1 files changed, 223 insertions, 0 deletions
diff --git a/src/pkg/io/io.go b/src/pkg/io/io.go
new file mode 100644
index 000000000..ba0449ac1
--- /dev/null
+++ b/src/pkg/io/io.go
@@ -0,0 +1,223 @@
+// 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.
+
+// This package provides basic interfaces to I/O primitives.
+// Its primary job is to wrap existing implementations of such primitives,
+// such as those in package os, into shared public interfaces that
+// abstract the functionality.
+// It also provides buffering primitives and some other basic operations.
+package io
+
+import (
+	"bytes";
+	"os";
+)
+
+// Error represents an unexpected I/O behavior.
+type Error struct {
+	os.ErrorString
+}
+
+// ErrEOF means that data was expected, but a read got EOF instead.
+var ErrEOF os.Error = &Error{"EOF"}
+
+// ErrShortWrite means that a write accepted fewer bytes than requested
+// but failed to return an explicit error.
+var ErrShortWrite os.Error = &Error{"short write"}
+
+
+// Reader is the interface that wraps the basic Read method.
+// An implementation of Read is allowed to use all of p for
+// scratch space during the call, even if it eventually returns
+// n < len(p).
+type Reader interface {
+	Read(p []byte) (n int, err os.Error);
+}
+
+// Writer is the interface that wraps the basic Write method.
+type Writer interface {
+	Write(p []byte) (n int, err os.Error);
+}
+
+// Closer is the interface that wraps the basic Close method.
+type Closer interface {
+	Close() os.Error;
+}
+
+// ReadWrite is the interface that groups the basic Read and Write methods.
+type ReadWriter interface {
+	Reader;
+	Writer;
+}
+
+// ReadCloser is the interface that groups the basic Read and Close methods.
+type ReadCloser interface {
+	Reader;
+	Closer;
+}
+
+// WriteCloser is the interface that groups the basic Write and Close methods.
+type WriteCloser interface {
+	Writer;
+	Closer;
+}
+
+// ReadWriteCloser is the interface that groups the basic Read, Write and Close methods.
+type ReadWriteCloser interface {
+	Reader;
+	Writer;
+	Closer;
+}
+
+// Convert a string to an array of bytes for easy marshaling.
+func StringBytes(s string) []byte {
+	b := make([]byte, len(s));
+	for i := 0; i < len(s); i++ {
+		b[i] = s[i];
+	}
+	return b;
+}
+
+// WriteString writes the contents of the string s to w, which accepts an array of bytes.
+func WriteString(w Writer, s string) (n int, err os.Error) {
+	return w.Write(StringBytes(s))
+}
+
+// ReadAtLeast reads r into buf until at least min bytes have been read,
+// or until EOF or error.
+func ReadAtLeast(r Reader, buf []byte, min int) (n int, err os.Error) {
+	n = 0;
+	for n < min {
+		nn, e := r.Read(buf[n:len(buf)]);
+		if nn > 0 {
+			n += nn
+		}
+		if e != nil {
+			return n, e
+		}
+		if nn <= 0 {
+			return n, ErrEOF	// no error but insufficient data
+		}
+	}
+	return n, nil
+}
+
+// FullRead reads r until the buffer buf is full, or until EOF or error.
+func FullRead(r Reader, buf []byte) (n int, err os.Error) {
+	// TODO(rsc): 6g bug prevents obvious return
+	n, err = ReadAtLeast(r, buf, len(buf));
+	return;
+}
+
+// Convert something that implements Read into something
+// whose Reads are always FullReads
+type fullRead struct {
+	r	Reader;
+}
+
+func (fr *fullRead) Read(p []byte) (n int, err os.Error) {
+	n, err = FullRead(fr.r, p);
+	return n, err
+}
+
+// MakeFullReader takes r, an implementation of Read, and returns an object
+// that still implements Read but always calls FullRead underneath.
+func MakeFullReader(r Reader) Reader {
+	if fr, ok := r.(*fullRead); ok {
+		// already a fullRead
+		return r
+	}
+	return &fullRead{r}
+}
+
+// Copy n copies n bytes (or until EOF is reached) from src to dst.
+// It returns the number of bytes copied and the error, if any.
+func Copyn(src Reader, dst Writer, n int64) (written int64, err os.Error) {
+	buf := make([]byte, 32*1024);
+	for written < n {
+		l := len(buf);
+		if d := n - written; d < int64(l) {
+			l = int(d);
+		}
+		nr, er := src.Read(buf[0 : l]);
+		if nr > 0 {
+			nw, ew := dst.Write(buf[0 : nr]);
+			if nw > 0 {
+				written += int64(nw);
+			}
+			if ew != nil {
+				err = ew;
+				break;
+			}
+			if nr != nw {
+				err = os.EIO;
+				break;
+			}
+		}
+		if er != nil {
+			err = er;
+			break;
+		}
+		if nr == 0 {
+			err = ErrEOF;
+			break;
+		}
+	}
+	return written, err
+}
+
+// Copy copies from src to dst until EOF is reached.
+// It returns the number of bytes copied and the error, if any.
+func Copy(src Reader, dst Writer) (written int64, err os.Error) {
+	buf := make([]byte, 32*1024);
+	for {
+		nr, er := src.Read(buf);
+		if nr > 0 {
+			nw, ew := dst.Write(buf[0:nr]);
+			if nw > 0 {
+				written += int64(nw);
+			}
+			if ew != nil {
+				err = ew;
+				break;
+			}
+			if nr != nw {
+				err = os.EIO;
+				break;
+			}
+		}
+		if er != nil {
+			err = er;
+			break;
+		}
+		if nr == 0 {
+			break;
+		}
+	}
+	return written, err
+}
+
+// A ByteReader satisfies Reads by consuming data from a slice of bytes.
+// Clients can call NewByteReader to create one or wrap pointers
+// to their own slices: r := ByteReader{&data}.
+type ByteReader struct {
+	Data *[]byte
+}
+
+func (r ByteReader) Read(p []byte) (int, os.Error) {
+	n := len(p);
+	b := r.Data;
+	if n > len(b) {
+		n = len(b);
+	}
+	bytes.Copy(p, b[0:n]);
+	*b = b[n:len(b)];
+	return n, nil;
+}
+
+// NewByteReader returns a new ByteReader reading from data.
+func NewByteReader(data []byte) ByteReader {
+	return ByteReader{ &data };
+}
+