c2047754c3
Compiler changes:
* Change map assignment to use mapassign and assign value directly.
* Change string iteration to use decoderune, faster for ASCII strings.
* Change makeslice to take int, and use makeslice64 for larger values.
* Add new noverflow field to hmap struct used for maps.
Unresolved problems, to be fixed later:
* Commented out test in go/types/sizes_test.go that doesn't compile.
* Commented out reflect.TestStructOf test for padding after zero-sized field.
Reviewed-on: https://go-review.googlesource.com/35231
gotools/:
Updates for Go 1.8rc1.
* Makefile.am (go_cmd_go_files): Add bug.go.
(s-zdefaultcc): Write defaultPkgConfig.
* Makefile.in: Rebuild.
From-SVN: r244456
485 lines
12 KiB
Go
485 lines
12 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package base64 implements base64 encoding as specified by RFC 4648.
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package base64
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import (
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"io"
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"strconv"
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)
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/*
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* Encodings
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*/
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// An Encoding is a radix 64 encoding/decoding scheme, defined by a
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// 64-character alphabet. The most common encoding is the "base64"
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// encoding defined in RFC 4648 and used in MIME (RFC 2045) and PEM
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// (RFC 1421). RFC 4648 also defines an alternate encoding, which is
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// the standard encoding with - and _ substituted for + and /.
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type Encoding struct {
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encode [64]byte
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decodeMap [256]byte
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padChar rune
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strict bool
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}
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const (
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StdPadding rune = '=' // Standard padding character
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NoPadding rune = -1 // No padding
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)
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const encodeStd = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
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const encodeURL = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
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// NewEncoding returns a new padded Encoding defined by the given alphabet,
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// which must be a 64-byte string.
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// The resulting Encoding uses the default padding character ('='),
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// which may be changed or disabled via WithPadding.
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func NewEncoding(encoder string) *Encoding {
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if len(encoder) != 64 {
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panic("encoding alphabet is not 64-bytes long")
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}
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e := new(Encoding)
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e.padChar = StdPadding
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copy(e.encode[:], encoder)
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for i := 0; i < len(e.decodeMap); i++ {
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e.decodeMap[i] = 0xFF
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}
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for i := 0; i < len(encoder); i++ {
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e.decodeMap[encoder[i]] = byte(i)
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}
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return e
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}
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// WithPadding creates a new encoding identical to enc except
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// with a specified padding character, or NoPadding to disable padding.
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func (enc Encoding) WithPadding(padding rune) *Encoding {
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enc.padChar = padding
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return &enc
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}
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// Strict creates a new encoding identical to enc except with
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// strict decoding enabled. In this mode, the decoder requires that
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// trailing padding bits are zero, as described in RFC 4648 section 3.5.
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func (enc Encoding) Strict() *Encoding {
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enc.strict = true
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return &enc
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}
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// StdEncoding is the standard base64 encoding, as defined in
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// RFC 4648.
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var StdEncoding = NewEncoding(encodeStd)
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// URLEncoding is the alternate base64 encoding defined in RFC 4648.
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// It is typically used in URLs and file names.
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var URLEncoding = NewEncoding(encodeURL)
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// RawStdEncoding is the standard raw, unpadded base64 encoding,
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// as defined in RFC 4648 section 3.2.
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// This is the same as StdEncoding but omits padding characters.
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var RawStdEncoding = StdEncoding.WithPadding(NoPadding)
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// RawURLEncoding is the unpadded alternate base64 encoding defined in RFC 4648.
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// It is typically used in URLs and file names.
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// This is the same as URLEncoding but omits padding characters.
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var RawURLEncoding = URLEncoding.WithPadding(NoPadding)
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/*
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* Encoder
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*/
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// Encode encodes src using the encoding enc, writing
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// EncodedLen(len(src)) bytes to dst.
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//
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// The encoding pads the output to a multiple of 4 bytes,
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// so Encode is not appropriate for use on individual blocks
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// of a large data stream. Use NewEncoder() instead.
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func (enc *Encoding) Encode(dst, src []byte) {
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if len(src) == 0 {
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return
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}
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di, si := 0, 0
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n := (len(src) / 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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val := uint(src[si+0])<<16 | uint(src[si+1])<<8 | uint(src[si+2])
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dst[di+0] = enc.encode[val>>18&0x3F]
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dst[di+1] = enc.encode[val>>12&0x3F]
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dst[di+2] = enc.encode[val>>6&0x3F]
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dst[di+3] = enc.encode[val&0x3F]
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si += 3
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di += 4
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}
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remain := len(src) - si
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if remain == 0 {
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return
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}
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// Add the remaining small block
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val := uint(src[si+0]) << 16
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if remain == 2 {
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val |= uint(src[si+1]) << 8
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}
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dst[di+0] = enc.encode[val>>18&0x3F]
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dst[di+1] = enc.encode[val>>12&0x3F]
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switch remain {
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case 2:
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dst[di+2] = enc.encode[val>>6&0x3F]
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if enc.padChar != NoPadding {
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dst[di+3] = byte(enc.padChar)
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}
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case 1:
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if enc.padChar != NoPadding {
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dst[di+2] = byte(enc.padChar)
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dst[di+3] = byte(enc.padChar)
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}
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}
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}
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// EncodeToString returns the base64 encoding of src.
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func (enc *Encoding) EncodeToString(src []byte) string {
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buf := make([]byte, enc.EncodedLen(len(src)))
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enc.Encode(buf, src)
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return string(buf)
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}
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type encoder struct {
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err error
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enc *Encoding
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w io.Writer
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buf [3]byte // buffered data waiting to be encoded
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nbuf int // number of bytes in buf
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out [1024]byte // output buffer
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}
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func (e *encoder) Write(p []byte) (n int, err error) {
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if e.err != nil {
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return 0, e.err
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}
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// Leading fringe.
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if e.nbuf > 0 {
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var i int
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for i = 0; i < len(p) && e.nbuf < 3; i++ {
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e.buf[e.nbuf] = p[i]
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e.nbuf++
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}
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n += i
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p = p[i:]
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if e.nbuf < 3 {
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return
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}
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e.enc.Encode(e.out[:], e.buf[:])
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if _, e.err = e.w.Write(e.out[:4]); e.err != nil {
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return n, e.err
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}
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e.nbuf = 0
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}
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// Large interior chunks.
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for len(p) >= 3 {
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nn := len(e.out) / 4 * 3
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if nn > len(p) {
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nn = len(p)
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nn -= nn % 3
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}
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e.enc.Encode(e.out[:], p[:nn])
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if _, e.err = e.w.Write(e.out[0 : nn/3*4]); e.err != nil {
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return n, e.err
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}
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n += nn
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p = p[nn:]
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}
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// Trailing fringe.
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for i := 0; i < len(p); i++ {
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e.buf[i] = p[i]
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}
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e.nbuf = len(p)
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n += len(p)
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return
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}
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// Close flushes any pending output from the encoder.
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// It is an error to call Write after calling Close.
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func (e *encoder) Close() error {
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// If there's anything left in the buffer, flush it out
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if e.err == nil && e.nbuf > 0 {
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e.enc.Encode(e.out[:], e.buf[:e.nbuf])
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_, e.err = e.w.Write(e.out[:e.enc.EncodedLen(e.nbuf)])
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e.nbuf = 0
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}
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return e.err
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}
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// NewEncoder returns a new base64 stream encoder. Data written to
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// the returned writer will be encoded using enc and then written to w.
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// Base64 encodings operate in 4-byte blocks; when finished
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// writing, the caller must Close the returned encoder to flush any
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// partially written blocks.
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func NewEncoder(enc *Encoding, w io.Writer) io.WriteCloser {
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return &encoder{enc: enc, w: w}
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}
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// EncodedLen returns the length in bytes of the base64 encoding
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// of an input buffer of length n.
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func (enc *Encoding) EncodedLen(n int) int {
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if enc.padChar == NoPadding {
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return (n*8 + 5) / 6 // minimum # chars at 6 bits per char
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}
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return (n + 2) / 3 * 4 // minimum # 4-char quanta, 3 bytes each
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}
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/*
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* Decoder
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*/
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type CorruptInputError int64
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func (e CorruptInputError) Error() string {
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return "illegal base64 data at input byte " + strconv.FormatInt(int64(e), 10)
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}
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// decode is like Decode but returns an additional 'end' value, which
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// indicates if end-of-message padding or a partial quantum was encountered
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// and thus any additional data is an error.
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func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {
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si := 0
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// skip over newlines
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for si < len(src) && (src[si] == '\n' || src[si] == '\r') {
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si++
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}
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for si < len(src) && !end {
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// Decode quantum using the base64 alphabet
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var dbuf [4]byte
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dinc, dlen := 3, 4
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for j := range dbuf {
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if len(src) == si {
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if enc.padChar != NoPadding || j < 2 {
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return n, false, CorruptInputError(si - j)
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}
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dinc, dlen, end = j-1, j, true
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break
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}
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in := src[si]
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si++
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// skip over newlines
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for si < len(src) && (src[si] == '\n' || src[si] == '\r') {
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si++
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}
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if rune(in) == enc.padChar {
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// We've reached the end and there's padding
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switch j {
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case 0, 1:
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// incorrect padding
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return n, false, CorruptInputError(si - 1)
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case 2:
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// "==" is expected, the first "=" is already consumed.
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if si == len(src) {
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// not enough padding
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return n, false, CorruptInputError(len(src))
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}
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if rune(src[si]) != enc.padChar {
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// incorrect padding
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return n, false, CorruptInputError(si - 1)
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}
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si++
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// skip over newlines
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for si < len(src) && (src[si] == '\n' || src[si] == '\r') {
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si++
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}
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}
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if si < len(src) {
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// trailing garbage
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err = CorruptInputError(si)
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}
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dinc, dlen, end = 3, j, true
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break
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}
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dbuf[j] = enc.decodeMap[in]
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if dbuf[j] == 0xFF {
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return n, false, CorruptInputError(si - 1)
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}
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}
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// Convert 4x 6bit source bytes into 3 bytes
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val := uint(dbuf[0])<<18 | uint(dbuf[1])<<12 | uint(dbuf[2])<<6 | uint(dbuf[3])
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dbuf[2], dbuf[1], dbuf[0] = byte(val>>0), byte(val>>8), byte(val>>16)
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switch dlen {
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case 4:
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dst[2] = dbuf[2]
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dbuf[2] = 0
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fallthrough
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case 3:
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dst[1] = dbuf[1]
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if enc.strict && dbuf[2] != 0 {
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return n, end, CorruptInputError(si - 1)
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}
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dbuf[1] = 0
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fallthrough
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case 2:
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dst[0] = dbuf[0]
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if enc.strict && (dbuf[1] != 0 || dbuf[2] != 0) {
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return n, end, CorruptInputError(si - 2)
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}
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}
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dst = dst[dinc:]
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n += dlen - 1
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}
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return n, end, err
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}
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// Decode decodes src using the encoding enc. It writes at most
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// DecodedLen(len(src)) bytes to dst and returns the number of bytes
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// written. If src contains invalid base64 data, it will return the
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// number of bytes successfully written and CorruptInputError.
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// New line characters (\r and \n) are ignored.
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func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
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n, _, err = enc.decode(dst, src)
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return
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}
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// DecodeString returns the bytes represented by the base64 string s.
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func (enc *Encoding) DecodeString(s string) ([]byte, error) {
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dbuf := make([]byte, enc.DecodedLen(len(s)))
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n, _, err := enc.decode(dbuf, []byte(s))
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return dbuf[:n], err
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}
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type decoder struct {
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err error
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readErr error // error from r.Read
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enc *Encoding
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r io.Reader
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end bool // saw end of message
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buf [1024]byte // leftover input
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nbuf int
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out []byte // leftover decoded output
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outbuf [1024 / 4 * 3]byte
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}
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func (d *decoder) Read(p []byte) (n int, err error) {
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// Use leftover decoded output from last read.
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if len(d.out) > 0 {
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n = copy(p, d.out)
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d.out = d.out[n:]
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return n, nil
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}
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if d.err != nil {
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return 0, d.err
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}
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// This code assumes that d.r strips supported whitespace ('\r' and '\n').
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// Refill buffer.
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for d.nbuf < 4 && d.readErr == nil {
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nn := len(p) / 3 * 4
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if nn < 4 {
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nn = 4
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}
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if nn > len(d.buf) {
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nn = len(d.buf)
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}
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nn, d.readErr = d.r.Read(d.buf[d.nbuf:nn])
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d.nbuf += nn
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}
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if d.nbuf < 4 {
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if d.enc.padChar == NoPadding && d.nbuf > 0 {
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// Decode final fragment, without padding.
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var nw int
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nw, _, d.err = d.enc.decode(d.outbuf[:], d.buf[:d.nbuf])
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d.nbuf = 0
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d.end = true
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d.out = d.outbuf[:nw]
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n = copy(p, d.out)
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d.out = d.out[n:]
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if n > 0 || len(p) == 0 && len(d.out) > 0 {
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return n, nil
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}
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if d.err != nil {
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return 0, d.err
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}
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}
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d.err = d.readErr
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if d.err == io.EOF && d.nbuf > 0 {
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d.err = io.ErrUnexpectedEOF
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}
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return 0, d.err
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}
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// Decode chunk into p, or d.out and then p if p is too small.
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nr := d.nbuf / 4 * 4
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nw := d.nbuf / 4 * 3
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if nw > len(p) {
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nw, d.end, d.err = d.enc.decode(d.outbuf[:], d.buf[:nr])
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d.out = d.outbuf[:nw]
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n = copy(p, d.out)
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d.out = d.out[n:]
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} else {
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n, d.end, d.err = d.enc.decode(p, d.buf[:nr])
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}
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d.nbuf -= nr
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copy(d.buf[:d.nbuf], d.buf[nr:])
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return n, d.err
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}
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type newlineFilteringReader struct {
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wrapped io.Reader
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}
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func (r *newlineFilteringReader) Read(p []byte) (int, error) {
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n, err := r.wrapped.Read(p)
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for n > 0 {
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offset := 0
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for i, b := range p[:n] {
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if b != '\r' && b != '\n' {
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if i != offset {
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p[offset] = b
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}
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offset++
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}
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}
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if offset > 0 {
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return offset, err
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}
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// Previous buffer entirely whitespace, read again
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n, err = r.wrapped.Read(p)
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}
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return n, err
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}
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// NewDecoder constructs a new base64 stream decoder.
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func NewDecoder(enc *Encoding, r io.Reader) io.Reader {
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return &decoder{enc: enc, r: &newlineFilteringReader{r}}
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}
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// DecodedLen returns the maximum length in bytes of the decoded data
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// corresponding to n bytes of base64-encoded data.
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func (enc *Encoding) DecodedLen(n int) int {
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if enc.padChar == NoPadding {
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// Unpadded data may end with partial block of 2-3 characters.
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return n * 6 / 8
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}
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// Padded base64 should always be a multiple of 4 characters in length.
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return n / 4 * 3
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}
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