From 2123bf4b18a030c01d55ff5597fd80769cc7f5e5 Mon Sep 17 00:00:00 2001
From: Dianne Skoll <dianne@skoll.ca>
Date: Sat, 30 Jan 2021 15:15:02 -0500
Subject: [PATCH] Check all Subtract implementations for overflow.

---
 src/expr.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/expr.c b/src/expr.c
index bbfc5aae..2d67d8d6 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -876,7 +876,9 @@ static int Subtract(void)
 
     /* If it's a date minus an int, do subtraction, checking for underflow */
     if (v1.type == DATE_TYPE && v2.type == INT_TYPE) {
+        int old = v1.v.val;
 	v1.v.val -= v2.v.val;
+        if (_private_sub_overflow(v1.v.val, v2.v.val, old)) return E_DATE_OVER;
 	if (v1.v.val < 0) return E_DATE_OVER;
 	PushValStack(v1);
 	return OK;
@@ -885,7 +887,9 @@ static int Subtract(void)
     /* If it's a datetime minus an int or a time, do subtraction,
      * checking for underflow */
     if (v1.type == DATETIME_TYPE && (v2.type == INT_TYPE || v2.type == TIME_TYPE)) {
+        int old = v1.v.val;
 	v1.v.val -= v2.v.val;
+        if (_private_sub_overflow(v1.v.val, v2.v.val, old)) return E_DATE_OVER;
 	if (v1.v.val < 0) return E_DATE_OVER;
 	PushValStack(v1);
 	return OK;
@@ -903,7 +907,9 @@ static int Subtract(void)
     if ((v1.type == TIME_TYPE && v2.type == TIME_TYPE) ||
 	(v1.type == DATETIME_TYPE && v2.type == DATETIME_TYPE) ||
 	(v1.type == DATE_TYPE && v2.type == DATE_TYPE)) {
+        int old = v1.v.val;
 	v1.v.val -= v2.v.val;
+        if (_private_sub_overflow(v1.v.val, v2.v.val, old)) return E_DATE_OVER;
 	v1.type = INT_TYPE;
 	PushValStack(v1);
 	return OK;