core/vm: polish RETURNDATA, add missing returns to CALL*

7 files changed, 75 insertions, 72 deletions

diff --git a/core/vm/evm.go b/core/vm/evm.go
index cc4214a16..448acd469 100644
--- a/core/vm/evm.go
+++ b/core/vm/evm.go
@@ -261,9 +261,9 @@ func (evm *EVM) StaticCall(caller ContractRef, addr common.Address, input []byte
 	// 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 {
-		evm.interpreter.readonly = true
-		defer func() { evm.interpreter.readonly = false }()
+	if !evm.interpreter.readOnly {
+		evm.interpreter.readOnly = true
+		defer func() { evm.interpreter.readOnly = false }()
 	}
 
 	var (
diff --git a/core/vm/gas_table.go b/core/vm/gas_table.go
index 6cdbc5c39..a6346bd80 100644
--- a/core/vm/gas_table.go
+++ b/core/vm/gas_table.go
@@ -65,7 +65,7 @@ func constGasFunc(gas uint64) gasFunc {
 	}
 }
 
-func gasCalldataCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+func gasCallDataCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
 	gas, err := memoryGasCost(mem, memorySize)
 	if err != nil {
 		return 0, err
diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index 0dd9af096..4d6197912 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -29,9 +29,9 @@ import (
 )
 
 var (
-	bigZero            = new(big.Int)
-	errWriteProtection = errors.New("evm: write protection")
-	errReadOutOfBound  = errors.New("evm: read out of bound")
+	bigZero                  = new(big.Int)
+	errWriteProtection       = errors.New("evm: write protection")
+	errReturnDataOutOfBounds = errors.New("evm: return data out of bounds")
 )
 
 func opAdd(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
@@ -243,6 +243,7 @@ func opAnd(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stac
 	evm.interpreter.intPool.put(y)
 	return nil, nil
 }
+
 func opOr(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(x.Or(x, y))
@@ -250,6 +251,7 @@ func opOr(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack
 	evm.interpreter.intPool.put(y)
 	return nil, nil
 }
+
 func opXor(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(x.Xor(x, y))
@@ -269,6 +271,7 @@ func opByte(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Sta
 	evm.interpreter.intPool.put(th)
 	return nil, nil
 }
+
 func opAddmod(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y, z := stack.pop(), stack.pop(), stack.pop()
 	if z.Cmp(bigZero) > 0 {
@@ -282,6 +285,7 @@ func opAddmod(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *S
 	evm.interpreter.intPool.put(y, z)
 	return nil, nil
 }
+
 func opMulmod(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y, z := stack.pop(), stack.pop(), stack.pop()
 	if z.Cmp(bigZero) > 0 {
@@ -339,25 +343,25 @@ func opCallValue(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack
 	return nil, nil
 }
 
-func opCalldataLoad(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opCallDataLoad(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(new(big.Int).SetBytes(getDataBig(contract.Input, stack.pop(), big32)))
 	return nil, nil
 }
 
-func opCalldataSize(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opCallDataSize(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(evm.interpreter.intPool.get().SetInt64(int64(len(contract.Input))))
 	return nil, nil
 }
 
-func opCalldataCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opCallDataCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
-		mOff = stack.pop()
-		cOff = stack.pop()
-		l    = stack.pop()
+		memOffset  = stack.pop()
+		dataOffset = stack.pop()
+		length     = stack.pop()
 	)
-	memory.Set(mOff.Uint64(), l.Uint64(), getDataBig(contract.Input, cOff, l))
+	memory.Set(memOffset.Uint64(), length.Uint64(), getDataBig(contract.Input, dataOffset, length))
 
-	evm.interpreter.intPool.put(mOff, cOff, l)
+	evm.interpreter.intPool.put(memOffset, dataOffset, length)
 	return nil, nil
 }
 
@@ -368,17 +372,17 @@ func opReturnDataSize(pc *uint64, evm *EVM, contract *Contract, memory *Memory,
 
 func opReturnDataCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
-		mOff = stack.pop()
-		cOff = stack.pop()
-		l    = stack.pop()
+		memOffset  = stack.pop()
+		dataOffset = stack.pop()
+		length     = stack.pop()
 	)
-	defer evm.interpreter.intPool.put(mOff, cOff, l)
+	defer evm.interpreter.intPool.put(memOffset, dataOffset, length)
 
-	cEnd := new(big.Int).Add(cOff, l)
-	if cEnd.BitLen() > 64 || uint64(len(evm.interpreter.returnData)) < cEnd.Uint64() {
-		return nil, errReadOutOfBound
+	end := new(big.Int).Add(dataOffset, length)
+	if end.BitLen() > 64 || uint64(len(evm.interpreter.returnData)) < end.Uint64() {
+		return nil, errReturnDataOutOfBounds
 	}
-	memory.Set(mOff.Uint64(), l.Uint64(), evm.interpreter.returnData[cOff.Uint64():cEnd.Uint64()])
+	memory.Set(memOffset.Uint64(), length.Uint64(), evm.interpreter.returnData[dataOffset.Uint64():end.Uint64()])
 
 	return nil, nil
 }
@@ -401,31 +405,28 @@ func opCodeSize(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack
 
 func opCodeCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
-		mOff = stack.pop()
-		cOff = stack.pop()
-		l    = stack.pop()
+		memOffset  = stack.pop()
+		codeOffset = stack.pop()
+		length     = stack.pop()
 	)
-	codeCopy := getDataBig(contract.Code, cOff, l)
-
-	memory.Set(mOff.Uint64(), l.Uint64(), codeCopy)
+	codeCopy := getDataBig(contract.Code, codeOffset, length)
+	memory.Set(memOffset.Uint64(), length.Uint64(), codeCopy)
 
-	evm.interpreter.intPool.put(mOff, cOff, l)
+	evm.interpreter.intPool.put(memOffset, codeOffset, length)
 	return nil, nil
 }
 
 func opExtCodeCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
-		addr = common.BigToAddress(stack.pop())
-		mOff = stack.pop()
-		cOff = stack.pop()
-		l    = stack.pop()
+		addr       = common.BigToAddress(stack.pop())
+		memOffset  = stack.pop()
+		codeOffset = stack.pop()
+		length     = stack.pop()
 	)
-	codeCopy := getDataBig(evm.StateDB.GetCode(addr), cOff, l)
-
-	memory.Set(mOff.Uint64(), l.Uint64(), codeCopy)
-
-	evm.interpreter.intPool.put(mOff, cOff, l)
+	codeCopy := getDataBig(evm.StateDB.GetCode(addr), codeOffset, length)
+	memory.Set(memOffset.Uint64(), length.Uint64(), codeCopy)
 
+	evm.interpreter.intPool.put(memOffset, codeOffset, length)
 	return nil, nil
 }
 
@@ -530,6 +531,7 @@ func opJump(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Sta
 	evm.interpreter.intPool.put(pos)
 	return nil, nil
 }
+
 func opJumpi(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	pos, cond := stack.pop(), stack.pop()
 	if cond.Sign() != 0 {
@@ -545,6 +547,7 @@ func opJumpi(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *St
 	evm.interpreter.intPool.put(pos, cond)
 	return nil, nil
 }
+
 func opJumpdest(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	return nil, nil
 }
diff --git a/core/vm/interpreter.go b/core/vm/interpreter.go
index 1c7481bc5..954839f2e 100644
--- a/core/vm/interpreter.go
+++ b/core/vm/interpreter.go
@@ -59,9 +59,8 @@ type Interpreter struct {
 	gasTable params.GasTable
 	intPool  *intPool
 
-	readonly bool
-	// returnData contains the last call's return data
-	returnData []byte
+	readOnly   bool   // Whether to throw on stateful modifications
+	returnData []byte // Last CALL's return data for subsequent reuse
 }
 
 // NewInterpreter returns a new instance of the Interpreter.
@@ -90,7 +89,7 @@ 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 in.readOnly {
 			// 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
@@ -221,7 +220,7 @@ func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret
 		}
 		// if the operation clears the return data (e.g. it has returning data)
 		// set the last return to the result of the operation.
-		if operation.clearsReturndata {
+		if operation.returns {
 			in.returnData = res
 		}
 	}
diff --git a/core/vm/jump_table.go b/core/vm/jump_table.go
index 7fb11021f..2d238f7a1 100644
--- a/core/vm/jump_table.go
+++ b/core/vm/jump_table.go
@@ -53,8 +53,8 @@ type operation struct {
 	valid bool
 	// reverts determined whether the operation reverts state
 	reverts bool
-	// clearsReturndata determines whether the opertions clears the return data
-	clearsReturndata bool
+	// returns determines whether the opertions sets the return data
+	returns bool
 }
 
 var (
@@ -74,6 +74,7 @@ func NewMetropolisInstructionSet() [256]operation {
 		validateStack: makeStackFunc(6, 1),
 		memorySize:    memoryStaticCall,
 		valid:         true,
+		returns:       true,
 	}
 	instructionSet[RETURNDATASIZE] = operation{
 		execute:       opReturnDataSize,
@@ -101,6 +102,7 @@ func NewHomesteadInstructionSet() [256]operation {
 		validateStack: makeStackFunc(6, 1),
 		memorySize:    memoryDelegateCall,
 		valid:         true,
+		returns:       true,
 	}
 	return instructionSet
 }
@@ -286,22 +288,22 @@ func NewFrontierInstructionSet() [256]operation {
 			valid:         true,
 		},
 		CALLDATALOAD: {
-			execute:       opCalldataLoad,
+			execute:       opCallDataLoad,
 			gasCost:       constGasFunc(GasFastestStep),
 			validateStack: makeStackFunc(1, 1),
 			valid:         true,
 		},
 		CALLDATASIZE: {
-			execute:       opCalldataSize,
+			execute:       opCallDataSize,
 			gasCost:       constGasFunc(GasQuickStep),
 			validateStack: makeStackFunc(0, 1),
 			valid:         true,
 		},
 		CALLDATACOPY: {
-			execute:       opCalldataCopy,
-			gasCost:       gasCalldataCopy,
+			execute:       opCallDataCopy,
+			gasCost:       gasCallDataCopy,
 			validateStack: makeStackFunc(3, 0),
-			memorySize:    memoryCalldataCopy,
+			memorySize:    memoryCallDataCopy,
 			valid:         true,
 		},
 		CODESIZE: {
@@ -876,29 +878,29 @@ func NewFrontierInstructionSet() [256]operation {
 			writes:        true,
 		},
 		CREATE: {
-			execute:          opCreate,
-			gasCost:          gasCreate,
-			validateStack:    makeStackFunc(3, 1),
-			memorySize:       memoryCreate,
-			valid:            true,
-			writes:           true,
-			clearsReturndata: true,
+			execute:       opCreate,
+			gasCost:       gasCreate,
+			validateStack: makeStackFunc(3, 1),
+			memorySize:    memoryCreate,
+			valid:         true,
+			writes:        true,
+			returns:       true,
 		},
 		CALL: {
-			execute:          opCall,
-			gasCost:          gasCall,
-			validateStack:    makeStackFunc(7, 1),
-			memorySize:       memoryCall,
-			valid:            true,
-			clearsReturndata: true,
+			execute:       opCall,
+			gasCost:       gasCall,
+			validateStack: makeStackFunc(7, 1),
+			memorySize:    memoryCall,
+			valid:         true,
+			returns:       true,
 		},
 		CALLCODE: {
-			execute:          opCallCode,
-			gasCost:          gasCallCode,
-			validateStack:    makeStackFunc(7, 1),
-			memorySize:       memoryCall,
-			valid:            true,
-			clearsReturndata: true,
+			execute:       opCallCode,
+			gasCost:       gasCallCode,
+			validateStack: makeStackFunc(7, 1),
+			memorySize:    memoryCall,
+			valid:         true,
+			returns:       true,
 		},
 		RETURN: {
 			execute:       opReturn,
diff --git a/core/vm/memory.go b/core/vm/memory.go
index 6dbee94ef..99a84d227 100644
--- a/core/vm/memory.go
+++ b/core/vm/memory.go
@@ -22,7 +22,6 @@ import "fmt"
 type Memory struct {
 	store       []byte
 	lastGasCost uint64
-	lastReturn  []byte
 }
 
 func NewMemory() *Memory {
diff --git a/core/vm/memory_table.go b/core/vm/memory_table.go
index 9f6533bbc..f1b671adc 100644
--- a/core/vm/memory_table.go
+++ b/core/vm/memory_table.go
@@ -26,7 +26,7 @@ func memorySha3(stack *Stack) *big.Int {
 	return calcMemSize(stack.Back(0), stack.Back(1))
 }
 
-func memoryCalldataCopy(stack *Stack) *big.Int {
+func memoryCallDataCopy(stack *Stack) *big.Int {
 	return calcMemSize(stack.Back(0), stack.Back(2))
 }