github.com/oskarth/go-ethereum@v1.6.8-0.20191013093314-dac24a9d3494/common/bytes.go (about)

     1  // Copyright 2014 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 common contains various helper functions.
    18  package common
    19  
    20  import "encoding/hex"
    21  
    22  // ToHex returns the hex representation of b, prefixed with '0x'.
    23  // For empty slices, the return value is "0x0".
    24  //
    25  // Deprecated: use hexutil.Encode instead.
    26  func ToHex(b []byte) string {
    27  	hex := Bytes2Hex(b)
    28  	if len(hex) == 0 {
    29  		hex = "0"
    30  	}
    31  	return "0x" + hex
    32  }
    33  
    34  // ToHexArray creates a array of hex-string based on []byte
    35  func ToHexArray(b [][]byte) []string {
    36  	r := make([]string, len(b))
    37  	for i := range b {
    38  		r[i] = ToHex(b[i])
    39  	}
    40  	return r
    41  }
    42  
    43  // FromHex returns the bytes represented by the hexadecimal string s.
    44  // s may be prefixed with "0x".
    45  func FromHex(s string) []byte {
    46  	if len(s) > 1 {
    47  		if s[0:2] == "0x" || s[0:2] == "0X" {
    48  			s = s[2:]
    49  		}
    50  	}
    51  	if len(s)%2 == 1 {
    52  		s = "0" + s
    53  	}
    54  	return Hex2Bytes(s)
    55  }
    56  
    57  // CopyBytes returns an exact copy of the provided bytes.
    58  func CopyBytes(b []byte) (copiedBytes []byte) {
    59  	if b == nil {
    60  		return nil
    61  	}
    62  	copiedBytes = make([]byte, len(b))
    63  	copy(copiedBytes, b)
    64  
    65  	return
    66  }
    67  
    68  // hasHexPrefix validates str begins with '0x' or '0X'.
    69  func hasHexPrefix(str string) bool {
    70  	return len(str) >= 2 && str[0] == '0' && (str[1] == 'x' || str[1] == 'X')
    71  }
    72  
    73  // isHexCharacter returns bool of c being a valid hexadecimal.
    74  func isHexCharacter(c byte) bool {
    75  	return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') || ('A' <= c && c <= 'F')
    76  }
    77  
    78  // isHex validates whether each byte is valid hexadecimal string.
    79  func isHex(str string) bool {
    80  	if len(str)%2 != 0 {
    81  		return false
    82  	}
    83  	for _, c := range []byte(str) {
    84  		if !isHexCharacter(c) {
    85  			return false
    86  		}
    87  	}
    88  	return true
    89  }
    90  
    91  // Bytes2Hex returns the hexadecimal encoding of d.
    92  func Bytes2Hex(d []byte) string {
    93  	return hex.EncodeToString(d)
    94  }
    95  
    96  // Hex2Bytes returns the bytes represented by the hexadecimal string str.
    97  func Hex2Bytes(str string) []byte {
    98  	h, _ := hex.DecodeString(str)
    99  	return h
   100  }
   101  
   102  // Hex2BytesFixed returns bytes of a specified fixed length flen.
   103  func Hex2BytesFixed(str string, flen int) []byte {
   104  	h, _ := hex.DecodeString(str)
   105  	if len(h) == flen {
   106  		return h
   107  	}
   108  	if len(h) > flen {
   109  		return h[len(h)-flen:]
   110  	}
   111  	hh := make([]byte, flen)
   112  	copy(hh[flen-len(h):flen], h)
   113  	return hh
   114  }
   115  
   116  // RightPadBytes zero-pads slice to the right up to length l.
   117  func RightPadBytes(slice []byte, l int) []byte {
   118  	if l <= len(slice) {
   119  		return slice
   120  	}
   121  
   122  	padded := make([]byte, l)
   123  	copy(padded, slice)
   124  
   125  	return padded
   126  }
   127  
   128  // LeftPadBytes zero-pads slice to the left up to length l.
   129  func LeftPadBytes(slice []byte, l int) []byte {
   130  	if l <= len(slice) {
   131  		return slice
   132  	}
   133  
   134  	padded := make([]byte, l)
   135  	copy(padded[l-len(slice):], slice)
   136  
   137  	return padded
   138  }