[Libguestfs] [PATCH 1/2] v2v: fix and implify the internal Convert_linux:discover_modpath

[Richard W.M. Jones]

On Fri, Jul 01, 2016 at 05:52:00PM +0200, Pino Toscano wrote:
> First check for the existence of the directory /etc/modprobe.d, in case
> using a file under it; this also skips all the other checks, since they
> are not needed at all.  Also /etc/modprobe.d exists on recent Linux
> versions, so let's give priority to the more common methods.
> When /etc/modprobe.d does not exist, check for the file to edit using a
> single list of possible files, now in order of priority, where the first
> find is used without checking further for the rest.
> 
> Also, make sure all the returned paths are absolute: they are used in
> Augeas paths later on, so relative paths will not do anything useful.
> ---
>  v2v/convert_linux.ml | 30 ++++++++++--------------------
>  1 file changed, 10 insertions(+), 20 deletions(-)
> 
> diff --git a/v2v/convert_linux.ml b/v2v/convert_linux.ml
> index cadfbb5..0296844 100644
> --- a/v2v/convert_linux.ml
> +++ b/v2v/convert_linux.ml
> @@ -1219,28 +1219,18 @@ let rec convert ~keep_serial_console (g : G.guestfs) inspect source rcaps =
>  
>    and discover_modpath () =
>      (* Find what /etc/modprobe.conf is called today. *)
> -    let modpath = ref "" in
> -
> -    (* Note that we're checking in ascending order of preference so
> -     * that the last discovered method will be chosen.
> -     *)
> -    List.iter (
> -      fun file ->
> -        if g#is_file ~followsymlinks:true file then
> -          modpath := file
> -    ) [ "/etc/conf.modules"; "/etc/modules.conf" ];
> -
> -    if g#is_file ~followsymlinks:true "/etc/modprobe.conf" then
> -      modpath := "modprobe.conf";
> -
> -    if g#is_dir ~followsymlinks:true "/etc/modprobe.d" then
> +    if g#is_dir ~followsymlinks:true "/etc/modprobe.d" then (
>        (* Create a new file /etc/modprobe.d/virt-v2v-added.conf. *)
> -      modpath := "modprobe.d/virt-v2v-added.conf";
> -
> -    if !modpath = "" then
> -      error (f_"unable to find any valid modprobe configuration file such as /etc/modprobe.conf");
> +      "/etc/modprobe.d/virt-v2v-added.conf"
> +    ) else (
> +      (* List of methods, in order of preference. *)
> +      let paths = [ "/etc/modprobe.conf"; "/etc/modules.conf"; "/etc/conf.modules" ] in
>  
> -    !modpath
> +      try
> +        List.find (g#is_file ~followsymlinks:true) paths
> +      with Not_found ->
> +        error (f_"unable to find any valid modprobe configuration file such as /etc/modprobe.conf");
> +    )
>  
>    and remap_block_devices block_type =
>      (* This function's job is to iterate over boot configuration

OK this looks like a natural rewrite of the existing function, except
always returning an absolute path instead of a mix.

ACK.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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