interpreter.go

// Copyright 2014 The Spectrum Authors
// This file is part of the Spectrum library.
//
// The Spectrum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The Spectrum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the Spectrum library. If not, see <http://www.gnu.org/licenses/>.

package vm

import (
	"hash"
	"sync/atomic"

	"github.com/SmartMeshFoundation/Spectrum/common"
	"github.com/SmartMeshFoundation/Spectrum/common/math"
)

// Config are the configuration options for the Interpreter
type Config struct {
	// Debug enabled debugging Interpreter options
	Debug bool
	// EnableJit enabled the JIT VM
	EnableJit bool
	// ForceJit forces the JIT VM
	ForceJit bool
	// Tracer is the op code logger
	Tracer EVMLogger
	// NoRecursion disabled Interpreter call, callcode,
	// delegate call and create.
	NoRecursion bool
	// Disable gas metering
	DisableGasMetering bool
	// Enable recording of SHA3/keccak preimages
	EnablePreimageRecording bool
	// JumpTable contains the EVM instruction table. This
	// may be left uninitialised and will be set to the default
	// table.
	JumpTable *JumpTable
}

// ScopeContext contains the things that are per-call, such as stack and memory,
// but not transients like pc and gas
type ScopeContext struct {
	Memory   *Memory
	Stack    *Stack
	Contract *Contract
}

type keccakState interface {
	hash.Hash
	Read([]byte) (int, error)
}

// Interpreter is used to run Ethereum based contracts and will utilise the
// passed evmironment to query external sources for state information.
// The Interpreter will run the byte code VM or JIT VM based on the passed
// configuration.
type Interpreter struct {
	evm       *EVM
	cfg       Config
	hasher    keccakState // Keccak256 hasher instance shared across opcodes
	hasherBuf common.Hash // Keccak256 hasher result array shared aross opcodes

	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.
func NewInterpreter(evm *EVM, cfg Config) *Interpreter {
	// We use the STOP instruction whether to see
	// the jump table was initialised. If it was not
	// we'll set the default jump table.
	if cfg.JumpTable == nil {
		switch {
		case evm.ChainConfig().IsSip004(evm.BlockNumber):
			cfg.JumpTable = &si004InstructionSet
		case evm.ChainConfig().IsByzantium(evm.BlockNumber):
			cfg.JumpTable = &byzantiumInstructionSet
		case evm.chainRules.IsEIP158:
			cfg.JumpTable = &spuriousDragonInstructionSet
		case evm.chainRules.IsEIP150:
			cfg.JumpTable = &tangerineWhistleInstructionSet
		case evm.ChainConfig().IsHomestead(evm.BlockNumber):
			cfg.JumpTable = &homesteadInstructionSet
		default:
			cfg.JumpTable = &frontierInstructionSet
		}
	}

	return &Interpreter{
		evm: evm,
		cfg: cfg,
	}
}

//func (in *Interpreter) enforceRestrictions(op OpCode, operation operation, stack *Stack) error {
//	if in.evm.chainRules.IsByzantium {
//		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. Transferring value from one
//			// account to the others means the state is modified and should also
//			// return with an error.
//			if operation.writes || (op == CALL && stack.Back(2).BitLen() > 0) {
//				return errWriteProtection
//			}
//		}
//	}
//	return nil
//}

// Run loops and evaluates the contract's code with the given input data and returns
// the return byte-slice and an error if one occurred.
//
// It's important to note that any errors returned by the interpreter should be
// considered a revert-and-consume-all-gas operation except for
// errExecutionReverted which means revert-and-keep-gas-left.
func (in *Interpreter) Run(contract *Contract, input []byte) (ret []byte, err error) {

	// Increment the call depth which is restricted to 1024
	in.evm.depth++
	defer func() { in.evm.depth-- }()

	//// Make sure the readOnly is only set if we aren't in readOnly yet.
	//// This also makes sure that the readOnly flag isn't removed for child calls.
	//if readOnly && !in.readOnly {
	//	in.readOnly = true
	//	defer func() { in.readOnly = false }()
	//}

	// Reset the previous call's return data. It's unimportant to preserve the old buffer
	// as every returning call will return new data anyway.
	in.returnData = nil
	// Don't bother with the execution if there's no code.
	if len(contract.Code) == 0 {
		return nil, nil
	}

	var (
		op          OpCode        // current opcode
		mem         = NewMemory() // bound memory
		stack       = newstack()  // local stack
		callContext = &ScopeContext{
			Memory:   mem,
			Stack:    stack,
			Contract: contract,
		}
		// For optimisation reason we're using uint64 as the program counter.
		// It's theoretically possible to go above 2^64. The YP defines the PC
		// to be uint256. Practically much less so feasible.
		pc   = uint64(0) // program counter
		cost uint64
		// copies used by tracer
		pcCopy  uint64 // needed for the deferred EVMLogger
		gasCopy uint64 // for EVMLogger to log gas remaining before execution
		logged  bool   // deferred EVMLogger should ignore already logged steps
		res     []byte // result of the opcode execution function
	)
	// Don't move this deferrred function, it's placed before the capturestate-deferred method,
	// so that it get's executed _after_: the capturestate needs the stacks before
	// they are returned to the pools
	defer func() {
		returnStack(stack)
	}()
	contract.Input = input

	if in.cfg.Debug {
		defer func() {
			if err != nil {
				if !logged {
					in.cfg.Tracer.CaptureState(pcCopy, op, gasCopy, cost, callContext, in.returnData, in.evm.depth, err)
				} else {
					in.cfg.Tracer.CaptureFault(pcCopy, op, gasCopy, cost, callContext, in.evm.depth, err)
				}
			}
		}()
	}
	// The Interpreter main run loop (contextual). This loop runs until either an
	// explicit STOP, RETURN or SELFDESTRUCT is executed, an error occurred during
	// the execution of one of the operations or until the done flag is set by the
	// parent context.
	steps := 0
	for {
		steps++
		if steps%1000 == 0 && atomic.LoadInt32(&in.evm.abort) != 0 {
			break
		}
		if in.cfg.Debug {
			// Capture pre-execution values for tracing.
			logged, pcCopy, gasCopy = false, pc, contract.Gas
		}

		// Get the operation from the jump table and validate the stack to ensure there are
		// enough stack items available to perform the operation.
		op = contract.GetOp(pc)
		operation := in.cfg.JumpTable[op]
		if operation == nil {
			return nil, &ErrInvalidOpCode{opcode: op}
		}
		// Validate stack
		if sLen := stack.len(); sLen < operation.minStack {
			return nil, &ErrStackUnderflow{stackLen: sLen, required: operation.minStack}
		} else if sLen > operation.maxStack {
			return nil, &ErrStackOverflow{stackLen: sLen, limit: operation.maxStack}
		}
		// If the operation is valid, enforce write restrictions
		if in.readOnly && in.evm.chainRules.IsByzantium {
			// 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. Transferring value from one
			// account to the others means the state is modified and should also
			// return with an error.
			if operation.writes || (op == CALL && stack.Back(2).Sign() != 0) {
				return nil, ErrWriteProtection
			}
		}

		// Static portion of gas
		if !in.cfg.DisableGasMetering {
			cost = operation.constantGas // For tracing
			//fmt.Println("-run1>>>",op,cost)
			if !contract.UseGas(operation.constantGas) {
				return nil, ErrOutOfGas
			}
		}
		var memorySize uint64
		// calculate the new memory size and expand the memory to fit
		// the operation
		// Memory check needs to be done prior to evaluating the dynamic gas portion,
		// to detect calculation overflows
		if operation.memorySize != nil {
			memSize, overflow := operation.memorySize(stack)
			if overflow {
				return nil, ErrGasUintOverflow
			}
			// memory is expanded in words of 32 bytes. Gas
			// is also calculated in words.
			if memorySize, overflow = math.SafeMul(toWordSize(memSize), 32); overflow {
				return nil, ErrGasUintOverflow
			}
		}
		// Dynamic portion of gas
		// consume the gas and return an error if not enough gas is available.
		// cost is explicitly set so that the capture state defer method can get the proper cost
		if !in.cfg.DisableGasMetering {
			if operation.dynamicGas != nil {
				var dynamicCost uint64
				dynamicCost, err = operation.dynamicGas(in.evm, contract, stack, mem, memorySize)
				cost += dynamicCost // total cost, for debug tracing
				//fmt.Println("-run2>>>",op,cost,dynamicCost)
				if err != nil || !contract.UseGas(dynamicCost) {
					return nil, ErrOutOfGas
				}
			}
		}
		if memorySize > 0 {
			mem.Resize(memorySize)
		}

		if in.cfg.Debug {
			in.cfg.Tracer.CaptureState(pc, op, gasCopy, cost, callContext, in.returnData, in.evm.depth, err)
			logged = true
		}

		// execute the operation
		res, err = operation.execute(&pc, in, callContext)
		// 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.returns {
			in.returnData = res
		}

		switch {
		case err != nil:
			return nil, err
		case operation.reverts:
			return res, ErrExecutionReverted
		case operation.halts:
			return res, nil
		case !operation.jumps:
			pc++
		}
	}
	return nil, nil
}