modules: golang/cgo modules compile, but bad linkage

daemon/worker.c

@@ -53,6 +53,7 @@ int worker_init(struct worker_ctx *worker, mm_ctx_t *mm)
 	kr_context_register(&worker->resolve, "iterate");
 	kr_context_register(&worker->resolve, "itercache");
 	kr_context_register(&worker->resolve, "hints");
+	kr_context_register(&worker->resolve, "gostats");
 
 	return KNOT_EOK;
 }

help.mk

@@ -16,4 +16,5 @@ info:
 	$(info [$(HAS_libuv)] daemon (libuv))
 	$(info [$(HAS_cmocka)] unit tests (libcmocka))
 	$(info [$(HAS_python)] integration tests (libpython))
+	$(info [$(HAS_gccgo)] golang modules (gccgo))
 	$(info )

lib/module.h

@@ -60,4 +60,4 @@ void kr_module_unload(struct kr_module *module);
  * @param module module name (f.e. hints)
  */
 #define KR_MODULE_EXPORT(module) \
-    uint32_t module ## _api() { return KR_MODULE_API; }
\ No newline at end of file
+    uint32_t module ## _api() { return KR_MODULE_API; }

modules/gostats/gostats.go

@@ -5,7 +5,7 @@ package gostats
 #include "lib/module.h"
 extern int gostats_begin(knot_layer_t *, void *);
 extern int gostats_finish(knot_layer_t *);
-static inline const knot_layer_api_t *_layer(void)
+static inline const knot_layer_api_t *_gostats_layer(void)
 {
 	static const knot_layer_api_t _module = {
 		.begin = &gostats_begin,
@@ -18,6 +18,18 @@ import "C"
 import "unsafe"
 import "fmt"
 
+//export gostats_init
+func gostats_init(module *C.struct_kr_module) C.int {
+	fmt.Println("go_init()")
+	return 0
+}
+
+//export gostats_deinit
+func gostats_deinit(module *C.struct_kr_module) C.int {
+	fmt.Println("go_deinit()")
+	return 0
+}
+
 //export gostats_begin
 func gostats_begin(ctx *C.knot_layer_t, param unsafe.Pointer) C.int {
 	fmt.Println("go_begin()")
@@ -32,5 +44,5 @@ func gostats_finish(ctx *C.knot_layer_t) C.int {
 
 //export gostats_layer
 func gostats_layer() *C.knot_layer_api_t {
-	return C._layer()
+	return C._gostats_layer()
 }
\ No newline at end of file

modules/gostats/gostats.mk

-hints_SOURCES := modules/gostats/gostats.g
+gostats_SOURCES := modules/gostats/gostats.go
 gostats_DEPEND := libkresolve
 gostats_LIBS := $(libkresolve_TARGET) $(libkresolve_LIBS)
 $(call make_go_module,gostats)
\ No newline at end of file

modules/modules.mk

 # List of built-in modules
 modules_TARGETS := hints
 
+# List of Golang modules
+$(eval $(call find_bin,gccgo))
+ifeq ($(HAS_gccgo),yes)
+modules_TARGETS += gostats
+endif
+
 # Make C module
 define make_c_module
 $(eval $(call make_module,$(1),modules/$(1)))
 endef
 
+# Go target definition
+define go_target
+$(1): $(2)/$(1)$(LIBEXT)
+$(2)/_obj/_cgo_.o: $$($(1)_SOURCES)
+	$(INSTALL) -d $(2)/_obj
+	$(call quiet,CGO,$$^) -gccgo=true -objdir=$(2)/_obj -- $(CFLAGS) $$^
+$(2)/_obj/$(1).o: $(2)/_obj/_cgo_.o
+	$(call quiet,GCCGO,$$@) -fPIC -c $(2)/_obj/*.go
+$(2)/$(1)$(LIBEXT): $(2)/_obj/$(1).o $$($(1)_DEPEND)
+	$(call quiet,GCCGO,$$@) $(CFLAGS) -$(LIBTYPE) -fPIC -Wno-return-type -o $$@ $(2)/_obj/*.o $(2)/_obj/*.c -lgcc $$($(1)_LIBS)
+$(1)-clean:
+	$(RM) -r $(2)/_obj $(2)/$(1)$(LIBEXT)
+$(1)-install: $(2)/$(1)$(LIBEXT)
+	$(INSTALL) -d $(PREFIX)/$(MODULEDIR)
+	$(INSTALL) $$^ $(PREFIX)/$(MODULEDIR)
+.PHONY: $(1) $(1)-clean $(1)-install
+endef
+
 # Make Go module
 define make_go_module
-# TODO: compilable only with gccgo -shared
-# go tool cgo -- $(CFLAGS) $$($(1)_SOURCES)
+$(eval $(call go_target,$(1),modules/$(1)))
 endef
 
 # Build rules

platform.mk

 # Platform-specific
 CCLD := $(CC)
+CGO := go tool cgo
+GCCGO := gccgo
 LIBEXT := .so
 MODEXT := $(LIBEXT)
 LIBTYPE := shared
@@ -85,6 +87,16 @@ define find_lib
 	$(call have_lib,$(1))
 endef
 
+# Find binary
+define find_bin
+	ifeq ($$(strip $$($(1)_BIN)),)
+		HAS_$(1) := $(shell $(1) --version >/dev/null && echo yes || echo no)
+	else
+		HAS_$(1) := yes
+		$(1) := $$($(1)_BIN)
+	endif
+endef
+
 # Find Python 
 define find_python
 	python_CFLAGS := $(shell $(PYTHON) -c "from distutils import sysconfig as c;print('-I%s' % c.get_python_inc())")