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Commit c3a087a0 authored by Austin Clements's avatar Austin Clements
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Base64 encoder/decoder package. 

R=rsc
APPROVED=rsc
DELTA=722  (722 added, 0 deleted, 0 changed)
OCL=30660
CL=30691
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src/pkg/Make.deps
View file @ c3a087a0
archive/tar.install: bufio.install bytes.install io.install os.install strconv.install
base64.install: io.install os.install strconv.install
bignum.install: fmt.install
bufio.install: io.install os.install utf8.install
bytes.install: utf8.install
......
src/pkg/Makefile
View file @ c3a087a0
......@@ -13,6 +13,7 @@ all: install
DIRS=\
archive/tar\
base64\
bignum\
bufio\
bytes\
......@@ -68,6 +69,7 @@ DIRS=\
TEST=\
archive/tar\
base64\
bignum\
bufio\
bytes\
......
src/pkg/base64/Makefile 0 → 100644
View file @ c3a087a0
# 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.
# DO NOT EDIT. Automatically generated by gobuild.
# gobuild -m >Makefile
D=
include $(GOROOT)/src/Make.$(GOARCH)
AR=gopack
default: packages
clean:
rm -rf *.[$(OS)] *.a [$(OS)].out _obj
test: packages
gotest
coverage: packages
gotest
6cov -g $$(pwd) | grep -v '_test\.go:'
%.$O: %.go
$(GC) -I_obj $*.go
%.$O: %.c
$(CC) $*.c
%.$O: %.s
$(AS) $*.s
O1=\
base64.$O\
phases: a1
_obj$D/base64.a: phases
a1: $(O1)
$(AR) grc _obj$D/base64.a base64.$O
rm -f $(O1)
newpkg: clean
mkdir -p _obj$D
$(AR) grc _obj$D/base64.a
$(O1): newpkg
$(O2): a1
nuke: clean
rm -f $(GOROOT)/pkg/$(GOOS)_$(GOARCH)$D/base64.a
packages: _obj$D/base64.a
install: packages
test -d $(GOROOT)/pkg && mkdir -p $(GOROOT)/pkg/$(GOOS)_$(GOARCH)$D
cp _obj$D/base64.a $(GOROOT)/pkg/$(GOOS)_$(GOARCH)$D/base64.a
src/pkg/base64/base64.go 0 → 100644
View file @ c3a087a0
// 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 (
"io";
"os";
"strconv";
)
/*
* Encodings
*/
// 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 string;
decodeMap [256]byte;
}
const encodeStd = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
const encodeURL = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
// NewEncoding returns a new Encoding defined by the given alphabet,
// which must be a 64-byte string.
func NewEncoding(encoder string) *Encoding {
e := new(Encoding);
e.encode = encoder;
for i := 0; i < len(e.decodeMap); i++ {
e.decodeMap[i] = 0xFF;
}
for i := 0; i < len(encoder); i++ {
e.decodeMap[encoder[i]] = byte(i);
}
return e;
}
// 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);
/*
* Encoder
*/
// Encode encodes src using the encoding enc, writing
// EncodedLen(len(input)) 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(src, dst []byte) {
if len(src) == 0 {
return;
}
for len(src) > 0 {
// Unpack 4x 6-bit source blocks into a 4 byte
// destination quantum
switch len(src) {
default:
dst[3] |= src[2]&0x3F;
dst[2] |= src[2]>>6;
fallthrough;
case 2:
dst[2] |= (src[1]<<2)&0x3F;
dst[1] |= src[1]>>4;
fallthrough;
case 1:
dst[1] |= (src[0]<<4)&0x3F;
dst[0] |= src[0]>>2;
}
// Encode 6-bit blocks using the base64 alphabet
for j := 0; j < 4; j++ {
dst[j] = enc.encode[dst[j]];
}
// Pad the final quantum
if len(src) < 3 {
dst[3] = '=';
if len(src) < 2 {
dst[2] = '=';
}
break;
}
src = src[3:len(src)];
dst = dst[4:len(dst)];
}
}
// encodeBlocker is a restricted FIFO for byte data that always
// returns byte arrays whose lengths are some multiple of 3.
type encodeBlocker struct {
// The overflow buffer contains data that should be returned
// before any data in nextbuf.
buffer [3]byte;
bufpos int;
nextbuf []byte;
}
// put appends the data contained in buf to the encode blocker's
// buffer. In general, you have to get everything out before you can
// put another array.
func (eb *encodeBlocker) put(buf []byte) {
if eb.nextbuf != nil {
panic("there is already a nextbuf");
}
// If we have anything in the overflow buffer, fill it up the
// rest of the way so we can return the overflow buffer.
bpos := 0;
if eb.bufpos != 0 {
for ; eb.bufpos < 3 && bpos < len(buf); eb.bufpos++ {
eb.buffer[eb.bufpos] = buf[bpos];
bpos++;
}
}
if bpos < len(buf) {
eb.nextbuf = buf[bpos:len(buf)];
}
}
// get retrieves an input quantum aligned byte array from the encode
// blocker.
func (eb *encodeBlocker) get() []byte {
// If there is data in the overflow buffer, return it first
if eb.bufpos > 0 {
if eb.bufpos < 3 {
// We don't have a full quantum
return nil;
}
eb.bufpos = 0;
return &eb.buffer;
}
// No overflow buffer, so return nextbuf. However, it has to
// be quantum-aligned, so copy the tail of the data into the
// overflow buffer for next time.
end := len(eb.nextbuf)/3*3;
for i := end; i < len(eb.nextbuf); i++ {
eb.buffer[eb.bufpos] = eb.nextbuf[i];
eb.bufpos++;
}
b := eb.nextbuf[0:end];
eb.nextbuf = nil;
if end == 0 {
return nil;
}
return b;
}
// size returns the number of bytes remaining in the encode blocker's
// buffer.
func (eb *encodeBlocker) size() int {
return (eb.bufpos + len(eb.nextbuf))/3*3;
}
type encoder struct {
w io.Writer;
enc *Encoding;
err os.Error;
eb encodeBlocker;
}
func (e *encoder) Write(b []byte) (int, os.Error) {
if e.err != nil {
return 0, e.err;
}
e.eb.put(b);
output := make([]byte, e.eb.size()/3*4);
opos := 0;
for {
block := e.eb.get();
if block == nil {
break;
}
e.enc.Encode(block, output[opos:len(output)]);
opos += len(block)/3*4;
}
n, err := e.w.Write(output);
if err != nil {
e.err = io.ErrShortWrite;
return n/4*3, e.err;
}
return len(b), nil;
}
// Close flushes any pending output from the encoder. It is an error
// to call Write after calling Close.
func (e *encoder) Close() os.Error {
// If there's anything left in the buffer, flush it out
if e.err == nil && e.eb.bufpos > 0 {
var output [4]byte;
e.enc.Encode(e.eb.buffer[0:e.eb.bufpos], &output);
e.eb.bufpos = 0;
n, err := e.w.Write(&output);
if err != nil {
e.err = io.ErrShortWrite;
}
}
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{w: w, enc: enc};
}
// EncodedLen returns the length in bytes of the base64 encoding
// of an input buffer of length n.
func (enc *Encoding) EncodedLen(n int) int {
return (n+2)/3*4;
}
/*
* Decoder
*/
type CorruptInputError int64;
func (e CorruptInputError) String() string {
return "illegal base64 data at input byte" + strconv.Itoa64(int64(e));
}
// decode is like Decode, but returns an additional 'end' value, which
// indicates if end-of-message padding was encountered and thus any
// additional data is an error. decode also assumes len(src)%4==0,
// since it is meant for internal use.
func (enc *Encoding) decode(src, dst []byte) (n int, end bool, err os.Error) {
for i := 0; i < len(src)/4 && !end; i++ {
// Decode quantum using the base64 alphabet
var dbuf [4]byte;
dlen := 4;
dbufloop:
for j := 0; j < 4; j++ {
in := src[i*4+j];
if in == '=' && j >= 2 && i == len(src)/4 - 1 {
// We've reached the end and there's
// padding
if src[i*4+3] != '=' {
return n, false, CorruptInputError(i*4+2);
}
dlen = j;
end = true;
break dbufloop;
}
dbuf[j] = enc.decodeMap[in];
if dbuf[j] == 0xFF {
return n, false, CorruptInputError(i*4+j);
}
}
// Pack 4x 6-bit source blocks into 3 byte destination
// quantum
switch dlen {
case 4:
dst[i*3+2] = dbuf[2]<<6 | dbuf[3];
fallthrough;
case 3:
dst[i*3+1] = dbuf[1]<<4 | dbuf[2]>>2;
fallthrough;
case 2:
dst[i*3+0] = dbuf[0]<<2 | dbuf[1]>>4;
}
n += dlen - 1;
}
return n, end, nil;
}
// 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.
func (enc *Encoding) Decode(src, dst []byte) (n int, err os.Error) {
if len(src)%4 != 0 {
return 0, CorruptInputError(len(src)/4*4);
}
var _ bool;
n, _, err = enc.decode(src, dst);
return;
}
// quantumReader wraps a regular reader and ensures that each read
// will return a slice whose length is a multiple of 4-bytes.
type quantumReader struct {
r io.Reader;
buf [4]byte;
buflen int;
}
func (q *quantumReader) Read(p []byte) (int, os.Error) {
// Copy buffered data into the output
for i := 0; i < q.buflen; i++ {
p[i] = q.buf[i];
}
// Read more data into the output
n, err := q.r.Read(p[q.buflen:len(p)]);
// Buffer tail data that does not fit into the quanta
end := (q.buflen+n)/4*4;
for i := end; i < q.buflen+n; i++ {
q.buf[i-end] = p[i];
}
// Is EOF misaligned?
if err == os.EOF && q.buflen > 0 {
err = io.ErrUnexpectedEOF;
}
return end, err;
}
// decodeBlocker takes a sequence of arbitrary size output byte slices
// and makes them available as a stream of byte slices whose lengths
// are always a multiple of 3.
type decodeBlocker struct {
output []byte;
noutput int;
overflow [3]byte;
overflowstart int;
}
// flush flushes as much data from the overflow buffer as possible in
// to the current output buffer, reseting the output buffer to nil if
// it fills it up. It returns the number of bytes written to the
// output buffer.
func (db *decodeBlocker) flush() int {
// Copy overflow into the beginning of this buffer
i := 0;
for ; i < len(db.output) && db.overflowstart < 3; i++ {
db.output[i] = db.overflow[db.overflowstart];
db.overflowstart++;
}
if i == len(db.output) {
db.output = nil;
} else {
db.output = db.output[i:len(db.output)];
}
return i;
}
// use begins using a new output buffer. Any data that did not fit in
// the previous output buffer will be placed at the beginning of this
// buffer.
func (db *decodeBlocker) use(buf []byte) {
db.output = buf;
db.noutput = 0;
// Copy left-over overflow from the previous buffer into this
// buffer
db.noutput += db.flush();
}
// checkout retrieve the next slice to fill with data. The length of
// the returned slice will always be a multiple of 3. It returns nil
// if there is no more buffer space.
func (db *decodeBlocker) checkout() []byte {
// If we can use the output buffer, do so
if len(db.output) >= 3 {
end := len(db.output)/3*3;
return db.output[0:end];
} else if db.overflowstart == 3 {
// Fill the overflow buffer
db.overflowstart = 0;
return &db.overflow;
}
// We're out of space
return nil;
}
// checking indicates that we're done with the checked-out slice and
// that we wrote count bytes to it.
func (db *decodeBlocker) checkin(count int) {
if db.overflowstart == 3 {
// Wrote to the output buffer
db.noutput += count;
db.output = db.output[count:len(db.output)];
} else {
// Wrote to the overflow buffer. Flush what we can to
// the output buffer.
n := db.flush();
if n > count {
n = count;
}
db.noutput += n;
}
}
// remaining returns the number of bytes remaining in the decode
// blocker's buffer. This will always be a multiple of 3.
func (db *decodeBlocker) remaining() int {
return (len(db.output)+2)/3*3;
}
// outlen returns the number of bytes written to the output buffer.
func (db *decodeBlocker) outlen() int {
return db.noutput;
}
type decoder struct {
r quantumReader;
enc *Encoding;
db decodeBlocker;
err os.Error;
// Have we definitely reached the end of the message?
end bool;
}
func min(a int, b int) int {
if a < b {
return a;
}
return b;
}
func (d *decoder) Read(output []byte) (int, os.Error) {
if d.err != nil {
return 0, d.err;
}
d.db.use(output);
var inbuf [512]byte;
// Read enough data to fill either our input buffer or our
// output buffer.
maxin := min(d.db.remaining()/3*4, len(inbuf));
n, err := d.r.Read(inbuf[0:maxin]);
// Decode into output buffer.
ipos := 0;
for ipos < n {
outbuf := d.db.checkout();
if outbuf == nil {
// Out of output buffer space
break;
}
inlen := min(len(outbuf)/3*4, n - ipos);
if d.end {
// We've seen end-of-message padding, but
// there's more data. The RFC says this is an
// error.
// XXX Should shift character count
d.err = CorruptInputError(0);
break;
}
count := 0;
count, d.end, d.err = d.enc.decode(inbuf[ipos:ipos+inlen], outbuf);
d.db.checkin(count);
if d.err != nil {
// XXX Should shift character count
break;
}
ipos += inlen;
}
if err != nil && d.err == nil {
d.err = err;
}
return d.db.outlen(), d.err;
}
// NewDecoder constructs a new base64 stream decoder.
func NewDecoder(enc *Encoding, r io.Reader) io.Reader {
return &decoder{r: quantumReader{r:r},
enc: enc,
db: decodeBlocker{overflowstart: 3}};
}
// DecodeLen 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 {
return n/4*3;
}
src/pkg/base64/base64_test.go 0 → 100644
View file @ c3a087a0
// 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 (
"base64";
"io";
"os";
"reflect";
"testing";
)
type testpair struct {
decoded, encoded string;
}
var pairs = []testpair {
// RFC 3548 examples
testpair{"\x14\xfb\x9c\x03\xd9\x7e", "FPucA9l+"},
testpair{"\x14\xfb\x9c\x03\xd9", "FPucA9k="},
testpair{"\x14\xfb\x9c\x03", "FPucAw=="},
// RFC 4648 examples
testpair{"", ""},
testpair{"f", "Zg=="},
testpair{"fo", "Zm8="},
testpair{"foo", "Zm9v"},
testpair{"foob", "Zm9vYg=="},
testpair{"fooba", "Zm9vYmE="},
testpair{"foobar", "Zm9vYmFy"},
// Wikipedia examples
testpair{"sure.", "c3VyZS4="},
testpair{"sure", "c3VyZQ=="},
testpair{"sur", "c3Vy"},
testpair{"su", "c3U="},
testpair{"leasure.", "bGVhc3VyZS4="},
testpair{"easure.", "ZWFzdXJlLg=="},
testpair{"asure.", "YXN1cmUu"},
testpair{"sure.", "c3VyZS4="},
}
var bigtest = testpair {
"Twas brillig, and the slithy toves",
"VHdhcyBicmlsbGlnLCBhbmQgdGhlIHNsaXRoeSB0b3Zlcw=="
}
func testEqual(t *testing.T, msg string, args ...) bool {
v := reflect.NewValue(args).(reflect.StructValue);
v1 := v.Field(v.Len() - 2);
v2 := v.Field(v.Len() - 1);
if v1.Interface() != v2.Interface() {
t.Errorf(msg, args);
return false;
}
return true;
}
func TestEncode(t *testing.T) {
for _, p := range pairs {
buf := make([]byte, StdEncoding.EncodedLen(len(p.decoded)));
StdEncoding.Encode(io.StringBytes(p.decoded), buf);
testEqual(t, "Encode(%q) = %q, want %q", p.decoded, string(buf), p.encoded);
}
}
func TestEncoder(t *testing.T) {
for _, p := range pairs {
bb := &io.ByteBuffer{};
encoder := NewEncoder(StdEncoding, bb);
encoder.Write(io.StringBytes(p.decoded));
encoder.Close();
testEqual(t, "Encode(%q) = %q, want %q", p.decoded, string(bb.Data()), p.encoded);
}
}
func TestEncoderBuffering(t *testing.T) {
input := io.StringBytes(bigtest.decoded);
for bs := 1; bs <= 12; bs++ {
buf := make([]byte, bs);
bb := &io.ByteBuffer{};
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, os.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, os.Error(nil));
testEqual(t, "Encoding/%d of %q = %q, want %q", bs, bigtest.decoded, string(bb.Data()), bigtest.encoded);
}
}
func TestDecode(t *testing.T) {
for _, p := range pairs {
dbuf := make([]byte, StdEncoding.DecodedLen(len(p.encoded)));
count, end, err := StdEncoding.decode(io.StringBytes(p.encoded), dbuf);
testEqual(t, "Decode(%q) = error %v, want %v", p.encoded, err, os.Error(nil));
testEqual(t, "Decode(%q) = length %v, want %v", p.encoded, count, len(p.decoded));
if len(p.encoded) > 0 {
testEqual(t, "Decode(%q) = end %v, want %v", p.encoded, end, (p.encoded[len(p.encoded)-1] == '='));
}
testEqual(t, "Decode(%q) = %q, want %q", p.encoded, string(dbuf[0:count]), p.decoded);
}
}
func TestDecoder(t *testing.T) {
for _, p := range pairs {
decoder := NewDecoder(StdEncoding, io.NewByteReader(io.StringBytes(p.encoded)));
dbuf := make([]byte, StdEncoding.DecodedLen(len(p.encoded)));
count, err := decoder.Read(dbuf);
if err != nil && err != os.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 != os.EOF {
count, err = decoder.Read(dbuf);
}
testEqual(t, "Read from %q = %v, want %v", p.encoded, err, os.EOF);
}
}
func TestDecoderBuffering(t *testing.T) {
input := io.StringBytes(bigtest.encoded);
for bs := 1; bs <= 12; bs++ {
decoder := NewDecoder(StdEncoding, io.NewByteReader(input));
buf := make([]byte, len(bigtest.decoded) + 12);
var total int;
for total = 0; total < len(bigtest.decoded); {
n, err := decoder.Read(buf[total:total+bs]);
testEqual(t, "Read from %q at pos %d = %d, %v, want _, %v", bigtest.encoded, total, n, err, os.Error(nil));
total += n;
}
testEqual(t, "Decoding/%d of %q = %q, want %q", bs, bigtest.encoded, string(buf[0:total]), bigtest.decoded);
}
}
func TestDecodeCorrupt(t *testing.T) {
type corrupt struct {
e string;
p int;
};
examples := []corrupt {
corrupt{"!!!!", 0},
corrupt{"x===", 1},
corrupt{"AA=A", 2},
corrupt{"AAA=AAAA", 3},
corrupt{"AAAAA", 4},
corrupt{"AAAAAA", 4},
};
for _, e := range examples {
dbuf := make([]byte, StdEncoding.DecodedLen(len(e.e)));
count, err := StdEncoding.Decode(io.StringBytes(e.e), dbuf);
switch err := err.(type) {
case CorruptInputError:
testEqual(t, "Corruption in %q at offset %v, want %v", e.e, int(err), e.p);
default:
t.Error("Decoder failed to detect corruption in", e);
}
}
}
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