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types.go
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types.go
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// Copyright 2013-2017 the u-root 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 cpio
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"os"
"time"
"golang.org/x/sys/unix"
)
const Trailer = "TRAILER!!!"
type Record struct {
io.ReadCloser
Info
}
var TrailerRecord = StaticRecord(nil, Info{Name: Trailer})
type RecordReader interface {
ReadRecord() (Record, error)
}
type RecordWriter interface {
WriteRecord(Record) error
}
type RecordFormat interface {
Reader(r io.ReaderAt) RecordReader
Writer(w io.Writer) RecordWriter
}
func StaticRecord(contents []byte, info Info) Record {
info.FileSize = uint64(len(contents))
return Record{
ReadCloser: ioutil.NopCloser(bytes.NewReader(contents)),
Info: info,
}
}
func StaticFile(name string, content string, perm uint64) Record {
return StaticRecord([]byte(content), Info{
Name: name,
Mode: unix.S_IFREG | perm,
})
}
// Symlink returns a symlink record at name pointing to target.
func Symlink(name string, target string) Record {
return Record{
ReadCloser: ioutil.NopCloser(bytes.NewReader([]byte(target))),
Info: Info{
FileSize: uint64(len(target)),
Mode: unix.S_IFLNK | 0777,
Name: name,
},
}
}
// Directory returns a directory record at `name`.
func Directory(name string, mode uint64) Record {
return Record{
Info: Info{
Name: name,
Mode: unix.S_IFDIR | mode&^unix.S_IFMT,
},
}
}
// CharDev returns a character device record at `name`.
func CharDev(name string, perm uint64, rmajor, rminor uint64) Record {
return Record{
Info: Info{
Name: name,
Mode: unix.S_IFCHR | perm,
Rmajor: rmajor,
Rminor: rminor,
},
}
}
func NewBytesReadCloser(contents []byte) io.ReadCloser {
return ioutil.NopCloser(bytes.NewReader(contents))
}
func NewReadCloser(r io.Reader) io.ReadCloser {
return ioutil.NopCloser(r)
}
type LazyOpen struct {
Name string
File *os.File
}
func (r *LazyOpen) Read(p []byte) (int, error) {
if r.File == nil {
f, err := os.Open(r.Name)
if err != nil {
return -1, err
}
r.File = f
}
return r.File.Read(p)
}
func (r *LazyOpen) Close() error {
return r.File.Close()
}
func NewDeferReadCloser(name string) io.ReadCloser {
return &LazyOpen{Name: name}
}
// Info holds metadata about files.
type Info struct {
Ino uint64
Mode uint64
UID uint64
GID uint64
NLink uint64
MTime uint64
FileSize uint64
Dev uint64
Major uint64
Minor uint64
Rmajor uint64
Rminor uint64
Name string
}
func Equal(r Record, s Record) bool {
if r.Info != s.Info {
return false
}
return ReadCloserEqual(r.ReadCloser, s.ReadCloser)
}
func ReadCloserEqual(r1, r2 io.ReadCloser) bool {
var c, d []byte
var err error
if r1 != nil {
c, err = ioutil.ReadAll(r1)
if err != nil {
return false
}
}
if r2 != nil {
d, err = ioutil.ReadAll(r2)
if err != nil {
return false
}
}
return bytes.Equal(c, d)
}
func (i Info) String() string {
return fmt.Sprintf("%s: Ino %d Mode %#o UID %d GID %d NLink %d MTime %v FileSize %d Major %d Minor %d Rmajor %d Rminor %d",
i.Name,
i.Ino,
i.Mode,
i.UID,
i.GID,
i.NLink,
time.Unix(int64(i.MTime), 0).UTC(),
i.FileSize,
i.Major,
i.Minor,
i.Rmajor,
i.Rminor)
}