>From 39ebc2d081139013e10ad3ac0e5266c4b1242b62 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Mon, 9 Oct 2017 13:11:35 +0100
Subject: [PATCH] builder: osinfo fold function

---
 builder/osinfo.ml          | 73 +++++++++++++++++++++-------------------------
 builder/osinfo.mli         |  6 ++--
 builder/repository_main.ml | 34 ++++++++++-----------
 3 files changed, 54 insertions(+), 59 deletions(-)

diff --git a/builder/osinfo.ml b/builder/osinfo.ml
index 9d89db510..69c5317ff 100644
--- a/builder/osinfo.ml
+++ b/builder/osinfo.ml
@@ -20,61 +20,56 @@ open Std_utils
 open Tools_utils
 open Osinfo_config
 
-let rec iterate_db fn =
-  let locations = ref [] in
-
-  (* (1) Try the shared osinfo directory, using either the
-   * $OSINFO_SYSTEM_DIR envvar or its default value.
-   *)
-  let () =
+let rec fold fn base =
+  let locations =
+    (* (1) Try the shared osinfo directory, using either the
+     * $OSINFO_SYSTEM_DIR envvar or its default value.
+     *)
     let dir =
       try Sys.getenv "OSINFO_SYSTEM_DIR"
       with Not_found -> "/usr/share/osinfo" in
-    List.push_back locations ((dir // "os"), read_osinfo_db_three_levels)
-  in
+    ((dir // "os"), read_osinfo_db_three_levels) ::
 
-  (* (2) Try the libosinfo directory, using the newer three-directory
-   * layout ($LIBOSINFO_DB_PATH / "os" / $group-ID / [file.xml]).
-   *)
-  let () =
-    let path = Osinfo_config.libosinfo_db_path // "os" in
-    List.push_back locations (path, read_osinfo_db_three_levels)
-  in
+      (* (2) Try the libosinfo directory, using the newer three-directory
+       * layout ($LIBOSINFO_DB_PATH / "os" / $group-ID / [file.xml]).
+       *)
+      let path = Osinfo_config.libosinfo_db_path // "os" in
+      (path, read_osinfo_db_three_levels) ::
 
-  (* (3) Try the libosinfo directory, using the old flat directory
-   * layout ($LIBOSINFO_DB_PATH / "oses" / [file.xml]).
-   *)
-  let () =
-    let path = Osinfo_config.libosinfo_db_path // "oses" in
-    List.push_back locations (path, read_osinfo_db_flat)
-  in
+        (* (3) Try the libosinfo directory, using the old flat directory
+         * layout ($LIBOSINFO_DB_PATH / "oses" / [file.xml]).
+         *)
+        let path = Osinfo_config.libosinfo_db_path // "oses" in
+        (path, read_osinfo_db_flat) :: [] in
 
-  let rec loop = function
-    | (path, f) :: paths ->
-      if is_directory path then f fn path
-      (* This is not an error: RHBZ#948324. *)
-      else loop paths
-    | [] -> ()
-  in
+  let files =
+    List.flatten (
+      filter_map (
+          fun (path, f) ->
+            if is_directory path then Some (f path)
+            (* This is not an error: RHBZ#948324. *)
+            else None
+      ) locations
+  ) in
 
-  loop !locations
+  List.fold_left fn base files
 
-and read_osinfo_db_three_levels fn path =
+and read_osinfo_db_three_levels path =
   debug "osinfo: loading 3-level-directories database from %s" path;
   let entries = Array.to_list (Sys.readdir path) in
   let entries = List.map ((//) path) entries in
   (* Iterate only on directories. *)
   let entries = List.filter is_directory entries in
-  List.iter (read_osinfo_db_directory fn) entries
+  List.flatten (List.map read_osinfo_db_directory entries)
 
-and read_osinfo_db_flat fn path =
+and read_osinfo_db_flat path =
   debug "osinfo: loading flat database from %s" path;
-  read_osinfo_db_directory fn path
+  read_osinfo_db_directory path
 
-and read_osinfo_db_directory fn path =
-  let entries = Array.to_list (Sys.readdir path) in
+and read_osinfo_db_directory path =
+  let entries = Sys.readdir path in
+  let entries = Array.to_list entries in
   let entries = List.filter (fun x -> Filename.check_suffix x ".xml") entries in
   let entries = List.map ((//) path) entries in
   let entries = List.filter is_regular_file entries in
-  List.iter fn entries
-
+  entries
diff --git a/builder/osinfo.mli b/builder/osinfo.mli
index 949d776a9..bf60157fe 100644
--- a/builder/osinfo.mli
+++ b/builder/osinfo.mli
@@ -16,7 +16,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *)
 
-val iterate_db : (string -> unit) -> unit
-(** [iterate_db fun] iterates over the osinfo-db/libosinfo database
-    of OS definitions, invoking the specified [fun] on each XML file.
+val fold : ('a -> string -> 'a) -> 'a -> 'a
+(** [fold f base] folds function [f] over every file in the
+    osinfo-db/libosinfo database of OS definitions.
  *)
diff --git a/builder/repository_main.ml b/builder/repository_main.ml
index 03a0ff4be..b02e37b54 100644
--- a/builder/repository_main.ml
+++ b/builder/repository_main.ml
@@ -132,25 +132,25 @@ let checksums_get_sha512 = function
 
 let osinfo_ids = ref None
 
-let osinfo_get_short_ids () =
+let rec osinfo_get_short_ids () =
   match !osinfo_ids with
   | Some ids -> ids
-  | None -> (
-    let set = ref StringSet.empty in
-    Osinfo.iterate_db (
-      fun filepath ->
-        let doc = Xml.parse_file filepath in
-        let xpathctx = Xml.xpath_new_context doc in
-        let nodes = xpath_get_nodes xpathctx "/libosinfo/os/short-id" in
-        List.iter (
-          fun node ->
-            let id = Xml.node_as_string node in
-            set := StringSet.add id !set
-        ) nodes
-    );
-    osinfo_ids := Some (!set);
-    !set
-  )
+  | None ->
+    osinfo_ids :=
+      Some (
+        Osinfo.fold (
+          fun set filepath ->
+            let doc = Xml.parse_file filepath in
+            let xpathctx = Xml.xpath_new_context doc in
+            let nodes = xpath_get_nodes xpathctx "/libosinfo/os/short-id" in
+            List.fold_left (
+              fun set node ->
+                let id = Xml.node_as_string node in
+                StringSet.add id set
+            ) set nodes
+        ) StringSet.empty
+      );
+    osinfo_get_short_ids ()
 
 let compress_to file outdir =
   let outimg = outdir // (Filename.basename file) ^ ".xz" in
-- 
2.13.2