efivarfs, osimage: fix boot entry handling
efivarfs was updated to handle partition UUIDs in the mixed-endian
format [1], enabling it to produce correct boot entries. Its interface
was changed in the process, leading to further changes in osimage.
In addition, BootEntry.Marshal will replace any backslash with a
forward slash in the EFI executable path.
[1] https://en.wikipedia.org/wiki/Universally_unique_identifier#Encoding
Change-Id: Ib8300e01fd1664d0c08bb033b1dc36addb925b20
Reviewed-on: https://review.monogon.dev/c/monogon/+/456
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/metropolis/pkg/efivarfs/format.go b/metropolis/pkg/efivarfs/format.go
new file mode 100644
index 0000000..a71dbf9
--- /dev/null
+++ b/metropolis/pkg/efivarfs/format.go
@@ -0,0 +1,33 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package efivarfs
+
+import (
+ "github.com/google/uuid"
+)
+
+// MarshalEFIGUID returns src represented in the EFI GUID format, as defined in
+// UEFI specification, version 2.9, appendix A:
+// https://uefi.org/sites/default/files/resources/UEFI_Spec_2_9_2021_03_18.pdf
+func MarshalEFIGUID(src uuid.UUID) []byte {
+ efi := make([]byte, 16)
+ transform := []int{3, 2, 1, 0, 5, 4, 7, 6, 8, 9, 10, 11, 12, 13, 14, 15}
+ for dest, from := range transform {
+ efi[dest] = src[from]
+ }
+ return efi
+}