[Libguestfs] [PATCH 02/27] daemon: Allow parts of the daemon and APIs to be written in OCaml.

[Richard W.M. Jones]

On Wed, Jul 19, 2017 at 03:13:47PM +0200, Pino Toscano wrote:
> On Friday, 14 July 2017 15:39:10 CEST Richard W.M. Jones wrote:
> >  .gitignore                 |   6 +-
> >  Makefile.am                |   2 +-
> >  common/mlutils/Makefile.am |   4 -
> >  daemon/Makefile.am         | 103 +++++++++++++++++++++++--
> >  daemon/chroot.ml           |  85 +++++++++++++++++++++
> >  daemon/chroot.mli          |  35 +++++++++
> >  daemon/daemon-c.c          |  35 +++++++++
> >  daemon/daemon.ml           |  39 ++++++++++
> >  daemon/guestfsd.c          |  50 ++++++++++++
> >  daemon/sysroot-c.c         |  37 +++++++++
> >  daemon/sysroot.ml          |  19 +++++
> >  daemon/sysroot.mli         |  22 ++++++
> >  daemon/utils.ml            | 156 +++++++++++++++++++++++++++++++++++++
> >  daemon/utils.mli           |  65 ++++++++++++++++
> 
> TBH I'd just have a single "Daemon" module for the OCaml helpers for
> the daemon, instead of different modules, wirh a single -c.c file for
> all the C implementations.  The Sysroot submodule could be implemented
> like the various submodules in Unix_utils.

Do you mean Daemon.Chroot, Daemon.Sysroot etc?

> > +val f : t -> ('a -> 'b) -> 'a -> 'b
> > +(** Run a function in the chroot, returning the result or re-raising
> > +    any exception thrown. *)
> 
> After reading patch #11, IMHO there should be a variant that takes a
> generic (unit -> unit) function (called 'fn', maybe?), and have 'f'
> use it:
> 
>   let f t fun arg =
>     f (fun () -> fun arg)

I'm a bit confused, do you have a compilable example?

> > +/* Convert an OCaml exception to a reply_with_error_errno call
> > + * as best we can.
> > + */
> > +extern void ocaml_exn_to_reply_with_error (const char *func, value exn);
> > +
> > +void
> > +ocaml_exn_to_reply_with_error (const char *func, value exn)
> > +{
> 
> Shouldn't this use CAMLparam1 + CAMLreturn?

It doesn't allocate on the OCaml heap so it should be safe.

> > +let udev_settle ?filename () =
> 
> Ditto.

‘Ditto’ means bind the C udev_settle_* functions?

Rich.

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