File size: 3,160 Bytes
d7a5f2f | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 | // 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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