From ef540fdb14cd7086fd0601ae89822c08d4e659d0 Mon Sep 17 00:00:00 2001
From: kdeme <kim.demey@gmail.com>
Date: Tue, 10 Sep 2019 12:16:57 +0200
Subject: [PATCH] Make go wrapper_example subscribe work with c gateway
 function

---
 Makefile                    |  4 ++--
 wrappers/cfuncs.go          | 14 ++++++++++++++
 wrappers/wrapper_example.c  |  4 +++-
 wrappers/wrapper_example.go | 21 ++++++++++++++++-----
 4 files changed, 35 insertions(+), 8 deletions(-)
 create mode 100644 wrappers/cfuncs.go

diff --git a/Makefile b/Makefile
index 1bccf7450..d9d838a9d 100644
--- a/Makefile
+++ b/Makefile
@@ -86,7 +86,7 @@ wrappers: | build deps libnimbus.so go-checks
 	echo -e $(BUILD_MSG) "build/C_wrapper_example" && \
 		$(CC) wrappers/wrapper_example.c -Wl,-rpath,'$$ORIGIN' -Lbuild -lnimbus -lm -g -o build/C_wrapper_example
 	echo -e $(BUILD_MSG) "build/go_wrapper_example" && \
-		go build -linkshared -o build/go_wrapper_example wrappers/wrapper_example.go
+		go build -linkshared -o build/go_wrapper_example wrappers/wrapper_example.go wrappers/cfuncs.go
 
 libnimbus.a: | build deps
 	echo -e $(BUILD_MSG) "build/$@" && \
@@ -97,5 +97,5 @@ wrappers-static: | build deps libnimbus.a go-checks
 	echo -e $(BUILD_MSG) "build/C_wrapper_example_static" && \
 		$(CC) wrappers/wrapper_example.c -static -pthread -Lbuild -lnimbus -lm -ldl -lpcre -g -o build/C_wrapper_example_static
 	echo -e $(BUILD_MSG) "build/go_wrapper_example_static" && \
-		go build -ldflags "-linkmode external -extldflags '-static -ldl -lpcre'" -o build/go_wrapper_example_static wrappers/wrapper_example.go
+		go build -ldflags "-linkmode external -extldflags '-static -ldl -lpcre'" -o build/go_wrapper_example_static wrappers/wrapper_example.go wrappers/cfuncs.go
 
diff --git a/wrappers/cfuncs.go b/wrappers/cfuncs.go
new file mode 100644
index 000000000..d85c1d6f1
--- /dev/null
+++ b/wrappers/cfuncs.go
@@ -0,0 +1,14 @@
+package main
+
+/*
+
+#include "libnimbus.h"
+
+// receiveHandler gateway function
+void receiveHandler_cgo(received_message * msg)
+{
+	void receiveHandler(received_message*);
+	receiveHandler(msg);
+}
+*/
+import "C"
\ No newline at end of file
diff --git a/wrappers/wrapper_example.c b/wrappers/wrapper_example.c
index 728005bb2..730ef3547 100644
--- a/wrappers/wrapper_example.c
+++ b/wrappers/wrapper_example.c
@@ -3,13 +3,15 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <time.h>
+#include <string.h>
 
 #include "libnimbus.h"
 
 void NimMain();
 
 void print_msg(received_message* msg) {
-  printf("Got message! %ld\n", msg->decodedLen);
+  // Note: early null chars will terminate string early
+  printf("received message %.*s\n", (int)msg->decodedLen, msg->decoded);
 }
 
 const char* channel = "status-test-c";
diff --git a/wrappers/wrapper_example.go b/wrappers/wrapper_example.go
index 9b392cee7..2eb985fa9 100644
--- a/wrappers/wrapper_example.go
+++ b/wrappers/wrapper_example.go
@@ -4,10 +4,16 @@ import (
 	"fmt"
 	"runtime"
 	"time"
+	"unsafe"
 )
 
-// #cgo LDFLAGS: -Wl,-rpath,'$ORIGIN' -L${SRCDIR}/../build -lnimbus -lm
-// #include "libnimbus.h"
+
+/*
+#cgo LDFLAGS: -Wl,-rpath,'$ORIGIN' -L${SRCDIR}/../build -lnimbus -lm
+#include "libnimbus.h"
+
+void receiveHandler_cgo(received_message * msg); // Forward declaration.
+*/
 import "C"
 
 // Arrange that main.main runs on main thread.
@@ -24,11 +30,16 @@ func poll() {
 	}
 }
 
+//export receiveHandler
+func receiveHandler(msg *C.received_message) {
+	fmt.Printf("[nim-status] received message %s\n", C.GoStringN((*C.char)(msg.decoded), (C.int)(msg.decodedLen)) )
+}
+
 func Start() {
 	C.NimMain()
 	fmt.Println("[nim-status] Start 1")
 	fmt.Println(C.nimbus_start(30306))
-	//C.nimbus_subscribe(C.CString("status-test-c"), nil)
+	C.nimbus_subscribe(C.CString("status-test-go"), (C.received_msg_handler)(unsafe.Pointer(C.receiveHandler_cgo)))
 	fmt.Println("[nim-status] Start 2")
 
 	peer1 := "enode://2d3e27d7846564f9b964308038dfadd4076e4373ac938e020708ad8819fd4fd90e5eb8314140768f782db704cb313b60707b968f8b61108a6fecd705b041746d@192.168.0.33:30303"
@@ -51,10 +62,10 @@ func ListenAndPost() {
 		t := time.Now().UnixNano() / int64(time.Millisecond)
 		i = i + 1
 		time.Sleep(1 * time.Microsecond)
-		message := fmt.Sprintf("[\"~#c4\",[\"Message:%d\",\"text/plain\",\"~:public-group-user-message\",%d,%d,[\"^ \",\"~:chat-id\",\"status-test-c\",\"~:text\",\"Message:%d\"]]]", i, t*100, t, i)
+		message := fmt.Sprintf("[\"~#c4\",[\"Message:%d\",\"text/plain\",\"~:public-group-user-message\",%d,%d,[\"^ \",\"~:chat-id\",\"status-test-go\",\"~:text\",\"Message:%d\"]]]", i, t*100, t, i)
 		if i%1000 == 0 {
 			fmt.Println("[nim-status] posting", message)
-			C.nimbus_post(C.CString("status-test-c"), C.CString(message))
+			C.nimbus_post(C.CString("status-test-go"), C.CString(message))
 		}
 	}
 }