[Libguestfs] [v2v PATCH 2/2] Consolidate handling of temporary files/dirs

[Eric Blake]

On 4/6/20 10:40 AM, Pino Toscano wrote:
> Create two temporary directories for all the files created during the
> virt-v2v run:
> 1) tmpdir, created as $TMPDIR/virt-v2v.XXXXXX, for all the small files
> 2) cachedir, created as $LIBGUESTFS_CACHEDIR/virt-v2v.XXXXXX, for the
>     big files (e.g. disks)
> This way there is no need to manually schedule all the temporary files
> and directories for removal when the application quits.
> ---

Side note:

> +++ b/v2v/output_glance.ml
> @@ -27,16 +27,6 @@ open Types
>   open Utils
>   
>   class output_glance () =
> -  (* Although glance can slurp in a stream from stdin, unfortunately
> -   * 'qemu-img convert' cannot write to a stream (although I guess
> -   * it could be implemented at least for raw).  Therefore we have
> -   * to write to a temporary file.  XXX
> -   *)
> -  let tmpdir =
> -    let base_dir = (open_guestfs ())#get_cachedir () in
> -    let t = Mkdtemp.temp_dir ~base_dir "glance." in
> -    rmdir_on_exit t;
> -    t in
>   object
>     inherit output
>   
> @@ -60,8 +50,12 @@ object
>     method supported_firmware = [ TargetBIOS; TargetUEFI ]
>   
>     method prepare_targets _ overlays _ =
> -    (* Write targets to a temporary local file - see above for reason. *)
> -    List.map (fun (_, ov) -> TargetFile (tmpdir // ov.ov_sd)) overlays
> +    (* Although glance can slurp in a stream from stdin, unfortunately
> +     * 'qemu-img convert' cannot write to a stream (although I guess
> +     * it could be implemented at least for raw).  Therefore we have
> +     * to write to a temporary file.  XXX
> +     *)
> +    List.map (fun (_, ov) -> TargetFile (cachedir // ov.ov_sd)) overlays

I know this was just code motion, but does the nbdkit streaming plugin 
help here?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org