libxl: idl: allow KeyedUnion members to be empty

This is useful when the key enum has an "invalid" option and avoids
the need to declare a dummy struct. Use this for domain_build_info
resulting in the generated API changing like so:
    --- tools/libxl/_libxl_BACKUP_types.h
    +++ tools/libxl/_libxl_types.h
    @@ -377,8 +377,6 @@ typedef struct libxl_domain_build_info {
                 const char * features;
                 libxl_defbool e820_host;
             } pv;
    -        struct {
    -        } invalid;
         } u;
     } libxl_domain_build_info;
     void libxl_domain_build_info_dispose(libxl_domain_build_info *p);

+ a related change to the JSON generation.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: fix code intended to output comments before definitions

I'm not sure how useful these comments actually are but erred on the
side of fixing rather than removing.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: support for Arrays in bindings generator.

No change in generated code because no arrays are currently generated.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: avoid reserved words in type and field names.

Current just s/type/ty/ and there are no such fields (yet) so no
change to generated code.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: support for KeyedUnion in the bindings generator.

A KeyedUnion consists of two fields in the containing struct. First an
enum field ("e") used as a descriminator and second a union ("u")
containing potentially anonymous structs associated with each enum
value.

We map the anonymous structs to structs named after the descriminator
field ("e") and the specific enum values. We then declare an ocaml
variant type name e__union mapping each enum value to its associated
struct.

So given IDL:

 foo = Enumeration("foo",
	(0, "BAR"),
	(1, "BAZ"),
 s = Struct("s", [
        ("u", KeyedUnion(none, foo, "blargle", [
		("bar", Struct(...xxx...)),
		("baz", Struct(...yyy...)),
	])),
 ])

We generate C:

 enum { FOO, BAR } foo;
 struct s {
 	enum foo blargle;
 	union {
 		struct { ...xxx... } bar;
 		struct { ...yyy... } baz;
 	} u;
 }

and map this to ocaml

 type foo = BAR | BAZ;

 module	s = Struct

 	type blargle_bar = ...xxx...;

 	type blargle_baz = ...yyy...;

 	type blargle__union = Bar of blargle_bar | Baz of blargle_baz;

 	type t =
 	{
 		blargle : blargle__union;
 	}

These type names are OK because they are already within the namespace
associated with the struct "s".

If the struct assiated with bar is empty then we don't bother iwht
blargle_bar of "of blargle_bar".

No actually change in the gnerated code since we don't generated any
KeyedUnions yet.

The actual implementation was inspired by
http://www.linux-nantes.org/~fmonnier/ocaml/ocaml-wrapping-c.php#ref_constvrnt

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: add some more builtin types.

  * bitmaps
  * string_list
  * key_value_list
  * cpuid_policy_list (left "empty" for now)

None of these are used yet, so no change to the generated code.

Bitmap_val requires a ctx, so leave it as an abort for now.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxc: ocaml: add simple binding for xentoollog (output only).

These bindings allow ocaml code to receive log message via xentoollog
but do not support injecting messages into xentoollog from ocaml.
Receiving log messages from libx{c,l} and forwarding them to ocaml is
the use case which is needed by the following patches.

Add a simple noddy test case (tools/ocaml/test).

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: allocate a long lived libxl context.

Rather than allocating a new context for every libxl call begin to
switch to a model where a context is allocated by the caller and may
then be used for multiple calls down into the library.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: switch all functions over to take a context.

Since the context has a logger we can get rid of the logger built into these
bindings and use the xentoollog bindings instead.

The gc is of limited use when most things are freed with libxl_FOO_dispose,
so get rid of that too.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: propagate the libxl return error code in exceptions

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: add domain_build/create_info/config and events to the bindings.

We now have enoguh infrastructure in place to do this trivially.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: idl: add domain_type field to libxl_dominfo struct

This allows a toolstack to find out whether a VM has booted as PV or HVM.

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: fix the META file

The "xl" module was renamed to "xenlight" some time ago, but the
META file was not updated.

It also needed to be added to the list of generated files in the
Makefile.

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: fix the handling of enums in the bindings generator

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: use the "string option" type for IDL strings

The libxl IDL is based on C type "char *", and therefore "strings" can
by NULL, or be an actual string. In ocaml, it is common to encode such
things as option types.

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: add with_ctx helper function

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: add xen_console_read

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: add dominfo_list and dominfo_get

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: implement some simple tests

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
libxl: ocaml: add wrappers for poll

We need this in order to wrap the event API of libxl.

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>