366 lines
11 KiB
Go
366 lines
11 KiB
Go
// Copyright 2015 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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"encoding/json"
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"fmt"
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"io"
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"math/big"
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"reflect"
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"strings"
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"github.com/ethereum/go-ethereum/common"
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)
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// The ABI holds information about a contract's context and available
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// invokable methods. It will allow you to type check function calls and
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// packs data accordingly.
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type ABI struct {
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Constructor Method
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Methods map[string]Method
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Events map[string]Event
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}
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// JSON returns a parsed ABI interface and error if it failed.
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func JSON(reader io.Reader) (ABI, error) {
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dec := json.NewDecoder(reader)
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var abi ABI
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if err := dec.Decode(&abi); err != nil {
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return ABI{}, err
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}
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return abi, nil
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}
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// Pack the given method name to conform the ABI. Method call's data
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// will consist of method_id, args0, arg1, ... argN. Method id consists
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// of 4 bytes and arguments are all 32 bytes.
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// Method ids are created from the first 4 bytes of the hash of the
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// methods string signature. (signature = baz(uint32,string32))
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func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
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// Fetch the ABI of the requested method
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var method Method
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if name == "" {
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method = abi.Constructor
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} else {
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m, exist := abi.Methods[name]
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if !exist {
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return nil, fmt.Errorf("method '%s' not found", name)
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}
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method = m
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}
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arguments, err := method.pack(method, args...)
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if err != nil {
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return nil, err
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}
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// Pack up the method ID too if not a constructor and return
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if name == "" {
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return arguments, nil
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}
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return append(method.Id(), arguments...), nil
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}
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// toGoSliceType parses the input and casts it to the proper slice defined by the ABI
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// argument in T.
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func toGoSlice(i int, t Argument, output []byte) (interface{}, error) {
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index := i * 32
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// The slice must, at very least be large enough for the index+32 which is exactly the size required
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// for the [offset in output, size of offset].
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if index+32 > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), index+32)
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}
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elem := t.Type.Elem
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// first we need to create a slice of the type
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var refSlice reflect.Value
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switch elem.T {
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case IntTy, UintTy, BoolTy: // int, uint, bool can all be of type big int.
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refSlice = reflect.ValueOf([]*big.Int(nil))
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case AddressTy: // address must be of slice Address
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refSlice = reflect.ValueOf([]common.Address(nil))
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case HashTy: // hash must be of slice hash
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refSlice = reflect.ValueOf([]common.Hash(nil))
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case FixedBytesTy:
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refSlice = reflect.ValueOf([]byte(nil))
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default: // no other types are supported
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return nil, fmt.Errorf("abi: unsupported slice type %v", elem.T)
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}
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// get the offset which determines the start of this array ...
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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 slice: offset %d would go over slice boundary (len=%d)", len(output), offset+32)
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}
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slice := output[offset:]
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// ... starting with the size of the array in elements ...
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size := int(common.BytesToBig(slice[:32]).Uint64())
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slice = slice[32:]
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// ... and make sure that we've at the very least the amount of bytes
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// available in the buffer.
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if size*32 > len(slice) {
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return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), offset+32+size*32)
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}
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// reslice to match the required size
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slice = slice[:(size * 32)]
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for i := 0; i < size; i++ {
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var (
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inter interface{} // interface type
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returnOutput = slice[i*32 : i*32+32] // the return output
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)
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// set inter to the correct type (cast)
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switch elem.T {
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case IntTy, UintTy:
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inter = common.BytesToBig(returnOutput)
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case BoolTy:
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inter = common.BytesToBig(returnOutput).Uint64() > 0
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case AddressTy:
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inter = common.BytesToAddress(returnOutput)
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case HashTy:
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inter = common.BytesToHash(returnOutput)
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}
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// append the item to our reflect slice
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refSlice = reflect.Append(refSlice, reflect.ValueOf(inter))
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}
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// return the interface
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return refSlice.Interface(), nil
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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(i int, t Argument, output []byte) (interface{}, error) {
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// we need to treat slices differently
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if (t.Type.IsSlice || t.Type.IsArray) && t.Type.T != BytesTy && t.Type.T != StringTy && t.Type.T != FixedBytesTy {
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return toGoSlice(i, t, output)
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}
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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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// convert the bytes to whatever is specified by the ABI.
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switch t.Type.T {
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case IntTy, UintTy:
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bigNum := common.BytesToBig(returnOutput)
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// If the type is a integer convert to the integer type
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// specified by the ABI.
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switch t.Type.Kind {
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case reflect.Uint8:
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return uint8(bigNum.Uint64()), nil
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case reflect.Uint16:
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return uint16(bigNum.Uint64()), nil
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case reflect.Uint32:
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return uint32(bigNum.Uint64()), nil
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case reflect.Uint64:
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return uint64(bigNum.Uint64()), nil
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case reflect.Int8:
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return int8(bigNum.Int64()), nil
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case reflect.Int16:
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return int16(bigNum.Int64()), nil
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case reflect.Int32:
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return int32(bigNum.Int64()), nil
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case reflect.Int64:
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return int64(bigNum.Int64()), nil
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case reflect.Ptr:
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return bigNum, nil
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}
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case BoolTy:
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return common.BytesToBig(returnOutput).Uint64() > 0, nil
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case AddressTy:
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return common.BytesToAddress(returnOutput), nil
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case HashTy:
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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, fmt.Errorf("abi: unknown type %v", t.Type.T)
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}
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// these variable are used to determine certain types during type assertion for
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// assignment.
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var (
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r_interSlice = reflect.TypeOf([]interface{}{})
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r_hash = reflect.TypeOf(common.Hash{})
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r_bytes = reflect.TypeOf([]byte{})
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r_byte = reflect.TypeOf(byte(0))
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)
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// Unpack output in v according to the abi specification
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func (abi ABI) Unpack(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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// make sure the passed value is a pointer
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valueOf := reflect.ValueOf(v)
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if reflect.Ptr != valueOf.Kind() {
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return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
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}
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var (
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value = valueOf.Elem()
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typ = value.Type()
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)
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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 err := set(value.Field(j), reflectValue, method.Outputs[i]); err != nil {
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return err
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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(r_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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// if the slice already contains values, set those instead of the interface slice itself.
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if value.Len() > 0 {
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if len(method.Outputs) > value.Len() {
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return fmt.Errorf("abi: cannot marshal in to slices of unequal size (require: %v, got: %v)", len(method.Outputs), value.Len())
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}
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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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if err := set(value.Index(i).Elem(), reflectValue, method.Outputs[i]); 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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// 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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if err := set(value, reflect.ValueOf(marshalledValue), method.Outputs[0]); 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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func (abi *ABI) UnmarshalJSON(data []byte) error {
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var fields []struct {
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Type string
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Name string
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Constant bool
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Indexed bool
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Inputs []Argument
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Outputs []Argument
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}
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if err := json.Unmarshal(data, &fields); err != nil {
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return err
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}
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abi.Methods = make(map[string]Method)
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abi.Events = make(map[string]Event)
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for _, field := range fields {
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switch field.Type {
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case "constructor":
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abi.Constructor = Method{
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Inputs: field.Inputs,
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}
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// empty defaults to function according to the abi spec
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case "function", "":
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abi.Methods[field.Name] = Method{
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Name: field.Name,
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Const: field.Constant,
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Inputs: field.Inputs,
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Outputs: field.Outputs,
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}
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case "event":
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abi.Events[field.Name] = Event{
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Name: field.Name,
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Inputs: field.Inputs,
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}
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}
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}
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return nil
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}
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