Return bool from evmc_gen_balance_fn()

ethereum · Sep 6, 2018 · e38c9ed · e38c9ed
1 parent 83a679c
commit e38c9ed
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Showing 4 changed files with 22 additions and 13 deletions.
diff --git a/bindings/go/evmc/host.c b/bindings/go/evmc/host.c
@@ -69,8 +69,8 @@ static inline void go_exported_functions_type_checks()
     storage_status = setStorage(context, address, uint256be, uint256be);
 
     evmc_get_balance_fn get_balance_fn = NULL;
-    get_balance_fn(uint256be, context, address);
-    getBalance(uint256be, context, address);
+    bool_flag = get_balance_fn(uint256be, context, address);
+    bool_flag = getBalance(uint256be, context, address);
 
     evmc_get_code_size_fn get_code_size_fn = NULL;
     size = get_code_size_fn(context, address);

diff --git a/bindings/go/evmc/host.go b/bindings/go/evmc/host.go
@@ -73,7 +73,7 @@ type HostContext interface {
 	AccountExists(addr common.Address) bool
 	GetStorage(addr common.Address, key common.Hash) common.Hash
 	SetStorage(addr common.Address, key common.Hash, value common.Hash) StorageStatus
-	GetBalance(addr common.Address) common.Hash
+	GetBalance(addr common.Address) (common.Hash, error)
 	GetCodeSize(addr common.Address) int
 	GetCodeHash(addr common.Address) common.Hash
 	GetCode(addr common.Address) []byte
@@ -110,11 +110,15 @@ func setStorage(pCtx unsafe.Pointer, pAddr *C.struct_evmc_address, pKey *C.struc
 }
 
 //export getBalance
-func getBalance(pResult *C.struct_evmc_uint256be, pCtx unsafe.Pointer, pAddr *C.struct_evmc_address) {
+func getBalance(pResult *C.struct_evmc_uint256be, pCtx unsafe.Pointer, pAddr *C.struct_evmc_address) C.bool {
 	idx := int((*C.struct_extended_context)(pCtx).index)
 	ctx := getHostContext(idx)
-	balance := ctx.GetBalance(goAddress(*pAddr))
+	balance, err := ctx.GetBalance(goAddress(*pAddr))
+	if err != nil {
+		return false
+	}
 	*pResult = evmcUint256be(balance)
+	return true
 }
 
 //export getCodeSize

diff --git a/examples/example_host.cpp b/examples/example_host.cpp
@@ -54,9 +54,10 @@ static enum evmc_storage_status set_storage(evmc_context* context,
     return EVMC_STORAGE_UNCHANGED;
 }
 
-static void get_balance(evmc_uint256be* result, evmc_context* context, const evmc_address* address)
+static bool get_balance(evmc_uint256be* result, evmc_context* context, const evmc_address* address)
 {
     *result = balance(context, address);
+    return true;
 }
 
 static size_t get_code_size(evmc_context* context, const evmc_address* address)

diff --git a/include/evmc/evmc.h b/include/evmc/evmc.h
@@ -475,14 +475,18 @@ typedef enum evmc_storage_status (*evmc_set_storage_fn)(struct evmc_context* con
 /**
  * Get balance callback function.
  *
- *  This callback function is used by an EVM to query the balance of the given
- *  address.
- *  @param[out] result   The returned balance value.
- *  @param      context  The pointer to the Host execution context.
- *                       @see ::evmc_context.
- *  @param      address  The address.
+ * This callback function is used by a VM to query the balance of the given address.
+ *
+ * @param[out] result   The pointer to the place where to put the result balance.
+ *                      The pointed memory is only modified when the function returns true.
+ * @param      context  The pointer to the Host execution context.
+ * @param      address  The address.
+ * @return              If the account exists its balance is put at the location
+ *                      pointed by @p result and true is returned.
+ *                      If the account does not exist false is returned without
+ *                      modifying the memory pointed by @p result.
  */
-typedef void (*evmc_get_balance_fn)(struct evmc_uint256be* result,
+typedef bool (*evmc_get_balance_fn)(struct evmc_uint256be* result,
                                     struct evmc_context* context,
                                     const struct evmc_address* address);