248 lines
7.6 KiB
V
248 lines
7.6 KiB
V
module base64
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// encode_in_buffer base64 encodes the `[]byte` passed in `data` into `buffer`.
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// encode_in_buffer returns the size of the encoded data in the buffer.
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// Please note: The buffer should be large enough (i.e. 4/3 of the data.len, or larger) to hold the encoded data.
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// Please note: The function does NOT allocate new memory, and is suitable for handling very large strings.
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pub fn encode_in_buffer(data []byte, buffer &byte) int {
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return encode_from_buffer(buffer, data.data, data.len)
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}
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// encode_from_buffer will perform encoding from any type of src buffer
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// and write the bytes into `dest`.
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// Please note: The `dest` buffer should be large enough (i.e. 4/3 of the src_len, or larger) to hold the encoded data.
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// Please note: This function is for internal base64 encoding
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fn encode_from_buffer(dest &byte, src &byte, src_len int) int {
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if src_len == 0 {
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return 0
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}
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output_length := 4 * ((src_len + 2) / 3)
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mut d := unsafe { src }
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mut b := unsafe { dest }
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etable := enc_table.str
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mut di := 0
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mut si := 0
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n := (src_len / 3) * 3
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for si < n {
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// Convert 3x 8bit source bytes into 4 bytes
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unsafe {
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val := u32(d[si + 0]) << 16 | u32(d[si + 1]) << 8 | u32(d[si + 2])
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b[di + 0] = etable[val >> 18 & 0x3F]
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b[di + 1] = etable[val >> 12 & 0x3F]
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b[di + 2] = etable[val >> 6 & 0x3F]
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b[di + 3] = etable[val & 0x3F]
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}
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si += 3
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di += 4
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}
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remain := src_len - si
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if remain == 0 {
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return output_length
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}
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// Add the remaining small block and padding
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unsafe {
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mut val := u32(d[si + 0]) << 16
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if remain == 2 {
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val |= u32(d[si + 1]) << 8
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}
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b[di + 0] = etable[val >> 18 & 0x3F]
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b[di + 1] = etable[val >> 12 & 0x3F]
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match remain {
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2 {
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b[di + 2] = etable[val >> 6 & 0x3F]
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b[di + 3] = u8(`=`)
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}
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1 {
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b[di + 2] = u8(`=`)
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b[di + 3] = u8(`=`)
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}
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else {
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panic('base64: This case should never occur.')
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}
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}
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}
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return output_length
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}
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// decode_in_buffer decodes the base64 encoded `string` reference passed in `data` into `buffer`.
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// decode_in_buffer returns the size of the decoded data in the buffer.
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// Please note: The `buffer` should be large enough (i.e. 3/4 of the data.len, or larger)
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// to hold the decoded data.
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// Please note: This function does NOT allocate new memory, and is thus suitable for handling very large strings.
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pub fn decode_in_buffer(data &string, buffer &byte) int {
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return decode_from_buffer(buffer, data.str, data.len)
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}
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// decode_from_buffer decodes the base64 encoded ASCII bytes from `data` into `buffer`.
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// decode_from_buffer returns the size of the decoded data in the buffer.
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// Please note: The `buffer` should be large enough (i.e. 3/4 of the data.len, or larger)
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// to hold the decoded data.
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// Please note: This function does NOT allocate new memory, and is thus suitable for handling very large strings.
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pub fn decode_in_buffer_bytes(data []byte, buffer &byte) int {
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return decode_from_buffer(buffer, data.data, data.len)
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}
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// decode_from_buffer decodes the base64 encoded ASCII bytes from `src` into `dest`.
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// decode_from_buffer returns the size of the decoded data in the buffer.
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// Please note: The `dest` buffer should be large enough (i.e. 3/4 of the `src_len`, or larger)
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// to hold the decoded data.
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// Please note: This function does NOT allocate new memory, and is thus suitable for handling very large strings.
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// Please note: This function is for internal base64 decoding
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fn decode_from_buffer(dest &byte, src &byte, src_len int) int {
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if src_len < 4 {
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return 0
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}
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mut padding := 0
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if unsafe { src[src_len - 1] == `=` } {
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if unsafe { src[src_len - 2] == `=` } {
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padding = 2
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} else {
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padding = 1
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}
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}
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mut d := unsafe { src }
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mut b := unsafe { dest }
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unsafe {
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mut n_decoded_bytes := 0 // padding bytes are also counted towards this.
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mut si := 0
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mut datablock_64 := B64_64_datablock{
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data: 0
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}
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mut datablock_32 := B64_32_datablock{
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data: 0
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}
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for src_len - si >= 8 {
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// Converting 8 bytes of input into 6 bytes of output. Storing these in the upper bytes of an u64.
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datablock_64.data = assemble64(u8(index[d[si + 0]]), u8(index[d[si + 1]]),
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u8(index[d[si + 2]]), u8(index[d[si + 3]]), u8(index[d[si + 4]]),
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u8(index[d[si + 5]]), u8(index[d[si + 6]]), u8(index[d[si + 7]]))
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// Reading out the individual bytes from the u64. Watch out with endianess.
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$if little_endian {
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b[n_decoded_bytes + 0] = datablock_64.data_byte[7]
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b[n_decoded_bytes + 1] = datablock_64.data_byte[6]
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b[n_decoded_bytes + 2] = datablock_64.data_byte[5]
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b[n_decoded_bytes + 3] = datablock_64.data_byte[4]
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b[n_decoded_bytes + 4] = datablock_64.data_byte[3]
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b[n_decoded_bytes + 5] = datablock_64.data_byte[2]
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} $else {
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b[n_decoded_bytes + 0] = datablock_64.data_byte[0]
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b[n_decoded_bytes + 1] = datablock_64.data_byte[1]
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b[n_decoded_bytes + 2] = datablock_64.data_byte[2]
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b[n_decoded_bytes + 3] = datablock_64.data_byte[3]
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b[n_decoded_bytes + 4] = datablock_64.data_byte[4]
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b[n_decoded_bytes + 5] = datablock_64.data_byte[5]
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}
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n_decoded_bytes += 6
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si += 8
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}
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for src_len - si >= 4 {
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datablock_32.data = assemble32(u8(index[d[si + 0]]), u8(index[d[si + 1]]),
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u8(index[d[si + 2]]), u8(index[d[si + 3]]))
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$if little_endian {
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b[n_decoded_bytes + 0] = datablock_32.data_byte[3]
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b[n_decoded_bytes + 1] = datablock_32.data_byte[2]
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b[n_decoded_bytes + 2] = datablock_32.data_byte[1]
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b[n_decoded_bytes + 3] = datablock_32.data_byte[0]
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} $else {
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b[n_decoded_bytes + 0] = datablock_32.data_byte[0]
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b[n_decoded_bytes + 1] = datablock_32.data_byte[1]
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b[n_decoded_bytes + 2] = datablock_32.data_byte[2]
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b[n_decoded_bytes + 3] = datablock_32.data_byte[3]
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}
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n_decoded_bytes += 3
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si += 4
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}
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return n_decoded_bytes - padding
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}
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}
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union B64_64_datablock {
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mut:
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data u64
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data_byte [8]byte
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}
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union B64_32_datablock {
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mut:
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data u32
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data_byte [4]byte
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}
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// decode decodes the base64 encoded `string` value passed in `data`.
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// Please note: If you need to decode many strings repeatedly, take a look at `decode_in_buffer`.
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// Example: assert base64.decode('ViBpbiBiYXNlIDY0') == 'V in base 64'
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pub fn decode(data string) []byte {
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mut size := i64(data.len) * 3 / 4
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if size <= 0 || data.len % 4 != 0 {
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return []
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}
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size = (size + 3) & ~0x03 // round to the next multiple of 4 (the decoding loop writes multiples of 4 bytes)
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unsafe {
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buffer := malloc(int(size))
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n := decode_in_buffer(data, buffer)
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return buffer.vbytes(n)
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}
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}
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// decode_str is the string variant of decode
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pub fn decode_str(data string) string {
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size := data.len * 3 / 4
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if size <= 0 || data.len % 4 != 0 {
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return ''
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}
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unsafe {
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buffer := malloc_noscan(size + 1)
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buffer[size] = 0
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blen := decode_in_buffer(data, buffer)
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return tos(buffer, blen)
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}
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}
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// encode encodes the `[]byte` value passed in `data` to base64.
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// Please note: base64 encoding returns a `string` that is ~ 4/3 larger than the input.
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// Please note: If you need to encode many strings repeatedly, take a look at `encode_in_buffer`.
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// Example: assert base64.encode('V in base 64') == 'ViBpbiBiYXNlIDY0'
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pub fn encode(data []byte) string {
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return alloc_and_encode(data.data, data.len)
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}
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// encode_str is the string variant of encode
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pub fn encode_str(data string) string {
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return alloc_and_encode(data.str, data.len)
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}
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// alloc_and_encode is a private function that allocates and encodes data into a string
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// Used by encode and encode_str
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fn alloc_and_encode(src &byte, len int) string {
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if len == 0 {
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return ''
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}
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size := 4 * ((len + 2) / 3)
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if size <= 0 {
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return ''
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}
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unsafe {
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buffer := malloc_noscan(size + 1)
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buffer[size] = 0
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blen := encode_from_buffer(buffer, src, len)
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return tos(buffer, blen)
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}
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}
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