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- // Copyright (C) 2016 The Syncthing Authors.
- //
- // This Source Code Form is subject to the terms of the Mozilla Public
- // License, v. 2.0. If a copy of the MPL was not distributed with this file,
- // You can obtain one at https://mozilla.org/MPL/2.0/.
- package osutil
- import (
- "fmt"
- "path/filepath"
- "strings"
- "github.com/syncthing/syncthing/lib/fs"
- )
- // TraversesSymlinkError is an error indicating symlink traversal
- type TraversesSymlinkError struct {
- path string
- }
- func (e TraversesSymlinkError) Error() string {
- return fmt.Sprintf("traverses symlink: %s", e.path)
- }
- // NotADirectoryError is an error indicating an expected path is not a directory
- type NotADirectoryError struct {
- path string
- }
- func (e NotADirectoryError) Error() string {
- return fmt.Sprintf("not a directory: %s", e.path)
- }
- // TraversesSymlink returns an error if base and any path component of name up to and
- // including filepath.Join(base, name) traverses a symlink.
- // Base and name must both be clean and name must be relative to base.
- func TraversesSymlink(filesystem fs.Filesystem, name string) error {
- base := "."
- path := base
- info, err := filesystem.Lstat(path)
- if err != nil {
- return err
- }
- if !info.IsDir() {
- return &NotADirectoryError{
- path: base,
- }
- }
- if name == "." {
- // The result of calling TraversesSymlink("some/where", filepath.Dir("foo"))
- return nil
- }
- parts := strings.Split(name, string(fs.PathSeparator))
- for _, part := range parts {
- path = filepath.Join(path, part)
- info, err := filesystem.Lstat(path)
- if err != nil {
- if fs.IsNotExist(err) {
- return nil
- }
- return err
- }
- if info.IsSymlink() {
- return &TraversesSymlinkError{
- path: strings.TrimPrefix(path, base),
- }
- }
- if !info.IsDir() {
- return &NotADirectoryError{
- path: strings.TrimPrefix(path, base),
- }
- }
- }
- return nil
- }
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