[PATCH v4 11/27] libxl: ocaml: propagate the libxl return error code in exceptions

[Rob Hoes <rob.hoes@citrix.com>]

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
Acked-by: David Scott <dave.scott@eu.citrix.com>
---
 tools/ocaml/libs/xl/genwrap.py       |   10 +++----
 tools/ocaml/libs/xl/xenlight.ml.in   |   10 +++++--
 tools/ocaml/libs/xl/xenlight.mli.in  |    9 ++++--
 tools/ocaml/libs/xl/xenlight_stubs.c |   50 ++++++++++++++++++++++++----------
 4 files changed, 55 insertions(+), 24 deletions(-)

diff --git a/tools/ocaml/libs/xl/genwrap.py b/tools/ocaml/libs/xl/genwrap.py
index 0f73e26..e072386 100644
--- a/tools/ocaml/libs/xl/genwrap.py
+++ b/tools/ocaml/libs/xl/genwrap.py
@@ -244,7 +244,7 @@ def c_val(ty, c, o, indent="", parent = None):
         for e in ty.values:
             s += "    case %d: *%s = %s; break;\n" % (n, c, e.name)
             n += 1
-        s += "    default: failwith_xl(\"cannot convert value to %s\"); break;\n" % ty.typename
+        s += "    default: failwith_xl(ERROR_FAIL, \"cannot convert value to %s\"); break;\n" % ty.typename
         s += "}"
     elif isinstance(ty, idl.KeyedUnion):
         s += "{\n"
@@ -257,7 +257,7 @@ def c_val(ty, c, o, indent="", parent = None):
                                                     parent + ty.keyvar.name,
                                                     f.enumname)
                 n += 1
-        s += "\t\t    default: failwith_xl(\"variant handling bug %s%s (long)\"); break;\n" % (parent, ty.keyvar.name)        
+        s += "\t\t    default: failwith_xl(ERROR_FAIL, \"variant handling bug %s%s (long)\"); break;\n" % (parent, ty.keyvar.name)        
         s += "\t\t}\n"
         s += "\t} else {\n"
         s += "\t\t/* Is block... */\n"
@@ -273,7 +273,7 @@ def c_val(ty, c, o, indent="", parent = None):
                 s += "%s" % c_val(f.type, fexpr, "Field(%s, 0)" % o, indent=indent+"\t\t        ")
                 s += "break;\n"
                 n += 1
-        s += "\t\t    default: failwith_xl(\"variant handling bug %s%s (block)\"); break;\n" % (parent, ty.keyvar.name)
+        s += "\t\t    default: failwith_xl(ERROR_FAIL, \"variant handling bug %s%s (block)\"); break;\n" % (parent, ty.keyvar.name)
         s += "\t\t}\n"
         s += "\t}\n"
         s += "}"
@@ -342,7 +342,7 @@ def ocaml_Val(ty, o, c, indent="", parent = None):
         for e in ty.values:
             s += "    case %s: %s = Int_val(%d); break;\n" % (e.name, o, n)
             n += 1
-        s += "    default: failwith_xl(\"cannot convert value from %s\"); break;\n" % ty.typename
+        s += "    default: failwith_xl(ERROR_FAIL, \"cannot convert value from %s\"); break;\n" % ty.typename
         s += "}"
     elif isinstance(ty, idl.KeyedUnion):
         n = 0
@@ -371,7 +371,7 @@ def ocaml_Val(ty, o, c, indent="", parent = None):
                 m += 1
                 #s += "\t        %s = caml_alloc(%d,%d);\n" % (o,len(f.type.fields),n)
             s += "\t        break;\n"
-        s += "\t    default: failwith_xl(\"cannot convert value from %s\"); break;\n" % ty.typename
+        s += "\t    default: failwith_xl(ERROR_FAIL, \"cannot convert value from %s\"); break;\n" % ty.typename
         s += "\t}"
     elif isinstance(ty,idl.Aggregate) and (parent is None or ty.rawname is None):
         s += "{\n"
diff --git a/tools/ocaml/libs/xl/xenlight.ml.in b/tools/ocaml/libs/xl/xenlight.ml.in
index dffba72..a281425 100644
--- a/tools/ocaml/libs/xl/xenlight.ml.in
+++ b/tools/ocaml/libs/xl/xenlight.ml.in
@@ -13,18 +13,22 @@
  * GNU Lesser General Public License for more details.
  *)
 
-exception Error of string
-
 type ctx
 type domid = int
 type devid = int
 
 (* @@LIBXL_TYPES@@ *)
 
+exception Error of (error * string)
+
 external ctx_alloc: Xentoollog.handle -> ctx = "stub_libxl_ctx_alloc"
 
+external test_raise_exception: unit -> unit = "stub_raise_exception"
+
 external send_trigger : ctx -> domid -> trigger -> int -> unit = "stub_xl_send_trigger"
 external send_sysrq : ctx -> domid -> char -> unit = "stub_xl_send_sysrq"
 external send_debug_keys : ctx -> string -> unit = "stub_xl_send_debug_keys"
 
-let _ = Callback.register_exception "Xenlight.Error" (Error(""))
+let register_exceptions () =
+	Callback.register_exception "Xenlight.Error" (Error(ERROR_FAIL, ""))
+
diff --git a/tools/ocaml/libs/xl/xenlight.mli.in b/tools/ocaml/libs/xl/xenlight.mli.in
index e2686bb..d663196 100644
--- a/tools/ocaml/libs/xl/xenlight.mli.in
+++ b/tools/ocaml/libs/xl/xenlight.mli.in
@@ -13,16 +13,21 @@
  * GNU Lesser General Public License for more details.
  *)
 
-exception Error of string
-
 type ctx
 type domid = int
 type devid = int
 
 (* @@LIBXL_TYPES@@ *)
 
+exception Error of (error * string)
+
+val register_exceptions: unit -> unit
+
 external ctx_alloc: Xentoollog.handle -> ctx = "stub_libxl_ctx_alloc"
 
+external test_raise_exception: unit -> unit = "stub_raise_exception"
+
 external send_trigger : ctx -> domid -> trigger -> int -> unit = "stub_xl_send_trigger"
 external send_sysrq : ctx -> domid -> char -> unit = "stub_xl_send_sysrq"
 external send_debug_keys : ctx -> string -> unit = "stub_xl_send_debug_keys"
+
diff --git a/tools/ocaml/libs/xl/xenlight_stubs.c b/tools/ocaml/libs/xl/xenlight_stubs.c
index dd6c781..67612f4 100644
--- a/tools/ocaml/libs/xl/xenlight_stubs.c
+++ b/tools/ocaml/libs/xl/xenlight_stubs.c
@@ -47,12 +47,34 @@ static char * dup_String_val(value s)
 	return c;
 }
 
-static void failwith_xl(char *fname)
+/* Forward reference: this is defined in the auto-generated include file below. */
+static value Val_error (libxl_error error_c);
+
+static void failwith_xl(int error, char *fname)
 {
-	value *exc = caml_named_value("Xenlight.Error");
+	CAMLlocal1(arg);
+	static value *exc = NULL;
+
+	/* First time around, lookup by name */
+	if (!exc)
+		exc = caml_named_value("Xenlight.Error");
+
 	if (!exc)
-		caml_invalid_argument("Exception Xenlight.Error not initialized, please link xl.cma");
-	caml_raise_with_string(*exc, fname);
+		caml_invalid_argument("Exception Xenlight.Error not initialized, please link xenlight.cma");
+
+	arg = caml_alloc(2, 0);
+
+	Store_field(arg, 0, Val_error(error));
+	Store_field(arg, 1, caml_copy_string(fname));
+
+	caml_raise_with_arg(*exc, arg);
+}
+
+CAMLprim value stub_raise_exception(value unit)
+{
+	CAMLparam1(unit);
+	failwith_xl(ERROR_FAIL, "test exception");
+	CAMLreturn(Val_unit);
 }
 
 void ctx_finalize(value ctx)
@@ -78,7 +100,7 @@ CAMLprim value stub_libxl_ctx_alloc(value logger)
 
 	ret = libxl_ctx_alloc(&ctx, LIBXL_VERSION, 0, (xentoollog_logger *) Xtl_val(logger));
 	if (ret != 0) \
-		failwith_xl("cannot init context");
+		failwith_xl(ERROR_FAIL, "cannot init context");
 
 	handle = caml_alloc_custom(&libxl_ctx_custom_operations, sizeof(ctx), 0, 1);
 	Ctx_val(handle) = ctx;
@@ -246,7 +268,7 @@ static int Bitmap_val(libxl_ctx *ctx, libxl_bitmap *c_val, value v)
 
 	c_val->size = 0;
 	if (len > 0 && libxl_bitmap_alloc(ctx, c_val, len))
-		failwith_xl("cannot allocate bitmap");
+		failwith_xl(ERROR_NOMEM, "cannot allocate bitmap");
 	for (i=0; i<len; i++) {
 		if (Int_val(Field(v, i)))
 			libxl_bitmap_set(c_val, i);
@@ -342,7 +364,7 @@ value stub_xl_device_##type##_##op(value ctx, value info, value domid)	\
 	libxl_device_##type##_dispose(&c_info);				\
 									\
 	if (ret != 0)							\
-		failwith_xl(STRINGIFY(type) "_" STRINGIFY(op));		\
+		failwith_xl(ret, STRINGIFY(type) "_" STRINGIFY(op));	\
 									\
 	CAMLreturn(Val_unit);						\
 }
@@ -368,7 +390,7 @@ value stub_xl_physinfo_get(value ctx)
 	ret = libxl_get_physinfo(CTX, &c_physinfo);
 
 	if (ret != 0)
-		failwith_xl("get_physinfo");
+		failwith_xl(ret, "get_physinfo");
 
 	physinfo = Val_physinfo(&c_physinfo);
 
@@ -387,7 +409,7 @@ value stub_xl_cputopology_get(value ctx)
 	c_topology = libxl_get_cpu_topology(CTX, &nr);
 
 	if (!c_topology)
-		failwith_xl("topologyinfo");
+		failwith_xl(ERROR_FAIL, "get_cpu_topologyinfo");
 
 	topology = caml_alloc_tuple(nr);
 	for (i = 0; i < nr; i++) {
@@ -414,7 +436,7 @@ value stub_xl_domain_sched_params_get(value ctx, value domid)
 
 	ret = libxl_domain_sched_params_get(CTX, Int_val(domid), &c_scinfo);
 	if (ret != 0)
-		failwith_xl("domain_sched_params_get");
+		failwith_xl(ret, "domain_sched_params_get");
 
 	scinfo = Val_domain_sched_params(&c_scinfo);
 
@@ -436,7 +458,7 @@ value stub_xl_domain_sched_params_set(value ctx, value domid, value scinfo)
 	libxl_domain_sched_params_dispose(&c_scinfo);
 
 	if (ret != 0)
-		failwith_xl("domain_sched_params_set");
+		failwith_xl(ret, "domain_sched_params_set");
 
 	CAMLreturn(Val_unit);
 }
@@ -453,7 +475,7 @@ value stub_xl_send_trigger(value ctx, value domid, value trigger, value vcpuid)
 				 c_trigger, Int_val(vcpuid));
 
 	if (ret != 0)
-		failwith_xl("send_trigger");
+		failwith_xl(ret, "send_trigger");
 
 	CAMLreturn(Val_unit);
 }
@@ -466,7 +488,7 @@ value stub_xl_send_sysrq(value ctx, value domid, value sysrq)
 	ret = libxl_send_sysrq(CTX, Int_val(domid), Int_val(sysrq));
 
 	if (ret != 0)
-		failwith_xl("send_sysrq");
+		failwith_xl(ret, "send_sysrq");
 
 	CAMLreturn(Val_unit);
 }
@@ -481,7 +503,7 @@ value stub_xl_send_debug_keys(value ctx, value keys)
 
 	ret = libxl_send_debug_keys(CTX, c_keys);
 	if (ret != 0)
-		failwith_xl("send_debug_keys");
+		failwith_xl(ret, "send_debug_keys");
 
 	free(c_keys);
 
-- 
1.7.10.4