(*Reader).ReadFull/ReadAtLeast, UnderlyingReader

bufiox/bufio.go

@@ -95,4 +95,40 @@ func Seek(b *bufio.Reader, offset int64, whence int) (int64, error) {
 	return 0, ErrSeekUnsupported
 }
 
+// ReadAtLeast reads from r into buf until it has read at least min bytes.
+// It returns the number of bytes copied and an error if fewer bytes were read.
+// The error is EOF only if no bytes were read.
+// If an EOF happens after reading fewer than min bytes,
+// ReadAtLeast returns ErrUnexpectedEOF.
+// If min is greater than the length of buf, ReadAtLeast returns ErrShortBuffer.
+// On return, n >= min if and only if err == nil.
+// If r returns an error having read at least min bytes, the error is dropped.
+func ReadAtLeast(r *bufio.Reader, buf []byte, min int) (n int, err error) {
+	if len(buf) < min {
+		return 0, io.ErrShortBuffer
+	}
+	for n < min && err == nil {
+		var nn int
+		nn, err = r.Read(buf[n:])
+		n += nn
+	}
+	if n >= min {
+		err = nil
+	} else if n > 0 && err == io.EOF {
+		err = io.ErrUnexpectedEOF
+	}
+	return
+}
+
+// ReadFull reads exactly len(buf) bytes from r into buf.
+// It returns the number of bytes copied and an error if fewer bytes were read.
+// The error is EOF only if no bytes were read.
+// If an EOF happens after reading some but not all the bytes,
+// ReadFull returns ErrUnexpectedEOF.
+// On return, n == len(buf) if and only if err == nil.
+// If r returns an error having read at least len(buf) bytes, the error is dropped.
+func ReadFull(r *bufio.Reader, buf []byte) (n int, err error) {
+	return ReadAtLeast(r, buf, len(buf))
+}
+
 // -----------------------------------------------------------------------------

bufiox/seek.go

@@ -40,8 +40,45 @@ func NewReaderSize(rd io.ReadSeeker, size int) *Reader {
 // relative to the end. Seek returns the new offset relative to the start
 // of the file and an error, if any.
 //
-func (p *Reader) Seek(offset int64, whence int) (int64, error) {
-	return Seek(&p.Reader, offset, whence)
+func (r *Reader) Seek(offset int64, whence int) (int64, error) {
+	return Seek(&r.Reader, offset, whence)
+}
+
+// ReadAtLeast reads from r into buf until it has read at least min bytes.
+// It returns the number of bytes copied and an error if fewer bytes were read.
+// The error is EOF only if no bytes were read.
+// If an EOF happens after reading fewer than min bytes,
+// ReadAtLeast returns ErrUnexpectedEOF.
+// If min is greater than the length of buf, ReadAtLeast returns ErrShortBuffer.
+// On return, n >= min if and only if err == nil.
+// If r returns an error having read at least min bytes, the error is dropped.
+func (r *Reader) ReadAtLeast(buf []byte, min int) (n int, err error) {
+	return ReadAtLeast(&r.Reader, buf, min)
+}
+
+// ReadFull reads exactly len(buf) bytes from r into buf.
+// It returns the number of bytes copied and an error if fewer bytes were read.
+// The error is EOF only if no bytes were read.
+// If an EOF happens after reading some but not all the bytes,
+// ReadFull returns ErrUnexpectedEOF.
+// On return, n == len(buf) if and only if err == nil.
+// If r returns an error having read at least len(buf) bytes, the error is dropped.
+func (r *Reader) ReadFull(buf []byte) (n int, err error) {
+	return ReadAtLeast(&r.Reader, buf, len(buf))
+}
+
+// -----------------------------------------------------------------------------
+
+// UnderlyingReader returns the underlying reader.
+func UnderlyingReader(b interface{}) io.Reader {
+	switch v := b.(type) {
+	case *Reader:
+		return getUnderlyingReader(&v.Reader)
+	case *bufio.Reader:
+		return getUnderlyingReader(v)
+	default:
+		panic("can only to get the underlying reader of *bufiox.Reader or *bufio.Reader")
+	}
 }
 
 // -----------------------------------------------------------------------------