m/p/efivarfs: refactor
This accomplishes three things:
First, split out the variable access layer from the rest of the code.
This cleans up the attribute handling, which is now done centrally as
well as making the high-level functions very short and clean. They now
also return better errors.
Second this introduces proper types for LoadOption, which can now also
be unmarshaled which was a requirement for A/B updates. This required
implementation of EFI's DevicePath structure.
While refactoring the higher-level functions for this, this also
fixes a bug where the variable index (the 4 hex nibbles at the end) were
improperly generated as lowercase hex.
Third, this adds new high-level functions for interacting with more
boot-related variables needed for the A/B effort.
Change-Id: I53490fa4898a5e7a5498ecc05a9078bd2d66c26e
Reviewed-on: https://review.monogon.dev/c/monogon/+/1855
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/metropolis/pkg/efivarfs/devicepath_test.go b/metropolis/pkg/efivarfs/devicepath_test.go
new file mode 100644
index 0000000..b5823ac
--- /dev/null
+++ b/metropolis/pkg/efivarfs/devicepath_test.go
@@ -0,0 +1,89 @@
+package efivarfs
+
+import (
+ "bytes"
+ "testing"
+
+ "github.com/google/uuid"
+)
+
+func TestMarshalExamples(t *testing.T) {
+ cases := []struct {
+ name string
+ path DevicePath
+ expected []byte
+ expectError bool
+ }{
+ {
+ name: "TestNone",
+ path: DevicePath{},
+ expected: []byte{
+ 0x7f, 0xff, // End of HW device path
+ 0x04, 0x00, // Length: 4 bytes
+ },
+ },
+ {
+ // From UEFI Device Path Examples, extracted single entry
+ name: "TestHD",
+ path: DevicePath{
+ &HardDrivePath{
+ PartitionNumber: 1,
+ PartitionStartBlock: 0x22,
+ PartitionSizeBlocks: 0x2710000,
+ PartitionMatch: PartitionGPT{
+ PartitionUUID: uuid.MustParse("15E39A00-1DD2-1000-8D7F-00A0C92408FC"),
+ },
+ },
+ },
+ expected: []byte{
+ 0x04, 0x01, // Hard Disk type
+ 0x2a, 0x00, // Length
+ 0x01, 0x00, 0x00, 0x00, // Partition Number
+ 0x22, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Part Start
+ 0x00, 0x00, 0x71, 0x02, 0x00, 0x00, 0x00, 0x00, // Part Size
+ 0x00, 0x9a, 0xe3, 0x15, 0xd2, 0x1d, 0x00, 0x10,
+ 0x8d, 0x7f, 0x00, 0xa0, 0xc9, 0x24, 0x08, 0xfc, // Signature
+ 0x02, // Part Format GPT
+ 0x02, // Signature GPT
+ 0x7f, 0xff, // End of HW device path
+ 0x04, 0x00, // Length: 4 bytes
+ },
+ },
+ {
+ name: "TestFilePath",
+ path: DevicePath{
+ FilePath("asdf"),
+ },
+ expected: []byte{
+ 0x04, 0x04, // File Path type
+ 0x0e, 0x00, // Length
+ 'a', 0x00, 's', 0x00, 'd', 0x00, 'f', 0x00,
+ 0x00, 0x00,
+ 0x7f, 0xff, // End of HW device path
+ 0x04, 0x00, // Length: 4 bytes
+ },
+ },
+ }
+
+ for _, c := range cases {
+ t.Run(c.name, func(t *testing.T) {
+ got, err := c.path.Marshal()
+ if err != nil && !c.expectError {
+ t.Fatalf("unexpected error: %v", err)
+ }
+ if err == nil && c.expectError {
+ t.Fatalf("expected error, got %x", got)
+ }
+ if err != nil && c.expectError {
+ // Do not compare result in case error is expected
+ return
+ }
+ if !bytes.Equal(got, c.expected) {
+ t.Fatalf("expected %x, got %x", c.expected, got)
+ }
+ if _, err := UnmarshalDevicePath(got); err != nil {
+ t.Errorf("failed to unmarshal value again: %v", err)
+ }
+ })
+ }
+}