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+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package vm
+
+import (
+ "fmt"
+ "hash"
+ "sync/atomic"
+
+ "github.com/ava-labs/go-ethereum/common"
+ "github.com/ava-labs/go-ethereum/common/math"
+ "github.com/ava-labs/go-ethereum/log"
+)
+
+var (
+ BuiltinAddr = common.Address{
+ 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ }
+)
+
+// Config are the configuration options for the Interpreter
+type Config struct {
+ Debug bool // Enables debugging
+ Tracer Tracer // Opcode logger
+ NoRecursion bool // Disables call, callcode, delegate call and create
+ EnablePreimageRecording bool // Enables recording of SHA3/keccak preimages
+
+ JumpTable [256]operation // EVM instruction table, automatically populated if unset
+
+ EWASMInterpreter string // External EWASM interpreter options
+ EVMInterpreter string // External EVM interpreter options
+
+ ExtraEips []int // Additional EIPS that are to be enabled
+}
+
+// Interpreter is used to run Ethereum based contracts and will utilise the
+// passed environment to query external sources for state information.
+// The Interpreter will run the byte code VM based on the passed
+// configuration.
+type Interpreter interface {
+ // 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.
+ Run(contract *Contract, input []byte, static bool) ([]byte, error)
+ // CanRun tells if the contract, passed as an argument, can be
+ // run by the current interpreter. This is meant so that the
+ // caller can do something like:
+ //
+ // ```golang
+ // for _, interpreter := range interpreters {
+ // if interpreter.CanRun(contract.code) {
+ // interpreter.Run(contract.code, input)
+ // }
+ // }
+ // ```
+ CanRun([]byte) bool
+}
+
+// keccakState wraps sha3.state. In addition to the usual hash methods, it also supports
+// Read to get a variable amount of data from the hash state. Read is faster than Sum
+// because it doesn't copy the internal state, but also modifies the internal state.
+type keccakState interface {
+ hash.Hash
+ Read([]byte) (int, error)
+}
+
+// EVMInterpreter represents an EVM interpreter
+type EVMInterpreter struct {
+ evm *EVM
+ cfg Config
+
+ intPool *intPool
+
+ 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
+}
+
+// NewEVMInterpreter returns a new instance of the Interpreter.
+func NewEVMInterpreter(evm *EVM, cfg Config) *EVMInterpreter {
+ // 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[STOP].valid {
+ var jt JumpTable
+ switch {
+ case evm.chainRules.IsIstanbul:
+ jt = istanbulInstructionSet
+ case evm.chainRules.IsConstantinople:
+ jt = constantinopleInstructionSet
+ case evm.chainRules.IsByzantium:
+ jt = byzantiumInstructionSet
+ case evm.chainRules.IsEIP158:
+ jt = spuriousDragonInstructionSet
+ case evm.chainRules.IsEIP150:
+ jt = tangerineWhistleInstructionSet
+ case evm.chainRules.IsHomestead:
+ jt = homesteadInstructionSet
+ default:
+ jt = frontierInstructionSet
+ }
+ for i, eip := range cfg.ExtraEips {
+ if err := EnableEIP(eip, &jt); err != nil {
+ // Disable it, so caller can check if it's activated or not
+ cfg.ExtraEips = append(cfg.ExtraEips[:i], cfg.ExtraEips[i+1:]...)
+ log.Error("EIP activation failed", "eip", eip, "error", err)
+ }
+ }
+ cfg.JumpTable = jt
+ }
+
+ return &EVMInterpreter{
+ evm: evm,
+ cfg: cfg,
+ }
+}
+
+// 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 *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (ret []byte, err error) {
+ if contract.Address() == BuiltinAddr {
+ self := AccountRef(contract.Caller())
+ if _, ok := contract.caller.(*Contract); ok {
+ contract = contract.AsDelegate()
+ }
+ contract.self = self
+ }
+ if in.intPool == nil {
+ in.intPool = poolOfIntPools.get()
+ defer func() {
+ poolOfIntPools.put(in.intPool)
+ in.intPool = nil
+ }()
+ }
+
+ // 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 makes also 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
+ // 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 Tracer
+ gasCopy uint64 // for Tracer to log gas remaining before execution
+ logged bool // deferred Tracer should ignore already logged steps
+ res []byte // result of the opcode execution function
+ )
+ contract.Input = input
+
+ // Reclaim the stack as an int pool when the execution stops
+ defer func() { in.intPool.put(stack.data...) }()
+
+ if in.cfg.Debug {
+ defer func() {
+ if err != nil {
+ if !logged {
+ in.cfg.Tracer.CaptureState(in.evm, pcCopy, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err)
+ } else {
+ in.cfg.Tracer.CaptureFault(in.evm, pcCopy, op, gasCopy, cost, mem, stack, contract, 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.
+ for atomic.LoadInt32(&in.evm.abort) == 0 {
+ 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.valid {
+ return nil, fmt.Errorf("invalid opcode 0x%x", int(op))
+ }
+ // Validate stack
+ if sLen := stack.len(); sLen < operation.minStack {
+ return nil, fmt.Errorf("stack underflow (%d <=> %d)", sLen, operation.minStack)
+ } else if sLen > operation.maxStack {
+ return nil, fmt.Errorf("stack limit reached %d (%d)", sLen, operation.maxStack)
+ }
+ // If the operation is valid, enforce and 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 || op == CALLEX) && stack.Back(2).Sign() != 0) {
+ return nil, errWriteProtection
+ }
+ }
+ // Static portion of gas
+ cost = operation.constantGas // For tracing
+ 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 operation.dynamicGas != nil {
+ var dynamicCost uint64
+ dynamicCost, err = operation.dynamicGas(in.evm, contract, stack, mem, memorySize)
+ cost += dynamicCost // total cost, for debug tracing
+ if err != nil || !contract.UseGas(dynamicCost) {
+ return nil, ErrOutOfGas
+ }
+ }
+ if memorySize > 0 {
+ mem.Resize(memorySize)
+ }
+
+ if in.cfg.Debug {
+ in.cfg.Tracer.CaptureState(in.evm, pc, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err)
+ logged = true
+ }
+
+ // execute the operation
+ res, err = operation.execute(&pc, in, contract, mem, stack)
+ // verifyPool is a build flag. Pool verification makes sure the integrity
+ // of the integer pool by comparing values to a default value.
+ if verifyPool {
+ verifyIntegerPool(in.intPool)
+ }
+ // 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
+}
+
+// CanRun tells if the contract, passed as an argument, can be
+// run by the current interpreter.
+func (in *EVMInterpreter) CanRun(code []byte) bool {
+ return true
+}