*: add go-proto package

This is just a simple "go generate" with a few helpers that I added for
umoci's use because it turns out that it's quite handy to have those
constants and helpers defined.

Signed-off-by: Aleksa Sarai <[email protected]>

README.md

@@ -36,8 +36,8 @@ This project (in particular the `rootlesscontainers.proto` file and generated
 sources) are all licensed under the Apache License 2.0.
 
 ```
-rootlesscontainers.proto
-Copyright (C) 2018 Rootless Containers authors
+rootlesscontainers-proto: persistent rootless filesystem emulation
+Copyright (C) 2018 Rootless Containers Authors
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.

go-proto/rootlesscontainers.proto

@@ -0,0 +1 @@
+../rootlesscontainers.proto

go-proto/rootlesscontainers_generate.go

@@ -0,0 +1,37 @@
+/*
+ * rootlesscontainers-proto: persistent rootless filesystem emulation
+ * Copyright (C) 2018 Rootless Containers Authors
+ *
+ * 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 rootlesscontainers
+
+// Generate everything for our protobuf.
+//go:generate protoc --go_out=import_path=rootlesscontainers:. rootlesscontainers.proto
+
+// Keyname is the official xattr key used to store rootlesscontainers.proto
+// blobs, and is the only key we will treat in this special way.
+const Keyname = "user.rootlesscontainers"
+
+// NoopID is the uint32 that represents the "noop" id for uid/gid values. It is
+// equal to uint32(-1) but since we cannot write that in Go we have to
+// explicitly write the wrapped value.
+var NoopID uint32 = 0xFFFFFFFF
+
+// IsDefault returns whether the given Resource is the default. If a Resource
+// is equal to the default Resource then it is not necesary to include it on
+// the filesystem.
+func IsDefault(r Resource) bool {
+	return r.Uid == NoopID && r.Gid == NoopID
+}

rootlesscontainers.proto

@@ -1,5 +1,5 @@
-// rootlesscontainers.proto
-// Copyright (C) 2018 Rootless Containers authors
+// rootlesscontainers-proto: persistent rootless filesystem emulation
+// Copyright (C) 2018 Rootless Containers Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.