[Libguestfs] [PATCH] v2v: fixed file_owner function

[Richard W.M. Jones]

On Mon, Aug 01, 2016 at 02:46:14PM +0200, Tomáš Golembiovský wrote:
> What was happening in file_owner function did not match the description
> in the comment. When a path is owned by multiple packages the returned
> string was in fact a concatenation of the names of all packages that own
> it. E.g. for `Linux.is_file_owned g inspect "/etc"` the returned value
> was "filesystemyum" (i.e. "filesystem" + "yum").
> 
> Signed-off-by: Tomáš Golembiovský <tgolembi at redhat.com>
> ---
>  v2v/linux.ml | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/v2v/linux.ml b/v2v/linux.ml
> index d20194b..aeff5c5 100644
> --- a/v2v/linux.ml
> +++ b/v2v/linux.ml
> @@ -99,14 +99,18 @@ let rec file_owner g inspect path =
>        (* Although it is possible in RPM for multiple packages to own
>         * a file, this deliberately only returns one package.
>         *)
> -      let cmd = [| "rpm"; "-qf"; "--qf"; "%{NAME}"; path |] in
> +      let cmd = [| "rpm"; "-qf"; "--qf"; "%{NAME}\\n"; path |] in
>        debug "%s" (String.concat " " (Array.to_list cmd));
> -      (try g#command cmd
> +      (try
> +         let pkgs = g#command_lines cmd in
> +         pkgs.(0)
>         with Guestfs.Error msg as exn ->
>           if String.find msg "is not owned" >= 0 then
>             raise Not_found
>           else
>             raise exn
> +       | Invalid_argument msg ->
> +           raise Not_found

My concern/confusion about this patch is what raises Invalid_argument?

I'm assuming it's the array index, which could raise `Invalid_argument
"index out of bounds"' if the g#command_lines returns a zero-length
list, but then my question would be why is the rpm command not
returning any lines?

Even if this can happen, the exception shouldn't be converted to
Not_found.  It should be an internal error or the exception should be
left unchanged.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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