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936084890a
The existing implementation of NameSpace implicitly assumes that a
FileSystem with a directory at the top will be mounted at the root
mount point "/" of the NameSpace. If this is not the case, then
Stat("/") will fail even if ReadDir("/") succeedes. This is unexpected
behavior which breaks directory traversal routines (eg. http.FileServer).
This CL adds an unexported implementation of FileSystem called emptyVFS
that emulates an empty directory and adds a NewNameSpace() function that
binds emptyVFS to "/" so that unexpected behavior does not arise even if
the use does not mount anything explicitly at "/".
Latest patch set causes the FileInfo of the empty top level emulated
directory to return "/" for Name() and Zero Time for ModTime() and
removes the related struct state fields being used in the previous
implementation.
Fixes golang/go#14190
Change-Id: Idce2fc3c9b81206847a33840d76b660059d53d18
Reviewed-on: https://go-review.googlesource.com/19445
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
86 lines
2.0 KiB
Go
86 lines
2.0 KiB
Go
// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package vfs
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import (
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"fmt"
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"os"
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"time"
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)
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// NewNameSpace returns a NameSpace pre-initialized with an empty
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// emulated directory mounted on the root mount point "/". This
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// allows directory traversal routines to work properly even if
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// a folder is not explicitly mounted at root by the user.
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func NewNameSpace() NameSpace {
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ns := NameSpace{}
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ns.Bind("/", &emptyVFS{}, "/", BindReplace)
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return ns
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}
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// type emptyVFS emulates a FileSystem consisting of an empty directory
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type emptyVFS struct{}
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// Open implements Opener. Since emptyVFS is an empty directory, all
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// attempts to open a file should returns errors.
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func (e *emptyVFS) Open(path string) (ReadSeekCloser, error) {
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if path == "/" {
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return nil, fmt.Errorf("open: / is a directory")
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}
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return nil, os.ErrNotExist
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}
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// Stat returns os.FileInfo for an empty directory if the path is
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// is root "/" or error. os.FileInfo is implemented by emptyVFS
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func (e *emptyVFS) Stat(path string) (os.FileInfo, error) {
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if path == "/" {
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return e, nil
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}
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return nil, os.ErrNotExist
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}
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func (e *emptyVFS) Lstat(path string) (os.FileInfo, error) {
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return e.Stat(path)
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}
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// ReadDir returns an empty os.FileInfo slice for "/", else error.
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func (e *emptyVFS) ReadDir(path string) ([]os.FileInfo, error) {
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if path == "/" {
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return []os.FileInfo{}, nil
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}
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return nil, os.ErrNotExist
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}
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func (e *emptyVFS) String() string {
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return "emptyVFS(/)"
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}
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// These functions below implement os.FileInfo for the single
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// empty emulated directory.
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func (e *emptyVFS) Name() string {
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return "/"
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}
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func (e *emptyVFS) Size() int64 {
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return 0
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}
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func (e *emptyVFS) Mode() os.FileMode {
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return os.ModeDir | os.ModePerm
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}
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func (e *emptyVFS) ModTime() time.Time {
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return time.Time{}
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}
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func (e *emptyVFS) IsDir() bool {
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return true
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}
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func (e *emptyVFS) Sys() interface{} {
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return nil
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}
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