From 256487c95aa9c303e173324caa5a074d5fe8b7b8 Mon Sep 17 00:00:00 2001
From: Michael Jumper <mjumper@apache.org>
Date: Thu, 29 Oct 2020 11:59:13 -0700
Subject: [PATCH] GUACAMOLE-1181: Only free wStream after send if FreeRDP
 requires this.

---
 configure.ac                                  | 25 ++++++++++++++++++-
 .../plugins/guac-common-svc/guac-common-svc.c |  2 ++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 1873a6fb..485be581 100644
--- a/configure.ac
+++ b/configure.ac
@@ -623,7 +623,7 @@ then
 
 fi
 
-# Variation in memory internal allocation/free behavior
+# Variation in memory internal allocation/free behavior for bitmaps
 if test "x${have_freerdp2}" = "xyes"
 then
 
@@ -647,6 +647,29 @@ then
 
 fi
 
+# Variation in memory internal allocation/free behavior for channel streams
+if test "x${have_freerdp2}" = "xyes"
+then
+
+    # FreeRDP 2.0.0-rc3 through 2.0.0-rc4 automatically free the wStream
+    # provided to pVirtualChannelWriteEx(). This changed in commit 1b78b59, and
+    # implementations must manually free the wStream after it is no longer
+    # needed (after the write is complete or cancelled).
+    AC_MSG_CHECKING([whether pVirtualChannelWriteEx() frees the wStream upon completion])
+    AC_EGREP_CPP([\"2\\.0\\.0-(rc|dev)[3-4]\"], [
+
+        #include <freerdp/version.h>
+        FREERDP_VERSION_FULL
+
+    ],
+    [AC_MSG_RESULT([yes])]
+    [AC_DEFINE([FREERDP_SVC_CORE_FREES_WSTREAM],,
+               [Whether pVirtualChannelWriteEx() frees the wStream upon completion])],
+    [AC_MSG_RESULT([no])])
+
+fi
+
+
 # Glyph callback variants
 if test "x${have_freerdp2}" = "xyes"
 then
diff --git a/src/protocols/rdp/plugins/guac-common-svc/guac-common-svc.c b/src/protocols/rdp/plugins/guac-common-svc/guac-common-svc.c
index d00af95b..0a464850 100644
--- a/src/protocols/rdp/plugins/guac-common-svc/guac-common-svc.c
+++ b/src/protocols/rdp/plugins/guac-common-svc/guac-common-svc.c
@@ -81,12 +81,14 @@ static VOID guac_rdp_common_svc_handle_open_event(LPVOID user_param,
         DWORD open_handle, UINT event, LPVOID data, UINT32 data_length,
         UINT32 total_length, UINT32 data_flags) {
 
+#ifndef FREERDP_SVC_CORE_FREES_WSTREAM
     /* Free stream data after send is complete */
     if ((event == CHANNEL_EVENT_WRITE_CANCELLED
             || event == CHANNEL_EVENT_WRITE_COMPLETE) && data != NULL) {
         Stream_Free((wStream*) data, TRUE);
         return;
     }
+#endif
 
     /* Ignore all events except for received data */
     if (event != CHANNEL_EVENT_DATA_RECEIVED)