feature: added pure C API function ngx_http_lua_ffi_master_pid() for the get_master_pid() Lua FFI API in ngx.process of lua-resty-core.

Signed-off-by: Yichun Zhang (agentzh) <agentzh@gmail.com>

Author: chronolaw

src/ngx_http_lua_worker.c

@@ -135,6 +135,21 @@ ngx_http_lua_ffi_worker_count(void)
 }
 
 
+int
+ngx_http_lua_ffi_master_pid(void)
+{
+#if (nginx_version >= 1013008)
+    if (ngx_process == NGX_PROCESS_SINGLE) {
+        return (int) ngx_pid;
+    }
+
+    return (int) ngx_parent;
+#else
+    return NGX_ERROR;
+#endif
+}
+
+
 int
 ngx_http_lua_ffi_get_process_type(void)
 {