Re: [Libguestfs] [PATCH v2v 1/3] lib/utils.ml: Make with_nbd_connect_unix meta_contexts erasable

Make the meta_contexts parameter of Utils.with_nbd_connect_unix optional and erasable. This involves three connected changes, we first make it optional (ie. '?meta_contexts'), providing the obvious default of empty list. We then need to move it to the first parameter so OCaml can erase it even if we partially apply this function. Finally remove the label from the function parameter 'f'. I'm not quite sure why the last change is necessary, but OCaml cannot erase ?meta_contexts without it,

and in any case it's not necessary to label this parameter as it doesn't add any extra type safety and you wouldn't want callers to swap over the socket and function parameter because that would make calling code less clear. (The same applies to ~socket but I didn't change that). --- lib/utils.ml | 4 ++-- lib/utils.mli | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/lib/utils.ml b/lib/utils.ml index d6861d0889..863cfc4eb0 100644 --- a/lib/utils.ml +++ b/lib/utils.ml @@ -165,7 +165,7 @@ let rec wait_for_file filename timeout = let metaversion = Digest.to_hex (Digest.string Config.package_version_full) -let with_nbd_connect_unix ~socket ~meta_contexts ~f = +let with_nbd_connect_unix ?(meta_contexts = []) ~socket f = let nbd = NBD.create () in protect ~f:(fun () -> @@ -181,7 +181,7 @@ let get_disk_allocated ~dir ~disknr = let socket = sprintf "%s/out%d" dir disknr and alloc_ctx = "base:allocation" in with_nbd_connect_unix ~socket ~meta_contexts:[alloc_ctx] - ~f:(fun nbd -> + (fun nbd -> if NBD.can_meta_context nbd alloc_ctx then ( (* Get the list of extents, using a 2GiB chunk size as hint. *) let size = NBD.get_size nbd diff --git a/lib/utils.mli b/lib/utils.mli index 3096eb1466..76a2ec8c40 100644 --- a/lib/utils.mli +++ b/lib/utils.mli @@ -78,9 +78,9 @@ val metaversion : string Eventually we may switch to using an "open metadata" format instead (eg. XML). *) -val with_nbd_connect_unix : socket:string -> - meta_contexts:string list -> - f:(NBD.t -> 'a) -> +val with_nbd_connect_unix : ?meta_contexts:string list -> + socket:string -> + (NBD.t -> 'a) -> 'a (** [with_nbd_connect_unix socket meta_contexts f] calls function [f] with the NBD server at Unix domain socket [socket] connected, and the metadata