Adding upstream version 1.21.8.upstream/1.21.8

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

3 files changed, 1253 insertions, 0 deletions

diff --git a/src/encoding/base64/base64.go b/src/encoding/base64/base64.go
new file mode 100644
index 0000000..6aa8a15
--- /dev/null
+++ b/src/encoding/base64/base64.go
@@ -0,0 +1,630 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package base64 implements base64 encoding as specified by RFC 4648.
+package base64
+
+import (
+	"encoding/binary"
+	"io"
+	"strconv"
+)
+
+/*
+ * Encodings
+ */
+
+// 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 struct {
+	encode    [64]byte
+	decodeMap [256]byte
+	padChar   rune
+	strict    bool
+}
+
+const (
+	StdPadding          rune = '=' // Standard padding character
+	NoPadding           rune = -1  // No padding
+	decodeMapInitialize      = "" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" +
+		"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
+)
+
+const encodeStd = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
+const encodeURL = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
+
+// NewEncoding returns a new padded Encoding defined by the given alphabet,
+// which must be a 64-byte string that does not contain the padding character
+// or CR / LF ('\r', '\n'). The alphabet is treated as sequence of byte values
+// without any special treatment for multi-byte UTF-8.
+// The resulting Encoding uses the default padding character ('='),
+// which may be changed or disabled via WithPadding.
+func NewEncoding(encoder string) *Encoding {
+	if len(encoder) != 64 {
+		panic("encoding alphabet is not 64-bytes long")
+	}
+	for i := 0; i < len(encoder); i++ {
+		if encoder[i] == '\n' || encoder[i] == '\r' {
+			panic("encoding alphabet contains newline character")
+		}
+	}
+
+	e := new(Encoding)
+	e.padChar = StdPadding
+	copy(e.encode[:], encoder)
+	copy(e.decodeMap[:], decodeMapInitialize)
+
+	for i := 0; i < len(encoder); i++ {
+		e.decodeMap[encoder[i]] = byte(i)
+	}
+	return e
+}
+
+// WithPadding creates a new encoding identical to enc except
+// with a specified padding character, or NoPadding to disable padding.
+// The padding character must not be '\r' or '\n', must not
+// be contained in the encoding's alphabet and must be a rune equal or
+// below '\xff'.
+// Padding characters above '\x7f' are encoded as their exact byte value
+// rather than using the UTF-8 representation of the codepoint.
+func (enc Encoding) WithPadding(padding rune) *Encoding {
+	if padding == '\r' || padding == '\n' || padding > 0xff {
+		panic("invalid padding")
+	}
+
+	for i := 0; i < len(enc.encode); i++ {
+		if rune(enc.encode[i]) == padding {
+			panic("padding contained in alphabet")
+		}
+	}
+
+	enc.padChar = padding
+	return &enc
+}
+
+// Strict creates a new encoding identical to enc except with
+// strict decoding enabled. In this mode, the decoder requires that
+// trailing padding bits are zero, as described in RFC 4648 section 3.5.
+//
+// Note that the input is still malleable, as new line characters
+// (CR and LF) are still ignored.
+func (enc Encoding) Strict() *Encoding {
+	enc.strict = true
+	return &enc
+}
+
+// StdEncoding is the standard base64 encoding, as defined in
+// RFC 4648.
+var StdEncoding = NewEncoding(encodeStd)
+
+// URLEncoding is the alternate base64 encoding defined in RFC 4648.
+// It is typically used in URLs and file names.
+var URLEncoding = NewEncoding(encodeURL)
+
+// 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.
+var RawStdEncoding = StdEncoding.WithPadding(NoPadding)
+
+// 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.
+var RawURLEncoding = URLEncoding.WithPadding(NoPadding)
+
+/*
+ * Encoder
+ */
+
+// Encode encodes src using the encoding enc, writing
+// EncodedLen(len(src)) bytes to dst.
+//
+// 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. Use NewEncoder() instead.
+func (enc *Encoding) Encode(dst, src []byte) {
+	if len(src) == 0 {
+		return
+	}
+	// enc is a pointer receiver, so the use of enc.encode within the hot
+	// loop below means a nil check at every operation. Lift that nil check
+	// outside of the loop to speed up the encoder.
+	_ = enc.encode
+
+	di, si := 0, 0
+	n := (len(src) / 3) * 3
+	for si < n {
+		// Convert 3x 8bit source bytes into 4 bytes
+		val := uint(src[si+0])<<16 | uint(src[si+1])<<8 | uint(src[si+2])
+
+		dst[di+0] = enc.encode[val>>18&0x3F]
+		dst[di+1] = enc.encode[val>>12&0x3F]
+		dst[di+2] = enc.encode[val>>6&0x3F]
+		dst[di+3] = enc.encode[val&0x3F]
+
+		si += 3
+		di += 4
+	}
+
+	remain := len(src) - si
+	if remain == 0 {
+		return
+	}
+	// Add the remaining small block
+	val := uint(src[si+0]) << 16
+	if remain == 2 {
+		val |= uint(src[si+1]) << 8
+	}
+
+	dst[di+0] = enc.encode[val>>18&0x3F]
+	dst[di+1] = enc.encode[val>>12&0x3F]
+
+	switch remain {
+	case 2:
+		dst[di+2] = enc.encode[val>>6&0x3F]
+		if enc.padChar != NoPadding {
+			dst[di+3] = byte(enc.padChar)
+		}
+	case 1:
+		if enc.padChar != NoPadding {
+			dst[di+2] = byte(enc.padChar)
+			dst[di+3] = byte(enc.padChar)
+		}
+	}
+}
+
+// EncodeToString returns the base64 encoding of src.
+func (enc *Encoding) EncodeToString(src []byte) string {
+	buf := make([]byte, enc.EncodedLen(len(src)))
+	enc.Encode(buf, src)
+	return string(buf)
+}
+
+type encoder struct {
+	err  error
+	enc  *Encoding
+	w    io.Writer
+	buf  [3]byte    // buffered data waiting to be encoded
+	nbuf int        // number of bytes in buf
+	out  [1024]byte // output buffer
+}
+
+func (e *encoder) Write(p []byte) (n int, err error) {
+	if e.err != nil {
+		return 0, e.err
+	}
+
+	// Leading fringe.
+	if e.nbuf > 0 {
+		var i int
+		for i = 0; i < len(p) && e.nbuf < 3; i++ {
+			e.buf[e.nbuf] = p[i]
+			e.nbuf++
+		}
+		n += i
+		p = p[i:]
+		if e.nbuf < 3 {
+			return
+		}
+		e.enc.Encode(e.out[:], e.buf[:])
+		if _, e.err = e.w.Write(e.out[:4]); e.err != nil {
+			return n, e.err
+		}
+		e.nbuf = 0
+	}
+
+	// Large interior chunks.
+	for len(p) >= 3 {
+		nn := len(e.out) / 4 * 3
+		if nn > len(p) {
+			nn = len(p)
+			nn -= nn % 3
+		}
+		e.enc.Encode(e.out[:], p[:nn])
+		if _, e.err = e.w.Write(e.out[0 : nn/3*4]); e.err != nil {
+			return n, e.err
+		}
+		n += nn
+		p = p[nn:]
+	}
+
+	// Trailing fringe.
+	copy(e.buf[:], p)
+	e.nbuf = len(p)
+	n += len(p)
+	return
+}
+
+// Close flushes any pending output from the encoder.
+// It is an error to call Write after calling Close.
+func (e *encoder) Close() error {
+	// If there's anything left in the buffer, flush it out
+	if e.err == nil && e.nbuf > 0 {
+		e.enc.Encode(e.out[:], e.buf[:e.nbuf])
+		_, e.err = e.w.Write(e.out[:e.enc.EncodedLen(e.nbuf)])
+		e.nbuf = 0
+	}
+	return e.err
+}
+
+// NewEncoder returns a new base64 stream encoder. Data written to
+// the returned writer will be encoded using enc and then written to w.
+// Base64 encodings operate in 4-byte blocks; when finished
+// writing, the caller must Close the returned encoder to flush any
+// partially written blocks.
+func NewEncoder(enc *Encoding, w io.Writer) io.WriteCloser {
+	return &encoder{enc: enc, w: w}
+}
+
+// EncodedLen returns the length in bytes of the base64 encoding
+// of an input buffer of length n.
+func (enc *Encoding) EncodedLen(n int) int {
+	if enc.padChar == NoPadding {
+		return (n*8 + 5) / 6 // minimum # chars at 6 bits per char
+	}
+	return (n + 2) / 3 * 4 // minimum # 4-char quanta, 3 bytes each
+}
+
+/*
+ * Decoder
+ */
+
+type CorruptInputError int64
+
+func (e CorruptInputError) Error() string {
+	return "illegal base64 data at input byte " + strconv.FormatInt(int64(e), 10)
+}
+
+// decodeQuantum decodes up to 4 base64 bytes. The received parameters are
+// the destination buffer dst, the source buffer src and an index in the
+// source buffer si.
+// It returns the number of bytes read from src, the number of bytes written
+// to dst, and an error, if any.
+func (enc *Encoding) decodeQuantum(dst, src []byte, si int) (nsi, n int, err error) {
+	// Decode quantum using the base64 alphabet
+	var dbuf [4]byte
+	dlen := 4
+
+	// Lift the nil check outside of the loop.
+	_ = enc.decodeMap
+
+	for j := 0; j < len(dbuf); j++ {
+		if len(src) == si {
+			switch {
+			case j == 0:
+				return si, 0, nil
+			case j == 1, enc.padChar != NoPadding:
+				return si, 0, CorruptInputError(si - j)
+			}
+			dlen = j
+			break
+		}
+		in := src[si]
+		si++
+
+		out := enc.decodeMap[in]
+		if out != 0xff {
+			dbuf[j] = out
+			continue
+		}
+
+		if in == '\n' || in == '\r' {
+			j--
+			continue
+		}
+
+		if rune(in) != enc.padChar {
+			return si, 0, CorruptInputError(si - 1)
+		}
+
+		// We've reached the end and there's padding
+		switch j {
+		case 0, 1:
+			// incorrect padding
+			return si, 0, CorruptInputError(si - 1)
+		case 2:
+			// "==" is expected, the first "=" is already consumed.
+			// skip over newlines
+			for si < len(src) && (src[si] == '\n' || src[si] == '\r') {
+				si++
+			}
+			if si == len(src) {
+				// not enough padding
+				return si, 0, CorruptInputError(len(src))
+			}
+			if rune(src[si]) != enc.padChar {
+				// incorrect padding
+				return si, 0, CorruptInputError(si - 1)
+			}
+
+			si++
+		}
+
+		// skip over newlines
+		for si < len(src) && (src[si] == '\n' || src[si] == '\r') {
+			si++
+		}
+		if si < len(src) {
+			// trailing garbage
+			err = CorruptInputError(si)
+		}
+		dlen = j
+		break
+	}
+
+	// Convert 4x 6bit source bytes into 3 bytes
+	val := uint(dbuf[0])<<18 | uint(dbuf[1])<<12 | uint(dbuf[2])<<6 | uint(dbuf[3])
+	dbuf[2], dbuf[1], dbuf[0] = byte(val>>0), byte(val>>8), byte(val>>16)
+	switch dlen {
+	case 4:
+		dst[2] = dbuf[2]
+		dbuf[2] = 0
+		fallthrough
+	case 3:
+		dst[1] = dbuf[1]
+		if enc.strict && dbuf[2] != 0 {
+			return si, 0, CorruptInputError(si - 1)
+		}
+		dbuf[1] = 0
+		fallthrough
+	case 2:
+		dst[0] = dbuf[0]
+		if enc.strict && (dbuf[1] != 0 || dbuf[2] != 0) {
+			return si, 0, CorruptInputError(si - 2)
+		}
+	}
+
+	return si, dlen - 1, err
+}
+
+// DecodeString returns the bytes represented by the base64 string s.
+func (enc *Encoding) DecodeString(s string) ([]byte, error) {
+	dbuf := make([]byte, enc.DecodedLen(len(s)))
+	n, err := enc.Decode(dbuf, []byte(s))
+	return dbuf[:n], err
+}
+
+type decoder struct {
+	err     error
+	readErr error // error from r.Read
+	enc     *Encoding
+	r       io.Reader
+	buf     [1024]byte // leftover input
+	nbuf    int
+	out     []byte // leftover decoded output
+	outbuf  [1024 / 4 * 3]byte
+}
+
+func (d *decoder) Read(p []byte) (n int, err error) {
+	// Use leftover decoded output from last read.
+	if len(d.out) > 0 {
+		n = copy(p, d.out)
+		d.out = d.out[n:]
+		return n, nil
+	}
+
+	if d.err != nil {
+		return 0, d.err
+	}
+
+	// This code assumes that d.r strips supported whitespace ('\r' and '\n').
+
+	// Refill buffer.
+	for d.nbuf < 4 && d.readErr == nil {
+		nn := len(p) / 3 * 4
+		if nn < 4 {
+			nn = 4
+		}
+		if nn > len(d.buf) {
+			nn = len(d.buf)
+		}
+		nn, d.readErr = d.r.Read(d.buf[d.nbuf:nn])
+		d.nbuf += nn
+	}
+
+	if d.nbuf < 4 {
+		if d.enc.padChar == NoPadding && d.nbuf > 0 {
+			// Decode final fragment, without padding.
+			var nw int
+			nw, d.err = d.enc.Decode(d.outbuf[:], d.buf[:d.nbuf])
+			d.nbuf = 0
+			d.out = d.outbuf[:nw]
+			n = copy(p, d.out)
+			d.out = d.out[n:]
+			if n > 0 || len(p) == 0 && len(d.out) > 0 {
+				return n, nil
+			}
+			if d.err != nil {
+				return 0, d.err
+			}
+		}
+		d.err = d.readErr
+		if d.err == io.EOF && d.nbuf > 0 {
+			d.err = io.ErrUnexpectedEOF
+		}
+		return 0, d.err
+	}
+
+	// Decode chunk into p, or d.out and then p if p is too small.
+	nr := d.nbuf / 4 * 4
+	nw := d.nbuf / 4 * 3
+	if nw > len(p) {
+		nw, d.err = d.enc.Decode(d.outbuf[:], d.buf[:nr])
+		d.out = d.outbuf[:nw]
+		n = copy(p, d.out)
+		d.out = d.out[n:]
+	} else {
+		n, d.err = d.enc.Decode(p, d.buf[:nr])
+	}
+	d.nbuf -= nr
+	copy(d.buf[:d.nbuf], d.buf[nr:])
+	return n, d.err
+}
+
+// Decode decodes src using the encoding enc. It writes at most
+// DecodedLen(len(src)) bytes to dst and returns the number of bytes
+// written. If src contains invalid base64 data, it will return the
+// number of bytes successfully written and CorruptInputError.
+// New line characters (\r and \n) are ignored.
+func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
+	if len(src) == 0 {
+		return 0, nil
+	}
+
+	// Lift the nil check outside of the loop. enc.decodeMap is directly
+	// used later in this function, to let the compiler know that the
+	// receiver can't be nil.
+	_ = enc.decodeMap
+
+	si := 0
+	for strconv.IntSize >= 64 && len(src)-si >= 8 && len(dst)-n >= 8 {
+		src2 := src[si : si+8]
+		if dn, ok := assemble64(
+			enc.decodeMap[src2[0]],
+			enc.decodeMap[src2[1]],
+			enc.decodeMap[src2[2]],
+			enc.decodeMap[src2[3]],
+			enc.decodeMap[src2[4]],
+			enc.decodeMap[src2[5]],
+			enc.decodeMap[src2[6]],
+			enc.decodeMap[src2[7]],
+		); ok {
+			binary.BigEndian.PutUint64(dst[n:], dn)
+			n += 6
+			si += 8
+		} else {
+			var ninc int
+			si, ninc, err = enc.decodeQuantum(dst[n:], src, si)
+			n += ninc
+			if err != nil {
+				return n, err
+			}
+		}
+	}
+
+	for len(src)-si >= 4 && len(dst)-n >= 4 {
+		src2 := src[si : si+4]
+		if dn, ok := assemble32(
+			enc.decodeMap[src2[0]],
+			enc.decodeMap[src2[1]],
+			enc.decodeMap[src2[2]],
+			enc.decodeMap[src2[3]],
+		); ok {
+			binary.BigEndian.PutUint32(dst[n:], dn)
+			n += 3
+			si += 4
+		} else {
+			var ninc int
+			si, ninc, err = enc.decodeQuantum(dst[n:], src, si)
+			n += ninc
+			if err != nil {
+				return n, err
+			}
+		}
+	}
+
+	for si < len(src) {
+		var ninc int
+		si, ninc, err = enc.decodeQuantum(dst[n:], src, si)
+		n += ninc
+		if err != nil {
+			return n, err
+		}
+	}
+	return n, err
+}
+
+// assemble32 assembles 4 base64 digits into 3 bytes.
+// Each digit comes from the decode map, and will be 0xff
+// if it came from an invalid character.
+func assemble32(n1, n2, n3, n4 byte) (dn uint32, ok bool) {
+	// Check that all the digits are valid. If any of them was 0xff, their
+	// bitwise OR will be 0xff.
+	if n1|n2|n3|n4 == 0xff {
+		return 0, false
+	}
+	return uint32(n1)<<26 |
+			uint32(n2)<<20 |
+			uint32(n3)<<14 |
+			uint32(n4)<<8,
+		true
+}
+
+// assemble64 assembles 8 base64 digits into 6 bytes.
+// Each digit comes from the decode map, and will be 0xff
+// if it came from an invalid character.
+func assemble64(n1, n2, n3, n4, n5, n6, n7, n8 byte) (dn uint64, ok bool) {
+	// Check that all the digits are valid. If any of them was 0xff, their
+	// bitwise OR will be 0xff.
+	if n1|n2|n3|n4|n5|n6|n7|n8 == 0xff {
+		return 0, false
+	}
+	return uint64(n1)<<58 |
+			uint64(n2)<<52 |
+			uint64(n3)<<46 |
+			uint64(n4)<<40 |
+			uint64(n5)<<34 |
+			uint64(n6)<<28 |
+			uint64(n7)<<22 |
+			uint64(n8)<<16,
+		true
+}
+
+type newlineFilteringReader struct {
+	wrapped io.Reader
+}
+
+func (r *newlineFilteringReader) Read(p []byte) (int, error) {
+	n, err := r.wrapped.Read(p)
+	for n > 0 {
+		offset := 0
+		for i, b := range p[:n] {
+			if b != '\r' && b != '\n' {
+				if i != offset {
+					p[offset] = b
+				}
+				offset++
+			}
+		}
+		if offset > 0 {
+			return offset, err
+		}
+		// Previous buffer entirely whitespace, read again
+		n, err = r.wrapped.Read(p)
+	}
+	return n, err
+}
+
+// NewDecoder constructs a new base64 stream decoder.
+func NewDecoder(enc *Encoding, r io.Reader) io.Reader {
+	return &decoder{enc: enc, r: &newlineFilteringReader{r}}
+}
+
+// DecodedLen returns the maximum length in bytes of the decoded data
+// corresponding to n bytes of base64-encoded data.
+func (enc *Encoding) DecodedLen(n int) int {
+	if enc.padChar == NoPadding {
+		// Unpadded data may end with partial block of 2-3 characters.
+		return n * 6 / 8
+	}
+	// Padded base64 should always be a multiple of 4 characters in length.
+	return n / 4 * 3
+}
diff --git a/src/encoding/base64/base64_test.go b/src/encoding/base64/base64_test.go
new file mode 100644
index 0000000..0ad88eb
--- /dev/null
+++ b/src/encoding/base64/base64_test.go
@@ -0,0 +1,540 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package base64
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"reflect"
+	"runtime/debug"
+	"strings"
+	"testing"
+	"time"
+)
+
+type testpair struct {
+	decoded, encoded string
+}
+
+var pairs = []testpair{
+	// RFC 3548 examples
+	{"\x14\xfb\x9c\x03\xd9\x7e", "FPucA9l+"},
+	{"\x14\xfb\x9c\x03\xd9", "FPucA9k="},
+	{"\x14\xfb\x9c\x03", "FPucAw=="},
+
+	// RFC 4648 examples
+	{"", ""},
+	{"f", "Zg=="},
+	{"fo", "Zm8="},
+	{"foo", "Zm9v"},
+	{"foob", "Zm9vYg=="},
+	{"fooba", "Zm9vYmE="},
+	{"foobar", "Zm9vYmFy"},
+
+	// Wikipedia examples
+	{"sure.", "c3VyZS4="},
+	{"sure", "c3VyZQ=="},
+	{"sur", "c3Vy"},
+	{"su", "c3U="},
+	{"leasure.", "bGVhc3VyZS4="},
+	{"easure.", "ZWFzdXJlLg=="},
+	{"asure.", "YXN1cmUu"},
+	{"sure.", "c3VyZS4="},
+}
+
+// Do nothing to a reference base64 string (leave in standard format)
+func stdRef(ref string) string {
+	return ref
+}
+
+// Convert a reference string to URL-encoding
+func urlRef(ref string) string {
+	ref = strings.ReplaceAll(ref, "+", "-")
+	ref = strings.ReplaceAll(ref, "/", "_")
+	return ref
+}
+
+// Convert a reference string to raw, unpadded format
+func rawRef(ref string) string {
+	return strings.TrimRight(ref, "=")
+}
+
+// Both URL and unpadding conversions
+func rawURLRef(ref string) string {
+	return rawRef(urlRef(ref))
+}
+
+// A nonstandard encoding with a funny padding character, for testing
+var funnyEncoding = NewEncoding(encodeStd).WithPadding(rune('@'))
+
+func funnyRef(ref string) string {
+	return strings.ReplaceAll(ref, "=", "@")
+}
+
+type encodingTest struct {
+	enc  *Encoding           // Encoding to test
+	conv func(string) string // Reference string converter
+}
+
+var encodingTests = []encodingTest{
+	{StdEncoding, stdRef},
+	{URLEncoding, urlRef},
+	{RawStdEncoding, rawRef},
+	{RawURLEncoding, rawURLRef},
+	{funnyEncoding, funnyRef},
+	{StdEncoding.Strict(), stdRef},
+	{URLEncoding.Strict(), urlRef},
+	{RawStdEncoding.Strict(), rawRef},
+	{RawURLEncoding.Strict(), rawURLRef},
+	{funnyEncoding.Strict(), funnyRef},
+}
+
+var bigtest = testpair{
+	"Twas brillig, and the slithy toves",
+	"VHdhcyBicmlsbGlnLCBhbmQgdGhlIHNsaXRoeSB0b3Zlcw==",
+}
+
+func testEqual(t *testing.T, msg string, args ...any) bool {
+	t.Helper()
+	if args[len(args)-2] != args[len(args)-1] {
+		t.Errorf(msg, args...)
+		return false
+	}
+	return true
+}
+
+func TestEncode(t *testing.T) {
+	for _, p := range pairs {
+		for _, tt := range encodingTests {
+			got := tt.enc.EncodeToString([]byte(p.decoded))
+			testEqual(t, "Encode(%q) = %q, want %q", p.decoded,
+				got, tt.conv(p.encoded))
+		}
+	}
+}
+
+func TestEncoder(t *testing.T) {
+	for _, p := range pairs {
+		bb := &strings.Builder{}
+		encoder := NewEncoder(StdEncoding, bb)
+		encoder.Write([]byte(p.decoded))
+		encoder.Close()
+		testEqual(t, "Encode(%q) = %q, want %q", p.decoded, bb.String(), p.encoded)
+	}
+}
+
+func TestEncoderBuffering(t *testing.T) {
+	input := []byte(bigtest.decoded)
+	for bs := 1; bs <= 12; bs++ {
+		bb := &strings.Builder{}
+		encoder := NewEncoder(StdEncoding, bb)
+		for pos := 0; pos < len(input); pos += bs {
+			end := pos + bs
+			if end > len(input) {
+				end = len(input)
+			}
+			n, err := encoder.Write(input[pos:end])
+			testEqual(t, "Write(%q) gave error %v, want %v", input[pos:end], err, error(nil))
+			testEqual(t, "Write(%q) gave length %v, want %v", input[pos:end], n, end-pos)
+		}
+		err := encoder.Close()
+		testEqual(t, "Close gave error %v, want %v", err, error(nil))
+		testEqual(t, "Encoding/%d of %q = %q, want %q", bs, bigtest.decoded, bb.String(), bigtest.encoded)
+	}
+}
+
+func TestDecode(t *testing.T) {
+	for _, p := range pairs {
+		for _, tt := range encodingTests {
+			encoded := tt.conv(p.encoded)
+			dbuf := make([]byte, tt.enc.DecodedLen(len(encoded)))
+			count, err := tt.enc.Decode(dbuf, []byte(encoded))
+			testEqual(t, "Decode(%q) = error %v, want %v", encoded, err, error(nil))
+			testEqual(t, "Decode(%q) = length %v, want %v", encoded, count, len(p.decoded))
+			testEqual(t, "Decode(%q) = %q, want %q", encoded, string(dbuf[0:count]), p.decoded)
+
+			dbuf, err = tt.enc.DecodeString(encoded)
+			testEqual(t, "DecodeString(%q) = error %v, want %v", encoded, err, error(nil))
+			testEqual(t, "DecodeString(%q) = %q, want %q", encoded, string(dbuf), p.decoded)
+		}
+	}
+}
+
+func TestDecoder(t *testing.T) {
+	for _, p := range pairs {
+		decoder := NewDecoder(StdEncoding, strings.NewReader(p.encoded))
+		dbuf := make([]byte, StdEncoding.DecodedLen(len(p.encoded)))
+		count, err := decoder.Read(dbuf)
+		if err != nil && err != io.EOF {
+			t.Fatal("Read failed", err)
+		}
+		testEqual(t, "Read from %q = length %v, want %v", p.encoded, count, len(p.decoded))
+		testEqual(t, "Decoding of %q = %q, want %q", p.encoded, string(dbuf[0:count]), p.decoded)
+		if err != io.EOF {
+			_, err = decoder.Read(dbuf)
+		}
+		testEqual(t, "Read from %q = %v, want %v", p.encoded, err, io.EOF)
+	}
+}
+
+func TestDecoderBuffering(t *testing.T) {
+	for bs := 1; bs <= 12; bs++ {
+		decoder := NewDecoder(StdEncoding, strings.NewReader(bigtest.encoded))
+		buf := make([]byte, len(bigtest.decoded)+12)
+		var total int
+		var n int
+		var err error
+		for total = 0; total < len(bigtest.decoded) && err == nil; {
+			n, err = decoder.Read(buf[total : total+bs])
+			total += n
+		}
+		if err != nil && err != io.EOF {
+			t.Errorf("Read from %q at pos %d = %d, unexpected error %v", bigtest.encoded, total, n, err)
+		}
+		testEqual(t, "Decoding/%d of %q = %q, want %q", bs, bigtest.encoded, string(buf[0:total]), bigtest.decoded)
+	}
+}
+
+func TestDecodeCorrupt(t *testing.T) {
+	testCases := []struct {
+		input  string
+		offset int // -1 means no corruption.
+	}{
+		{"", -1},
+		{"\n", -1},
+		{"AAA=\n", -1},
+		{"AAAA\n", -1},
+		{"!!!!", 0},
+		{"====", 0},
+		{"x===", 1},
+		{"=AAA", 0},
+		{"A=AA", 1},
+		{"AA=A", 2},
+		{"AA==A", 4},
+		{"AAA=AAAA", 4},
+		{"AAAAA", 4},
+		{"AAAAAA", 4},
+		{"A=", 1},
+		{"A==", 1},
+		{"AA=", 3},
+		{"AA==", -1},
+		{"AAA=", -1},
+		{"AAAA", -1},
+		{"AAAAAA=", 7},
+		{"YWJjZA=====", 8},
+		{"A!\n", 1},
+		{"A=\n", 1},
+	}
+	for _, tc := range testCases {
+		dbuf := make([]byte, StdEncoding.DecodedLen(len(tc.input)))
+		_, err := StdEncoding.Decode(dbuf, []byte(tc.input))
+		if tc.offset == -1 {
+			if err != nil {
+				t.Error("Decoder wrongly detected corruption in", tc.input)
+			}
+			continue
+		}
+		switch err := err.(type) {
+		case CorruptInputError:
+			testEqual(t, "Corruption in %q at offset %v, want %v", tc.input, int(err), tc.offset)
+		default:
+			t.Error("Decoder failed to detect corruption in", tc)
+		}
+	}
+}
+
+func TestDecodeBounds(t *testing.T) {
+	var buf [32]byte
+	s := StdEncoding.EncodeToString(buf[:])
+	defer func() {
+		if err := recover(); err != nil {
+			t.Fatalf("Decode panicked unexpectedly: %v\n%s", err, debug.Stack())
+		}
+	}()
+	n, err := StdEncoding.Decode(buf[:], []byte(s))
+	if n != len(buf) || err != nil {
+		t.Fatalf("StdEncoding.Decode = %d, %v, want %d, nil", n, err, len(buf))
+	}
+}
+
+func TestEncodedLen(t *testing.T) {
+	for _, tt := range []struct {
+		enc  *Encoding
+		n    int
+		want int
+	}{
+		{RawStdEncoding, 0, 0},
+		{RawStdEncoding, 1, 2},
+		{RawStdEncoding, 2, 3},
+		{RawStdEncoding, 3, 4},
+		{RawStdEncoding, 7, 10},
+		{StdEncoding, 0, 0},
+		{StdEncoding, 1, 4},
+		{StdEncoding, 2, 4},
+		{StdEncoding, 3, 4},
+		{StdEncoding, 4, 8},
+		{StdEncoding, 7, 12},
+	} {
+		if got := tt.enc.EncodedLen(tt.n); got != tt.want {
+			t.Errorf("EncodedLen(%d): got %d, want %d", tt.n, got, tt.want)
+		}
+	}
+}
+
+func TestDecodedLen(t *testing.T) {
+	for _, tt := range []struct {
+		enc  *Encoding
+		n    int
+		want int
+	}{
+		{RawStdEncoding, 0, 0},
+		{RawStdEncoding, 2, 1},
+		{RawStdEncoding, 3, 2},
+		{RawStdEncoding, 4, 3},
+		{RawStdEncoding, 10, 7},
+		{StdEncoding, 0, 0},
+		{StdEncoding, 4, 3},
+		{StdEncoding, 8, 6},
+	} {
+		if got := tt.enc.DecodedLen(tt.n); got != tt.want {
+			t.Errorf("DecodedLen(%d): got %d, want %d", tt.n, got, tt.want)
+		}
+	}
+}
+
+func TestBig(t *testing.T) {
+	n := 3*1000 + 1
+	raw := make([]byte, n)
+	const alpha = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	for i := 0; i < n; i++ {
+		raw[i] = alpha[i%len(alpha)]
+	}
+	encoded := new(bytes.Buffer)
+	w := NewEncoder(StdEncoding, encoded)
+	nn, err := w.Write(raw)
+	if nn != n || err != nil {
+		t.Fatalf("Encoder.Write(raw) = %d, %v want %d, nil", nn, err, n)
+	}
+	err = w.Close()
+	if err != nil {
+		t.Fatalf("Encoder.Close() = %v want nil", err)
+	}
+	decoded, err := io.ReadAll(NewDecoder(StdEncoding, encoded))
+	if err != nil {
+		t.Fatalf("io.ReadAll(NewDecoder(...)): %v", err)
+	}
+
+	if !bytes.Equal(raw, decoded) {
+		var i int
+		for i = 0; i < len(decoded) && i < len(raw); i++ {
+			if decoded[i] != raw[i] {
+				break
+			}
+		}
+		t.Errorf("Decode(Encode(%d-byte string)) failed at offset %d", n, i)
+	}
+}
+
+func TestNewLineCharacters(t *testing.T) {
+	// Each of these should decode to the string "sure", without errors.
+	const expected = "sure"
+	examples := []string{
+		"c3VyZQ==",
+		"c3VyZQ==\r",
+		"c3VyZQ==\n",
+		"c3VyZQ==\r\n",
+		"c3VyZ\r\nQ==",
+		"c3V\ryZ\nQ==",
+		"c3V\nyZ\rQ==",
+		"c3VyZ\nQ==",
+		"c3VyZQ\n==",
+		"c3VyZQ=\n=",
+		"c3VyZQ=\r\n\r\n=",
+	}
+	for _, e := range examples {
+		buf, err := StdEncoding.DecodeString(e)
+		if err != nil {
+			t.Errorf("Decode(%q) failed: %v", e, err)
+			continue
+		}
+		if s := string(buf); s != expected {
+			t.Errorf("Decode(%q) = %q, want %q", e, s, expected)
+		}
+	}
+}
+
+type nextRead struct {
+	n   int   // bytes to return
+	err error // error to return
+}
+
+// faultInjectReader returns data from source, rate-limited
+// and with the errors as written to nextc.
+type faultInjectReader struct {
+	source string
+	nextc  <-chan nextRead
+}
+
+func (r *faultInjectReader) Read(p []byte) (int, error) {
+	nr := <-r.nextc
+	if len(p) > nr.n {
+		p = p[:nr.n]
+	}
+	n := copy(p, r.source)
+	r.source = r.source[n:]
+	return n, nr.err
+}
+
+// tests that we don't ignore errors from our underlying reader
+func TestDecoderIssue3577(t *testing.T) {
+	next := make(chan nextRead, 10)
+	wantErr := errors.New("my error")
+	next <- nextRead{5, nil}
+	next <- nextRead{10, wantErr}
+	next <- nextRead{0, wantErr}
+	d := NewDecoder(StdEncoding, &faultInjectReader{
+		source: "VHdhcyBicmlsbGlnLCBhbmQgdGhlIHNsaXRoeSB0b3Zlcw==", // twas brillig...
+		nextc:  next,
+	})
+	errc := make(chan error, 1)
+	go func() {
+		_, err := io.ReadAll(d)
+		errc <- err
+	}()
+	select {
+	case err := <-errc:
+		if err != wantErr {
+			t.Errorf("got error %v; want %v", err, wantErr)
+		}
+	case <-time.After(5 * time.Second):
+		t.Errorf("timeout; Decoder blocked without returning an error")
+	}
+}
+
+func TestDecoderIssue4779(t *testing.T) {
+	encoded := `CP/EAT8AAAEF
+AQEBAQEBAAAAAAAAAAMAAQIEBQYHCAkKCwEAAQUBAQEBAQEAAAAAAAAAAQACAwQFBgcICQoLEAAB
+BAEDAgQCBQcGCAUDDDMBAAIRAwQhEjEFQVFhEyJxgTIGFJGhsUIjJBVSwWIzNHKC0UMHJZJT8OHx
+Y3M1FqKygyZEk1RkRcKjdDYX0lXiZfKzhMPTdePzRieUpIW0lcTU5PSltcXV5fVWZnaGlqa2xtbm
+9jdHV2d3h5ent8fX5/cRAAICAQIEBAMEBQYHBwYFNQEAAhEDITESBEFRYXEiEwUygZEUobFCI8FS
+0fAzJGLhcoKSQ1MVY3M08SUGFqKygwcmNcLSRJNUoxdkRVU2dGXi8rOEw9N14/NGlKSFtJXE1OT0
+pbXF1eX1VmZ2hpamtsbW5vYnN0dXZ3eHl6e3x//aAAwDAQACEQMRAD8A9VSSSSUpJJJJSkkkJ+Tj
+1kiy1jCJJDnAcCTykpKkuQ6p/jN6FgmxlNduXawwAzaGH+V6jn/R/wCt71zdn+N/qL3kVYFNYB4N
+ji6PDVjWpKp9TSXnvTf8bFNjg3qOEa2n6VlLpj/rT/pf567DpX1i6L1hs9Py67X8mqdtg/rUWbbf
++gkp0kkkklKSSSSUpJJJJT//0PVUkkklKVLq3WMDpGI7KzrNjADtYNXvI/Mqr/Pd/q9W3vaxjnvM
+NaCXE9gNSvGPrf8AWS3qmba5jjsJhoB0DAf0NDf6sevf+/lf8Hj0JJATfWT6/dV6oXU1uOLQeKKn
+EQP+Hubtfe/+R7Mf/g7f5xcocp++Z11JMCJPgFBxOg7/AOuqDx8I/ikpkXkmSdU8mJIJA/O8EMAy
+j+mSARB/17pKVXYWHXjsj7yIex0PadzXMO1zT5KHoNA3HT8ietoGhgjsfA+CSnvvqh/jJtqsrwOv
+2b6NGNzXfTYexzJ+nU7/ALkf4P8Awv6P9KvTQQ4AgyDqCF85Pho3CTB7eHwXoH+LT65uZbX9X+o2
+bqbPb06551Y4
+`
+	encodedShort := strings.ReplaceAll(encoded, "\n", "")
+
+	dec := NewDecoder(StdEncoding, strings.NewReader(encoded))
+	res1, err := io.ReadAll(dec)
+	if err != nil {
+		t.Errorf("ReadAll failed: %v", err)
+	}
+
+	dec = NewDecoder(StdEncoding, strings.NewReader(encodedShort))
+	var res2 []byte
+	res2, err = io.ReadAll(dec)
+	if err != nil {
+		t.Errorf("ReadAll failed: %v", err)
+	}
+
+	if !bytes.Equal(res1, res2) {
+		t.Error("Decoded results not equal")
+	}
+}
+
+func TestDecoderIssue7733(t *testing.T) {
+	s, err := StdEncoding.DecodeString("YWJjZA=====")
+	want := CorruptInputError(8)
+	if !reflect.DeepEqual(want, err) {
+		t.Errorf("Error = %v; want CorruptInputError(8)", err)
+	}
+	if string(s) != "abcd" {
+		t.Errorf("DecodeString = %q; want abcd", s)
+	}
+}
+
+func TestDecoderIssue15656(t *testing.T) {
+	_, err := StdEncoding.Strict().DecodeString("WvLTlMrX9NpYDQlEIFlnDB==")
+	want := CorruptInputError(22)
+	if !reflect.DeepEqual(want, err) {
+		t.Errorf("Error = %v; want CorruptInputError(22)", err)
+	}
+	_, err = StdEncoding.Strict().DecodeString("WvLTlMrX9NpYDQlEIFlnDA==")
+	if err != nil {
+		t.Errorf("Error = %v; want nil", err)
+	}
+	_, err = StdEncoding.DecodeString("WvLTlMrX9NpYDQlEIFlnDB==")
+	if err != nil {
+		t.Errorf("Error = %v; want nil", err)
+	}
+}
+
+func BenchmarkEncodeToString(b *testing.B) {
+	data := make([]byte, 8192)
+	b.SetBytes(int64(len(data)))
+	for i := 0; i < b.N; i++ {
+		StdEncoding.EncodeToString(data)
+	}
+}
+
+func BenchmarkDecodeString(b *testing.B) {
+	sizes := []int{2, 4, 8, 64, 8192}
+	benchFunc := func(b *testing.B, benchSize int) {
+		data := StdEncoding.EncodeToString(make([]byte, benchSize))
+		b.SetBytes(int64(len(data)))
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			StdEncoding.DecodeString(data)
+		}
+	}
+	for _, size := range sizes {
+		b.Run(fmt.Sprintf("%d", size), func(b *testing.B) {
+			benchFunc(b, size)
+		})
+	}
+}
+
+func BenchmarkNewEncoding(b *testing.B) {
+	b.SetBytes(int64(len(Encoding{}.decodeMap)))
+	for i := 0; i < b.N; i++ {
+		e := NewEncoding(encodeStd)
+		for _, v := range e.decodeMap {
+			_ = v
+		}
+	}
+}
+
+func TestDecoderRaw(t *testing.T) {
+	source := "AAAAAA"
+	want := []byte{0, 0, 0, 0}
+
+	// Direct.
+	dec1, err := RawURLEncoding.DecodeString(source)
+	if err != nil || !bytes.Equal(dec1, want) {
+		t.Errorf("RawURLEncoding.DecodeString(%q) = %x, %v, want %x, nil", source, dec1, err, want)
+	}
+
+	// Through reader. Used to fail.
+	r := NewDecoder(RawURLEncoding, bytes.NewReader([]byte(source)))
+	dec2, err := io.ReadAll(io.LimitReader(r, 100))
+	if err != nil || !bytes.Equal(dec2, want) {
+		t.Errorf("reading NewDecoder(RawURLEncoding, %q) = %x, %v, want %x, nil", source, dec2, err, want)
+	}
+
+	// Should work with padding.
+	r = NewDecoder(URLEncoding, bytes.NewReader([]byte(source+"==")))
+	dec3, err := io.ReadAll(r)
+	if err != nil || !bytes.Equal(dec3, want) {
+		t.Errorf("reading NewDecoder(URLEncoding, %q) = %x, %v, want %x, nil", source+"==", dec3, err, want)
+	}
+}
diff --git a/src/encoding/base64/example_test.go b/src/encoding/base64/example_test.go
new file mode 100644
index 0000000..61a3adc
--- /dev/null
+++ b/src/encoding/base64/example_test.go
@@ -0,0 +1,83 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Keep in sync with ../base32/example_test.go.
+
+package base64_test
+
+import (
+	"encoding/base64"
+	"fmt"
+	"os"
+)
+
+func Example() {
+	msg := "Hello, 世界"
+	encoded := base64.StdEncoding.EncodeToString([]byte(msg))
+	fmt.Println(encoded)
+	decoded, err := base64.StdEncoding.DecodeString(encoded)
+	if err != nil {
+		fmt.Println("decode error:", err)
+		return
+	}
+	fmt.Println(string(decoded))
+	// Output:
+	// SGVsbG8sIOS4lueVjA==
+	// Hello, 世界
+}
+
+func ExampleEncoding_EncodeToString() {
+	data := []byte("any + old & data")
+	str := base64.StdEncoding.EncodeToString(data)
+	fmt.Println(str)
+	// Output:
+	// YW55ICsgb2xkICYgZGF0YQ==
+}
+
+func ExampleEncoding_Encode() {
+	data := []byte("Hello, world!")
+	dst := make([]byte, base64.StdEncoding.EncodedLen(len(data)))
+	base64.StdEncoding.Encode(dst, data)
+	fmt.Println(string(dst))
+	// Output:
+	// SGVsbG8sIHdvcmxkIQ==
+}
+
+func ExampleEncoding_DecodeString() {
+	str := "c29tZSBkYXRhIHdpdGggACBhbmQg77u/"
+	data, err := base64.StdEncoding.DecodeString(str)
+	if err != nil {
+		fmt.Println("error:", err)
+		return
+	}
+	fmt.Printf("%q\n", data)
+	// Output:
+	// "some data with \x00 and \ufeff"
+}
+
+func ExampleEncoding_Decode() {
+	str := "SGVsbG8sIHdvcmxkIQ=="
+	dst := make([]byte, base64.StdEncoding.DecodedLen(len(str)))
+	n, err := base64.StdEncoding.Decode(dst, []byte(str))
+	if err != nil {
+		fmt.Println("decode error:", err)
+		return
+	}
+	dst = dst[:n]
+	fmt.Printf("%q\n", dst)
+	// Output:
+	// "Hello, world!"
+}
+
+func ExampleNewEncoder() {
+	input := []byte("foo\x00bar")
+	encoder := base64.NewEncoder(base64.StdEncoding, os.Stdout)
+	encoder.Write(input)
+	// Must close the encoder when finished to flush any partial blocks.
+	// If you comment out the following line, the last partial block "r"
+	// won't be encoded.
+	encoder.Close()
+	// Output:
+	// Zm9vAGJhcg==
+}