lua: push flb_null as a nil value

Signed-off-by: Takahiro Yamashita <[email protected]>
fluent · Sep 23, 2023 · 86672e8 · 86672e8
1 parent ecdbd6f
commit 86672e8
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Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/include/fluent-bit/flb_lua.h b/include/fluent-bit/flb_lua.h
@@ -29,6 +29,9 @@
 #include <monkey/mk_core/mk_list.h>
 #include <msgpack/pack.h>
 
+/* global variables in Lua */
+#define FLB_LUA_VAR_FLB_NULL "flb_null"
+
 #define FLB_LUA_L2C_TYPES_NUM_MAX   16
 
 enum flb_lua_l2c_type_enum {
@@ -74,5 +77,6 @@ void flb_lua_tompack(lua_State *l,
                      int index,
                      struct flb_lua_l2c_config *l2cc);
 void flb_lua_dump_stack(FILE *out, lua_State *l);
+int flb_lua_enable_flb_null(lua_State *l);
 
 #endif
diff --git a/src/flb_lua.c b/src/flb_lua.c
@@ -25,6 +25,17 @@
 #include <fluent-bit/flb_lua.h>
 #include <stdint.h>
 
+int flb_lua_enable_flb_null(lua_State *l)
+{
+    /* set flb.null */
+    lua_pushlightuserdata(l, NULL);
+
+    flb_info("[%s] set %s", __FUNCTION__, FLB_LUA_VAR_FLB_NULL);
+    lua_setglobal(l, FLB_LUA_VAR_FLB_NULL);
+
+    return 0;
+}
+
 void flb_lua_pushtimetable(lua_State *l, struct flb_time *tm)
 {
     lua_createtable(l, 0, 2);
@@ -63,7 +74,7 @@ int flb_lua_pushmpack(lua_State *l, mpack_reader_t *reader)
     tag = mpack_read_tag(reader);
     switch (mpack_tag_type(&tag)) {
         case mpack_type_nil:
-            lua_pushnil(l);
+            lua_getglobal(l, FLB_LUA_VAR_FLB_NULL);
             break;
         case mpack_type_bool:
             lua_pushboolean(l, mpack_tag_bool_value(&tag));
@@ -128,7 +139,7 @@ void flb_lua_pushmsgpack(lua_State *l, msgpack_object *o)
 
     switch(o->type) {
         case MSGPACK_OBJECT_NIL:
-            lua_pushnil(l);
+            lua_getglobal(l, FLB_LUA_VAR_FLB_NULL);
             break;
 
         case MSGPACK_OBJECT_BOOLEAN: