From 696fcbe07ac7926b2ba12d50e55b6c7dd66979dc Mon Sep 17 00:00:00 2001
From: "Demi M. Obenour" <demiobenour@gmail.com>
Date: Wed, 26 Dec 2018 18:05:41 -0500
Subject: [PATCH] Enable overflow checking on the release build
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This is probably best for smart contracts, where math errors are likely
to be security vulnerabilities, and so overflow should be caught at
run-time.  Ideally, this could be done without enabling all debug
assertions, but Rust doesn’t provide for this.

The fold in src/bridge.rs has had overflow checking added explicitly.
---
 Cargo.toml    |  3 +++
 src/bridge.rs |  8 +++++++-
 src/lib.rs    | 13 ++++---------
 3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 646a0e9..e33eb21 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -43,3 +43,6 @@ std = [
     "srml-timestamp/std",
     "srml-democracy/std",
 ]
+
+[profile.release]
+debug-assertions = true
diff --git a/src/bridge.rs b/src/bridge.rs
index 5ccb128..3f377b8 100644
--- a/src/bridge.rs
+++ b/src/bridge.rs
@@ -114,7 +114,13 @@ decl_module! {
                     // TODO: Ensure that checking balances is sufficient vs. finding explicit stake amounts
                     let stake_sum = new_signers.iter()
                         .map(|s| <balances::Module<T>>::total_balance(s))
-                        .fold(Zero::zero(), |a, b| a + b);
+                        .fold(Zero::zero(), |a, b| {
+                            let res = a + b;
+                            if res < a || res < b || res - b != a {
+                                panic!("Integer overflow in balance calculation")
+                            }
+                            res
+                        });
 
                     // Check if we approve the proposal, if so, mark approved
                     let total_issuance = <balances::Module<T>>::total_issuance();
diff --git a/src/lib.rs b/src/lib.rs
index 6e7cd47..bc926be 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -47,11 +47,6 @@ extern crate srml_timestamp as timestamp;
 extern crate srml_democracy as democracy;
 extern crate srml_consensus as consensus;
 
-// use council::{voting, motions, seats};
-
-use runtime_support::dispatch::Result;
-// use primitives::ed25519;
-
 pub mod bridge;
 pub use bridge::{Module, Trait, RawEvent, Event};
 
@@ -154,19 +149,19 @@ mod tests {
         t.into()
     }
 
-    fn deposit(who: u64, target: u64, transaction_hash: H256, quantity: u64) -> super::Result {
+    fn deposit(who: u64, target: u64, transaction_hash: H256, quantity: u64) -> runtime_support::dispatch::Result {
         Bridge::deposit(Origin::signed(who), target, transaction_hash, quantity)
     }
 
-    fn sign_deposit(who: u64, target: u64, transaction_hash: H256, quantity: u64) -> super::Result {
+    fn sign_deposit(who: u64, target: u64, transaction_hash: H256, quantity: u64) -> runtime_support::dispatch::Result {
         Bridge::sign_deposit(Origin::signed(who), target, transaction_hash, quantity)
     }
 
-    fn withdraw(who: u64, quantity: u64, signed_cross_chain_tx: &[u8]) -> super::Result {
+    fn withdraw(who: u64, quantity: u64, signed_cross_chain_tx: &[u8]) -> runtime_support::dispatch::Result {
         Bridge::withdraw(Origin::signed(who), quantity, signed_cross_chain_tx.to_vec())
     }
 
-    fn sign_withdraw(who: u64, target: u64, record_hash: H256, quantity: u64, signed_cross_chain_tx: &[u8]) -> super::Result {
+    fn sign_withdraw(who: u64, target: u64, record_hash: H256, quantity: u64, signed_cross_chain_tx: &[u8]) -> runtime_support::dispatch::Result {
         Bridge::sign_withdraw(Origin::signed(who), target, record_hash, quantity, signed_cross_chain_tx.to_vec())
     }