-

libs/filer/local_client.go

@@ -18,11 +18,8 @@ type LocalClient struct {
 }
 
 func NewLocalClient(root string) (Filer, error) {
-	if runtime.GOOS == "windows" && root == "/" {
-		// Windows file systems do not have a "root" directory. Instead paths require
-		// a Volume/Drive letter specified. This allows us to refer to files across
-		// different drives from a single client
-		return &LocalClient{root: NopRootPath{}}, nil
+	if runtime.GOOS == "windows" {
+		return &LocalClient{root: WindowsRootPath{root}}, nil
 	}
 	return &LocalClient{
 		root: NewUnixRootPath(root),

libs/filer/root_path.go

@@ -1,7 +1,12 @@
 package filer
 
+// RootPath can be joined with a relative path and ensures that
+// the returned path is always a strict child of the root path.
 type RootPath interface {
+	// Join returns the specified path name joined to the root.
+	// It returns an error if the resulting path is not a strict child of the root path.
 	Join(string) (string, error)
+
 	Root() string
 }
 

libs/filer/unix_root_path.go

@@ -6,8 +6,6 @@ import (
 	"strings"
 )
 
-// UnixRootPath can be joined with a relative path and ensures that
-// the returned path is always a strict child of the root path.
 type UnixRootPath struct {
 	rootPath string
 }
@@ -20,8 +18,6 @@ func NewUnixRootPath(name string) UnixRootPath {
 	}
 }
 
-// Join returns the specified path name joined to the root.
-// It returns an error if the resulting path is not a strict child of the root path.
 func (p UnixRootPath) Join(name string) (string, error) {
 	absPath := path.Join(p.rootPath, name)
 

libs/filer/windows_root_path.go

@@ -0,0 +1,39 @@
+package filer
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+)
+
+type WindowsRootPath struct {
+	rootPath string
+}
+
+func NewWindowsRootPath(name string) WindowsRootPath {
+	// Windows file systems do not have a "root" directory. Instead paths require
+	// a Volume/Drive letter specified. If a user of this struct specifies "/" then
+	// we treat it as the "root" and skip any validation
+	if name == "/" {
+		return WindowsRootPath{""}
+	}
+
+	return WindowsRootPath{filepath.Clean(name)}
+}
+
+// Join returns the specified path name joined to the root.
+// It returns an error if the resulting path is not a strict child of the root path.
+func (p WindowsRootPath) Join(name string) (string, error) {
+	absPath := filepath.Join(p.rootPath, name)
+
+	// Don't allow escaping the specified root using relative paths.
+	if !strings.HasPrefix(absPath, p.rootPath) {
+		return "", fmt.Errorf("relative path escapes root: %s", name)
+	}
+
+	return absPath, nil
+}
+
+func (p WindowsRootPath) Root() string {
+	return p.rootPath
+}

libs/filer/windows_root_path_test.go

@@ -0,0 +1,63 @@
+package filer
+
+import (
+	"runtime"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWindowsRootPathForRoot(t *testing.T) {
+	if runtime.GOOS != "windows" {
+		t.Skip("this test is meant for windows")
+	}
+
+	rp := NewWindowsRootPath("/")
+
+	// Assert root value returned
+	assert.Equal(t, "", rp.Root())
+
+	// case: absolute windows path
+	path, err := rp.Join(`c:\a\b`)
+	assert.NoError(t, err)
+	assert.Equal(t, `c:\a\b`, path)
+
+	// case: absolute windows path following file URI scheme
+	path, err = rp.Join(`D:/a/b`)
+	assert.NoError(t, err)
+	assert.Equal(t, `D:/a/b`, path)
+
+	// case: relative windows paths
+	path, err = rp.Join(`c:a\b`)
+	assert.NoError(t, err)
+	assert.Equal(t, `c:a\b`, path)
+
+	path, err = rp.Join(`c:a`)
+	assert.NoError(t, err)
+	assert.Equal(t, `c:a`, path)
+
+	// case: relative windows paths following file URI scheme
+	path, err = rp.Join(`c:a/b`)
+	assert.NoError(t, err)
+	assert.Equal(t, `C:a/b`, path)
+}
+
+func TestWindowsRootPath(t *testing.T) {
+	if runtime.GOOS != "windows" {
+		t.Skip("this test is meant for windows")
+	}
+
+	tmpDir := t.TempDir()
+	rp := NewWindowsRootPath(t.TempDir())
+
+	// Assert root value returned
+	assert.Equal(t, tmpDir, rp.Root())
+
+	path, err := rp.Join(`a\b\c`)
+	assert.NoError(t, err)
+	assert.Equal(t, tmpDir+`\a\b`, path)
+
+	path, err = rp.Join("a/b")
+	assert.NoError(t, err)
+	assert.Equal(t, tmpDir + `\a/b`, path)
+}