From a1f603f0a388a519771ef77ae18f44a448a81c5a Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Fri, 1 Jan 2021 12:55:35 -0800
Subject: [PATCH] Add overflow check for INPUT_EVENT_POS_MIN
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* src/keyboard.c (INPUT_EVENT_POS_MIN): Don’t assume (-1 -
INPUT_EVENT_POS_MAX) fits into ptrdiff_t.  This fixes a
purely-theoretical problem that cannot occur on two’s-complement
arithmetic.  The Solaris 10 compiler still complains incorrectly,
but oh well.
---
 src/keyboard.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/keyboard.c b/src/keyboard.c
index 0cf7adae741..d2f0cb405f0 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -3647,7 +3647,8 @@ kbd_buffer_unget_event (struct selection_input_event *event)
 #define INPUT_EVENT_POS_MAX \
   ((ptrdiff_t) min (PTRDIFF_MAX, min (TYPE_MAXIMUM (Time) / 2, \
 				      MOST_POSITIVE_FIXNUM)))
-#define INPUT_EVENT_POS_MIN (-1 - INPUT_EVENT_POS_MAX)
+#define INPUT_EVENT_POS_MIN (PTRDIFF_MIN < -INPUT_EVENT_POS_MAX \
+			     ? -1 - INPUT_EVENT_POS_MAX : PTRDIFF_MIN)
 
 /* Return a Time that encodes position POS.  POS must be in range.  */
 
-- 
2.39.5