First commit

io.go

@@ -0,0 +1,75 @@
+package common
+
+import (
+	"bytes"
+	"errors"
+	"io"
+)
+
+type PrefixedReader struct {
+	Prefix []byte
+	reader io.Reader
+}
+
+func NewPrefixedReader(prefix []byte, reader io.Reader) *PrefixedReader {
+	return &PrefixedReader{prefix, reader}
+}
+
+func (pr *PrefixedReader) Read(p []byte) (n int, err error) {
+	if len(pr.Prefix) > 0 {
+		read := copy(p, pr.Prefix)
+		pr.Prefix = pr.Prefix[read:]
+		return read, nil
+	} else {
+		return pr.reader.Read(p)
+	}
+}
+
+// NOTE: Not goroutine safe
+type BufferCloser struct {
+	bytes.Buffer
+	Closed bool
+}
+
+func NewBufferCloser(buf []byte) *BufferCloser {
+	return &BufferCloser{
+		*bytes.NewBuffer(buf),
+		false,
+	}
+}
+
+func (bc *BufferCloser) Close() error {
+	if bc.Closed {
+		return errors.New("BufferCloser already closed")
+	}
+	bc.Closed = true
+	return nil
+}
+
+func (bc *BufferCloser) Write(p []byte) (n int, err error) {
+	if bc.Closed {
+		return 0, errors.New("Cannot write to closed BufferCloser")
+	}
+	return bc.Buffer.Write(p)
+}
+
+func (bc *BufferCloser) WriteByte(c byte) error {
+	if bc.Closed {
+		return errors.New("Cannot write to closed BufferCloser")
+	}
+	return bc.Buffer.WriteByte(c)
+}
+
+func (bc *BufferCloser) WriteRune(r rune) (n int, err error) {
+	if bc.Closed {
+		return 0, errors.New("Cannot write to closed BufferCloser")
+	}
+	return bc.Buffer.WriteRune(r)
+}
+
+func (bc *BufferCloser) WriteString(s string) (n int, err error) {
+	if bc.Closed {
+		return 0, errors.New("Cannot write to closed BufferCloser")
+	}
+	return bc.Buffer.WriteString(s)
+}