tevent: add tevent_req_cancel() infrastructure

[metze/samba/wip.git] / lib / tevent / tevent_req.c

diff --git a/lib/tevent/tevent_req.c b/lib/tevent/tevent_req.c
index c6b11601dc28dfbf410e81d3460932655899059f..345a2fdcd1aa75a4e48f60be5b0e7c097a7ab4f0 100644 (file)
--- a/lib/tevent/tevent_req.c
+++ b/lib/tevent/tevent_req.c
@@ -398,3 +398,46 @@ void tevent_req_set_print_fn(struct tevent_req *req, tevent_req_print_fn fn)
 {
        req->private_print = fn;
 }
+
+/**
+ * @brief This function sets a cancel function for the given request
+ * @param[in] req      The given request
+ * @param[in] fn       A pointer to the cancel function
+ *
+ * This function can be used to setup a cancel function for the given request.
+ * This will be triggered if the tevent_req_cancel() function was
+ * called on the given request.
+ *
+ */
+void tevent_req_set_cancel_fn(struct tevent_req *req, tevent_req_cancel_fn fn)
+{
+       req->private_cancel = fn;
+}
+
+/**
+ * @brief This function tries to cancel the given request
+ * @param[in] req      The given request
+ * @param[in] location Automaticly filled with the __location__ macro
+ *                     via the tevent_req_cancel() macro. This is for debugging
+ *                     only!
+ * @retval             This function returns true is the request is cancelable.
+ *                     Otherwise false is returned.
+ *
+ * This function can be used to cancel the given request.
+ *
+ * It is only possible to cancel a request when the implementation
+ * has registered a cancel function via the tevent_req_set_cancel_fn().
+ *
+ * Note: Even if the function returns true, the caller need to wait
+ *       for the function to complete normally.
+ *       Only the _recv() function of the given request indicates
+ *       if the request was really canceled.
+ */
+bool _tevent_req_cancel(struct tevent_req *req, const char *location)
+{
+       if (req->private_cancel == NULL) {
+               return false;
+       }
+
+       return req->private_cancel(req);
+}