Fixing PAX Header handling (#8086)

* Fixing issue with PAX headers in plugin archive

PAX Headers can be added by some systems that create archives. Helm
should ignore them when extracting.

There are two PAX headers. One is global and the other is not. Both
are ignored. The test adds only the PAX global header because the
Go tar package is unable to write the header that is not global.

Closes #8084

Signed-off-by: Matt Farina <matt@mattfarina.com>

* Removing the PAX header test as it is not working

The PAX header test was making a WriteHeader call and ignoring the
error. When writing the type TypeXHeader it was causing an error
that was being silently ignored. The Go tar package cannot write
this type and produces an error when one tries to. The error reads
"cannot manually encode TypeXHeader, TypeGNULongName, or TypeGNULongLink
headers"

Signed-off-by: Matt Farina <matt@mattfarina.com>

* Adding check of returned error in test

Adding a check for the returned error to make sure a non-nil value
is not returned.

Signed-off-by: Matt Farina <matt@mattfarina.com>

pkg/chart/loader/archive_test.go

@@ -43,46 +43,26 @@ func TestLoadArchiveFiles(t *testing.T) {
 			generate: func(w *tar.Writer) {
 				// simulate the presence of a `pax_global_header` file like you would get when
 				// processing a GitHub release archive.
-				_ = w.WriteHeader(&tar.Header{
+				err := w.WriteHeader(&tar.Header{
 					Typeflag: tar.TypeXGlobalHeader,
 					Name:     "pax_global_header",
 				})
-
-				// we need to have at least one file, otherwise we'll get the "no files in chart archive" error
-				_ = w.WriteHeader(&tar.Header{
-					Typeflag: tar.TypeReg,
-					Name:     "dir/empty",
-				})
-			},
-			check: func(t *testing.T, files []*BufferedFile, err error) {
 				if err != nil {
-					t.Fatalf(`got unwanted error [%#v] for tar file with pax_global_header content`, err)
+					t.Fatal(err)
 				}
 
-				if len(files) != 1 {
-					t.Fatalf(`expected to get one file but got [%v]`, files)
-				}
-			},
-		},
-		{
-			name: "should ignore files with TypeXHeader type",
-			generate: func(w *tar.Writer) {
-				// simulate the presence of a `pax_header` file like you might get when
-				// processing a GitHub release archive.
-				_ = w.WriteHeader(&tar.Header{
-					Typeflag: tar.TypeXHeader,
-					Name:     "pax_header",
-				})
-
 				// we need to have at least one file, otherwise we'll get the "no files in chart archive" error
-				_ = w.WriteHeader(&tar.Header{
+				err = w.WriteHeader(&tar.Header{
 					Typeflag: tar.TypeReg,
 					Name:     "dir/empty",
 				})
+				if err != nil {
+					t.Fatal(err)
+				}
 			},
 			check: func(t *testing.T, files []*BufferedFile, err error) {
 				if err != nil {
-					t.Fatalf(`got unwanted error [%#v] for tar file with pax_header content`, err)
+					t.Fatalf(`got unwanted error [%#v] for tar file with pax_global_header content`, err)
 				}
 
 				if len(files) != 1 {

pkg/plugin/installer/http_installer.go

@@ -188,6 +188,9 @@ func (g *TarGzExtractor) Extract(buffer *bytes.Buffer, targetDir string) error {
 				return err
 			}
 			outFile.Close()
+		// We don't want to process these extension header files.
+		case tar.TypeXGlobalHeader, tar.TypeXHeader:
+			continue
 		default:
 			return errors.Errorf("unknown type: %b in %s", header.Typeflag, header.Name)
 		}

pkg/plugin/installer/http_installer_test.go

@@ -222,6 +222,19 @@ func TestExtract(t *testing.T) {
 			t.Fatal(err)
 		}
 	}
+
+	// Add pax global headers. This should be ignored.
+	// Note the PAX header that isn't global cannot be written using WriteHeader.
+	// Details are in the internal Go function for the tar packaged named
+	// allowedFormats. For a TypeXHeader it will return a message stating
+	// "cannot manually encode TypeXHeader, TypeGNULongName, or TypeGNULongLink headers"
+	if err := tw.WriteHeader(&tar.Header{
+		Name:     "pax_global_header",
+		Typeflag: tar.TypeXGlobalHeader,
+	}); err != nil {
+		t.Fatal(err)
+	}
+
 	if err := tw.Close(); err != nil {
 		t.Fatal(err)
 	}