2 files changed, 16 insertions, 0 deletions

diff --git a/src/ext/Util/ca/test.cpp b/src/ext/Util/ca/test.cpp
index e9d02ed3..8f1c238b 100644
--- a/src/ext/Util/ca/test.cpp
+++ b/src/ext/Util/ca/test.cpp
@@ -40,6 +40,21 @@ static LRESULT CALLBACK WndProc(
 
 
 /******************************************************************
+WixCancelWhenDeferred - entry point for WixCancelWhenDeferred
+    custom action which always cancels when running as a deferred
+    custom action (otherwise it blindly succeeds). It's useful when
+    testing the rollback of deferred custom actions: Schedule it
+    immediately after the rollback/deferred CA pair you're testing
+    and it will fail, causing your rollback CA to get invoked.
+********************************************************************/
+extern "C" UINT __stdcall WixCancelWhenDeferred(
+    __in MSIHANDLE hInstall
+)
+{
+    return ::MsiGetMode(hInstall, MSIRUNMODE_SCHEDULED) ? ERROR_INSTALL_USEREXIT : ERROR_SUCCESS;
+}
+
+/******************************************************************
 WixFailWhenDeferred - entry point for WixFailWhenDeferred
     custom action which always fails when running as a deferred
     custom action (otherwise it blindly succeeds). It's useful when
diff --git a/src/ext/Util/ca/utilca.def b/src/ext/Util/ca/utilca.def
index 2aeb54f4..f525233d 100644
--- a/src/ext/Util/ca/utilca.def
+++ b/src/ext/Util/ca/utilca.def
@@ -82,6 +82,7 @@ EXPORTS
     WixShellExecBinary
     WixUnelevatedShellExec
 ; test.cpp
+    WixCancelWhenDeferred
     WixFailWhenDeferred
     WixWaitForEvent
 ; TouchFile.cpp