path: root/common/bytes.go

// Copyright 2014 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 common contains various helper functions.
package common

import "encoding/hex"

// 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
    }
    if len(h) > flen {
        return h[len(h)-flen:]
    }
    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
}