[Libguestfs] [PATCH v2] v2v: linux: use NEVR for querying RPM packages (RHBZ#1669395)

[Richard W.M. Jones]

On Wed, Jan 30, 2019 at 01:28:51PM +0100, Pino Toscano wrote:
> Use NEVR when querying RPM for the list of files of a package, instead
> of ENVR.  Also, use the epoch only when non-zero, and version of RPM
> supports it.
> 
> The approach is basically copied from what supermin does in its RPM
> package handler.
> ---
>  v2v/linux.ml | 55 ++++++++++++++++++++++++++++++++--------------------
>  1 file changed, 34 insertions(+), 21 deletions(-)
> 
> diff --git a/v2v/linux.ml b/v2v/linux.ml
> index 43449157b..63489c334 100644
> --- a/v2v/linux.ml
> +++ b/v2v/linux.ml
> @@ -27,6 +27,8 @@ open Utils
>  
>  module G = Guestfs
>  
> +let re_version = PCRE.compile "(\\d+)\\.(\\d+)"
> +
>  let augeas_reload g =
>    g#aug_load ();
>    debug_augeas_errors g
> @@ -80,29 +82,40 @@ let file_list_of_package (g : Guestfs.guestfs) inspect app =
>  
>    | "rpm" ->
>      (* Since RPM allows multiple packages installed with the same
> -     * name, always check the full ENVR here (RHBZ#1161250).
> +     * name, always check the full NEVR here (RHBZ#1161250).
> +     *
> +     * In RPM < 4.11 query commands that use the epoch number in the
> +     * package name did not work.
> +     *
> +     * For example:
> +     * RHEL 6 (rpm 4.8.0):
> +     *   $ rpm -q tar-2:1.23-11.el6.x86_64
> +     *   package tar-2:1.23-11.el6.x86_64 is not installed
> +     * Fedora 20 (rpm 4.11.2):
> +     *   $ rpm -q tar-2:1.26-30.fc20.x86_64
> +     *   tar-1.26-30.fc20.x86_64
>       *)
> -    let pkg_name =
> -      sprintf "%s-%s-%s" app.G.app2_name
> -        app.G.app2_version app.G.app2_release in
> -    let pkg_name =
> -      if app.G.app2_epoch > 0_l then (
> -        (* RHEL 3/4 'rpm' does not support using the epoch prefix.
> -         * (RHBZ#1170685).
> -         *)
> -        let is_rhel_lt_5 =
> -          match inspect with
> -          | { i_type = "linux";
> -              i_distro = "rhel" | "centos" | "scientificlinux" |
> -                  "oraclelinux" | "redhat-based";
> -              i_major_version = v } when v < 5 -> true
> -          | _ -> false in
> -        if is_rhel_lt_5 then
> -          pkg_name
> +    let is_rpm_lt_4_11 () =
> +      let ver = List.find_map (
> +        function
> +        | { G.app2_name = name; G.app2_version = version }
> +            when name = "rpm" -> Some version
> +        | _ -> None
> +      ) inspect.i_apps in

I really think we should catch the Not_found case.  I know that an
RPM-based guest should have an rpm package - that's obvious - but we
have to deal with all kinds of weirdness, and Not_found exceptions are
an absolute pain to track down when they happen.

The patch is fine with the addition of a suitable try/catch around
this function call.

Rich.

> +      let ver =
> +        if PCRE.matches re_version ver then
> +          (int_of_string (PCRE.sub 1), int_of_string (PCRE.sub 2))
>          else
> -          sprintf "%ld:%s" app.G.app2_epoch pkg_name
> -      ) else
> -        pkg_name in
> +          (0, 0) in
> +      ver < (4, 11)
> +    in
> +    let pkg_name =
> +      if app.G.app2_epoch = Int32.zero || is_rpm_lt_4_11 () then
> +        sprintf "%s-%s-%s" app.G.app2_name app.G.app2_version
> +          app.G.app2_release
> +      else
> +        sprintf "%s-%ld:%s-%s" app.G.app2_name app.G.app2_epoch
> +          app.G.app2_version app.G.app2_release in
>      let cmd = [| "rpm"; "-ql"; pkg_name |] in
>      debug "%s" (String.concat " " (Array.to_list cmd));
>      let files = g#command_lines cmd in
> -- 
> 2.20.1
> 
> _______________________________________________
> Libguestfs mailing list
> Libguestfs at redhat.com
> https://www.redhat.com/mailman/listinfo/libguestfs

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org