final touches

cosmwasm/packages/wasmi-runtime/src/exports.rs

@@ -119,7 +119,13 @@ pub unsafe extern "C" fn ecall_init(
     let _recursion_guard = match recursion_depth::guard() {
         Ok(rg) => rg,
         Err(err) => {
-            warn!("recursion limit exceeded, can not perform init!");
+            // https://github.com/enigmampc/SecretNetwork/pull/517#discussion_r481924571
+            // I believe that this error condition is currently unreachable.
+            // I think we can safely remove it completely right now, and have
+            // recursion_depth::increment() simply increment the counter with no further checks,
+            // but i wanted to stay on the safe side here, in case something changes in the
+            // future, and we can easily spot that we forgot to add a limit somewhere.
+            error!("recursion limit exceeded, can not perform init!");
             return InitResult::Failure { err };
         }
     };
@@ -210,7 +216,13 @@ pub unsafe extern "C" fn ecall_handle(
     let _recursion_guard = match recursion_depth::guard() {
         Ok(rg) => rg,
         Err(err) => {
-            warn!("recursion limit exceeded, can not perform handle!");
+            // https://github.com/enigmampc/SecretNetwork/pull/517#discussion_r481924571
+            // I believe that this error condition is currently unreachable.
+            // I think we can safely remove it completely right now, and have
+            // recursion_depth::increment() simply increment the counter with no further checks,
+            // but i wanted to stay on the safe side here, in case something changes in the
+            // future, and we can easily spot that we forgot to add a limit somewhere.
+            error!("recursion limit exceeded, can not perform handle!");
             return HandleResult::Failure { err };
         }
     };
@@ -297,7 +309,13 @@ pub unsafe extern "C" fn ecall_query(
     let _recursion_guard = match recursion_depth::guard() {
         Ok(rg) => rg,
         Err(err) => {
-            warn!("recursion limit exceeded, can not perform query!");
+            // https://github.com/enigmampc/SecretNetwork/pull/517#discussion_r481924571
+            // I believe that this error condition is currently unreachable.
+            // I think we can safely remove it completely right now, and have
+            // recursion_depth::increment() simply increment the counter with no further checks,
+            // but i wanted to stay on the safe side here, in case something changes in the
+            // future, and we can easily spot that we forgot to add a limit somewhere.
+            error!("recursion limit exceeded, can not perform query!");
             return QueryResult::Failure { err };
         }
     };

cosmwasm/packages/wasmi-runtime/src/recursion_depth.rs

@@ -4,28 +4,28 @@ use lazy_static::lazy_static;
 
 use enclave_ffi_types::EnclaveError;
 
-const RECURSION_LIMIT: i32 = 5;
+const RECURSION_LIMIT: u8 = 5;
 
 lazy_static! {
     /// This counter tracks the recursion depth of queries,
     /// and effectively the amount of loaded instances of WASMI.
     ///
     /// It is incremented before each computation begins and is decremented after each computation ends.
-    static ref RECURSION_DEPTH: SgxMutex<i32> = SgxMutex::new(0);
+    static ref RECURSION_DEPTH: SgxMutex<u8> = SgxMutex::new(0);
 }
 
 fn increment() -> Result<(), EnclaveError> {
     let mut depth = RECURSION_DEPTH.lock().unwrap();
     if *depth == RECURSION_LIMIT {
         return Err(EnclaveError::ExceededRecursionLimit);
     }
-    *depth += 1;
+    *depth = depth.saturating_add(1);
     Ok(())
 }
 
 fn decrement() {
     let mut depth = RECURSION_DEPTH.lock().unwrap();
-    *depth -= 1;
+    *depth = depth.saturating_sub(1);
 }
 
 /// Returns whether or not this is the last possible level of recursion