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package afero
import (
"io/fs"
"os"
"path/filepath"
"runtime"
"strings"
"time"
)
var (
_ Lstater = (*BasePathFs)(nil)
_ fs.ReadDirFile = (*BasePathFile)(nil)
)
// The BasePathFs restricts all operations to a given path within an Fs.
// The given file name to the operations on this Fs will be prepended with
// the base path before calling the base Fs.
// Any file name (after filepath.Clean()) outside this base path will be
// treated as non existing file.
//
// Note that it does not clean the error messages on return, so you may
// reveal the real path on errors.
type BasePathFs struct {
source Fs
path string
}
type BasePathFile struct {
File
path string
}
func (f *BasePathFile) Name() string {
sourcename := f.File.Name()
return strings.TrimPrefix(sourcename, filepath.Clean(f.path))
}
func (f *BasePathFile) ReadDir(n int) ([]fs.DirEntry, error) {
if rdf, ok := f.File.(fs.ReadDirFile); ok {
return rdf.ReadDir(n)
}
return readDirFile{f.File}.ReadDir(n)
}
func NewBasePathFs(source Fs, path string) Fs {
return &BasePathFs{source: source, path: path}
}
// on a file outside the base path it returns the given file name and an error,
// else the given file with the base path prepended
func (b *BasePathFs) RealPath(name string) (path string, err error) {
if err := validateBasePathName(name); err != nil {
return name, err
}
bpath := filepath.Clean(b.path)
path = filepath.Clean(filepath.Join(bpath, name))
if !strings.HasPrefix(path, bpath) {
return name, os.ErrNotExist
}
return path, nil
}
func validateBasePathName(name string) error {
if runtime.GOOS != "windows" {
// Not much to do here;
// the virtual file paths all look absolute on *nix.
return nil
}
// On Windows a common mistake would be to provide an absolute OS path
// We could strip out the base part, but that would not be very portable.
if filepath.IsAbs(name) {
return os.ErrNotExist
}
return nil
}
func (b *BasePathFs) Chtimes(name string, atime, mtime time.Time) (err error) {
if name, err = b.RealPath(name); err != nil {
return &os.PathError{Op: "chtimes", Path: name, Err: err}
}
return b.source.Chtimes(name, atime, mtime)
}
func (b *BasePathFs) Chmod(name string, mode os.FileMode) (err error) {
if name, err = b.RealPath(name); err != nil {
return &os.PathError{Op: "chmod", Path: name, Err: err}
}
return b.source.Chmod(name, mode)
}
func (b *BasePathFs) Chown(name string, uid, gid int) (err error) {
if name, err = b.RealPath(name); err != nil {
return &os.PathError{Op: "chown", Path: name, Err: err}
}
return b.source.Chown(name, uid, gid)
}
func (b *BasePathFs) Name() string {
return "BasePathFs"
}
func (b *BasePathFs) Stat(name string) (fi os.FileInfo, err error) {
if name, err = b.RealPath(name); err != nil {
return nil, &os.PathError{Op: "stat", Path: name, Err: err}
}
return b.source.Stat(name)
}
func (b *BasePathFs) Rename(oldname, newname string) (err error) {
if oldname, err = b.RealPath(oldname); err != nil {
return &os.PathError{Op: "rename", Path: oldname, Err: err}
}
if newname, err = b.RealPath(newname); err != nil {
return &os.PathError{Op: "rename", Path: newname, Err: err}
}
return b.source.Rename(oldname, newname)
}
func (b *BasePathFs) RemoveAll(name string) (err error) {
if name, err = b.RealPath(name); err != nil {
return &os.PathError{Op: "remove_all", Path: name, Err: err}
}
return b.source.RemoveAll(name)
}
func (b *BasePathFs) Remove(name string) (err error) {
if name, err = b.RealPath(name); err != nil {
return &os.PathError{Op: "remove", Path: name, Err: err}
}
return b.source.Remove(name)
}
func (b *BasePathFs) OpenFile(name string, flag int, mode os.FileMode) (f File, err error) {
if name, err = b.RealPath(name); err != nil {
return nil, &os.PathError{Op: "openfile", Path: name, Err: err}
}
sourcef, err := b.source.OpenFile(name, flag, mode)
if err != nil {
return nil, err
}
return &BasePathFile{sourcef, b.path}, nil
}
func (b *BasePathFs) Open(name string) (f File, err error) {
if name, err = b.RealPath(name); err != nil {
return nil, &os.PathError{Op: "open", Path: name, Err: err}
}
sourcef, err := b.source.Open(name)
if err != nil {
return nil, err
}
return &BasePathFile{File: sourcef, path: b.path}, nil
}
func (b *BasePathFs) Mkdir(name string, mode os.FileMode) (err error) {
if name, err = b.RealPath(name); err != nil {
return &os.PathError{Op: "mkdir", Path: name, Err: err}
}
return b.source.Mkdir(name, mode)
}
func (b *BasePathFs) MkdirAll(name string, mode os.FileMode) (err error) {
if name, err = b.RealPath(name); err != nil {
return &os.PathError{Op: "mkdir", Path: name, Err: err}
}
return b.source.MkdirAll(name, mode)
}
func (b *BasePathFs) Create(name string) (f File, err error) {
if name, err = b.RealPath(name); err != nil {
return nil, &os.PathError{Op: "create", Path: name, Err: err}
}
sourcef, err := b.source.Create(name)
if err != nil {
return nil, err
}
return &BasePathFile{File: sourcef, path: b.path}, nil
}
func (b *BasePathFs) LstatIfPossible(name string) (os.FileInfo, bool, error) {
name, err := b.RealPath(name)
if err != nil {
return nil, false, &os.PathError{Op: "lstat", Path: name, Err: err}
}
if lstater, ok := b.source.(Lstater); ok {
return lstater.LstatIfPossible(name)
}
fi, err := b.source.Stat(name)
return fi, false, err
}
func (b *BasePathFs) SymlinkIfPossible(oldname, newname string) error {
oldname, err := b.RealPath(oldname)
if err != nil {
return &os.LinkError{Op: "symlink", Old: oldname, New: newname, Err: err}
}
newname, err = b.RealPath(newname)
if err != nil {
return &os.LinkError{Op: "symlink", Old: oldname, New: newname, Err: err}
}
if linker, ok := b.source.(Linker); ok {
return linker.SymlinkIfPossible(oldname, newname)
}
return &os.LinkError{Op: "symlink", Old: oldname, New: newname, Err: ErrNoSymlink}
}
func (b *BasePathFs) ReadlinkIfPossible(name string) (string, error) {
name, err := b.RealPath(name)
if err != nil {
return "", &os.PathError{Op: "readlink", Path: name, Err: err}
}
if reader, ok := b.source.(LinkReader); ok {
return reader.ReadlinkIfPossible(name)
}
return "", &os.PathError{Op: "readlink", Path: name, Err: ErrNoReadlink}
}
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