diff --git a/core/vm/evm.go b/core/vm/evm.go
index 97a9d31053a0f641bd826a3fcae7f290733368e3..cc4214a163d569b3a564cc1310b71fbe13ca8120 100644
--- a/core/vm/evm.go
+++ b/core/vm/evm.go
@@ -123,19 +123,20 @@ func (evm *EVM) Cancel() {
atomic.StoreInt32(&evm.abort, 1)
}
-// Call executes the contract associated with the addr with the given input as parameters. It also handles any
-// necessary value transfer required and takes the necessary steps to create accounts and reverses the state in
-// case of an execution error or failed value transfer.
+// Call executes the contract associated with the addr with the given input as
+// parameters. It also handles any necessary value transfer required and takes
+// the necessary steps to create accounts and reverses the state in case of an
+// execution error or failed value transfer.
func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
if evm.vmConfig.NoRecursion && evm.depth > 0 {
return nil, gas, nil
}
- // Depth check execution. Fail if we're trying to execute above the
- // limit.
+ // Fail if we're trying to execute above the call depth limit
if evm.depth > int(params.CallCreateDepth) {
return nil, gas, ErrDepth
}
+ // Fail if we're trying to transfer more than the available balance
if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) {
return nil, gas, ErrInsufficientBalance
}
@@ -173,21 +174,23 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas
return ret, contract.Gas, err
}
-// CallCode executes the contract associated with the addr with the given input as parameters. It also handles any
-// necessary value transfer required and takes the necessary steps to create accounts and reverses the state in
-// case of an execution error or failed value transfer.
+// CallCode executes the contract associated with the addr with the given input
+// as parameters. It also handles any necessary value transfer required and takes
+// the necessary steps to create accounts and reverses the state in case of an
+// execution error or failed value transfer.
//
-// CallCode differs from Call in the sense that it executes the given address' code with the caller as context.
+// CallCode differs from Call in the sense that it executes the given address'
+// code with the caller as context.
func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
if evm.vmConfig.NoRecursion && evm.depth > 0 {
return nil, gas, nil
}
- // Depth check execution. Fail if we're trying to execute above the
- // limit.
+ // Fail if we're trying to execute above the call depth limit
if evm.depth > int(params.CallCreateDepth) {
return nil, gas, ErrDepth
}
+ // Fail if we're trying to transfer more than the available balance
if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
return nil, gas, ErrInsufficientBalance
}
@@ -211,18 +214,16 @@ func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte,
return ret, contract.Gas, err
}
-// DelegateCall executes the contract associated with the addr with the given input as parameters.
-// It reverses the state in case of an execution error.
+// DelegateCall executes the contract associated with the addr with the given input
+// as parameters. It reverses the state in case of an execution error.
//
-// DelegateCall differs from CallCode in the sense that it executes the given address' code with the caller as context
-// and the caller is set to the caller of the caller.
+// DelegateCall differs from CallCode in the sense that it executes the given address'
+// code with the caller as context and the caller is set to the caller of the caller.
func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
if evm.vmConfig.NoRecursion && evm.depth > 0 {
return nil, gas, nil
}
-
- // Depth check execution. Fail if we're trying to execute above the
- // limit.
+ // Fail if we're trying to execute above the call depth limit
if evm.depth > int(params.CallCreateDepth) {
return nil, gas, ErrDepth
}
@@ -232,7 +233,7 @@ func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []by
to = AccountRef(caller.Address())
)
- // Iinitialise a new contract and make initialise the delegate values
+ // Initialise a new contract and make initialise the delegate values
contract := NewContract(caller, to, nil, gas).AsDelegate()
contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
@@ -245,18 +246,19 @@ func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []by
return ret, contract.Gas, err
}
+// StaticCall executes the contract associated with the addr with the given input
+// as parameters while disallowing any modifications to the state during the call.
+// Opcodes that attempt to perform such modifications will result in exceptions
+// instead of performing the modifications.
func (evm *EVM) StaticCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
if evm.vmConfig.NoRecursion && evm.depth > 0 {
return nil, gas, nil
}
-
- // Depth check execution. Fail if we're trying to execute above the
- // limit.
+ // Fail if we're trying to execute above the call depth limit
if evm.depth > int(params.CallCreateDepth) {
return nil, gas, ErrDepth
}
-
- // make sure the readonly is only set if we aren't in readonly yet
+ // Make sure the readonly is only set if we aren't in readonly yet
// this makes also sure that the readonly flag isn't removed for
// child calls.
if !evm.interpreter.readonly {
@@ -268,23 +270,18 @@ func (evm *EVM) StaticCall(caller ContractRef, addr common.Address, input []byte
to = AccountRef(addr)
snapshot = evm.StateDB.Snapshot()
)
- if !evm.StateDB.Exist(addr) {
- return nil, gas, nil
- }
-
- // initialise a new contract and set the code that is to be used by the
- // EVM. The contract is a scoped evmironment for this execution context
+ // Initialise a new contract and set the code that is to be used by the
+ // EVM. The contract is a scoped environment for this execution context
// only.
contract := NewContract(caller, to, new(big.Int), gas)
contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
- ret, err = evm.interpreter.Run(snapshot, contract, input)
// When an error was returned by the EVM or when setting the creation code
// above we revert to the snapshot and consume any gas remaining. Additionally
- // when we're in homestead this also counts for code storage gas errors.
+ // when we're in Homestead this also counts for code storage gas errors.
+ ret, err = run(evm, snapshot, contract, input)
if err != nil {
contract.UseGas(contract.Gas)
-
evm.StateDB.RevertToSnapshot(snapshot)
}
return ret, contract.Gas, err
diff --git a/core/vm/interpreter.go b/core/vm/interpreter.go
index 32d764b9f47ac5a1650b68a8d734de2898869da8..661ada6910c9370e398f724354c541454164584b 100644
--- a/core/vm/interpreter.go
+++ b/core/vm/interpreter.go
@@ -89,13 +89,12 @@ func NewInterpreter(evm *EVM, cfg Config) *Interpreter {
func (in *Interpreter) enforceRestrictions(op OpCode, operation operation, stack *Stack) error {
if in.evm.chainRules.IsMetropolis {
if in.readonly {
- // if the interpreter is operating in readonly mode, make sure no
- // state-modifying operation is performed. The 4th stack item
+ // If the interpreter is operating in readonly mode, make sure no
+ // state-modifying operation is performed. The 3rd stack item
// for a call operation is the value. Transfering value from one
// account to the others means the state is modified and should also
// return with an error.
- if operation.writes ||
- ((op == CALL || op == CALLCODE) && stack.Back(3).BitLen() > 0) {
+ if operation.writes || (op == CALL && stack.Back(2).BitLen() > 0) {
return errWriteProtection
}
}