[PATCH] tools/ocaml: Factor out compatiblity handling

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

... rather than having each library implement its own subset.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Christian Lindig <christian.lindig@xxxxxxxxxx>
CC: David Scott <dave@xxxxxxxxxx>
CC: Edwin Török <edwin.torok@xxxxxxxxx>
CC: Rob Hoes <Rob.Hoes@xxxxxxxxxx>
CC: Andrii Sultanov <andrii.sultanov@xxxxxxxxx>

Broken out of a larger series, to help Andrii with his dynlib work.
---
 tools/ocaml/libs/xc/Makefile        |  2 +-
 tools/ocaml/libs/xc/xenctrl_stubs.c | 13 +++----------
 tools/ocaml/libs/xen-caml-compat.h  | 23 +++++++++++++++++++++++
 3 files changed, 27 insertions(+), 11 deletions(-)
 create mode 100644 tools/ocaml/libs/xen-caml-compat.h

diff --git a/tools/ocaml/libs/xc/Makefile b/tools/ocaml/libs/xc/Makefile
index 1d9fecb06ef2..cdf4d01dac52 100644
--- a/tools/ocaml/libs/xc/Makefile
+++ b/tools/ocaml/libs/xc/Makefile
@@ -2,7 +2,7 @@ OCAML_TOPLEVEL=$(CURDIR)/../..
 XEN_ROOT=$(OCAML_TOPLEVEL)/../..
 include $(OCAML_TOPLEVEL)/common.make
 
-CFLAGS += -I../mmap $(CFLAGS_libxenctrl) $(CFLAGS_libxenguest)
+CFLAGS += -I../ -I../mmap $(CFLAGS_libxenctrl) $(CFLAGS_libxenguest)
 CFLAGS += $(APPEND_CFLAGS)
 OCAMLINCLUDE += -I ../mmap -I ../eventchn
 
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c 
b/tools/ocaml/libs/xc/xenctrl_stubs.c
index a52908012960..c78191f95abc 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -25,6 +25,8 @@
 #include <caml/fail.h>
 #include <caml/callback.h>
 
+#include "xen-caml-compat.h"
+
 #include <sys/mman.h>
 #include <stdint.h>
 #include <string.h>
@@ -37,14 +39,6 @@
 
 #include "mmap_stubs.h"
 
-#ifndef Val_none
-#define Val_none (Val_int(0))
-#endif
-
-#ifndef Tag_some
-#define Tag_some 0
-#endif
-
 static inline xc_interface *xch_of_val(value v)
 {
        xc_interface *xch = *(xc_interface **)Data_custom_val(v);
@@ -744,8 +738,7 @@ CAMLprim value stub_xc_evtchn_status(value xch_val, value 
domid, value port)
        Store_field(result_status, 0, Val_int(status.vcpu));
        Store_field(result_status, 1, stat);
 
-       result = caml_alloc_small(1, Tag_some);
-       Store_field(result, 0, result_status);
+       result = caml_alloc_some(result_status);
 
        CAMLreturn(result);
 }
diff --git a/tools/ocaml/libs/xen-caml-compat.h 
b/tools/ocaml/libs/xen-caml-compat.h
new file mode 100644
index 000000000000..b4a0ca4ce90c
--- /dev/null
+++ b/tools/ocaml/libs/xen-caml-compat.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: LGPL-2.1-only WITH OCaml-LGPL-linking-exception */
+#ifndef XEN_CAML_COMPAT_H
+#define XEN_CAML_COMPAT_H
+
+#ifndef Val_none /* Option handling.  Compat for Ocaml < 4.12 */
+
+#define Val_none Val_int(0)
+#define Tag_some 0
+#define Some_val(v) Field(v, 0)
+
+static inline value caml_alloc_some(value v)
+{
+    CAMLparam1(v);
+
+    value some = caml_alloc_small(1, Tag_some);
+    Store_field(some, 0, v);
+
+    CAMLreturn(some);
+}
+
+#endif /* !Val_none */
+
+#endif /* XEN_CAML_COMPAT_H */

base-commit: 75c64db3722f0245137a1e8cfd3435f4790d0fd7
-- 
2.39.2