util.ringbuffer: Allocate buffer itself as part of userdata (simpler, single allocation, no need for __gc)

util-src/ringbuffer.c

@@ -13,7 +13,7 @@ typedef struct {
 	size_t wpos; /* write position */
 	size_t alen; /* allocated size */
 	size_t blen; /* current content size */
-	char* buffer;
+	char buffer[];
 } ringbuffer;
 
 char readchar(ringbuffer* b) {
@@ -166,16 +166,12 @@ int rb_free(lua_State* L) {
 
 int rb_new(lua_State* L) {
 	size_t size = luaL_optinteger(L, 1, sysconf(_SC_PAGESIZE));
-	ringbuffer* b = lua_newuserdata(L, sizeof(ringbuffer));
+	ringbuffer *b = lua_newuserdata(L, sizeof(ringbuffer) + size);
+
 	b->rpos = 0;
 	b->wpos = 0;
 	b->alen = size;
 	b->blen = 0;
-	b->buffer = malloc(size);
-
-	if(b->buffer == NULL) {
-		return 0;
-	}
 
 	luaL_getmetatable(L, "ringbuffer_mt");
 	lua_setmetatable(L, -2);
@@ -183,16 +179,6 @@ int rb_new(lua_State* L) {
 	return 1;
 }
 
-int rb_gc(lua_State* L) {
-	ringbuffer* b = luaL_checkudata(L, 1, "ringbuffer_mt");
-
-	if(b->buffer != NULL) {
-		free(b->buffer);
-	}
-
-	return 0;
-}
-
 int luaopen_util_ringbuffer(lua_State* L) {
 #if (LUA_VERSION_NUM > 501)
 	luaL_checkversion(L);
@@ -202,8 +188,6 @@ int luaopen_util_ringbuffer(lua_State* L) {
 		lua_setfield(L, -2, "__tostring");
 		lua_pushcfunction(L, rb_length);
 		lua_setfield(L, -2, "__len");
-		lua_pushcfunction(L, rb_gc);
-		lua_setfield(L, -2, "__gc");
 
 		lua_newtable(L); /* __index */
 		{