[Libguestfs] [PATCH common] mlcustomize: Add accessors for block driver priority list

[Laszlo Ersek]

On 3/6/23 17:50, Richard W.M. Jones wrote:
> When injecting virtio-win drivers, allow the list of block drivers
> that we search to be modified.
> ---
>  mlcustomize/inject_virtio_win.ml  | 12 +++++++++---
>  mlcustomize/inject_virtio_win.mli | 10 ++++++++++
>  2 files changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/mlcustomize/inject_virtio_win.ml b/mlcustomize/inject_virtio_win.ml
> index 4e977b3..2a7c742 100644
> --- a/mlcustomize/inject_virtio_win.ml
> +++ b/mlcustomize/inject_virtio_win.ml
> @@ -49,6 +49,9 @@ type t = {
>        of libosinfo.  Although this behaviour is documented, IMHO it has
>        always been a bad idea.  We should change this in future to allow
>        the user to select where they want to get drivers from. XXX *)
> +
> +  mutable block_driver_priority : string list
> +  (** List of block drivers *)
>  }
>  
>  type block_type = Virtio_blk | IDE
> @@ -107,7 +110,11 @@ and get_inspection g root =
>    { g; root;
>      i_arch; i_major_version; i_minor_version; i_osinfo;
>      i_product_variant; i_windows_current_control_set; i_windows_systemroot;
> -    virtio_win = ""; was_set = false }
> +    virtio_win = ""; was_set = false;
> +    block_driver_priority = ["virtio_blk"; "vrtioblk"; "viostor"] }
> +
> +let get_block_driver_priority t   = t.block_driver_priority
> +let set_block_driver_priority t v = t.block_driver_priority <- v
>  
>  let scsi_class_guid = "{4D36E97B-E325-11CE-BFC1-08002BE10318}"
>  let viostor_legacy_pciid = "VEN_1AF4&DEV_1001&SUBSYS_00021AF4&REV_00"
> @@ -176,14 +183,13 @@ let rec inject_virtio_win_drivers ({ g } as t) reg =
>    else (
>      (* Can we install the block driver? *)
>      let block : block_type =
> -      let filenames = ["virtio_blk"; "vrtioblk"; "viostor"] in
>        let viostor_driver = try (
>          Some (
>            List.find (
>              fun driver_file ->
>                let source = driverdir // driver_file ^ ".sys" in
>                g#exists source
> -          ) filenames
> +          ) t.block_driver_priority
>          )
>        ) with Not_found -> None in
>        match viostor_driver with
> diff --git a/mlcustomize/inject_virtio_win.mli b/mlcustomize/inject_virtio_win.mli
> index 0ced02e..7bd9b9f 100644
> --- a/mlcustomize/inject_virtio_win.mli
> +++ b/mlcustomize/inject_virtio_win.mli
> @@ -64,6 +64,16 @@ val from_environment : Guestfs.guestfs -> string -> string -> t
>  
>      This should only be used by [virt-v2v] and is considered a legacy method. *)
>  
> +val get_block_driver_priority : t -> string list
> +val set_block_driver_priority : t -> string list -> unit
> +(** Get or set the current block driver priority list.  This is
> +    a list of virtio-win block driver names (eg. ["viostor"]) that
> +    we search until we come to the first [name ^ ".sys"] that
> +    we find, and that is the block driver which gets installed.
> +
> +    This module contains a default priority list which should
> +    be suitable for most use cases. *)
> +
>  val inject_virtio_win_drivers : t -> Registry.t -> virtio_win_installed
>  (** [inject_virtio_win_drivers t reg]
>      installs virtio drivers from the driver directory or driver

I'm struggling to review this because the series containing e.g. the
patch that is now commit 1794e6bc7a88 ("convert: Add a handle type to
Windows_virtio", 2023-01-16) had never been posted to the list, and so I
didn't get a chance to study what was going to be the foundation of this
patch.

Anyway. We now have three handle-creating functions in the
Inject_virtio_win module in common: "from_path", "from_libosinfo", and
"from_environment". The first two are used by guestfs-tools/customize
(i.e., virt-customize and virt-sysprep), and the last one is used by
virt-v2v.

The "inject_virtio_win_drivers" function operates on the handle that was
created by either of those three functions (and is used by both
customize and virt-v2v).

This patch moves the (implicit) block driver priority list, from
"inject_virtio_win_drivers", to the handle, and adds functions to query
and set the list inside the handle.

Removing the list from "inject_virtio_win_drivers" affects both virt-v2v
and customize; they both call "inject_virtio_win_drivers".

Populating the (now settable) block driver priority list inside
"get_inspection" with the default values restores the default list for
both virt-v2v and customize. Namely, "from_path" (called only by
customize), "from_libosinfo" (called only by customize), and
"from_environment" (called only by virt-v2v) *all* derive their return
values from that of "get_inspection".

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