# HG changeset patch
# User John W. Eaton <jwe@octave.org>
# Date 1669500510 18000
# Node ID 9978ef12aea3a02b2fea84d970522b2fef18db90
# Parent  9d0d37acafbeadde935b7aca667fafde26d00d80
avoid overflow due to abs(min_val) in signed int64 multiplication (bug #63416)

* oct-inttypes.cc (octave_int_arith_base<int64_t, true>::mul_internal):
Avoid calling abs on min_val.

diff -r 9d0d37acafbe -r 9978ef12aea3 liboctave/util/oct-inttypes.cc
--- a/liboctave/util/oct-inttypes.cc	Sat Nov 26 17:05:21 2022 -0500
+++ b/liboctave/util/oct-inttypes.cc	Sat Nov 26 17:08:30 2022 -0500
@@ -378,6 +378,14 @@
   // Essentially, what we do is compute sign, multiply absolute values
   // (as above) and impose the sign.
 
+  // But first, avoid overflow in computation of abs (min_val ()).
+
+  if (x == min_val ())
+    return y == 0 ? 0 : (y < 0 ? max_val () : min_val ());
+
+  if (y == min_val ())
+    return x == 0 ? 0 : (x < 0 ? max_val () : min_val ());
+
   uint64_t usx = octave_int_abs (x);
   uint64_t usy = octave_int_abs (y);
   bool positive = (x < 0) == (y < 0);