[Libguestfs] [PATCH v3] v2v: bootloaders: search grub config for all distributions
Pino Toscano
ptoscano at redhat.com
Tue Nov 1 17:29:06 UTC 2016
On Tuesday, 1 November 2016 17:07:04 CET Richard W.M. Jones wrote:
> From: Pavel Butsykin <pbutsykin at virtuozzo.com>
>
> This patch improves the search of grub config on EFI partition. This
> means that the config will be found not only for rhel but also for
> many other distributions. Tests were performed on the following
> distributions: centos, fedora, ubuntu, suse. In all cases, the config
> path was /boot/efi/EFI/*distname*/grub.cfg
>
> The main purpose of the patch is to improve support for converting of
> vm with UEFI for most distributions. Unfortunately this patch does not
> solve the problem for all distributions, for example Debian does not
> store grub config on the EFI partition, therefore for such
> distributions another solution is necessary.
>
> Signed-off-by: Pavel Butsykin <pbutsykin at virtuozzo.com>
> Signed-off-by: Richard W.M. Jones <rjones at redhat.com>
> ---
> v2v/linux_bootloaders.ml | 78 +++++++++++++++++++++++++++++-------------------
> 1 file changed, 47 insertions(+), 31 deletions(-)
>
> diff --git a/v2v/linux_bootloaders.ml b/v2v/linux_bootloaders.ml
> index e03d22b..0c236e1 100644
> --- a/v2v/linux_bootloaders.ml
> +++ b/v2v/linux_bootloaders.ml
> @@ -49,6 +49,14 @@ let remove_hd_prefix path =
>
> (* Grub1 (AKA grub-legacy) representation. *)
> class bootloader_grub1 (g : G.guestfs) inspect grub_config =
> + (* We expect Augeas to parse the grub_config file. However
> + * the upstream lens only lists a subset of the possible
> + * locations for this file. Therefore tell Augeas that
> + * grub_config is a grub file (this apparently doesn't affect
> + * Augeas if it already parsed the file).
> + *)
> + let () = g#aug_transform "grub" grub_config in
> +
> (* Grub prefix? Usually "/boot". *)
> let grub_prefix =
> let mounts = g#inspect_get_mountpoints inspect.i_root in
> @@ -191,7 +199,7 @@ type default_kernel_method =
> | MethodNone (** No known way. *)
>
> (* Grub2 representation. *)
> -class bootloader_grub2 (g : G.guestfs) grub_config =
> +class bootloader_grub2 (g : G.guestfs) inspect grub_config =
>
> let grub2_mkconfig_cmd =
> let elems = [
> @@ -333,34 +341,42 @@ object (self)
> ignore (g#command [| grub2_mkconfig_cmd; "-o"; grub_config |])
> end
>
> +(* We can determine if the bootloader config file is grub 1 or
> + * grub 2 just by looking at the filename.
> + *)
> +let bootloader_type_of_filename path =
> + if String.is_suffix path "/grub.cfg" then
> + Some Grub2
> + else if String.is_suffix path "/grub.conf" ||
> + String.is_suffix path "/menu.lst" then
> + Some Grub1
> + else
> + None
Our String.is_suffix is a does String.sub every time, so this is a bit
inefficient -- I'd use Common_utils.last_part_of:
let bootloader_type_of_filename path =
match last_part_of path '/' with
| Some "grub.cfg" -> Some Grub2
| Some ("grub.conf"|"menu.lst") -> Some Grub1
| Some _ | None -> None
> +(* Where to start searching for bootloaders. *)
> +let bootloader_mountpoint = function
> + | { i_firmware = I_BIOS } -> "/boot"
> + | { i_firmware = I_UEFI _ } -> "/boot/efi/EFI"
It seems to be used only once, so I'd just put it inline below (it's
small to read).
> +
> let detect_bootloader (g : G.guestfs) inspect =
> - let config_file, typ =
> - let locations = [
> - "/boot/grub2/grub.cfg", Grub2;
> - "/boot/grub/grub.cfg", Grub2;
> - "/boot/grub/menu.lst", Grub1;
> - "/boot/grub/grub.conf", Grub1;
> - ] in
> - let locations =
> - match inspect.i_firmware with
> - | I_UEFI _ ->
> - [
> - "/boot/efi/EFI/redhat/grub.cfg", Grub2;
> - "/boot/efi/EFI/redhat/grub.conf", Grub1;
> - ] @ locations
> - | I_BIOS -> locations in
> - try
> - List.find (
> - fun (config_file, _) -> g#is_file ~followsymlinks:true config_file
> - ) locations
> - with
> - Not_found ->
> - error (f_"no bootloader detected") in
> -
> - match typ with
> - | Grub1 ->
> - if config_file = "/boot/efi/EFI/redhat/grub.conf" then
> - g#aug_transform "grub" "/boot/efi/EFI/redhat/grub.conf";
> -
> - new bootloader_grub1 g inspect config_file
> - | Grub2 -> new bootloader_grub2 g config_file
> + let mp = bootloader_mountpoint inspect in
> + let paths =
> + try List.map ((^) mp) (Array.to_list (g#find mp))
> + with G.Error msg ->
> + error (f_"could not find bootloader mount point (%s): %s") mp msg in
> +
> + let grub_config, typ =
> + let rec loop = function
> + | [] -> error (f_"no bootloader detected")
> + | path :: paths ->
> + match bootloader_type_of_filename path with
> + | None -> loop paths
> + | Some typ ->
> + if not (g#is_file ~followsymlinks:true path) then loop paths
> + else path, typ
The g#is_file is there to exclude non-files (like directories), right?
Otherwise it would be weird for g#find to return paths which don't
exist..
LGTM otherwise.
Thanks,
--
Pino Toscano
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