1 files changed, 148 insertions, 0 deletions
diff --git a/src/cmd/internal/bio/buf.go b/src/cmd/internal/bio/buf.go
new file mode 100644
index 0000000..c4c2514
--- /dev/null
+++ b/src/cmd/internal/bio/buf.go
@@ -0,0 +1,148 @@
+// Copyright 2015 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.
+
+// Package bio implements common I/O abstractions used within the Go toolchain.
+package bio
+
+import (
+	"bufio"
+	"io"
+	"log"
+	"os"
+)
+
+// Reader implements a seekable buffered io.Reader.
+type Reader struct {
+	f *os.File
+	*bufio.Reader
+}
+
+// Writer implements a seekable buffered io.Writer.
+type Writer struct {
+	f *os.File
+	*bufio.Writer
+}
+
+// Create creates the file named name and returns a Writer
+// for that file.
+func Create(name string) (*Writer, error) {
+	f, err := os.Create(name)
+	if err != nil {
+		return nil, err
+	}
+	return &Writer{f: f, Writer: bufio.NewWriter(f)}, nil
+}
+
+// Open returns a Reader for the file named name.
+func Open(name string) (*Reader, error) {
+	f, err := os.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	return NewReader(f), nil
+}
+
+// NewReader returns a Reader from an open file.
+func NewReader(f *os.File) *Reader {
+	return &Reader{f: f, Reader: bufio.NewReader(f)}
+}
+
+func (r *Reader) MustSeek(offset int64, whence int) int64 {
+	if whence == 1 {
+		offset -= int64(r.Buffered())
+	}
+	off, err := r.f.Seek(offset, whence)
+	if err != nil {
+		log.Fatalf("seeking in output: %v", err)
+	}
+	r.Reset(r.f)
+	return off
+}
+
+func (w *Writer) MustSeek(offset int64, whence int) int64 {
+	if err := w.Flush(); err != nil {
+		log.Fatalf("writing output: %v", err)
+	}
+	off, err := w.f.Seek(offset, whence)
+	if err != nil {
+		log.Fatalf("seeking in output: %v", err)
+	}
+	return off
+}
+
+func (r *Reader) Offset() int64 {
+	off, err := r.f.Seek(0, 1)
+	if err != nil {
+		log.Fatalf("seeking in output [0, 1]: %v", err)
+	}
+	off -= int64(r.Buffered())
+	return off
+}
+
+func (w *Writer) Offset() int64 {
+	if err := w.Flush(); err != nil {
+		log.Fatalf("writing output: %v", err)
+	}
+	off, err := w.f.Seek(0, 1)
+	if err != nil {
+		log.Fatalf("seeking in output [0, 1]: %v", err)
+	}
+	return off
+}
+
+func (r *Reader) Close() error {
+	return r.f.Close()
+}
+
+func (w *Writer) Close() error {
+	err := w.Flush()
+	err1 := w.f.Close()
+	if err == nil {
+		err = err1
+	}
+	return err
+}
+
+func (r *Reader) File() *os.File {
+	return r.f
+}
+
+func (w *Writer) File() *os.File {
+	return w.f
+}
+
+// Slice reads the next length bytes of r into a slice.
+//
+// This slice may be backed by mmap'ed memory. Currently, this memory
+// will never be unmapped. The second result reports whether the
+// backing memory is read-only.
+func (r *Reader) Slice(length uint64) ([]byte, bool, error) {
+	if length == 0 {
+		return []byte{}, false, nil
+	}
+
+	data, ok := r.sliceOS(length)
+	if ok {
+		return data, true, nil
+	}
+
+	data = make([]byte, length)
+	_, err := io.ReadFull(r, data)
+	if err != nil {
+		return nil, false, err
+	}
+	return data, false, nil
+}
+
+// SliceRO returns a slice containing the next length bytes of r
+// backed by a read-only mmap'd data. If the mmap cannot be
+// established (limit exceeded, region too small, etc) a nil slice
+// will be returned. If mmap succeeds, it will never be unmapped.
+func (r *Reader) SliceRO(length uint64) []byte {
+	data, ok := r.sliceOS(length)
+	if ok {
+		return data
+	}
+	return nil
+}