New API: inspect_get_build_id

Add an API to return the build ID of the guest.  This to allow a
future change to be able to distinguish between Windows 10 and Windows 11
which can only be done using the build ID.

For Windows we can read the CurrentBuildNumber key from the registry.
For Linux there happens to be a BUILD_ID field in /etc/os-release.
I've never seen a Linux distro that actually uses this.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

daemon/inspect.ml

@@ -335,6 +335,12 @@ and inspect_get_hostname root =
   | Some v -> v
   | None -> "unknown"
 
+and inspect_get_build_id root =
+  let root = search_for_root root in
+  match root.inspection_data.build_id with
+  | Some v -> v
+  | None -> "unknown"
+
 and inspect_get_windows_systemroot root =
   let root = search_for_root root in
   match root.inspection_data.windows_systemroot with

daemon/inspect_fs_unix.ml

@@ -96,6 +96,8 @@ let rec parse_os_release release_file data =
            data.product_name <- Some value
          else if key = "VERSION_ID" then
            parse_os_release_version_id value data
+         else if key = "BUILD_ID" then
+           data.build_id <- Some value
        ) values;
 
      (* If we haven't got all the fields, exit right away. *)

daemon/inspect_fs_windows.ml

@@ -263,6 +263,20 @@ and check_windows_software_registry software_hive data =
          with
            Not_found -> ()
         );
+
+        (* CurrentBuildNumber (build_id).
+         *
+         * In modern Windows, the "CurrentBuild" and "CurrentBuildNumber"
+         * keys are the same.  But in Windows XP, "CurrentBuild"
+         * contained something quite different.  So always use
+         * "CurrentBuildNumber".
+         *)
+        (try
+           let v = List.assoc "CurrentBuildNumber" values in
+           data.build_id <- Some (Hivex.value_string h v)
+         with
+           Not_found -> ()
+        );
       with
       | Not_found ->
          if verbose () then

daemon/inspect_types.ml

@@ -48,6 +48,7 @@ and inspection_data = {
   mutable version : version option;
   mutable arch : string option;
   mutable hostname : string option;
+  mutable build_id : string option;
   mutable fstab : fstab_entry list;
   mutable windows_systemroot : string option;
   mutable windows_software_hive : string option;
@@ -167,6 +168,8 @@ and string_of_inspection_data data =
              data.arch;
   Option.may (fun v -> bpf "    hostname: %s\n" v)
              data.hostname;
+  Option.may (fun v -> bpf "    build ID: %s\n" v)
+             data.build_id;
   if data.fstab <> [] then (
     let v = List.map (
       fun (a, b) -> sprintf "(%s, %s)" (Mountable.to_string a) b
@@ -272,6 +275,7 @@ let null_inspection_data = {
   version = None;
   arch = None;
   hostname = None;
+  build_id = None;
   fstab = [];
   windows_systemroot = None;
   windows_software_hive = None;
@@ -294,6 +298,7 @@ let merge_inspection_data child parent =
   parent.version <-         merge child.version parent.version;
   parent.arch <-            merge child.arch parent.arch;
   parent.hostname <-        merge child.hostname parent.hostname;
+  parent.build_id <-        merge child.build_id parent.build_id;
   parent.fstab <-           child.fstab @ parent.fstab;
   parent.windows_systemroot <-
     merge child.windows_systemroot parent.windows_systemroot;

daemon/inspect_types.mli

@@ -51,6 +51,7 @@ and inspection_data = {
   mutable version : version option;
   mutable arch : string option;
   mutable hostname : string option;
+  mutable build_id : string option;
   mutable fstab : fstab_entry list;
   mutable windows_systemroot : string option;
   mutable windows_software_hive : string option;