我怀疑有人可以在没有完整示例的情况下实际诊断出问题，但这是处理Lua-to-C调用的惯用方式，并且对代码本身:

I doubt that someone can actually diagnose the problem in question without full example, but here is idiomatic way to handle Lua-to-C calls and some comments on the code itself:

static int // not int32_t
lua_set_popup_memory(lua_State *L)
{
    luaL_checktype(L, 1, LUA_TTABLE);
    // let alone excessive arguments (idiomatic), or do:
    lua_settop(L, 1);

    int a_size = lua_rawlen(L, 1); // absolute indexing for arguments
    uint8_t *buf = malloc((size_t)a_size);

    for (int i = 1; i <= a_size; i++) {
        lua_pushinteger(L, i);
        lua_gettable(L, 1); // always give a chance to metamethods
        // OTOH, metamethods are already broken here with lua_rawlen()
        // if you are on 5.2, use lua_len()

        if (lua_isnil(L, -1)) { // relative indexing for "locals"
            a_size = i-1; // fix actual size (e.g. 4th nil means a_size==3)
            break;
        }

        if (!lua_isnumber(L, -1)) // optional check
            return luaL_error(L, "item %d invalid (number required, got %s)",
                              i, luaL_typename(L, -1));

        lua_Integer b = lua_tointeger(L, -1);

        if (b < 0 || b > UINT8_MAX) // optional
            return luaL_error(L, "item %d out of range", i);

        buf[i-1] = b; // Lua is 1-based, C is 0-based
        lua_pop(L, 1);
    }

    set_popup_memory(memory_popup, 0, buf, a_size);
    free(buf);

    return 0;
}

请注意，lua_CFunction被定义为int (*)(lua_State *)，因此int32_t的返回类型可能(很可能会)在非32位平台上引起问题.另外，原始代码可能会溢出buf[i]，因为C索引以零而不是1开头.还有一个更明显的问题:lua_rawlen()可能会将大于循环计数的索引返回给(例如，具有零孔的数组)，导致不必要的零被传递给set_popup_memory(假设first-nil方法的优先级超过表的长度).

Please note that lua_CFunction is defined as int (*)(lua_State *), so return type of int32_t may (and most likely will) cause problems on non-32-bit platforms. Also, original code is probably overflowing buf[i], because C indexes start with zero, not 1. And there is one more obvious issue: lua_rawlen() may return the index greater than loop counts to (e.g. array with nil-holes), causing unneeded zeroes being passed to set_popup_memory (assuming priority of first-nil method over table length).

不确定out_error，使用Lua错误可能会提供更清晰的诊断，尤其是当使用lua_pcall的traceback参数调用入口点时.

Not sure about out_error, the use of Lua errors may give cleaner diagnostics, especially when entry point was called with lua_pcall's traceback argument.

此代码段未经实际测试.

This code snippet was not actually tested.