Add unit tests and correct bugs detected by the tests

modules/lua/lualib.h

@@ -14,15 +14,43 @@
 #define SLICE "slice"
 
 typedef struct {
+    size_t magic;
 	size_t len;
     uint8_t* data;
 } slice_t;
 
+
+#ifndef LUA_SLICE_MAGIC
+/**
+ * @brief Send data to the server via fastCGI protocol
+ * This function is defined by the luad fcgi server
+ * 
+ * @param fd the socket fd
+ * @param id the request id
+ * @param ptr data pointer
+ * @param size data size
+ * @return int 
+ */
+int fcgi_send_slice(int fd, uint16_t id, uint8_t* ptr, size_t size);
+
+/**
+ * @brief Get the magic number of the slice
+ * This value is defined by the luad fastCGI server
+ * 
+ * @return size_t 
+ */
+size_t lua_slice_magic();
+#else
+#define lua_slice_magic() (LUA_SLICE_MAGIC)
+#define fcgi_send_slice(fd,id,ptr,size) (-1)
+#endif
+
 void lua_new_slice(lua_State*L, int n)
 {
     size_t nbytes = sizeof(slice_t) + n * 1U;
     slice_t *a = (slice_t *)lua_newuserdata(L, nbytes);
     a->data = &((char *)a)[sizeof(slice_t)];
+    a->magic = lua_slice_magic();
     luaL_getmetatable(L, SLICE);
     lua_setmetatable(L, -2);