Rename funnybase and add more serializations.

common/cmpbin/string.go

+// Copyright 2015 The Chromium 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 cmpbin
+
+import (
+        "bytes"
+        "errors"
+        "io"
+        "math"
+)
+
+// ReadByteLimit is the limit of how many bytes ReadBytes and ReadString are
+// willing to deserialize before returning ErrByteLimitExceeded. It is currently
+// set to allow 2MB of user data (taking encoding size increase into account).

[M-A Ruel, 2015/07/06 23:21:35]

s/increase/overhead/

[iannucci, 2015/07/07 00:03:27]

Done.

+var ReadByteLimit = int(math.Ceil(2 * 1024 * 1024 * 8 / 7))
+
+// ErrByteLimitExceeded is returned from ReadBytes and ReadString when they
+// attempt to read more than ReadByteLimit bytes.
+var ErrByteLimitExceeded = errors.New("cmbpin: too big! tried to read > cmpbin.ReadByteLimit")
+
+// WriteString writes an encoded string to buf, returning the number of bytes
+// written, and any write error encountered.
+func WriteString(buf io.ByteWriter, s string) (n int, err error) {
+        return WriteBytes(buf, []byte(s))
+}
+
+// ReadString reads an encoded string from buf, returning the number of bytes
+// read, and any read error encountered.
+func ReadString(buf io.ByteReader) (ret string, n int, err error) {
+        b, n, err := ReadBytes(buf)
+        if err != nil {
+                return
+        }
+        ret = string(b)
+        return
+}
+
+// WriteBytes writes an encoded []byte to buf, returning the number of bytes
+// written, and any write error encountered.
+func WriteBytes(buf io.ByteWriter, data []byte) (n int, err error) {
+        wb := func(b byte) (err error) {
+                if err = buf.WriteByte(b); err == nil {
+                        n++
+                }
+                return
+        }
+
+        acc := byte(0)
+        for i := 0; i < len(data); i++ {
+                m := uint(i % 7)
+                b := data[i]
+                if err = wb(acc | 1 | ((b & (0xff << (m + 1))) >> m)); err != nil {
+                        return
+                }
+                acc = (b << (7 - m))
+                if m == 6 {
+                        if err = wb(acc | 1); err != nil {
+                                return
+                        }
+                        acc = 0
+                }
+        }
+        err = wb(acc)
+        return
+}
+
+// ReadBytes reads an encoded []byte from buf, returning the number of bytes
+// read, and any read error encountered.
+func ReadBytes(buf io.ByteReader) (ret []byte, n int, err error) {
+        tmpBuf := &bytes.Buffer{}

[M-A Ruel, 2015/07/06 23:21:35]

It doesn't need to be in heap, so use:
tmpBuf := bytes.Buffer{}

[iannucci, 2015/07/07 00:03:27]

Done.

+        acc := byte(0)
+        for i := 0; i < ReadByteLimit; i++ {
+                o := byte(0)
+                if o, err = buf.ReadByte(); err != nil {
+                        return
+                }
+                n++
+
+                b := o & 0xfe // user data
+                m := uint(i % 8)
+
+                if m == 0 {
+                        acc = b
+                } else {
+                        // ignore err since bytes.Buffer.WriteByte can never return one.
+                        _ = tmpBuf.WriteByte(acc | (b >> (8 - m)))
+                        acc = (b << m)
+                }
+
+                if o&1 == 0 { // stop bit is 0
+                        ret = tmpBuf.Bytes()
+                        return
+                }
+        }
+        err = ErrByteLimitExceeded
+        return
+}