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encoding: document all of the encoding.base64 module (#8276)

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Larpon 2021-01-22 21:29:05 +01:00 committed by GitHub
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119
vlib/encoding/base64/base64.v
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@ -1,44 +1,34 @@
// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module base64
const (
index = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
62, 63, 62, 62, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0,
0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 63, 0, 26, 27, 28, 29,
30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46,
47, 48, 49, 50, 51]!
index = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 63, 62, 62, 63, 52, 53, 54, 55,
56, 57, 58, 59, 60, 61, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 63, 0, 26, 27, 28, 29,
30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51]!
ending_table = [0, 2, 1]!
enc_table = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
enc_table = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
)
/*
decode - expects a base64 encoded string. Returns its decoded version.
@param data - the encoded input string.
@return the decoded version of the input string data.
NB: if you need to decode many strings repeatedly, take a look at decode_in_buffer too.
*/
// decode decodes the base64 encoded `string` value passed in `data`.
// Please note: If you need to decode many strings repeatedly, take a look at `decode_in_buffer`.
// Example: assert base64.decode('ViBpbiBiYXNlIDY0') == 'V in base 64'
pub fn decode(data string) string {
size := data.len * 3 / 4
if size <= 0 {
return ''
}
buffer := malloc(size)
return tos(buffer, decode_in_buffer(data, buffer) )
return tos(buffer, decode_in_buffer(data, buffer))
}
/*
decode - expects a string. Returns its base64 encoded version.
@param data - the input string.
@return the base64 encoded version of the input string.
NB: base64 encoding returns a string that is ~ 4/3 larger than the input.
NB: if you need to encode many strings repeatedly, take a look at encode_in_buffer too.
*/
// encode encodes the `string` value passed in `data` to base64.
// Please note: base64 encoding returns a `string` that is ~ 4/3 larger than the input.
// Please note: If you need to encode many strings repeatedly, take a look at `encode_in_buffer`.
// Example: assert base64.encode('V in base 64') == 'ViBpbiBiYXNlIDY0'
pub fn encode(data string) string {
size := 4 * ((data.len + 2) / 3)
if size <= 0 {
@ -48,34 +38,33 @@ pub fn encode(data string) string {
return tos(buffer, encode_in_buffer(data, buffer))
}
// decode decodes base64url string to string
// decode_url returns a decoded URL `string` version of
// the a base64 url encoded `string` passed in `data`.
pub fn decode_url(data string) string {
mut result := data.replace('-', '+') // 62nd char of encoding
result = data.replace('_', '/') // 63rd char of encoding
match result.len % 4 { // Pad with trailing '='s
2 { result += "==" } // 2 pad chars
3 { result += "=" } // 1 pad char
else { } // no padding
2 { result += '==' } // 2 pad chars
3 { result += '=' } // 1 pad char
else {} // no padding
}
return base64.decode(data)
return decode(data)
}
// encode encodes given string to base64url string
// encode_url returns a base64 URL encoded `string` version
// of the value passed in `data`.
pub fn encode_url(data string) string {
mut result := base64.encode(data)
mut result := encode(data)
// 62nd char of encoding, 63rd char of encoding, remove any trailing '='s
result = result.replace_each(['+', '-', '/', '_', '=', ''])
return result
}
/*
decode_in_buffer - expects a string reference, and a buffer in which to store its decoded version.
@param data - a reference/pointer to the input string that will be decoded.
@param buffer - a reference/pointer to the buffer that will hold the result.
The buffer should be large enough (i.e. 3/4 of the data.len, or larger) to hold the decoded data.
@return the actual size of the decoded data in the buffer.
NB: this function does NOT allocate new memory, and is suitable for handling very large strings.
*/
// decode_in_buffer decodes the base64 encoded `string` reference passed in `data` into `buffer`.
// decode_in_buffer returns the size of the decoded data in the buffer.
// Please note: The `buffer` should be large enough (i.e. 3/4 of the data.len, or larger)
// to hold the decoded data.
// Please note: This function does NOT allocate new memory, and is thus suitable for handling very large strings.
pub fn decode_in_buffer(data &string, buffer byteptr) int {
mut padding := 0
if data.ends_with('=') {
@ -85,7 +74,7 @@ pub fn decode_in_buffer(data &string, buffer byteptr) int {
padding = 1
}
}
//input_length is the length of meaningful data
// input_length is the length of meaningful data
input_length := data.len - padding
output_length := input_length * 3 / 4
@ -93,52 +82,47 @@ pub fn decode_in_buffer(data &string, buffer byteptr) int {
mut j := 0
mut b := &byte(0)
mut d := &byte(0)
unsafe{
unsafe {
d = byteptr(data.str)
b = byteptr(buffer)
}
for i < input_length {
mut char_a := 0
mut char_b := 0
mut char_c := 0
mut char_d := 0
if i < input_length {
char_a = index[unsafe {d[i]}]
char_a = index[unsafe { d[i] }]
i++
}
if i < input_length {
char_b = index[unsafe {d[i]}]
char_b = index[unsafe { d[i] }]
i++
}
if i < input_length {
char_c = index[unsafe {d[i]}]
char_c = index[unsafe { d[i] }]
i++
}
if i < input_length {
char_d = index[unsafe {d[i]}]
char_d = index[unsafe { d[i] }]
i++
}
decoded_bytes := (char_a << 18) | (char_b << 12) | (char_c << 6) | (char_d << 0)
unsafe {
b[j] = byte(decoded_bytes >> 16)
b[j+1] = byte((decoded_bytes >> 8) & 0xff)
b[j+2] = byte((decoded_bytes >> 0) & 0xff)
b[j] = byte(decoded_bytes >> 16)
b[j + 1] = byte((decoded_bytes >> 8) & 0xff)
b[j + 2] = byte((decoded_bytes >> 0) & 0xff)
}
j += 3
}
return output_length
}
/*
encode_in_buffer - expects a string reference, and a buffer in which to store its base64 encoded version.
@param data - a reference/pointer to the input string.
@param buffer - a reference/pointer to the buffer that will hold the result.
The buffer should be large enough (i.e. 4/3 of the data.len, or larger) to hold the encoded data.
@return the actual size of the encoded data in the buffer.
NB: this function does NOT allocate new memory, and is suitable for handling very large strings.
*/
// encode_in_buffer base64 encodes the `string` reference passed in `data` into `buffer`.
// encode_in_buffer returns the size of the encoded data in the buffer.
// Please note: The buffer should be large enough (i.e. 4/3 of the data.len, or larger) to hold the encoded data.
// Please note: The function does NOT allocate new memory, and is suitable for handling very large strings.
pub fn encode_in_buffer(data &string, buffer byteptr) int {
input_length := data.len
output_length := 4 * ((input_length + 2) / 3)
@ -146,40 +130,39 @@ pub fn encode_in_buffer(data &string, buffer byteptr) int {
mut i := 0
mut j := 0
mut d := byteptr(0)
mut b := byteptr(0)
mut d := byteptr(0)
mut b := byteptr(0)
mut etable := byteptr(0)
unsafe{
unsafe {
d = data.str
b = buffer
etable = enc_table.str
}
for i < input_length {
mut octet_a := 0
mut octet_b := 0
mut octet_c := 0
if i < input_length {
octet_a = int(unsafe {d[i]})
octet_a = int(unsafe { d[i] })
i++
}
if i < input_length {
octet_b = int(unsafe {d[i]})
octet_b = int(unsafe { d[i] })
i++
}
if i < input_length {
octet_c = int(unsafe {d[i]})
octet_c = int(unsafe { d[i] })
i++
}
triple := ((octet_a << 0x10) + (octet_b << 0x08) + octet_c)
unsafe {
b[j] = etable[ (triple >> 3 * 6) & 63 ] // 63 is 0x3F
b[j+1] = etable[ (triple >> 2 * 6) & 63 ]
b[j+2] = etable[ (triple >> 1 * 6) & 63 ]
b[j+3] = etable[ (triple >> 0 * 6) & 63 ]
b[j] = etable[(triple >> 3 * 6) & 63] // 63 is 0x3F
b[j + 1] = etable[(triple >> 2 * 6) & 63]
b[j + 2] = etable[(triple >> 1 * 6) & 63]
b[j + 3] = etable[(triple >> 0 * 6) & 63]
}
j += 4
}