Update Makefile to include android, adding extra function in main.go …

…for debug purposes on Android

cmd/btfs/Makefile

@@ -1,4 +1,8 @@
 # go/Makefile
+ANDROID_OUT=./jniLibs
+ANDROID_SDK=$(HOME)/Library/Android/sdk
+NDK_BIN=$(ANDROID_SDK)/ndk/21.4.7075529/toolchains/llvm/prebuilt/darwin-x86_64/bin
+
 
 ios-arm64:
 	CGO_ENABLED=1 \
@@ -21,4 +25,36 @@ ios-x86_64:
 
 ios: ios-arm64 ios-x86_64
 	lipo $(IOS_OUT)/x86_64.a $(IOS_OUT)/arm64.a -create -output $(IOS_OUT)/btfs.a
-	cp $(IOS_OUT)/arm64.h $(IOS_OUT)/btfs.h
+	cp $(IOS_OUT)/arm64.h $(IOS_OUT)/btfs.h
+
+
+android-armv7a:
+	CGO_ENABLED=1 \
+	GOOS=android \
+	GOARCH=arm \
+	GOARM=7 \
+	CC=$(NDK_BIN)/armv7a-linux-androideabi21-clang \
+	go build -buildmode=c-shared -o $(ANDROID_OUT)/armeabi-v7a/libfoo.so .
+
+android-arm64:
+	CGO_ENABLED=1 \
+	GOOS=android \
+	GOARCH=arm64 \
+	CC=$(NDK_BIN)/aarch64-linux-android21-clang \
+	go build -buildmode=c-shared -o $(ANDROID_OUT)/arm64-v8a/libfoo.so .
+
+android-x86:
+	CGO_ENABLED=1 \
+	GOOS=android \
+	GOARCH=386 \
+	CC=$(NDK_BIN)/i686-linux-android21-clang \
+	go build -buildmode=c-shared -o $(ANDROID_OUT)/x86/libfoo.so .
+
+android-x86_64:
+	CGO_ENABLED=1 \
+	GOOS=android \
+	GOARCH=amd64 \
+	CC=$(NDK_BIN)/x86_64-linux-android21-clang \
+	go build -buildmode=c-shared -o $(ANDROID_OUT)/x86_64/libfoo.so .
+
+android: android-armv7a android-arm64 android-x86 android-x86_64

cmd/btfs/main.go

@@ -82,6 +82,10 @@ func mainC(in *C.char) *C.char {
 	exitCode := mainRet(args)
 	return C.CString("exit code:" + strconv.Itoa(exitCode))
 }
+//export mainCMod
+func mainCMod(in *C.char) *C.char{
+	return C.CString(C.GoString(in))
+}
 
 func mainRet(args []string) int {
 	rand.Seed(time.Now().UnixNano())