Auto download Berkeley DB from Oralce then needed

Makefile

@@ -1,8 +1,25 @@
-all:  c_src/system/lib/libdb.a 
-	./rebar compile eunit ct
+BDB_VERSION=5.1.25
+BDB_DIST=db-$(BDB_VERSION).tar.gz
+BDB_LOCAL_DIST=c_src/$(BDB_DIST)
+BDB_LOCAL_LIB=c_src/system/lib/libdb.a
+BDB_DIST_URL=http://download.oracle.com/berkeley-db/$(BDB_DIST)
 
-c_src/system/lib/libdb.a:
+ERL = erl
+REBAR = ./rebar
+REBAR_FLAGS=
+
+all: $(BDB_LOCAL_LIB)
+	$(REBAR) $(REBAR_FLAGS) compile eunit ct
+
+$(BDB_LOCAL_DIST):
+	$(ERL) -noshell -s inets -eval 'httpc:request(get, {"$(BDB_DIST_URL)", []}, [], [{stream, "$(BDB_LOCAL_DIST)"}])' -s init stop
+
+$(BDB_LOCAL_LIB): $(BDB_LOCAL_DIST)
 	c_src/buildlib.sh
 clean: 
-	./rebar clean
+	$(REBAR) $(REBAR_FLAGS) clean
 
+distclean: clean
+	-rm -rf $(BDB_LOCAL_DIST)
+	-rm -rf c_src/sources 
+	-rm -rf priv