From 43ba4e4ef5155cc242ae0f1dda5c8a8054027cc5 Mon Sep 17 00:00:00 2001
From: Andy Green <andy@warmcat.com>
Date: Fri, 19 Jun 2020 19:54:17 +0100
Subject: [PATCH] libevent: enforce no event state duplication

https://github.com/warmcat/libwebsockets/issues/1956
---
 lib/event-libs/libevent/libevent.c              | 17 +++++++++++++----
 .../libevent/private-lib-event-libs-libevent.h  |  1 +
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/lib/event-libs/libevent/libevent.c b/lib/event-libs/libevent/libevent.c
index bd59d30f8..7805fc108 100644
--- a/lib/event-libs/libevent/libevent.c
+++ b/lib/event-libs/libevent/libevent.c
@@ -200,6 +200,7 @@ elops_init_pt_event(struct lws_context *context, void *_loop, int tsi)
 					(EV_READ | EV_PERSIST), lws_event_cb,
 					&vh->lserv_wsi->w_read);
 			event_add(vh->lserv_wsi->w_read.event.watcher, NULL);
+			vh->lserv_wsi->w_read.event.set = 1;
 		}
 		vh = vh->vhost_next;
 	}
@@ -277,17 +278,25 @@ elops_io_event(struct lws *wsi, int flags)
 	       (flags & (LWS_EV_READ | LWS_EV_WRITE)));
 
 	if (flags & LWS_EV_START) {
-		if (flags & LWS_EV_WRITE)
+		if ((flags & LWS_EV_WRITE) && !wsi->w_write.event.set) {
 			event_add(wsi->w_write.event.watcher, NULL);
+			wsi->w_write.event.set = 1;
+		}
 
-		if (flags & LWS_EV_READ)
+		if ((flags & LWS_EV_READ) && !wsi->w_read.event.set) {
 			event_add(wsi->w_read.event.watcher, NULL);
+			wsi->w_read.event.set = 1;
+		}
 	} else {
-		if (flags & LWS_EV_WRITE)
+		if ((flags & LWS_EV_WRITE) && wsi->w_write.event.set) {
 			event_del(wsi->w_write.event.watcher);
+			wsi->w_write.event.set = 0;
+		}
 
-		if (flags & LWS_EV_READ)
+		if ((flags & LWS_EV_READ) && wsi->w_read.event.set) {
 			event_del(wsi->w_read.event.watcher);
+			wsi->w_read.event.set = 0;
+		}
 	}
 }
 
diff --git a/lib/event-libs/libevent/private-lib-event-libs-libevent.h b/lib/event-libs/libevent/private-lib-event-libs-libevent.h
index 6d0029548..9bc8e6841 100644
--- a/lib/event-libs/libevent/private-lib-event-libs-libevent.h
+++ b/lib/event-libs/libevent/private-lib-event-libs-libevent.h
@@ -32,6 +32,7 @@ struct lws_pt_eventlibs_libevent {
 
 struct lws_io_watcher_libevent {
 	struct event *watcher;
+	char		set;
 };
 
 struct lws_signal_watcher_libevent {