[Libguestfs] [PATCH 2/8] v2v: add basic support for the "deb" package manager

[Tomáš Golembiovský]

On Tue, 09 Aug 2016 15:24:21 +0200
Pino Toscano <ptoscano at redhat.com> wrote:

> On Tuesday, 9 August 2016 13:55:36 CEST Tomáš Golembiovský wrote:
> > On Mon,  8 Aug 2016 18:38:49 +0200
> > Pino Toscano <ptoscano at redhat.com> wrote:
> >   
> > > Implement the 'remove', 'file_list_of_package', and 'file_owner' methods
> > > of the Linux module for the "deb" package manager (dpkg basically, on
> > > Debian and derived distributions).
> > > 
> > > Also allow it for the main conversion code.
> > > ---
> > >  v2v/convert_linux.ml |  2 +-
> > >  v2v/linux.ml         | 23 +++++++++++++++++++++++
> > >  2 files changed, 24 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/v2v/convert_linux.ml b/v2v/convert_linux.ml
> > > index 4b1ce99..65796d6 100644
> > > --- a/v2v/convert_linux.ml
> > > +++ b/v2v/convert_linux.ml
> > > @@ -79,7 +79,7 @@ let rec convert ~keep_serial_console (g : G.guestfs) inspect source rcaps =
> > >      | "sles" | "suse-based" | "opensuse" -> `SUSE_family
> > >      | _ -> assert false in
> > >  
> > > -  assert (inspect.i_package_format = "rpm");
> > > +  assert (inspect.i_package_format = "rpm" || inspect.i_package_format = "deb");
> > >  
> > >    (* We use Augeas for inspection and conversion, so initialize it early. *)
> > >    Linux.augeas_init g;
> > > diff --git a/v2v/linux.ml b/v2v/linux.ml
> > > index ed639c1..5713f64 100644
> > > --- a/v2v/linux.ml
> > > +++ b/v2v/linux.ml
> > > @@ -48,6 +48,10 @@ and do_remove g inspect packages =
> > >    assert (List.length packages > 0);
> > >    let package_format = inspect.i_package_format in
> > >    match package_format with
> > > +  | "deb" ->
> > > +    let cmd = [ "dpkg"; "--purge" ] @ packages in
> > > +    let cmd = Array.of_list cmd in
> > > +    ignore (g#command cmd);
> > >    | "rpm" ->
> > >      let cmd = [ "rpm"; "-e" ] @ packages in
> > >      let cmd = Array.of_list cmd in
> > > @@ -61,6 +65,12 @@ let file_list_of_package (g : Guestfs.guestfs) inspect app =
> > >    let package_format = inspect.i_package_format in
> > >  
> > >    match package_format with
> > > +  | "deb" ->
> > > +    let cmd = [| "dpkg"; "-L"; app.G.app2_name |] in
> > > +    debug "%s" (String.concat " " (Array.to_list cmd));
> > > +    let files = g#command_lines cmd in
> > > +    let files = Array.to_list files in
> > > +    List.sort compare files
> > >    | "rpm" ->
> > >      (* Since RPM allows multiple packages installed with the same
> > >       * name, always check the full ENVR here (RHBZ#1161250).
> > > @@ -98,6 +108,19 @@ let file_list_of_package (g : Guestfs.guestfs) inspect app =
> > >  let rec file_owner (g : G.guestfs) inspect path =
> > >    let package_format = inspect.i_package_format in
> > >    match package_format with
> > > +  | "deb" ->
> > > +      let cmd = [| "dpkg"; "-S"; path |] in
> > > +      debug "%s" (String.concat " " (Array.to_list cmd));
> > > +      let lines =
> > > +        try g#command_lines cmd  
> > 
> > This is not good. dpkg-query command behaves differently from rpm.  
> 
> AFAIR, dpkg doesn't allow a file to be owned by different packages
> (and even if it does, it will complain hard when the file is not exactly
> the same in all the packages).

Good point. I take it then that the function should focus only on files
(as the name suggests).

> This is not what happens with directories, which can be owned by every
> package (and indeed usually every debian package owns all the
> directories, / included, that contain the shipped files).
> 
> There could be also multiarch to take into account, but that's something
> that could be dealt with later.

Still the fact remains, that the returned string contains not just a
package name, but also the path itself. I.e: "package: /some/file"

> 
> > First, the returned packages are all on one line separated by commas.
> > What I came up with is this:
> > 
> >       let cmd = [| "dpkg-query"; "-S"; path |] in
> >       debug "%s" (String.concat " " (Array.to_list cmd));
> >       (try
> >          let pkg = g#command cmd in
> >          (* What we get is a string of form "pkg1, pkg2:arch, pkg3: /path" *)
> >          let len = String.length pkg in
> >          let rec loop i =
> >              if i >= len then
> >                (* This is fishy. Internal bug? *)
> >                error (f_"internal error: file_owner: failed to process string '%s'") pkg
> >              else if pkg.[i] = ' ' &&
> >                (pkg.[i-1] = ':' || pkg.[i-1] = ',') then
> >                  String.sub pkg 0 (i-1)
> >              else loop (i+1)
> >          in loop 1
> >        with Guestfs.Error msg as exn ->
> >          if String.find msg "no path found matching pattern" >= 0 then
> >            raise Not_found
> >          else
> >            raise exn
> >       )
> > 
> > The other concern is, whether we should escape the argument somehow. The
> > fact is that dpkg-query accepts a glob expression, not just a simple
> > path. If you provide it with a pattern you will get all the matching
> > paths, each on a single line (prefixed by the package list).  
> 
> rpm seems to accept glob expression too -- OTOH we seem to provide only
> package names to Linux.remove calls (which were read from the package
> manager itself).
> 
> -- 
> Pino Toscano


-- 
Tomáš Golembiovský <tgolembi at redhat.com>