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// Copyright 2024 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.
//go:build (js && wasm) || plan9
package os
import (
"errors"
"internal/filepathlite"
"internal/stringslite"
"sync/atomic"
"syscall"
"time"
)
// root implementation for platforms with no openat.
// Currently plan9 and js.
type root struct {
name string
closed atomic.Bool
}
// openRootNolog is OpenRoot.
func openRootNolog(name string) (*Root, error) {
r, err := newRoot(name)
if err != nil {
return nil, &PathError{Op: "open", Path: name, Err: err}
}
return r, nil
}
// openRootInRoot is Root.OpenRoot.
func openRootInRoot(r *Root, name string) (*Root, error) {
if err := checkPathEscapes(r, name); err != nil {
return nil, &PathError{Op: "openat", Path: name, Err: err}
}
r, err := newRoot(joinPath(r.root.name, name))
if err != nil {
return nil, &PathError{Op: "openat", Path: name, Err: err}
}
return r, nil
}
// newRoot returns a new Root.
// If fd is not a directory, it closes it and returns an error.
func newRoot(name string) (*Root, error) {
fi, err := Stat(name)
if err != nil {
return nil, err.(*PathError).Err
}
if !fi.IsDir() {
return nil, errors.New("not a directory")
}
return &Root{&root{name: name}}, nil
}
func (r *root) Close() error {
// For consistency with platforms where Root.Close closes a handle,
// mark the Root as closed and return errors from future calls.
r.closed.Store(true)
return nil
}
func (r *root) Name() string {
return r.name
}
// rootOpenFileNolog is Root.OpenFile.
func rootOpenFileNolog(r *Root, name string, flag int, perm FileMode) (*File, error) {
if err := checkPathEscapes(r, name); err != nil {
return nil, &PathError{Op: "openat", Path: name, Err: err}
}
f, err := openFileNolog(joinPath(r.root.name, name), flag, perm)
if err != nil {
return nil, &PathError{Op: "openat", Path: name, Err: underlyingError(err)}
}
return f, nil
}
func rootStat(r *Root, name string, lstat bool) (FileInfo, error) {
var fi FileInfo
var err error
if lstat {
err = checkPathEscapesLstat(r, name)
if err == nil {
fi, err = Lstat(joinPath(r.root.name, name))
}
} else {
err = checkPathEscapes(r, name)
if err == nil {
fi, err = Stat(joinPath(r.root.name, name))
}
}
if err != nil {
return nil, &PathError{Op: "statat", Path: name, Err: underlyingError(err)}
}
return fi, nil
}
func rootChmod(r *Root, name string, mode FileMode) error {
if err := checkPathEscapes(r, name); err != nil {
return &PathError{Op: "chmodat", Path: name, Err: err}
}
if err := Chmod(joinPath(r.root.name, name), mode); err != nil {
return &PathError{Op: "chmodat", Path: name, Err: underlyingError(err)}
}
return nil
}
func rootChown(r *Root, name string, uid, gid int) error {
if err := checkPathEscapes(r, name); err != nil {
return &PathError{Op: "chownat", Path: name, Err: err}
}
if err := Chown(joinPath(r.root.name, name), uid, gid); err != nil {
return &PathError{Op: "chownat", Path: name, Err: underlyingError(err)}
}
return nil
}
func rootLchown(r *Root, name string, uid, gid int) error {
if err := checkPathEscapesLstat(r, name); err != nil {
return &PathError{Op: "lchownat", Path: name, Err: err}
}
if err := Lchown(joinPath(r.root.name, name), uid, gid); err != nil {
return &PathError{Op: "lchownat", Path: name, Err: underlyingError(err)}
}
return nil
}
func rootChtimes(r *Root, name string, atime time.Time, mtime time.Time) error {
if err := checkPathEscapes(r, name); err != nil {
return &PathError{Op: "chtimesat", Path: name, Err: err}
}
if err := Chtimes(joinPath(r.root.name, name), atime, mtime); err != nil {
return &PathError{Op: "chtimesat", Path: name, Err: underlyingError(err)}
}
return nil
}
func rootMkdir(r *Root, name string, perm FileMode) error {
if err := checkPathEscapes(r, name); err != nil {
return &PathError{Op: "mkdirat", Path: name, Err: err}
}
if err := Mkdir(joinPath(r.root.name, name), perm); err != nil {
return &PathError{Op: "mkdirat", Path: name, Err: underlyingError(err)}
}
return nil
}
func rootMkdirAll(r *Root, name string, perm FileMode) error {
// We only check for errPathEscapes here.
// For errors such as ENOTDIR (a non-directory file appeared somewhere along the path),
// we let MkdirAll generate the error.
// MkdirAll will return a PathError referencing the exact location of the error,
// and we want to preserve that property.
if err := checkPathEscapes(r, name); err == errPathEscapes {
return &PathError{Op: "mkdirat", Path: name, Err: err}
}
prefix := r.root.name + string(PathSeparator)
if err := MkdirAll(prefix+name, perm); err != nil {
if pe, ok := err.(*PathError); ok {
pe.Op = "mkdirat"
pe.Path = stringslite.TrimPrefix(pe.Path, prefix)
return pe
}
return &PathError{Op: "mkdirat", Path: name, Err: underlyingError(err)}
}
return nil
}
func rootRemove(r *Root, name string) error {
if err := checkPathEscapesLstat(r, name); err != nil {
return &PathError{Op: "removeat", Path: name, Err: err}
}
if endsWithDot(name) {
// We don't want to permit removing the root itself, so check for that.
if filepathlite.Clean(name) == "." {
return &PathError{Op: "removeat", Path: name, Err: errPathEscapes}
}
}
if err := Remove(joinPath(r.root.name, name)); err != nil {
return &PathError{Op: "removeat", Path: name, Err: underlyingError(err)}
}
return nil
}
func rootRemoveAll(r *Root, name string) error {
if endsWithDot(name) {
// Consistency with os.RemoveAll: Return EINVAL when trying to remove .
return &PathError{Op: "RemoveAll", Path: name, Err: syscall.EINVAL}
}
if err := checkPathEscapesLstat(r, name); err != nil {
if err == syscall.ENOTDIR {
// Some intermediate path component is not a directory.
// RemoveAll treats this as success (since the target doesn't exist).
return nil
}
return &PathError{Op: "RemoveAll", Path: name, Err: err}
}
if err := RemoveAll(joinPath(r.root.name, name)); err != nil {
return &PathError{Op: "RemoveAll", Path: name, Err: underlyingError(err)}
}
return nil
}
func rootReadlink(r *Root, name string) (string, error) {
if err := checkPathEscapesLstat(r, name); err != nil {
return "", &PathError{Op: "readlinkat", Path: name, Err: err}
}
name, err := Readlink(joinPath(r.root.name, name))
if err != nil {
return "", &PathError{Op: "readlinkat", Path: name, Err: underlyingError(err)}
}
return name, nil
}
func rootRename(r *Root, oldname, newname string) error {
if err := checkPathEscapesLstat(r, oldname); err != nil {
return &PathError{Op: "renameat", Path: oldname, Err: err}
}
if err := checkPathEscapesLstat(r, newname); err != nil {
return &PathError{Op: "renameat", Path: newname, Err: err}
}
err := Rename(joinPath(r.root.name, oldname), joinPath(r.root.name, newname))
if err != nil {
return &LinkError{"renameat", oldname, newname, underlyingError(err)}
}
return nil
}
func rootLink(r *Root, oldname, newname string) error {
if err := checkPathEscapesLstat(r, oldname); err != nil {
return &PathError{Op: "linkat", Path: oldname, Err: err}
}
fullOldName := joinPath(r.root.name, oldname)
if fs, err := Lstat(fullOldName); err == nil && fs.Mode()&ModeSymlink != 0 {
return &PathError{Op: "linkat", Path: oldname, Err: errors.New("cannot create a hard link to a symlink")}
}
if err := checkPathEscapesLstat(r, newname); err != nil {
return &PathError{Op: "linkat", Path: newname, Err: err}
}
err := Link(fullOldName, joinPath(r.root.name, newname))
if err != nil {
return &LinkError{"linkat", oldname, newname, underlyingError(err)}
}
return nil
}
func rootSymlink(r *Root, oldname, newname string) error {
if err := checkPathEscapesLstat(r, newname); err != nil {
return &PathError{Op: "symlinkat", Path: newname, Err: err}
}
err := Symlink(oldname, joinPath(r.root.name, newname))
if err != nil {
return &LinkError{"symlinkat", oldname, newname, underlyingError(err)}
}
return nil
}
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