osbase/oci: add package

This adds the oci package, which contains types and tools for working
with OCI images.

Change-Id: Ie2a1d82c7ac007f5d1ad47666880dbf8a8bd931d
Reviewed-on: https://review.monogon.dev/c/monogon/+/4085
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/osbase/oci/BUILD.bazel b/osbase/oci/BUILD.bazel
new file mode 100644
index 0000000..ec1d590
--- /dev/null
+++ b/osbase/oci/BUILD.bazel
@@ -0,0 +1,23 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "oci",
+    srcs = [
+        "layout.go",
+        "oci.go",
+    ],
+    importpath = "source.monogon.dev/osbase/oci",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//osbase/structfs",
+        "@com_github_opencontainers_go_digest//:go-digest",
+        "@com_github_opencontainers_image_spec//specs-go",
+        "@com_github_opencontainers_image_spec//specs-go/v1:specs-go",
+    ],
+)
+
+go_test(
+    name = "oci_test",
+    srcs = ["oci_test.go"],
+    embed = [":oci"],
+)