SDL_GetAsyncIOSize - Use this function to get the size of the data stream in an SDL_AsyncIO.

       This function is available since SDL 3.2.0.

Simple Directmedia Layer                           SDL 3.2.20                              SDL_GetAsyncIOSize(3)

       This  call is _not_ asynchronous; it assumes that obtaining this info is a non-blocking operation in most
       reasonable cases.

asyncio
              the SDL_AsyncIO to get the size of the data stream from.

       SDL_GetAsyncIOSize - Use this function to get the size of the data stream in an SDL_AsyncIO.

       Returns the size of the data stream in the SDL_IOStream on success or a negative error code  on  failure;
       call SDL_GetError() for more information.

#include<SDL3/SDL_asyncio.h>Sint64SDL_GetAsyncIOSize(SDL_AsyncIO*asyncio);

       It is safe to call this function from any thread.