Improve libwaku and C wrappers (#613)

- Move stuff to Makefile
- Move libwaku to root
- Make examples compile for C and Go
- Update README

.gitignore

@@ -34,5 +34,3 @@ rln
 package-lock.json
 node_modules/
 /.update.timestamp
-
-libwaku

Makefile

@@ -29,6 +29,8 @@ DOCKER_IMAGE_NIM_PARAMS ?= -d:chronicles_colors:none -d:insecure
 	bridge \
 	test \
 	clean \
+	libwaku.so \
+	wrappers \
 	libbacktrace
 
 ifeq ($(NIM_PARAMS),)
@@ -128,7 +130,7 @@ rlnlib:
 ifeq ($(RLN), true)
 	cargo build --manifest-path vendor/rln/Cargo.toml
 endif
-	
+
 test2: | build deps installganache
 	echo -e $(BUILD_MSG) "build/$@" && \
 		$(ENV_SCRIPT) nim test2 $(NIM_PARAMS) waku.nims
@@ -185,3 +187,17 @@ ifneq ($(USE_LIBBACKTRACE), 0)
 endif
 
 endif # "variables.mk" was not included
+
+libwaku.so: | build deps
+	echo -e $(BUILD_MSG) "build/$@" && \
+		$(ENV_SCRIPT) nim c --app:lib --noMain --nimcache:nimcache/libwaku $(NIM_PARAMS) -o:build/$@.0 wrappers/libwaku.nim && \
+		rm -f build/$@ && \
+		ln -s $@.0 build/$@
+
+# libraries for dynamic linking of non-Nim objects
+EXTRA_LIBS_DYNAMIC := -L"$(CURDIR)/build" -lwaku -lm
+wrappers: | build deps libwaku.so
+	echo -e $(BUILD_MSG) "build/C_wrapper_example" && \
+		 $(CC) wrappers/wrapper_example.c -Wl,-rpath,'$$ORIGIN' $(EXTRA_LIBS_DYNAMIC) -g -o build/C_wrapper_example
+	echo -e $(BUILD_MSG) "build/go_wrapper_example" && \
+		go build -ldflags "-linkmode external -extldflags '$(EXTRA_LIBS_DYNAMIC)'" -o build/go_wrapper_example wrappers/wrapper_example.go #wrappers/cfuncs.go

waku/v2/node/libwaku/build.sh

@@ -1,4 +0,0 @@
-#!/usr/bin/env sh
-
-nim c --skipParentCfg libwaku.nim
-gcc libwaku.c ./libwaku.a -lm -g -o libwaku

waku/v2/node/libwaku/nim.cfg

@@ -1,5 +0,0 @@
--app:staticlib
-o:"libwaku.a"
-noMain
-header
--d:"chronicles_sinks=textlines"

wrappers/README.md

@@ -4,9 +4,6 @@ Exposes a C API that can be used by other environments other than C.
 
 ## Running
 
-Make sure you run `$PROJECTDIR/env.sh bash` first. Then:
-
 ```
-./build.sh
-./libwaku
+make wrappers
 ```

wrappers/libwaku.h

@@ -1,3 +1,6 @@
+#ifndef __LIBWAKU_H__
+#define __LIBWAKU_H__
+
 #include <stdint.h>
 #include <stddef.h>
 
@@ -7,3 +10,5 @@ void NimMain();
 char* info(const char* wakuNode);
 
 void echo();
+
+#endif //__LIBWAKU_H__

wrappers/libwaku.nim

@@ -10,7 +10,7 @@
 # TODO Init a node
 
 # proc info*(node: WakuNode): WakuInfo =
-proc info(foo: cstring): cstring {.exportc.} =
+proc info(foo: cstring): cstring {.exportc, dynlib.} =
   echo "info about node"
   echo foo
   return foo
@@ -34,3 +34,5 @@ proc echo() {.exportc.} =
 #  await node.start()
 #
 #main()
+
+  # When main done stuff

wrappers/wrapper_example.c

@@ -3,6 +3,8 @@
 
 #include "libwaku.h"
 
+void NimMain();
+
 int main(int argc, char* argv[]) {
   char* string;
   NimMain();

wrappers/wrapper_example.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"fmt"
+	"runtime"
+)
+
+/*
+#include <stdlib.h>
+
+// Passing "-lwaku" to the Go linker through "-extldflags" is not enough. We need it in here, for some reason.
+#cgo LDFLAGS: -Wl,-rpath,'$ORIGIN' -L${SRCDIR}/../build -lwaku
+#include "libwaku.h"
+
+*/
+import "C"
+
+// Arrange that main.main runs on main thread.
+func init() {
+	runtime.LockOSThread()
+}
+
+func Start() {
+	C.NimMain()
+
+	messageC := C.CString("Calling info")
+	fmt.Println("Start nim-waku")
+	var str = C.info(messageC)
+	fmt.Println("Info", str)
+}
+
+func main() {
+	fmt.Println("Hi main")
+	Start()
+}