gotosocial/vendor/github.com/chenzhuoyu/base64x/base64x.go
2023-02-25 12:12:40 +00:00

157 lines
4.6 KiB
Go

package base64x
import (
`encoding/base64`
)
// An Encoding is a radix 64 encoding/decoding scheme, defined by a
// 64-character alphabet. The most common encoding is the "base64"
// encoding defined in RFC 4648 and used in MIME (RFC 2045) and PEM
// (RFC 1421). RFC 4648 also defines an alternate encoding, which is
// the standard encoding with - and _ substituted for + and /.
type Encoding int
const (
_MODE_URL = 1 << 0
_MODE_RAW = 1 << 1
_MODE_AVX2 = 1 << 2
_MODE_JSON = 1 << 3
)
// StdEncoding is the standard base64 encoding, as defined in
// RFC 4648.
const StdEncoding Encoding = 0
// URLEncoding is the alternate base64 encoding defined in RFC 4648.
// It is typically used in URLs and file names.
const URLEncoding Encoding = _MODE_URL
// RawStdEncoding is the standard raw, unpadded base64 encoding,
// as defined in RFC 4648 section 3.2.
//
// This is the same as StdEncoding but omits padding characters.
const RawStdEncoding Encoding = _MODE_RAW
// RawURLEncoding is the unpadded alternate base64 encoding defined in RFC 4648.
// It is typically used in URLs and file names.
//
// This is the same as URLEncoding but omits padding characters.
const RawURLEncoding Encoding = _MODE_RAW | _MODE_URL
// JSONStdEncoding is the StdEncoding and encoded as JSON string as RFC 8259.
const JSONStdEncoding Encoding = _MODE_JSON;
var (
archFlags = 0
)
/** Encoder Functions **/
// Encode encodes src using the specified encoding, writing
// EncodedLen(len(src)) bytes to out.
//
// The encoding pads the output to a multiple of 4 bytes,
// so Encode is not appropriate for use on individual blocks
// of a large data stream.
//
// If out is not large enough to contain the encoded result,
// it will panic.
func (self Encoding) Encode(out []byte, src []byte) {
if len(src) != 0 {
if buf := out[:0:len(out)]; self.EncodedLen(len(src)) <= len(out) {
self.EncodeUnsafe(&buf, src)
} else {
panic("encoder output buffer is too small")
}
}
}
// EncodeUnsafe behaves like Encode, except it does NOT check if
// out is large enough to contain the encoded result.
//
// It will also update the length of out.
func (self Encoding) EncodeUnsafe(out *[]byte, src []byte) {
__b64encode(out, &src, int(self) | archFlags)
}
// EncodeToString returns the base64 encoding of src.
func (self Encoding) EncodeToString(src []byte) string {
nbs := len(src)
ret := make([]byte, 0, self.EncodedLen(nbs))
/* encode in native code */
self.EncodeUnsafe(&ret, src)
return mem2str(ret)
}
// EncodedLen returns the length in bytes of the base64 encoding
// of an input buffer of length n.
func (self Encoding) EncodedLen(n int) int {
if (self & _MODE_RAW) == 0 {
return (n + 2) / 3 * 4
} else {
return (n * 8 + 5) / 6
}
}
/** Decoder Functions **/
// Decode decodes src using the encoding enc. It writes at most
// DecodedLen(len(src)) bytes to out and returns the number of bytes
// written. If src contains invalid base64 data, it will return the
// number of bytes successfully written and base64.CorruptInputError.
//
// New line characters (\r and \n) are ignored.
//
// If out is not large enough to contain the encoded result,
// it will panic.
func (self Encoding) Decode(out []byte, src []byte) (int, error) {
if len(src) == 0 {
return 0, nil
} else if buf := out[:0:len(out)]; self.DecodedLen(len(src)) <= len(out) {
return self.DecodeUnsafe(&buf, src)
} else {
panic("decoder output buffer is too small")
}
}
// DecodeUnsafe behaves like Decode, except it does NOT check if
// out is large enough to contain the decoded result.
//
// It will also update the length of out.
func (self Encoding) DecodeUnsafe(out *[]byte, src []byte) (int, error) {
if n := __b64decode(out, mem2addr(src), len(src), int(self) | archFlags); n >= 0 {
return n, nil
} else {
return 0, base64.CorruptInputError(-n - 1)
}
}
// DecodeString returns the bytes represented by the base64 string s.
func (self Encoding) DecodeString(s string) ([]byte, error) {
src := str2mem(s)
ret := make([]byte, 0, self.DecodedLen(len(s)))
/* decode into the allocated buffer */
if _, err := self.DecodeUnsafe(&ret, src); err != nil {
return nil, err
} else {
return ret, nil
}
}
// DecodedLen returns the maximum length in bytes of the decoded data
// corresponding to n bytes of base64-encoded data.
func (self Encoding) DecodedLen(n int) int {
if (self & _MODE_RAW) == 0 {
return n / 4 * 3
} else {
return n * 6 / 8
}
}
func init() {
if hasAVX2() {
archFlags = _MODE_AVX2
}
}