accounts/abi: fixed return tuple and string, bytes return type parsing
Removed old unmarshalling of return types: `abi.Call(...).([]byte)`. This is now replaced by a new syntax: ``` var a []byte err := abi.Call(&a, ...) ``` It also addresses a few issues with Bytes and Strings and can also handle both fixed and arbitrary sized byte slices, including strings.
This commit is contained in:
Jeffrey Wilcke
@ -20,11 +20,10 @@ import (
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"encoding/json"
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"fmt"
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"io"
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"math"
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"reflect"
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"strings"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/logger"
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"github.com/ethereum/go-ethereum/logger/glog"
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)
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// Executer is an executer method for performing state executions. It takes one
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@ -101,52 +100,143 @@ func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
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}
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// toGoType parses the input and casts it to the proper type defined by the ABI
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// argument in t.
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func toGoType(t Argument, input []byte) interface{} {
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// argument in T.
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func toGoType(i int, t Argument, output []byte) (interface{}, error) {
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index := i * 32
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if index+32 > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), index+32)
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}
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// Parse the given index output and check whether we need to read
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// a different offset and length based on the type (i.e. string, bytes)
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var returnOutput []byte
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switch t.Type.T {
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case StringTy, BytesTy: // variable arrays are written at the end of the return bytes
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// parse offset from which we should start reading
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offset := int(common.BytesToBig(output[index : index+32]).Uint64())
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if offset+32 > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32)
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}
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// parse the size up until we should be reading
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size := int(common.BytesToBig(output[offset : offset+32]).Uint64())
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if offset+32+size > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32+size)
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}
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// get the bytes for this return value
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returnOutput = output[offset+32 : offset+32+size]
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default:
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returnOutput = output[index : index+32]
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}
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// cast bytes to abi return type
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switch t.Type.T {
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case IntTy:
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return common.BytesToBig(input)
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return common.BytesToBig(returnOutput), nil
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case UintTy:
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return common.BytesToBig(input)
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return common.BytesToBig(returnOutput), nil
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case BoolTy:
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return common.BytesToBig(input).Uint64() > 0
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return common.BytesToBig(returnOutput).Uint64() > 0, nil
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case AddressTy:
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return common.BytesToAddress(input)
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return common.BytesToAddress(returnOutput), nil
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case HashTy:
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return common.BytesToHash(input)
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return common.BytesToHash(returnOutput), nil
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case BytesTy, FixedBytesTy:
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return returnOutput, nil
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case StringTy:
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return string(returnOutput), nil
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}
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return nil
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return nil, fmt.Errorf("abi: unknown type %v", t.Type.T)
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}
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// Call executes a call and attemps to parse the return values and returns it as
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// an interface. It uses the executer method to perform the actual call since
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// the abi knows nothing of the lower level calling mechanism.
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// Call will unmarshal the output of the call in v. It will return an error if
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// invalid type is given or if the output is too short to conform to the ABI
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// spec.
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//
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// Call supports all abi types and includes multiple return values. When only
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// one item is returned a single interface{} will be returned, if a contract
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// method returns multiple values an []interface{} slice is returned.
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func (abi ABI) Call(executer Executer, name string, args ...interface{}) interface{} {
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// Call supports all of the available types and accepts a struct or an interface
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// slice if the return is a tuple.
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func (abi ABI) Call(executer Executer, v interface{}, name string, args ...interface{}) error {
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callData, err := abi.Pack(name, args...)
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if err != nil {
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glog.V(logger.Debug).Infoln("pack error:", err)
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return nil
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return err
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}
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output := executer(callData)
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return abi.unmarshal(v, name, executer(callData))
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}
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method := abi.Methods[name]
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ret := make([]interface{}, int(math.Max(float64(len(method.Outputs)), float64(len(output)/32))))
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for i := 0; i < len(ret); i += 32 {
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index := i / 32
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ret[index] = toGoType(method.Outputs[index], output[i:i+32])
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var interSlice = reflect.TypeOf([]interface{}{})
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// unmarshal output in v according to the abi specification
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func (abi ABI) unmarshal(v interface{}, name string, output []byte) error {
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var method = abi.Methods[name]
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if len(output) == 0 {
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return fmt.Errorf("abi: unmarshalling empty output")
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}
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// return single interface
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if len(ret) == 1 {
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return ret[0]
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value := reflect.ValueOf(v).Elem()
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typ := value.Type()
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if len(method.Outputs) > 1 {
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switch value.Kind() {
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// struct will match named return values to the struct's field
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// names
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case reflect.Struct:
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for i := 0; i < len(method.Outputs); i++ {
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marshalledValue, err := toGoType(i, method.Outputs[i], output)
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if err != nil {
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return err
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}
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reflectValue := reflect.ValueOf(marshalledValue)
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for j := 0; j < typ.NumField(); j++ {
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field := typ.Field(j)
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// TODO read tags: `abi:"fieldName"`
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if field.Name == strings.ToUpper(method.Outputs[i].Name[:1])+method.Outputs[i].Name[1:] {
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if field.Type.AssignableTo(reflectValue.Type()) {
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value.Field(j).Set(reflectValue)
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break
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} else {
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return fmt.Errorf("abi: cannot unmarshal %v in to %v", field.Type, reflectValue.Type())
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}
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}
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}
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}
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case reflect.Slice:
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if !value.Type().AssignableTo(interSlice) {
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return fmt.Errorf("abi: cannot marshal tuple in to slice %T (only []interface{} is supported)", v)
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}
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// create a new slice and start appending the unmarshalled
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// values to the new interface slice.
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z := reflect.MakeSlice(typ, 0, len(method.Outputs))
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for i := 0; i < len(method.Outputs); i++ {
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marshalledValue, err := toGoType(i, method.Outputs[i], output)
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if err != nil {
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return err
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}
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z = reflect.Append(z, reflect.ValueOf(marshalledValue))
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}
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value.Set(z)
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default:
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return fmt.Errorf("abi: cannot unmarshal tuple in to %v", typ)
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}
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} else {
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marshalledValue, err := toGoType(0, method.Outputs[0], output)
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if err != nil {
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return err
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}
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reflectValue := reflect.ValueOf(marshalledValue)
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if typ.AssignableTo(reflectValue.Type()) {
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value.Set(reflectValue)
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} else {
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return fmt.Errorf("abi: cannot unmarshal %v in to %v", reflectValue.Type(), value.Type())
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}
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}
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return ret
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return nil
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}
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func (abi *ABI) UnmarshalJSON(data []byte) error {
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