Add EROFS library
This adds a library to write EROFS filesystems. It supports most of the non-deprecated features the
filesystem supports other than extended inodes (which have no benefits for most use cases where EROFS would be
appropriate). EROFS's variable-length extent compression is partially implemented but it requires an LZ4
compressor with support for fixed-size output which Go's https://github.com/pierrec/lz4 doesn't have. This means
that VLE compression is currently not wired up.
This will be used later as a replacement for our current initramfs-based root filesystem.
Test Plan: Has both integration and some unit tests. Confirmed working for our whole rootfs.
X-Origin-Diff: phab/D692
GitOrigin-RevId: 8c52b45ea05c617c80047e99c04c2b63e1b60c7c
diff --git a/metropolis/pkg/erofs/compression_test.go b/metropolis/pkg/erofs/compression_test.go
new file mode 100644
index 0000000..8d5d656
--- /dev/null
+++ b/metropolis/pkg/erofs/compression_test.go
@@ -0,0 +1,91 @@
+// 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 erofs
+
+import (
+ "reflect"
+ "testing"
+)
+
+func TestEncodeSmallVLEBlock(t *testing.T) {
+ type args struct {
+ vals [2]uint16
+ blkaddr uint32
+ }
+ tests := []struct {
+ name string
+ args args
+ want [8]byte
+ }{
+ {
+ name: "Reference",
+ args: args{vals: [2]uint16{vleClusterTypeHead | 1527, vleClusterTypeNonhead | 1}, blkaddr: 1},
+ want: [8]byte{0xf7, 0x15, 0x01, 0x20, 0x01, 0x00, 0x00, 0x00},
+ },
+ }
+ for _, tt := range tests {
+ t.Run(tt.name, func(t *testing.T) {
+ if got := encodeSmallVLEBlock(tt.args.vals, tt.args.blkaddr); !reflect.DeepEqual(got, tt.want) {
+ t.Errorf("encodeSmallVLEBlock() = %v, want %v", got, tt.want)
+ }
+ })
+ }
+}
+
+func TestEncodeBigVLEBlock(t *testing.T) {
+ type args struct {
+ vals [16]uint16
+ blkaddr uint32
+ }
+ tests := []struct {
+ name string
+ args args
+ want [32]byte
+ }{
+ {
+ name: "Reference",
+ args: args{
+ vals: [16]uint16{
+ vleClusterTypeNonhead | 2,
+ vleClusterTypeHead | 1460,
+ vleClusterTypeNonhead | 1,
+ vleClusterTypeNonhead | 2,
+ vleClusterTypeHead | 2751,
+ vleClusterTypeNonhead | 1,
+ vleClusterTypeNonhead | 2,
+ vleClusterTypeHead | 940,
+ vleClusterTypeNonhead | 1,
+ vleClusterTypeHead | 3142,
+ vleClusterTypeNonhead | 1,
+ vleClusterTypeNonhead | 2,
+ vleClusterTypeHead | 1750,
+ vleClusterTypeNonhead | 1,
+ vleClusterTypeNonhead | 2,
+ vleClusterTypeHead | 683,
+ },
+ blkaddr: 3,
+ },
+ want: [32]byte{0x02, 0x20, 0x6d, 0x15, 0x00, 0x0a, 0x80, 0xbf, 0x5a, 0x00, 0x28, 0x00, 0xb2, 0x4e, 0x01, 0xa0, 0x11, 0x17, 0x00, 0x0a, 0x80, 0xd6, 0x56, 0x00, 0x28, 0x00, 0xae, 0x4a, 0x03, 0x00, 0x00, 0x00}},
+ }
+ for _, tt := range tests {
+ t.Run(tt.name, func(t *testing.T) {
+ if got := encodeBigVLEBlock(tt.args.vals, tt.args.blkaddr); !reflect.DeepEqual(got, tt.want) {
+ t.Errorf("encodeBigVLEBlock() = %v, want %v", got, tt.want)
+ }
+ })
+ }
+}