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