Closures and vm based on closures

Status: Work in progress

3 files changed, 217 insertions, 5 deletions

diff --git a/ethchain/closure.go b/ethchain/closure.go
new file mode 100644
index 000000000..4ef43a2da
--- /dev/null
+++ b/ethchain/closure.go
@@ -0,0 +1,68 @@
+package ethchain
+
+// TODO Re write VM to use values instead of big integers?
+
+import (
+	"github.com/ethereum/eth-go/ethutil"
+	"math/big"
+)
+
+type Callee interface {
+	ReturnGas(*big.Int, *State)
+}
+
+type ClosureBody interface {
+	Callee
+	ethutil.RlpEncodable
+	GetMem(int64) *ethutil.Value
+}
+
+// Basic inline closure object which implement the 'closure' interface
+type Closure struct {
+	callee Callee
+	object ClosureBody
+	state  *State
+
+	gas *big.Int
+	val *big.Int
+}
+
+// Create a new closure for the given data items
+func NewClosure(callee Callee, object ClosureBody, state *State, gas, val *big.Int) *Closure {
+	return &Closure{callee, object, state, gas, val}
+}
+
+// Retuns the x element in data slice
+func (c *Closure) GetMem(x int64) *ethutil.Value {
+	m := c.object.GetMem(x)
+	if m == nil {
+		return ethutil.EmptyValue()
+	}
+
+	return m
+}
+
+func (c *Closure) Return(ret []byte) []byte {
+	// Return the remaining gas to the callee
+	// If no callee is present return it to
+	// the origin (i.e. contract or tx)
+	if c.callee != nil {
+		c.callee.ReturnGas(c.gas, c.state)
+	} else {
+		c.object.ReturnGas(c.gas, c.state)
+		// TODO incase it's a POST contract we gotta serialise the contract again.
+		// But it's not yet defined
+	}
+
+	return ret
+}
+
+// Implement the Callee interface
+func (c *Closure) ReturnGas(gas *big.Int, state *State) {
+	// Return the gas to the closure
+	c.gas.Add(c.gas, gas)
+}
+
+func (c *Closure) GetGas() *big.Int {
+	return c.gas
+}
diff --git a/ethchain/vm.go b/ethchain/vm.go
index 7e119ac99..861b041d8 100644
--- a/ethchain/vm.go
+++ b/ethchain/vm.go
@@ -32,13 +32,101 @@ type RuntimeVars struct {
 	txData      []string
 }
 
+func (vm *Vm) RunClosure(closure *Closure, state *State, vars RuntimeVars) []byte {
+	// If the amount of gas supplied is less equal to 0
+	if closure.GetGas().Cmp(big.NewInt(0)) <= 0 {
+		// TODO Do something
+	}
+
+	// Memory for the current closure
+	var mem []byte
+	// New stack (should this be shared?)
+	stack := NewStack()
+	// Instruction pointer
+	pc := int64(0)
+	// Current address
+	//addr := vars.address
+	step := 0
+
+	if ethutil.Config.Debug {
+		ethutil.Config.Log.Debugf("#   op\n")
+	}
+
+	for {
+		step++
+		// Get the memory location of pc
+		val := closure.GetMem(pc)
+		// Get the opcode (it must be an opcode!)
+		op := OpCode(val.Uint())
+		if ethutil.Config.Debug {
+			ethutil.Config.Log.Debugf("%-3d %-4s", pc, op.String())
+		}
+
+		// TODO Get each instruction cost properly
+		fee := new(big.Int)
+		fee.Add(fee, big.NewInt(1000))
+
+		if closure.GetGas().Cmp(fee) < 0 {
+			return closure.Return(nil)
+		}
+
+		switch op {
+		case oSTOP:
+			return closure.Return(nil)
+		case oPUSH:
+			pc++
+			val := closure.GetMem(pc).BigInt()
+			stack.Push(val)
+		case oMSTORE:
+			// Pop value of the stack
+			val := stack.Pop()
+			// Set the bytes to the memory field
+			mem = append(mem, ethutil.BigToBytes(val, 256)...)
+		case oCALL:
+			// Pop return size and offset
+			retSize, retOffset := stack.Popn()
+			// Pop input size and offset
+			inSize, inOffset := stack.Popn()
+			// TODO remove me.
+			fmt.Sprintln(inSize, inOffset)
+			// Pop gas and value of the stack.
+			gas, value := stack.Popn()
+			// Closure addr
+			addr := stack.Pop()
+
+			contract := state.GetContract(addr.Bytes())
+			closure := NewClosure(closure, contract, state, gas, value)
+			ret := vm.RunClosure(closure, state, vars)
+
+			// Ensure that memory is large enough to hold the returned data
+			totSize := new(big.Int).Add(retOffset, retSize)
+			lenSize := big.NewInt(int64(len(mem)))
+			// Resize the current memory slice so that the return value may fit
+			if totSize.Cmp(lenSize) > 0 {
+				diff := new(big.Int).Sub(totSize, lenSize)
+				newSlice := make([]byte, diff.Int64()+1)
+				mem = append(mem, newSlice...)
+			}
+			copy(mem[retOffset.Int64():retOffset.Int64()+retSize.Int64()+1], ret)
+		case oRETURN:
+			size, offset := stack.Popn()
+			ret := mem[offset.Int64() : offset.Int64()+size.Int64()+1]
+
+			return closure.Return(ret)
+		}
+
+		pc++
+	}
+}
+
+// Old VM code
 func (vm *Vm) Process(contract *Contract, state *State, vars RuntimeVars) {
 	vm.mem = make(map[string]*big.Int)
 	vm.stack = NewStack()
 
 	addr := vars.address // tx.Hash()[12:]
 	// Instruction pointer
-	pc := 0
+	pc := int64(0)
 
 	if contract == nil {
 		fmt.Println("Contract not found")
@@ -344,7 +432,7 @@ out:
 			contract.SetAddr(addr, y)
 			//contract.State().Update(string(idx), string(y))
 		case oJMP:
-			x := int(vm.stack.Pop().Uint64())
+			x := vm.stack.Pop().Int64()
 			// Set pc to x - 1 (minus one so the incrementing at the end won't effect it)
 			pc = x
 			pc--
@@ -352,7 +440,7 @@ out:
 			x := vm.stack.Pop()
 			// Set pc to x if it's non zero
 			if x.Cmp(ethutil.BigFalse) != 0 {
-				pc = int(x.Uint64())
+				pc = x.Int64()
 				pc--
 			}
 		case oIND:
@@ -400,9 +488,9 @@ out:
 
 func makeInlineTx(addr []byte, value, from, length *big.Int, contract *Contract, state *State) {
 	ethutil.Config.Log.Debugf(" => creating inline tx %x %v %v %v", addr, value, from, length)
-	j := 0
+	j := int64(0)
 	dataItems := make([]string, int(length.Uint64()))
-	for i := from.Uint64(); i < length.Uint64(); i++ {
+	for i := from.Int64(); i < length.Int64(); i++ {
 		dataItems[j] = contract.GetMem(j).Str()
 		j++
 	}
diff --git a/ethchain/vm_test.go b/ethchain/vm_test.go
index 6ceb0ff15..4e72c9249 100644
--- a/ethchain/vm_test.go
+++ b/ethchain/vm_test.go
@@ -8,6 +8,8 @@ import (
 	"testing"
 )
 
+/*
+
 func TestRun(t *testing.T) {
 	InitFees()
 
@@ -104,3 +106,57 @@ func TestRun2(t *testing.T) {
 		txData:      tx.Data,
 	})
 }
+*/
+
+// XXX Full stack test
+func TestRun3(t *testing.T) {
+	ethutil.ReadConfig("")
+
+	db, _ := ethdb.NewMemDatabase()
+	state := NewState(ethutil.NewTrie(db, ""))
+
+	script := Compile([]string{
+		"PUSH", "300",
+		"MSTORE",
+		"PUSH", "300",
+		"MSTORE",
+		"PUSH", "62",
+		"PUSH", "0",
+		"RETURN",
+	})
+	tx := NewTransaction(ContractAddr, ethutil.Big("100000000000000000000000000000000000000000000000000"), script)
+	addr := tx.Hash()[12:]
+	fmt.Printf("addr contract %x\n", addr)
+	contract := MakeContract(tx, state)
+	state.UpdateContract(addr, contract)
+
+	callerScript := Compile([]string{
+		"PUSH", "62", // REND
+		"PUSH", "0", // RSTART
+		"PUSH", "22", // MEND
+		"PUSH", "15", // MSTART
+		"PUSH", "1000", /// Gas
+		"PUSH", "0", /// value
+		"PUSH", string(addr), // Sender
+		"CALL",
+	})
+	callerTx := NewTransaction(ContractAddr, ethutil.Big("100000000000000000000000000000000000000000000000000"), callerScript)
+	callerAddr := callerTx.Hash()[12:]
+	executer := NewTransaction(ContractAddr, ethutil.Big("10000"), nil)
+
+	executer.Sign([]byte("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"))
+	callerClosure := NewClosure(executer, MakeContract(callerTx, state), state, big.NewInt(1000000000), new(big.Int))
+
+	vm := &Vm{}
+	vm.RunClosure(callerClosure, state, RuntimeVars{
+		address:     callerAddr,
+		blockNumber: 1,
+		sender:      ethutil.FromHex("cd1722f3947def4cf144679da39c4c32bdc35681"),
+		prevHash:    ethutil.FromHex("5e20a0453cecd065ea59c37ac63e079ee08998b6045136a8ce6635c7912ec0b6"),
+		coinbase:    ethutil.FromHex("2adc25665018aa1fe0e6bc666dac8fc2697ff9ba"),
+		time:        1,
+		diff:        big.NewInt(256),
+		txValue:     big.NewInt(10000),
+		txData:      nil,
+	})
+}