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Odin/core/encoding/base64/base64.odin
Yawning Angel 82a18797b4 core/encoding/base64: Misc fixes and improvements 
- Add error checking to `decode`
- Add `encode_into_buf`/`decode_into_buf`
2026-05-26 00:38:50 +09:00

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/*
`Base64` encoding and decoding.
A secondary param can be used to supply a custom alphabet to `encode` and a matching decoding table to `decode`.
If none is supplied it just uses the standard Base64 alphabet.
In case your specific version does not use padding, you may
truncate it from the encoded output.
*/
package encoding_base64
import "base:intrinsics"
import "base:runtime"
import "core:io"
@(rodata)
ENC_TABLE := [64]byte {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3',
'4', '5', '6', '7', '8', '9', '+', '/',
}
// Encoding table for Base64url variant
@(rodata)
ENC_URL_TABLE := [64]byte {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3',
'4', '5', '6', '7', '8', '9', '-', '_',
}
PADDING :: '='
@(rodata)
DEC_TABLE := [256]i8 {
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, 62, -1, -1, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59,
60, 61, -1, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
}
// Decoding table for Base64url variant
@(rodata)
DEC_URL_TABLE := [256]i8 {
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, 62, -1, -1,
52, 53, 54, 55, 56, 57, 58, 59,
60, 61, -1, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, 63,
-1, 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, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
}
Error :: union #shared_nil {
runtime.Allocator_Error,
io.Error,
Decode_Error,
}
Decode_Error :: enum {
None,
Invalid_Character,
}
encode :: proc(data: []byte, ENC_TBL := ENC_TABLE, allocator := context.allocator) -> (encoded: string, err: runtime.Allocator_Error) #optional_allocator_error {
out_length := encoded_len(data)
if out_length == 0 {
return
}
out := make([]byte, out_length, allocator) or_return
_, ioerr := encode_impl(out, data, ENC_TBL)
assert(ioerr == nil, "encode should not IO error")
assert(len(out) == out_length, "buffer resized, `encoded_len` was wrong")
encoded = transmute(string)(out)
return
}
encode_into_buf :: proc(dst, data: []byte, ENC_TBL := ENC_TABLE) -> (encoded: []byte, err: Error) {
out_length := encoded_len(data)
if out_length == 0 {
return
}
return encode_impl(dst, data, ENC_TBL)
}
encode_into :: proc(w: io.Writer, data: []byte, ENC_TBL := ENC_TABLE) -> io.Error {
_, err := encode_impl(w, data, ENC_TBL)
return err
}
@(private)
encode_impl :: proc(dst: $T, data: []byte, ENC_TBL := ENC_TABLE) -> ([]byte, io.Error) where T == io.Writer || T == []byte {
length := len(data)
when T == []byte {
out_length := encoded_len(data)
if len(dst) < out_length {
return nil, io.Error.Short_Buffer
}
buf := dst
} else {
if length == 0 {
return nil, nil
}
buf: [4]byte
}
c0, c1, c2, block: int
for i := 0; i < length; i += 3 {
#no_bounds_check {
c0, c1, c2 = int(data[i]), -1, -1
if i + 1 < length { c1 = int(data[i + 1]) }
if i + 2 < length { c2 = int(data[i + 2]) }
block = (c0 << 16) | (max(c1, 0) << 8) | max(c2, 0)
buf[0] = ENC_TBL[block >> 18 & 63]
buf[1] = ENC_TBL[block >> 12 & 63]
buf[2] = c1 == -1 ? PADDING : ENC_TBL[block >> 6 & 63]
buf[3] = c2 == -1 ? PADDING : ENC_TBL[block & 63]
when T == []byte {
buf = buf[4:]
}
}
when T == io.Writer {
if _, err := io.write_full(dst, buf[:]); err != nil {
return nil, err
}
}
}
when T == io.Writer {
return nil, nil
} else {
return dst[:out_length], nil
}
}
encoded_len :: proc(data: []byte) -> int {
length := len(data)
if length == 0 {
return 0
}
return ((4 * length / 3) + 3) &~ 3
}
decode :: proc(data: string, DEC_TBL := DEC_TABLE, dst: []byte = nil, allocator := context.allocator) -> (decoded: []byte, err: Error) {
out_length := decoded_len(data)
if out_length == 0 {
return nil, nil
}
buf: []byte
if buf, err = make([]byte, out_length, allocator); err != nil {
return
}
decoded, err = decode_impl(buf, data, DEC_TBL)
if err != nil {
delete(buf, allocator)
}
assert(err != nil || len(decoded) == out_length, "buffer unexpectedly resized, `decoded_len` was wrong")
return
}
decode_into_buf :: proc(dst: []byte, data: string, DEC_TBL := DEC_TABLE) -> (decoded: []byte, err: Error) {
out_length := decoded_len(data)
if out_length == 0 {
return
}
return decode_impl(dst, data, DEC_TBL)
}
decode_into :: proc(w: io.Writer, data: string, DEC_TBL := DEC_TABLE) -> Error {
_, err := decode_impl(w, data, DEC_TBL)
return err
}
@(private)
decode_impl :: proc(dst: $T, data: string, DEC_TBL := DEC_TABLE) -> ([]byte, Error) where T == io.Writer || T == []byte {
length := decoded_len(data)
when T == []byte {
if len(dst) < length {
return nil, io.Error.Short_Buffer
}
off: int
} else {
if length == 0 {
return nil, nil
}
buf: [3]byte
}
c0, c1, c2, c3: int
d0, d1, d2, d3: i8
b0, b1, b2: int
i, j: int
for ; j + 3 <= length; i, j = i + 4, j + 3 {
#no_bounds_check {
d0 = DEC_TBL[data[i]]
d1 = DEC_TBL[data[i + 1]]
d2 = DEC_TBL[data[i + 2]]
d3 = DEC_TBL[data[i + 3]]
if intrinsics.unlikely((d0 | d1 | d2 | d3) & ~i8(0x3f) != 0) {
return nil, Decode_Error.Invalid_Character
}
c0, c1, c2, c3 = int(d0), int(d1), int(d2), int(d3)
b0 = (c0 << 2) | (c1 >> 4)
b1 = (c1 << 4) | (c2 >> 2)
b2 = (c2 << 6) | c3
when T == []byte {
dst[off+0] = byte(b0)
dst[off+1] = byte(b1)
dst[off+2] = byte(b2)
off += 3
} else {
buf[0] = byte(b0)
buf[1] = byte(b1)
buf[2] = byte(b2)
}
}
when T == io.Writer {
if _, err := io.write_full(dst, buf[:]); err != .None {
return nil, err
}
}
}
rest := length - j
if rest > 0 {
#no_bounds_check {
// Note: decoded_len handles removing padding.
d0 = DEC_TBL[data[i]]
d1 = DEC_TBL[data[i + 1]]
if d2 = 0; rest == 2 {
d2 = DEC_TBL[data[i + 2]]
}
if intrinsics.unlikely((d0 | d1 | d2) & ~i8(0x3f) != 0) {
return nil, Decode_Error.Invalid_Character
}
c0, c1, c2 = int(d0), int(d1), int(d2)
b0 = (c0 << 2) | (c1 >> 4)
b1 = (c1 << 4) | (c2 >> 2)
when T == []byte {
switch rest {
case 2:
dst[off+1] = byte(b1)
fallthrough
case 1:
dst[off] = byte(b0)
}
} else {
buf[0] = byte(b0)
buf[1] = byte(b1)
}
}
when T == io.Writer {
if _, err := io.write_full(dst, buf[:rest]); err != .None {
return nil, err
}
}
}
when T == io.Writer {
return nil, nil
} else {
return dst[:length], nil
}
}
decoded_len :: proc(data: string) -> int {
length := len(data)
if length == 0 {
return 0
}
padding: int
if data[length - 1] == PADDING {
if length > 1 && data[length - 2] == PADDING {
padding = 2
} else {
padding = 1
}
}
return ((length * 6) >> 3) - padding
}
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