github.com/ethereum/go-ethereum@v1.16.1/accounts/abi/pack.go (about)

     1  // Copyright 2016 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package abi
    18  
    19  import (
    20  	"errors"
    21  	"fmt"
    22  	"math/big"
    23  	"reflect"
    24  
    25  	"github.com/ethereum/go-ethereum/common"
    26  	"github.com/ethereum/go-ethereum/common/math"
    27  )
    28  
    29  // packBytesSlice packs the given bytes as [L, V] as the canonical representation
    30  // bytes slice.
    31  func packBytesSlice(bytes []byte, l int) []byte {
    32  	len := packNum(reflect.ValueOf(l))
    33  	return append(len, common.RightPadBytes(bytes, (l+31)/32*32)...)
    34  }
    35  
    36  // packElement packs the given reflect value according to the abi specification in
    37  // t.
    38  func packElement(t Type, reflectValue reflect.Value) ([]byte, error) {
    39  	switch t.T {
    40  	case UintTy:
    41  		// make sure to not pack a negative value into a uint type.
    42  		if reflectValue.Kind() == reflect.Ptr {
    43  			val := new(big.Int).Set(reflectValue.Interface().(*big.Int))
    44  			if val.Sign() == -1 {
    45  				return nil, errInvalidSign
    46  			}
    47  		}
    48  		return packNum(reflectValue), nil
    49  	case IntTy:
    50  		return packNum(reflectValue), nil
    51  	case StringTy:
    52  		return packBytesSlice([]byte(reflectValue.String()), reflectValue.Len()), nil
    53  	case AddressTy:
    54  		if reflectValue.Kind() == reflect.Array {
    55  			reflectValue = mustArrayToByteSlice(reflectValue)
    56  		}
    57  
    58  		return common.LeftPadBytes(reflectValue.Bytes(), 32), nil
    59  	case BoolTy:
    60  		if reflectValue.Bool() {
    61  			return math.PaddedBigBytes(common.Big1, 32), nil
    62  		}
    63  		return math.PaddedBigBytes(common.Big0, 32), nil
    64  	case BytesTy:
    65  		if reflectValue.Kind() == reflect.Array {
    66  			reflectValue = mustArrayToByteSlice(reflectValue)
    67  		}
    68  		if reflectValue.Type() != reflect.TypeOf([]byte{}) {
    69  			return []byte{}, errors.New("bytes type is neither slice nor array")
    70  		}
    71  		return packBytesSlice(reflectValue.Bytes(), reflectValue.Len()), nil
    72  	case FixedBytesTy, FunctionTy:
    73  		if reflectValue.Kind() == reflect.Array {
    74  			reflectValue = mustArrayToByteSlice(reflectValue)
    75  		}
    76  		return common.RightPadBytes(reflectValue.Bytes(), 32), nil
    77  	default:
    78  		return []byte{}, fmt.Errorf("could not pack element, unknown type: %v", t.T)
    79  	}
    80  }
    81  
    82  // packNum packs the given number (using the reflect value) and will cast it to appropriate number representation.
    83  func packNum(value reflect.Value) []byte {
    84  	switch kind := value.Kind(); kind {
    85  	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
    86  		return math.U256Bytes(new(big.Int).SetUint64(value.Uint()))
    87  	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
    88  		return math.U256Bytes(big.NewInt(value.Int()))
    89  	case reflect.Ptr:
    90  		return math.U256Bytes(new(big.Int).Set(value.Interface().(*big.Int)))
    91  	default:
    92  		panic("abi: fatal error")
    93  	}
    94  }