_cliprdr_format_data_request;
+    cliprdr->ServerFormatDataRequest = guac_rdp_cliprdr_format_data_request;
-    cliprdr->ServerFormatDataResponse = (pcCliprdrServerFormatDataResponse) guac_rdp_cliprdr_format_data_response;
+    cliprdr->ServerFormatDataResponse = guac_rdp_cliprdr_format_data_response;
 
     guac_client_log(client, GUAC_LOG_DEBUG, "CLIPRDR (clipboard redirection) "
             "channel connected.");