From 75c8701df60956254c8bd57cd9015d72134dc6bf Mon Sep 17 00:00:00 2001
From: Pierre Ossman <ossman@cendio.se>
Date: Fri, 19 Jul 2024 17:37:04 +0200
Subject: [PATCH] Fix overflow; "Timer: gettimeofday is broken"

The rounding misbehaved when the tv_usec calculation overflows.

Fixes issue #1782.

(cherry picked from commit 422444acf3a519b75709fb14c02118b75ecbc898)
---
 common/rfb/Timer.cxx | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/common/rfb/Timer.cxx b/common/rfb/Timer.cxx
index e77a9ac3cc..fc3a54d869 100644
--- a/common/rfb/Timer.cxx
+++ b/common/rfb/Timer.cxx
@@ -52,7 +52,10 @@ inline static timeval addMillis(timeval inTime, int millis) {
 }
 
 inline static int diffTimeMillis(timeval later, timeval earlier) {
-  return ((later.tv_sec - earlier.tv_sec) * 1000) + ((later.tv_usec - earlier.tv_usec + 999) / 1000);
+  long udiff;
+  udiff = ((later.tv_sec - earlier.tv_sec) * 1000000) +
+          (later.tv_usec - earlier.tv_usec);
+  return (udiff + 999) / 1000;
 }
 
 std::list<Timer*> Timer::pending;