mirror of
https://github.com/golang/go
synced 2024-11-26 06:07:57 -07:00
base64: cut out some middle layers
R=austin DELTA=352 (67 added, 196 deleted, 89 changed) OCL=30694 CL=30713
This commit is contained in:
Russ Cox
parent
a1646fd50e
commit
2ce8b444b9
@ -1,5 +1,5 @@
|
||||
archive/tar.install: bufio.install bytes.install io.install os.install strconv.install
|
||||
base64.install: io.install os.install strconv.install
|
||||
base64.install: bytes.install io.install os.install strconv.install
|
||||
bignum.install: fmt.install
|
||||
bufio.install: io.install os.install utf8.install
|
||||
bytes.install: utf8.install
|
||||
|
||||
@ -6,6 +6,7 @@
|
||||
package base64
|
||||
|
||||
import (
|
||||
"bytes";
|
||||
"io";
|
||||
"os";
|
||||
"strconv";
|
||||
@ -66,6 +67,11 @@ func (enc *Encoding) Encode(src, dst []byte) {
|
||||
}
|
||||
|
||||
for len(src) > 0 {
|
||||
dst[0] = 0;
|
||||
dst[1] = 0;
|
||||
dst[2] = 0;
|
||||
dst[3] = 0;
|
||||
|
||||
// Unpack 4x 6-bit source blocks into a 4 byte
|
||||
// destination quantum
|
||||
switch len(src) {
|
||||
@ -101,120 +107,76 @@ func (enc *Encoding) Encode(src, dst []byte) {
|
||||
}
|
||||
}
|
||||
|
||||
// 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;
|
||||
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(b []byte) (int, os.Error) {
|
||||
func (e *encoder) Write(p []byte) (n int, err 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;
|
||||
// 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++;
|
||||
}
|
||||
e.enc.Encode(block, output[opos:len(output)]);
|
||||
opos += len(block)/3*4;
|
||||
n += i;
|
||||
p = p[i:len(p)];
|
||||
if e.nbuf < 3 {
|
||||
return;
|
||||
}
|
||||
e.enc.Encode(&e.buf, &e.out);
|
||||
var _ int;
|
||||
if _, e.err = e.w.Write(e.out[0:4]); e.err != nil {
|
||||
return n, e.err;
|
||||
}
|
||||
e.nbuf = 0;
|
||||
}
|
||||
|
||||
n, err := e.w.Write(output);
|
||||
if err != nil {
|
||||
e.err = io.ErrShortWrite;
|
||||
return n/4*3, e.err;
|
||||
// Large interior chunks.
|
||||
for len(p) > 3 {
|
||||
nn := len(e.out)/4 * 3;
|
||||
if nn > len(p) {
|
||||
nn = len(p);
|
||||
}
|
||||
return len(b), nil;
|
||||
nn -= nn % 3;
|
||||
if nn > 0 {
|
||||
e.enc.Encode(p[0:nn], &e.out);
|
||||
var _ int;
|
||||
if _, e.err = e.w.Write(e.out[0:nn/3*4]); e.err != nil {
|
||||
return n, e.err;
|
||||
}
|
||||
}
|
||||
n += nn;
|
||||
p = p[nn:len(p)];
|
||||
}
|
||||
|
||||
// Trailing fringe.
|
||||
for i := 0; i < len(p); i++ {
|
||||
e.buf[i] = p[i];
|
||||
}
|
||||
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.
|
||||
// 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;
|
||||
}
|
||||
if e.err == nil && e.nbuf > 0 {
|
||||
e.enc.Encode(e.buf[0:e.nbuf], &e.out);
|
||||
e.nbuf = 0;
|
||||
var _ int;
|
||||
_, e.err = e.w.Write(e.out[0:4]);
|
||||
}
|
||||
return e.err;
|
||||
}
|
||||
@ -225,7 +187,7 @@ func (e *encoder) Close() os.Error {
|
||||
// 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};
|
||||
return &encoder{enc: enc, w: w};
|
||||
}
|
||||
|
||||
// EncodedLen returns the length in bytes of the base64 encoding
|
||||
@ -254,7 +216,7 @@ func (enc *Encoding) decode(src, dst []byte) (n int, end bool, err os.Error) {
|
||||
var dbuf [4]byte;
|
||||
dlen := 4;
|
||||
|
||||
dbufloop:
|
||||
dbufloop:
|
||||
for j := 0; j < 4; j++ {
|
||||
in := src[i*4+j];
|
||||
if in == '=' && j >= 2 && i == len(src)/4 - 1 {
|
||||
@ -305,193 +267,68 @@ func (enc *Encoding) Decode(src, dst []byte) (n int, err os.Error) {
|
||||
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;
|
||||
enc *Encoding;
|
||||
r io.Reader;
|
||||
end bool; // saw end of message
|
||||
buf [1024]byte; // leftover input
|
||||
nbuf int;
|
||||
out []byte; // leftover decoded output
|
||||
outbuf [1024/4*3]byte;
|
||||
}
|
||||
|
||||
func min(a int, b int) int {
|
||||
if a < b {
|
||||
return a;
|
||||
}
|
||||
return b;
|
||||
}
|
||||
|
||||
func (d *decoder) Read(output []byte) (int, os.Error) {
|
||||
func (d *decoder) Read(p []byte) (n int, err 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;
|
||||
// Use leftover decoded output from last read.
|
||||
if len(d.out) > 0 {
|
||||
n = bytes.Copy(p, d.out);
|
||||
d.out = d.out[n:len(d.out)];
|
||||
return n, nil;
|
||||
}
|
||||
|
||||
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;
|
||||
// Read a chunk.
|
||||
nn := len(p)/3*4;
|
||||
if nn < 4 {
|
||||
nn = 4;
|
||||
}
|
||||
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;
|
||||
if nn > len(d.buf) {
|
||||
nn = len(d.buf);
|
||||
}
|
||||
ipos += inlen;
|
||||
nn, d.err = io.ReadAtLeast(d.r, d.buf[d.nbuf:nn], 4-d.nbuf);
|
||||
d.nbuf += nn;
|
||||
if d.nbuf < 4 {
|
||||
return 0, d.err;
|
||||
}
|
||||
|
||||
if err != nil && d.err == nil {
|
||||
// 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.end, d.err = d.enc.decode(d.buf[0:nr], &d.outbuf);
|
||||
d.out = d.outbuf[0:nw];
|
||||
n = bytes.Copy(p, d.out);
|
||||
d.out = d.out[n:len(d.out)];
|
||||
} else {
|
||||
n, d.end, d.err = d.enc.decode(d.buf[0:nr], p);
|
||||
}
|
||||
d.nbuf -= nr;
|
||||
for i := 0; i < d.nbuf; i++ {
|
||||
d.buf[i] = d.buf[i+nr];
|
||||
}
|
||||
|
||||
if d.err == nil {
|
||||
d.err = err;
|
||||
}
|
||||
|
||||
return d.db.outlen(), d.err;
|
||||
return n, 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}};
|
||||
return &decoder{enc: enc, r: r};
|
||||
}
|
||||
|
||||
// DecodeLen returns the maximum length in bytes of the decoded data
|
||||
|
||||
@ -6,6 +6,7 @@ package base64
|
||||
|
||||
import (
|
||||
"base64";
|
||||
"bytes";
|
||||
"io";
|
||||
"os";
|
||||
"reflect";
|
||||
@ -167,3 +168,36 @@ func TestDecodeCorrupt(t *testing.T) {
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
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(io.ByteBuffer);
|
||||
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);
|
||||
}
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user