v/vlib/encoding/base64/base64.c.v

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module base64
// encode_in_buffer base64 encodes the `[]byte` 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 []byte, buffer &byte) int {
return encode_from_buffer(buffer, data.data, data.len)
}
// encode_from_buffer will perform encoding from any type of src buffer
// and write the bytes into `dest`.
// Please note: The `dest` buffer should be large enough (i.e. 4/3 of the src_len, or larger) to hold the encoded data.
// Please note: This function is for internal base64 encoding
fn encode_from_buffer(dest &byte, src &byte, src_len int) int {
if src_len == 0 {
return 0
}
output_length := 4 * ((src_len + 2) / 3)
mut d := unsafe { src }
mut b := unsafe { dest }
etable := enc_table.str
mut di := 0
mut si := 0
n := (src_len / 3) * 3
for si < n {
// Convert 3x 8bit source bytes into 4 bytes
unsafe {
val := u32(d[si + 0]) << 16 | u32(d[si + 1]) << 8 | u32(d[si + 2])
b[di + 0] = etable[val >> 18 & 0x3F]
b[di + 1] = etable[val >> 12 & 0x3F]
b[di + 2] = etable[val >> 6 & 0x3F]
b[di + 3] = etable[val & 0x3F]
}
si += 3
di += 4
}
remain := src_len - si
if remain == 0 {
return output_length
}
// Add the remaining small block and padding
unsafe {
mut val := u32(d[si + 0]) << 16
if remain == 2 {
val |= u32(d[si + 1]) << 8
}
b[di + 0] = etable[val >> 18 & 0x3F]
b[di + 1] = etable[val >> 12 & 0x3F]
match remain {
2 {
b[di + 2] = etable[val >> 6 & 0x3F]
b[di + 3] = byte(`=`)
}
1 {
b[di + 2] = byte(`=`)
b[di + 3] = byte(`=`)
}
else {
panic('base64: This case should never occur.')
}
}
}
return output_length
}
// 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 &byte) int {
return decode_from_buffer(buffer, data.str, data.len)
}
// decode_from_buffer decodes the base64 encoded ASCII bytes from `data` into `buffer`.
// decode_from_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_bytes(data []byte, buffer &byte) int {
return decode_from_buffer(buffer, data.data, data.len)
}
// decode_from_buffer decodes the base64 encoded ASCII bytes from `src` into `dest`.
// decode_from_buffer returns the size of the decoded data in the buffer.
// Please note: The `dest` buffer should be large enough (i.e. 3/4 of the `src_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.
// Please note: This function is for internal base64 decoding
fn decode_from_buffer(dest &byte, src &byte, src_len int) int {
if src_len < 4 {
return 0
}
mut padding := 0
if unsafe { src[src_len - 1] == `=` } {
if unsafe { src[src_len - 2] == `=` } {
padding = 2
} else {
padding = 1
}
}
mut d := unsafe { src }
mut b := unsafe { dest }
unsafe {
mut n_decoded_bytes := 0 // padding bytes are also counted towards this.
mut si := 0
mut datablock_64 := B64_64_datablock{
data: 0
}
mut datablock_32 := B64_32_datablock{
data: 0
}
for src_len - si >= 8 {
// Converting 8 bytes of input into 6 bytes of output. Storing these in the upper bytes of an u64.
datablock_64.data = assemble64(byte(index[d[si + 0]]), byte(index[d[si + 1]]),
byte(index[d[si + 2]]), byte(index[d[si + 3]]), byte(index[d[si + 4]]),
byte(index[d[si + 5]]), byte(index[d[si + 6]]), byte(index[d[si + 7]]))
// Reading out the individual bytes from the u64. Watch out with endianess.
$if little_endian {
b[n_decoded_bytes + 0] = datablock_64.data_byte[7]
b[n_decoded_bytes + 1] = datablock_64.data_byte[6]
b[n_decoded_bytes + 2] = datablock_64.data_byte[5]
b[n_decoded_bytes + 3] = datablock_64.data_byte[4]
b[n_decoded_bytes + 4] = datablock_64.data_byte[3]
b[n_decoded_bytes + 5] = datablock_64.data_byte[2]
} $else {
b[n_decoded_bytes + 0] = datablock_64.data_byte[0]
b[n_decoded_bytes + 1] = datablock_64.data_byte[1]
b[n_decoded_bytes + 2] = datablock_64.data_byte[2]
b[n_decoded_bytes + 3] = datablock_64.data_byte[3]
b[n_decoded_bytes + 4] = datablock_64.data_byte[4]
b[n_decoded_bytes + 5] = datablock_64.data_byte[5]
}
n_decoded_bytes += 6
si += 8
}
for src_len - si >= 4 {
datablock_32.data = assemble32(byte(index[d[si + 0]]), byte(index[d[si + 1]]),
byte(index[d[si + 2]]), byte(index[d[si + 3]]))
$if little_endian {
b[n_decoded_bytes + 0] = datablock_32.data_byte[3]
b[n_decoded_bytes + 1] = datablock_32.data_byte[2]
b[n_decoded_bytes + 2] = datablock_32.data_byte[1]
b[n_decoded_bytes + 3] = datablock_32.data_byte[0]
} $else {
b[n_decoded_bytes + 0] = datablock_32.data_byte[0]
b[n_decoded_bytes + 1] = datablock_32.data_byte[1]
b[n_decoded_bytes + 2] = datablock_32.data_byte[2]
b[n_decoded_bytes + 3] = datablock_32.data_byte[3]
}
n_decoded_bytes += 3
si += 4
}
return n_decoded_bytes - padding
}
}
union B64_64_datablock {
mut:
data u64
data_byte [8]byte
}
union B64_32_datablock {
mut:
data u32
data_byte [4]byte
}
// 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) []byte {
mut size := i64(data.len) * 3 / 4
if size <= 0 || data.len % 4 != 0 {
return []
}
size = (size + 3) & ~0x03 // round to the next multiple of 4 (the decoding loop writes multiples of 4 bytes)
unsafe {
buffer := malloc(int(size))
n := decode_in_buffer(data, buffer)
return buffer.vbytes(n)
}
}
// decode_str is the string variant of decode
pub fn decode_str(data string) string {
size := data.len * 3 / 4
if size <= 0 || data.len % 4 != 0 {
return ''
}
unsafe {
buffer := malloc_noscan(size + 1)
buffer[size] = 0
blen := decode_in_buffer(data, buffer)
return tos(buffer, blen)
}
}
// encode encodes the `[]byte` 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 []byte) string {
return alloc_and_encode(data.data, data.len)
}
// encode_str is the string variant of encode
pub fn encode_str(data string) string {
return alloc_and_encode(data.str, data.len)
}
// alloc_and_encode is a private function that allocates and encodes data into a string
// Used by encode and encode_str
fn alloc_and_encode(src &byte, len int) string {
if len == 0 {
return ''
2021-11-28 19:37:08 +01:00
}
size := 4 * ((len + 2) / 3)
if size <= 0 {
return ''
}
unsafe {
buffer := malloc_noscan(size + 1)
buffer[size] = 0
blen := encode_from_buffer(buffer, src, len)
return tos(buffer, blen)
}
}