memfs: more portable file handling; test relative RemoveAll

* test: add test passing a relative path to RemoveAll.

* memfs: simplify isInDir code using path package.

memfs/memory.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path"
 	"path/filepath"
 	"strings"
 	"time"
@@ -392,15 +393,18 @@ func isWriteOnly(flag int) bool {
 	return flag&os.O_WRONLY != 0
 }
 
-func isInDir(dir, path string) bool {
-	p, err := filepath.Rel(dir, path)
-	if err != nil {
-		return false
-	}
+func isInDir(dir, other string) bool {
+	dir = path.Clean(dir)
+	dir = toTrailingSlash(dir)
+	other = path.Clean(other)
+
+	return strings.HasPrefix(other, dir)
+}
 
-	if p == "." || p == ".." {
-		return false
+func toTrailingSlash(p string) string {
+	if strings.HasSuffix(p, "/") {
+		return p
 	}
 
-	return !strings.HasPrefix(p, "../")
+	return p + "/"
 }

test/fs_suite.go

@@ -542,3 +542,30 @@ func (s *FilesystemSuite) TestRemoveAll(c *C) {
 		c.Assert(os.IsNotExist(err), Equals, true, comment)
 	}
 }
+
+func (s *FilesystemSuite) TestRemoveAllRelative(c *C) {
+	fnames := []string{
+		"foo/1",
+		"foo/2",
+		"foo/bar/1",
+		"foo/bar/2",
+		"foo/bar/baz/1",
+		"foo/bar/baz/qux/1",
+		"foo/bar/baz/qux/2",
+		"foo/bar/baz/qux/3",
+	}
+
+	for _, fname := range fnames {
+		f, err := s.Fs.Create(fname)
+		c.Assert(err, IsNil)
+		c.Assert(f.Close(), IsNil)
+	}
+
+	c.Assert(RemoveAll(s.Fs, "foo/bar/.."), IsNil)
+
+	for _, fname := range fnames {
+		_, err := s.Fs.Stat(fname)
+		comment := Commentf("not removed: %s %s", fname, err)
+		c.Assert(os.IsNotExist(err), Equals, true, comment)
+	}
+}