afero/tarfs/fs.go

135 lines
2.9 KiB
Go

// package tarfs implements a read-only in-memory representation of a tar archive
package tarfs
import (
"archive/tar"
"bytes"
"io"
"os"
"path/filepath"
"syscall"
"time"
"github.com/spf13/afero"
)
type Fs struct {
files map[string]map[string]*File
}
func splitpath(name string) (dir, file string) {
name = filepath.ToSlash(name)
if len(name) == 0 || name[0] != '/' {
name = "/" + name
}
name = filepath.Clean(name)
dir, file = filepath.Split(name)
dir = filepath.Clean(dir)
return
}
func New(t *tar.Reader) *Fs {
fs := &Fs{files: make(map[string]map[string]*File)}
for {
hdr, err := t.Next()
if err == io.EOF {
break
}
if err != nil {
return nil
}
d, f := splitpath(hdr.Name)
if _, ok := fs.files[d]; !ok {
fs.files[d] = make(map[string]*File)
}
var buf bytes.Buffer
size, err := buf.ReadFrom(t)
if err != nil {
panic("tarfs: reading from tar:" + err.Error())
}
if size != hdr.Size {
panic("tarfs: size mismatch")
}
file := &File{
h: hdr,
data: bytes.NewReader(buf.Bytes()),
fs: fs,
}
fs.files[d][f] = file
}
// Add a pseudoroot
fs.files[afero.FilePathSeparator][""] = &File{
h: &tar.Header{
Name: afero.FilePathSeparator,
Typeflag: tar.TypeDir,
Size: 0,
},
data: bytes.NewReader(nil),
fs: fs,
}
return fs
}
func (fs *Fs) Open(name string) (afero.File, error) {
d, f := splitpath(name)
if _, ok := fs.files[d]; !ok {
return nil, &os.PathError{Op: "open", Path: name, Err: syscall.ENOENT}
}
file, ok := fs.files[d][f]
if !ok {
return nil, &os.PathError{Op: "open", Path: name, Err: syscall.ENOENT}
}
nf := *file
return &nf, nil
}
func (fs *Fs) Name() string { return "tarfs" }
func (fs *Fs) Create(name string) (afero.File, error) { return nil, syscall.EROFS }
func (fs *Fs) Mkdir(name string, perm os.FileMode) error { return syscall.EROFS }
func (fs *Fs) MkdirAll(path string, perm os.FileMode) error { return syscall.EROFS }
func (fs *Fs) OpenFile(name string, flag int, perm os.FileMode) (afero.File, error) {
if flag != os.O_RDONLY {
return nil, &os.PathError{Op: "open", Path: name, Err: syscall.EPERM}
}
return fs.Open(name)
}
func (fs *Fs) Remove(name string) error { return syscall.EROFS }
func (fs *Fs) RemoveAll(path string) error { return syscall.EROFS }
func (fs *Fs) Rename(oldname string, newname string) error { return syscall.EROFS }
func (fs *Fs) Stat(name string) (os.FileInfo, error) {
d, f := splitpath(name)
if _, ok := fs.files[d]; !ok {
return nil, &os.PathError{Op: "stat", Path: name, Err: syscall.ENOENT}
}
file, ok := fs.files[d][f]
if !ok {
return nil, &os.PathError{Op: "stat", Path: name, Err: syscall.ENOENT}
}
return file.h.FileInfo(), nil
}
func (fs *Fs) Chmod(name string, mode os.FileMode) error { return syscall.EROFS }
func (fs *Fs) Chtimes(name string, atime time.Time, mtime time.Time) error { return syscall.EROFS }