helper: chroot dedicated test

Author: mcuadros

fs.go

@@ -18,23 +18,12 @@ var (
 // at the os package from the standard library.
 type Filesystem interface {
 	Basic
+	TempFile
 	Dir
 	Symlink
-	TempFile
 	Chroot
 }
 
-// Chroot abstract the chroot related operations in a storage-agnostic interface
-// as an extension to the Basic interface.
-type Chroot interface {
-	// Chroot returns a new filesystem from the same type where the new root is
-	// the given path. Files outside of the designated directory tree cannot be
-	// accessed.
-	Chroot(path string) (Basic, error)
-	// Root returns the root path of the filesystem.
-	Root() string
-}
-
 // Basic abstract the basic operations in a storage-agnostic interface as
 // an extension to the Basic interface.
 type Basic interface {
@@ -72,8 +61,14 @@ type Basic interface {
 }
 
 type TempFile interface {
-	// TempDir returns the default directory to use for temporary files.
-	//TempDir() string
+	// TempFile creates a new temporary file in the directory dir with a name
+	// beginning with prefix, opens the file for reading and writing, and
+	// returns the resulting *os.File. If dir is the empty string, TempFile
+	// uses the default directory for temporary files (see os.TempDir).
+	// Multiple programs calling TempFile simultaneously will not choose the
+	// same file. The caller can use f.Name() to find the pathname of the file.
+	// It is the caller's responsibility to remove the file when no longer
+	// needed.
 	TempFile(dir, prefix string) (File, error)
 }
 
@@ -129,19 +124,31 @@ type Change interface {
 	Chtimes(name string, atime time.Time, mtime time.Time) error
 }
 
+// Chroot abstract the chroot related operations in a storage-agnostic interface
+// as an extension to the Basic interface.
+type Chroot interface {
+	// Chroot returns a new filesystem from the same type where the new root is
+	// the given path. Files outside of the designated directory tree cannot be
+	// accessed.
+	Chroot(path string) (Basic, error)
+	// Root returns the root path of the filesystem.
+	Root() string
+}
+
+type underlying interface {
+	Underlying() Basic
+}
+type removerAll interface {
+	RemoveAll(string) error
+}
+
 // File represent a file, being a subset of the os.File
 type File interface {
 	// Name returns the name of the file as presented to Open.
 	Name() string
-	// Stat returns the FileInfo structure describing file. If there is an
-	// error, it will be of type *PathError.
-	//	Stat() (os.FileInfo, error)
 	io.Writer
 	io.Reader
+	io.ReaderAt
 	io.Seeker
 	io.Closer
 }
-
-type removerAll interface {
-	RemoveAll(string) error
-}

helper/chroot/chroot.go

@@ -1,29 +1,33 @@
 package chroot
 
 import (
-	"errors"
 	"os"
 	"path/filepath"
 	"strings"
 
 	"gopkg.in/src-d/go-billy.v2"
 )
 
-// ErrSymlinkNotSupported is returned by Symlink() and Readfile() if the
-// underlying filesystem does not support symlinking.
-var ErrSymlinkNotSupported = errors.New("symlink not supported")
-
 // ChrootHelper is a helper to implement billy.Chroot.
 type ChrootHelper struct {
-	underlying billy.Filesystem
+	underlying billy.Basic
 	base       string
+
+	tempFileSupport bool
+	dirSupport      bool
+	symlinkSupport  bool
 }
 
 // New creates a new filesystem wrapping up the given 'fs'.
 // The created filesystem has its base in the given ChrootHelperectory of the
 // underlying filesystem.
-func New(fs billy.Filesystem, base string) billy.Filesystem {
-	return &ChrootHelper{fs, base}
+func New(fs billy.Basic, base string) billy.Filesystem {
+	helper := &ChrootHelper{underlying: fs, base: base}
+	_, helper.tempFileSupport = fs.(billy.TempFile)
+	_, helper.dirSupport = fs.(billy.Dir)
+	_, helper.symlinkSupport = fs.(billy.Symlink)
+
+	return helper
 }
 
 func (fs *ChrootHelper) underlyingPath(filename string) (string, error) {
@@ -83,18 +87,13 @@ func (fs *ChrootHelper) OpenFile(filename string, flag int, mode os.FileMode) (b
 	return newFile(fs, f, filename), nil
 }
 
-func (fs *ChrootHelper) TempFile(dir, prefix string) (billy.File, error) {
-	fullpath, err := fs.underlyingPath(dir)
-	if err != nil {
-		return nil, err
-	}
-
-	f, err := fs.underlying.TempFile(fullpath, prefix)
+func (fs *ChrootHelper) Stat(filename string) (os.FileInfo, error) {
+	fullpath, err := fs.underlyingPath(filename)
 	if err != nil {
 		return nil, err
 	}
 
-	return newFile(fs, f, fs.Join(dir, filepath.Base(f.Name()))), nil
+	return fs.underlying.Stat(fullpath)
 }
 
 func (fs *ChrootHelper) Rename(from, to string) error {
@@ -121,52 +120,78 @@ func (fs *ChrootHelper) Remove(path string) error {
 	return fs.underlying.Remove(fullpath)
 }
 
-func (fs *ChrootHelper) MkdirAll(filename string, perm os.FileMode) error {
-	fullpath, err := fs.underlyingPath(filename)
+func (fs *ChrootHelper) Join(elem ...string) string {
+	return fs.underlying.Join(elem...)
+}
+
+func (fs *ChrootHelper) TempFile(dir, prefix string) (billy.File, error) {
+	if !fs.tempFileSupport {
+		return nil, billy.ErrNotSupported
+	}
+
+	fullpath, err := fs.underlyingPath(dir)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
-	return fs.underlying.MkdirAll(fullpath, perm)
+	f, err := fs.underlying.(billy.TempFile).TempFile(fullpath, prefix)
+	if err != nil {
+		return nil, err
+	}
+
+	return newFile(fs, f, fs.Join(dir, filepath.Base(f.Name()))), nil
 }
 
-func (fs *ChrootHelper) Stat(filename string) (os.FileInfo, error) {
-	fullpath, err := fs.underlyingPath(filename)
+func (fs *ChrootHelper) ReadDir(path string) ([]os.FileInfo, error) {
+	if !fs.dirSupport {
+		return nil, billy.ErrNotSupported
+	}
+
+	fullpath, err := fs.underlyingPath(path)
 	if err != nil {
 		return nil, err
 	}
 
-	return fs.underlying.Stat(fullpath)
+	return fs.underlying.(billy.Dir).ReadDir(fullpath)
 }
 
-func (fs *ChrootHelper) Lstat(filename string) (os.FileInfo, error) {
+func (fs *ChrootHelper) MkdirAll(filename string, perm os.FileMode) error {
+	if !fs.dirSupport {
+		return billy.ErrNotSupported
+	}
+
 	fullpath, err := fs.underlyingPath(filename)
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return fs.underlying.Lstat(fullpath)
+	return fs.underlying.(billy.Dir).MkdirAll(fullpath, perm)
 }
 
-func (fs *ChrootHelper) ReadDir(path string) ([]os.FileInfo, error) {
-	fullpath, err := fs.underlyingPath(path)
+func (fs *ChrootHelper) Lstat(filename string) (os.FileInfo, error) {
+	if !fs.symlinkSupport {
+		return nil, billy.ErrNotSupported
+	}
+
+	fullpath, err := fs.underlyingPath(filename)
 	if err != nil {
 		return nil, err
 	}
 
-	return fs.underlying.ReadDir(fullpath)
-}
-
-func (fs *ChrootHelper) Join(elem ...string) string {
-	return fs.underlying.Join(elem...)
+	return fs.underlying.(billy.Symlink).Lstat(fullpath)
 }
 
 func (fs *ChrootHelper) Symlink(target, link string) error {
+	if !fs.symlinkSupport {
+		return billy.ErrNotSupported
+	}
+
 	target = filepath.FromSlash(target)
 
 	// only rewrite target if it's already absolute
 	if filepath.IsAbs(target) || strings.HasPrefix(target, string(filepath.Separator)) {
 		target = fs.Join(fs.Root(), target)
+		target = filepath.Clean(filepath.FromSlash(target))
 	}
 
 	if fs.isTargetOutBounders(link, target) {
@@ -178,7 +203,7 @@ func (fs *ChrootHelper) Symlink(target, link string) error {
 		return err
 	}
 
-	return fs.underlying.Symlink(target, link)
+	return fs.underlying.(billy.Symlink).Symlink(target, link)
 }
 
 func (fs *ChrootHelper) isTargetOutBounders(link, target string) bool {
@@ -193,12 +218,16 @@ func (fs *ChrootHelper) isTargetOutBounders(link, target string) bool {
 }
 
 func (fs *ChrootHelper) Readlink(link string) (string, error) {
+	if !fs.symlinkSupport {
+		return "", billy.ErrNotSupported
+	}
+
 	fullpath, err := fs.underlyingPath(link)
 	if err != nil {
 		return "", err
 	}
 
-	target, err := fs.underlying.Readlink(fullpath)
+	target, err := fs.underlying.(billy.Symlink).Readlink(fullpath)
 	if err != nil {
 		return "", err
 	}
@@ -227,3 +256,26 @@ func (fs *ChrootHelper) Chroot(path string) (billy.Basic, error) {
 func (fs *ChrootHelper) Root() string {
 	return fs.base
 }
+
+func (fs *ChrootHelper) Underlying() billy.Basic {
+	return fs.underlying
+}
+
+type file struct {
+	billy.File
+	name string
+}
+
+func newFile(fs billy.Filesystem, f billy.File, filename string) billy.File {
+	filename = fs.Join(fs.Root(), filename)
+	filename, _ = filepath.Rel(fs.Root(), filename)
+
+	return &file{
+		File: f,
+		name: filename,
+	}
+}
+
+func (f *file) Name() string {
+	return f.name
+}