path: root/accounts/abi/pack.go

// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package abi

import (
    "math/big"
    "reflect"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/common/math"
)

// packBytesSlice packs the given bytes as [L, V] as the canonical representation
// bytes slice
func packBytesSlice(bytes []byte, l int) []byte {
    len := packNum(reflect.ValueOf(l))
    return append(len, common.RightPadBytes(bytes, (l+31)/32*32)...)
}

// packElement packs the given reflect value according to the abi specification in
// t.
func packElement(t Type, reflectValue reflect.Value) []byte {
    switch t.T {
    case IntTy, UintTy:
        return packNum(reflectValue)
    case StringTy:
        return packBytesSlice([]byte(reflectValue.String()), reflectValue.Len())
    case AddressTy:
        if reflectValue.Kind() == reflect.Array {
            reflectValue = mustArrayToByteSlice(reflectValue)
        }

        return common.LeftPadBytes(reflectValue.Bytes(), 32)
    case BoolTy:
        if reflectValue.Bool() {
            return math.PaddedBigBytes(common.Big1, 32)
        }
        return math.PaddedBigBytes(common.Big0, 32)
    case BytesTy:
        if reflectValue.Kind() == reflect.Array {
            reflectValue = mustArrayToByteSlice(reflectValue)
        }
        return packBytesSlice(reflectValue.Bytes(), reflectValue.Len())
    case FixedBytesTy, FunctionTy:
        if reflectValue.Kind() == reflect.Array {
            reflectValue = mustArrayToByteSlice(reflectValue)
        }
        return common.RightPadBytes(reflectValue.Bytes(), 32)
    default:
        panic("abi: fatal error")
    }
}

// packNum packs the given number (using the reflect value) and will cast it to appropriate number representation
func packNum(value reflect.Value) []byte {
    switch kind := value.Kind(); kind {
    case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
        return U256(new(big.Int).SetUint64(value.Uint()))
    case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
        return U256(big.NewInt(value.Int()))
    case reflect.Ptr:
        return U256(value.Interface().(*big.Int))
    default:
        panic("abi: fatal error")
    }

}