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// 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
}
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