From 0856f6ccf256b55650276fd40649807d5cf849a8 Mon Sep 17 00:00:00 2001
From: alessandrokonrad <akonrad6@gmail.com>
Date: Mon, 17 Oct 2022 12:07:12 +0200
Subject: [PATCH] added checked operators to some DefaultFunction

---
 crates/uplc/src/machine/error.rs   |  2 ++
 crates/uplc/src/machine/runtime.rs | 15 ++++++++++++---
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/crates/uplc/src/machine/error.rs b/crates/uplc/src/machine/error.rs
index ba81ab79..d9de5344 100644
--- a/crates/uplc/src/machine/error.rs
+++ b/crates/uplc/src/machine/error.rs
@@ -46,4 +46,6 @@ pub enum Error {
     UnexpectedEd25519SignatureLength(usize),
     #[error("Failed to deserialise PlutusData:\n\n{0:#?}")]
     DeserialisationError(Value),
+    #[error("Integer overflow")]
+    OverflowError,
 }
diff --git a/crates/uplc/src/machine/runtime.rs b/crates/uplc/src/machine/runtime.rs
index 5cca10c2..cd93ea1e 100644
--- a/crates/uplc/src/machine/runtime.rs
+++ b/crates/uplc/src/machine/runtime.rs
@@ -328,19 +328,28 @@ impl DefaultFunction {
         match self {
             DefaultFunction::AddInteger => match (&args[0], &args[1]) {
                 (Value::Con(Constant::Integer(arg1)), Value::Con(Constant::Integer(arg2))) => {
-                    Ok(Value::Con(Constant::Integer(arg1 + arg2)))
+                    match arg1.checked_add(*arg2) {
+                        Some(res) => Ok(Value::Con(Constant::Integer(res))),
+                        None => return Err(Error::OverflowError),
+                    }
                 }
                 _ => unreachable!(),
             },
             DefaultFunction::SubtractInteger => match (&args[0], &args[1]) {
                 (Value::Con(Constant::Integer(arg1)), Value::Con(Constant::Integer(arg2))) => {
-                    Ok(Value::Con(Constant::Integer(arg1 - arg2)))
+                    match arg1.checked_sub(*arg2) {
+                        Some(res) => Ok(Value::Con(Constant::Integer(res))),
+                        None => return Err(Error::OverflowError),
+                    }
                 }
                 _ => unreachable!(),
             },
             DefaultFunction::MultiplyInteger => match (&args[0], &args[1]) {
                 (Value::Con(Constant::Integer(arg1)), Value::Con(Constant::Integer(arg2))) => {
-                    Ok(Value::Con(Constant::Integer(arg1 * arg2)))
+                    match arg1.checked_mul(*arg2) {
+                        Some(res) => Ok(Value::Con(Constant::Integer(res))),
+                        None => return Err(Error::OverflowError),
+                    }
                 }
                 _ => unreachable!(),
             },