github.com/klaytn/klaytn@v1.12.1/common/bytes.go

// Modifications Copyright 2018 The klaytn Authors
// Copyright 2015 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/>.
//
// This file is derived from common/bytes.go (2018/06/04).
// Modified and improved for the klaytn development.

package common

import (
	"crypto/rand"
	"encoding/binary"
	"encoding/hex"
	"io"
)

// ToHex returns the hex representation of b, prefixed with '0x'.
// For empty slices, the return value is "0x0".
//
// Deprecated: use hexutil.Encode instead.
func ToHex(b []byte) string {
	hex := Bytes2Hex(b)
	if len(hex) == 0 {
		hex = "0"
	}
	return "0x" + hex
}

// FromHex returns the bytes represented by the hexadecimal string s.
// s may be prefixed with "0x".
func FromHex(s string) []byte {
	if len(s) > 1 {
		if s[0:2] == "0x" || s[0:2] == "0X" {
			s = s[2:]
		}
	}
	if len(s)%2 == 1 {
		s = "0" + s
	}
	return Hex2Bytes(s)
}

// CopyBytes returns an exact copy of the provided bytes.
func CopyBytes(b []byte) (copiedBytes []byte) {
	if b == nil {
		return nil
	}
	copiedBytes = make([]byte, len(b))
	copy(copiedBytes, b)

	return
}

// hasHexPrefix validates str begins with '0x' or '0X'.
func hasHexPrefix(str string) bool {
	return len(str) >= 2 && str[0] == '0' && (str[1] == 'x' || str[1] == 'X')
}

// isHexCharacter returns bool of c being a valid hexadecimal.
func isHexCharacter(c byte) bool {
	return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') || ('A' <= c && c <= 'F')
}

// isHex validates whether each byte is valid hexadecimal string.
func isHex(str string) bool {
	if len(str)%2 != 0 {
		return false
	}
	for _, c := range []byte(str) {
		if !isHexCharacter(c) {
			return false
		}
	}
	return true
}

// Bytes2Hex returns the hexadecimal encoding of d.
func Bytes2Hex(d []byte) string {
	return hex.EncodeToString(d)
}

// Hex2Bytes returns the bytes represented by the hexadecimal string str.
func Hex2Bytes(str string) []byte {
	h, _ := hex.DecodeString(str)
	return h
}

// Hex2BytesFixed returns bytes of a specified fixed length flen.
func Hex2BytesFixed(str string, flen int) []byte {
	h, _ := hex.DecodeString(str)
	if len(h) == flen {
		return h
	} else {
		if len(h) > flen {
			return h[len(h)-flen:]
		} else {
			hh := make([]byte, flen)
			copy(hh[flen-len(h):flen], h[:])
			return hh
		}
	}
}

// RightPadBytes zero-pads slice to the right up to length l.
func RightPadBytes(slice []byte, l int) []byte {
	if l <= len(slice) {
		return slice
	}

	padded := make([]byte, l)
	copy(padded, slice)

	return padded
}

// LeftPadBytes zero-pads slice to the left up to length l.
func LeftPadBytes(slice []byte, l int) []byte {
	if l <= len(slice) {
		return slice
	}

	padded := make([]byte, l)
	copy(padded[l-len(slice):], slice)

	return padded
}

// TrimLeftZeroes returns a subslice of s without leading zeroes
func TrimLeftZeroes(s []byte) []byte {
	idx := 0
	for ; idx < len(s); idx++ {
		if s[idx] != 0 {
			break
		}
	}
	return s[idx:]
}

// TrimRightZeroes returns a subslice of s without trailing zeroes
func TrimRightZeroes(s []byte) []byte {
	idx := len(s)
	for ; idx > 0; idx-- {
		if s[idx-1] != 0 {
			break
		}
	}
	return s[:idx]
}

func MakeRandomBytes(n int) []byte {
	s := make([]byte, n)
	_, err := io.ReadFull(rand.Reader, s)
	if err != nil {
		return nil
	}
	return s
}

// IntToByteLittleEndian encodes a number as little endian uint64
func Int64ToByteLittleEndian(num uint64) []byte {
	enc := make([]byte, 8)
	binary.LittleEndian.PutUint64(enc, num)

	return enc
}

// Int64ToByteBigEndian encodes a number as big endian uint64
func Int64ToByteBigEndian(number uint64) []byte {
	enc := make([]byte, 8)
	binary.BigEndian.PutUint64(enc, number)

	return enc
}

type Entry struct {
	Key, Val []byte
}

// CreateEntries creates random key/value pairs.
func CreateEntries(entryNum int) []Entry {
	entries := make([]Entry, entryNum)
	for i := 0; i < entryNum; i++ {
		entries[i] = Entry{Key: MakeRandomBytes(256), Val: MakeRandomBytes(300)}
	}
	return entries
}