feat: untested vm.PrecompileEnvironment.Create() and Create2()

Author: ARR4N

core/vm/contracts.libevm.go

@@ -61,6 +61,12 @@ const (
 	CallCode     = CallType(CALLCODE)
 	DelegateCall = CallType(DELEGATECALL)
 	StaticCall   = CallType(STATICCALL)
+
+	// Although not technically calls, the CREATE OpCodes also enter a new call
+	// frame and therefore have similar setup to _outgoing_ *CALL* types. They
+	// are only used internally, by [environment].
+	create  = CallType(CREATE)
+	create2 = CallType(CREATE2)
 )
 
 func (t CallType) isValid() bool {
@@ -162,6 +168,9 @@ type PrecompileEnvironment interface {
 	// removed and automatically determined according to the type of call that
 	// invoked the precompile.
 	Call(addr common.Address, input []byte, gas uint64, value *uint256.Int, _ ...CallOption) (ret []byte, _ error)
+
+	Create(code []byte, gas uint64, value *uint256.Int) ([]byte, common.Address, error)
+	Create2(code []byte, gas uint64, value, salt *uint256.Int) ([]byte, common.Address, error)
 }
 
 func (args *evmCallArgs) env() *environment {

core/vm/environment.libevm.go

@@ -100,49 +100,63 @@ func (e *environment) BlockHeader() (types.Header, error) {
 	return *hdr, nil
 }
 
-func (e *environment) Call(addr common.Address, input []byte, gas uint64, value *uint256.Int, opts ...CallOption) ([]byte, error) {
-	return e.callContract(Call, addr, input, gas, value, opts...)
-}
-
-func (e *environment) callContract(typ CallType, addr common.Address, input []byte, gas uint64, value *uint256.Int, opts ...CallOption) (retData []byte, retErr error) {
+func (e *environment) beforeNewCallFrame(typ CallType, gas uint64, value *uint256.Int, opts ...CallOption) (ContractRef, func(), error) {
 	// Depth and read-only setting are handled by [EVMInterpreter.Run], which
 	// isn't used for precompiles, so we need to do it ourselves to maintain the
 	// expected invariants.
 	in := e.evm.interpreter
+	var deferred []func()
 
 	in.evm.depth++
-	defer func() { in.evm.depth-- }()
+	deferred = append(deferred, func() { in.evm.depth-- })
 
 	if e.ReadOnly() && !in.readOnly { // i.e. the precompile was StaticCall()ed
 		in.readOnly = true
-		defer func() { in.readOnly = false }()
+		deferred = append(deferred, func() { in.readOnly = false })
 	}
 
-	var caller ContractRef = e.self
-	for _, o := range opts {
-		switch o := o.(type) {
-		case callOptUNSAFECallerAddressProxy:
-			// Note that, in addition to being unsafe, this breaks an EVM
-			// assumption that the caller ContractRef is always a *Contract.
-			caller = AccountRef(e.self.CallerAddress)
-			if e.callType == DelegateCall {
-				// self was created with AsDelegate(), which means that
-				// CallerAddress was inherited.
-				caller = AccountRef(e.self.Address())
-			}
-		case nil:
-		default:
-			return nil, fmt.Errorf("unsupported option %T", o)
+	var (
+		caller ContractRef = e.self
+		config libevmCallConfig
+	)
+	config.apply(opts...)
+	if config.proxyCallerAddressUNSAFE {
+		// Note that, in addition to being unsafe, this breaks an EVM
+		// assumption that the caller ContractRef is always a *Contract.
+		caller = AccountRef(e.self.CallerAddress)
+		if e.callType == DelegateCall {
+			// self was created with AsDelegate(), which means that
+			// CallerAddress was inherited.
+			caller = AccountRef(e.self.Address())
 		}
 	}
 
-	if in.readOnly && value != nil && !value.IsZero() {
-		return nil, ErrWriteProtection
+	writes := (value != nil && !value.IsZero()) || typ == create || typ == create2
+	if in.readOnly && writes {
+		return nil, nil, ErrWriteProtection
 	}
 	if !e.UseGas(gas) {
-		return nil, ErrOutOfGas
+		return nil, nil, ErrOutOfGas
 	}
 
+	return caller, func() {
+		for _, fn := range deferred {
+			fn()
+		}
+	}, nil
+}
+
+func (e *environment) Call(addr common.Address, input []byte, gas uint64, value *uint256.Int, opts ...CallOption) ([]byte, error) {
+	return e.callContract(Call, addr, input, gas, value, opts...)
+}
+
+func (e *environment) callContract(typ CallType, addr common.Address, input []byte, gas uint64, value *uint256.Int, opts ...CallOption) (retData []byte, retErr error) {
+	caller, cleanup, err := e.beforeNewCallFrame(typ, gas, value, opts...)
+	if err != nil {
+		return nil, err
+	}
+	defer cleanup()
+
 	if t := e.evm.Config.Tracer; t != nil {
 		var bigVal *big.Int
 		if value != nil {
@@ -174,3 +188,31 @@ func (e *environment) callContract(typ CallType, addr common.Address, input []by
 		return nil, fmt.Errorf("unimplemented precompile call type %v", typ)
 	}
 }
+
+func (e *environment) Create(code []byte, gas uint64, value *uint256.Int) ([]byte, common.Address, error) {
+	return e.create(create, gas, value, func(caller ContractRef) ([]byte, common.Address, uint64, error) {
+		return e.evm.Create(caller, code, gas, value)
+	})
+}
+
+func (e *environment) Create2(code []byte, gas uint64, value, salt *uint256.Int) ([]byte, common.Address, error) {
+	return e.create(create2, gas, value, func(caller ContractRef) ([]byte, common.Address, uint64, error) {
+		return e.evm.Create2(caller, code, gas, value, salt)
+	})
+}
+
+type creator func(ContractRef) ([]byte, common.Address, uint64, error)
+
+func (e *environment) create(typ CallType, gas uint64, value *uint256.Int, do creator) ([]byte, common.Address, error) {
+	caller, cleanup, err := e.beforeNewCallFrame(typ, gas, value)
+	if err != nil {
+		return nil, common.Address{}, err
+	}
+	defer cleanup()
+
+	ret, contract, returnGas, err := do(caller)
+	if err := e.refundGas(returnGas); err != nil {
+		return nil, common.Address{}, err
+	}
+	return ret, contract, err
+}

core/vm/options.libevm.go

@@ -18,9 +18,23 @@ package vm
 
 // A CallOption modifies the default behaviour of a contract call.
 type CallOption interface {
-	libevmCallOption() // noop to only allow internally defined options
+	apply(*libevmCallConfig)
 }
 
+type libevmCallConfig struct {
+	proxyCallerAddressUNSAFE bool
+}
+
+func (c *libevmCallConfig) apply(opts ...CallOption) {
+	for _, o := range opts {
+		o.apply(c)
+	}
+}
+
+type libevmFuncOpt func(*libevmCallConfig)
+
+func (f libevmFuncOpt) apply(c *libevmCallConfig) { f(c) }
+
 // WithUNSAFECallerAddressProxying results in precompiles making contract calls
 // specifying their own caller's address as the caller. This is NOT SAFE for
 // regular use as callers of the precompile may not understand that they are
@@ -29,10 +43,7 @@ type CallOption interface {
 // Deprecated: this option MUST NOT be used other than to allow migration to
 // libevm when backwards compatibility is required.
 func WithUNSAFECallerAddressProxying() CallOption {
-	return callOptUNSAFECallerAddressProxy{}
+	return libevmFuncOpt(func(c *libevmCallConfig) {
+		c.proxyCallerAddressUNSAFE = true
+	})
 }
-
-// Deprecated: see [WithUNSAFECallerAddressProxying].
-type callOptUNSAFECallerAddressProxy struct{}
-
-func (callOptUNSAFECallerAddressProxy) libevmCallOption() {}