265 lines
8.0 KiB
Go
265 lines
8.0 KiB
Go
// Copyright 2016 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package abi
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import (
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"errors"
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"fmt"
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"math/big"
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"reflect"
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"strings"
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)
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// ConvertType converts an interface of a runtime type into a interface of the
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// given type, e.g. turn this code:
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//
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// var fields []reflect.StructField
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//
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// fields = append(fields, reflect.StructField{
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// Name: "X",
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// Type: reflect.TypeOf(new(big.Int)),
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// Tag: reflect.StructTag("json:\"" + "x" + "\""),
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// }
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//
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// into:
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//
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// type TupleT struct { X *big.Int }
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func ConvertType(in interface{}, proto interface{}) interface{} {
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protoType := reflect.TypeOf(proto)
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if reflect.TypeOf(in).ConvertibleTo(protoType) {
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return reflect.ValueOf(in).Convert(protoType).Interface()
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}
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// Use set as a last ditch effort
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if err := set(reflect.ValueOf(proto), reflect.ValueOf(in)); err != nil {
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panic(err)
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}
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return proto
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}
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// indirect recursively dereferences the value until it either gets the value
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// or finds a big.Int
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func indirect(v reflect.Value) reflect.Value {
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if v.Kind() == reflect.Ptr && v.Elem().Type() != reflect.TypeOf(big.Int{}) {
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return indirect(v.Elem())
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}
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return v
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}
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// reflectIntType returns the reflect using the given size and
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// unsignedness.
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func reflectIntType(unsigned bool, size int) reflect.Type {
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if unsigned {
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switch size {
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case 8:
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return reflect.TypeOf(uint8(0))
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case 16:
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return reflect.TypeOf(uint16(0))
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case 32:
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return reflect.TypeOf(uint32(0))
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case 64:
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return reflect.TypeOf(uint64(0))
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}
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}
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switch size {
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case 8:
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return reflect.TypeOf(int8(0))
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case 16:
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return reflect.TypeOf(int16(0))
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case 32:
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return reflect.TypeOf(int32(0))
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case 64:
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return reflect.TypeOf(int64(0))
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}
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return reflect.TypeOf(&big.Int{})
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}
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// mustArrayToByteSlice creates a new byte slice with the exact same size as value
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// and copies the bytes in value to the new slice.
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func mustArrayToByteSlice(value reflect.Value) reflect.Value {
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slice := reflect.MakeSlice(reflect.TypeOf([]byte{}), value.Len(), value.Len())
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reflect.Copy(slice, value)
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return slice
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}
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// set attempts to assign src to dst by either setting, copying or otherwise.
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//
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// set is a bit more lenient when it comes to assignment and doesn't force an as
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// strict ruleset as bare `reflect` does.
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func set(dst, src reflect.Value) error {
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dstType, srcType := dst.Type(), src.Type()
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switch {
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case dstType.Kind() == reflect.Interface && dst.Elem().IsValid() && (dst.Elem().Type().Kind() == reflect.Ptr || dst.Elem().CanSet()):
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return set(dst.Elem(), src)
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case dstType.Kind() == reflect.Ptr && dstType.Elem() != reflect.TypeOf(big.Int{}):
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return set(dst.Elem(), src)
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case srcType.AssignableTo(dstType) && dst.CanSet():
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dst.Set(src)
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case dstType.Kind() == reflect.Slice && srcType.Kind() == reflect.Slice && dst.CanSet():
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return setSlice(dst, src)
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case dstType.Kind() == reflect.Array:
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return setArray(dst, src)
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case dstType.Kind() == reflect.Struct:
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return setStruct(dst, src)
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default:
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return fmt.Errorf("abi: cannot unmarshal %v in to %v", src.Type(), dst.Type())
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}
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return nil
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}
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// setSlice attempts to assign src to dst when slices are not assignable by default
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// e.g. src: [][]byte -> dst: [][15]byte
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// setSlice ignores if we cannot copy all of src' elements.
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func setSlice(dst, src reflect.Value) error {
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slice := reflect.MakeSlice(dst.Type(), src.Len(), src.Len())
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for i := 0; i < src.Len(); i++ {
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if err := set(slice.Index(i), src.Index(i)); err != nil {
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return err
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}
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}
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if dst.CanSet() {
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dst.Set(slice)
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return nil
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}
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return errors.New("cannot set slice, destination not settable")
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}
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func setArray(dst, src reflect.Value) error {
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if src.Kind() == reflect.Ptr {
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return set(dst, indirect(src))
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}
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array := reflect.New(dst.Type()).Elem()
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min := src.Len()
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if src.Len() > dst.Len() {
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min = dst.Len()
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}
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for i := 0; i < min; i++ {
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if err := set(array.Index(i), src.Index(i)); err != nil {
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return err
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}
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}
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if dst.CanSet() {
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dst.Set(array)
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return nil
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}
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return errors.New("cannot set array, destination not settable")
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}
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func setStruct(dst, src reflect.Value) error {
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for i := 0; i < src.NumField(); i++ {
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srcField := src.Field(i)
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dstField := dst.Field(i)
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if !dstField.IsValid() || !srcField.IsValid() {
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return fmt.Errorf("could not find src field: %v value: %v in destination", srcField.Type().Name(), srcField)
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}
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if err := set(dstField, srcField); err != nil {
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return err
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}
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}
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return nil
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}
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// mapArgNamesToStructFields maps a slice of argument names to struct fields.
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//
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// first round: for each Exportable field that contains a `abi:""` tag and this field name
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// exists in the given argument name list, pair them together.
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//
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// second round: for each argument name that has not been already linked, find what
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// variable is expected to be mapped into, if it exists and has not been used, pair them.
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//
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// Note this function assumes the given value is a struct value.
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func mapArgNamesToStructFields(argNames []string, value reflect.Value) (map[string]string, error) {
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typ := value.Type()
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abi2struct := make(map[string]string)
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struct2abi := make(map[string]string)
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// first round ~~~
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for i := 0; i < typ.NumField(); i++ {
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structFieldName := typ.Field(i).Name
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// skip private struct fields.
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if structFieldName[:1] != strings.ToUpper(structFieldName[:1]) {
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continue
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}
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// skip fields that have no abi:"" tag.
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tagName, ok := typ.Field(i).Tag.Lookup("abi")
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if !ok {
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continue
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}
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// check if tag is empty.
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if tagName == "" {
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return nil, fmt.Errorf("struct: abi tag in '%s' is empty", structFieldName)
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}
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// check which argument field matches with the abi tag.
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found := false
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for _, arg := range argNames {
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if arg == tagName {
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if abi2struct[arg] != "" {
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return nil, fmt.Errorf("struct: abi tag in '%s' already mapped", structFieldName)
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}
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// pair them
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abi2struct[arg] = structFieldName
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struct2abi[structFieldName] = arg
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found = true
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}
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}
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// check if this tag has been mapped.
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if !found {
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return nil, fmt.Errorf("struct: abi tag '%s' defined but not found in abi", tagName)
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}
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}
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// second round ~~~
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for _, argName := range argNames {
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structFieldName := ToCamelCase(argName)
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if structFieldName == "" {
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return nil, errors.New("abi: purely underscored output cannot unpack to struct")
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}
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// this abi has already been paired, skip it... unless there exists another, yet unassigned
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// struct field with the same field name. If so, raise an error:
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// abi: [ { "name": "value" } ]
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// struct { Value *big.Int , Value1 *big.Int `abi:"value"`}
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if abi2struct[argName] != "" {
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if abi2struct[argName] != structFieldName &&
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struct2abi[structFieldName] == "" &&
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value.FieldByName(structFieldName).IsValid() {
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return nil, fmt.Errorf("abi: multiple variables maps to the same abi field '%s'", argName)
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}
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continue
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}
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// return an error if this struct field has already been paired.
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if struct2abi[structFieldName] != "" {
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return nil, fmt.Errorf("abi: multiple outputs mapping to the same struct field '%s'", structFieldName)
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}
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if value.FieldByName(structFieldName).IsValid() {
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// pair them
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abi2struct[argName] = structFieldName
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struct2abi[structFieldName] = argName
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} else {
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// not paired, but annotate as used, to detect cases like
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// abi : [ { "name": "value" }, { "name": "_value" } ]
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// struct { Value *big.Int }
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struct2abi[structFieldName] = argName
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}
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}
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return abi2struct, nil
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}
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