pub unsafe extern "C" fn FMOD_System_AttachFileSystem(
system: *mut FMOD_SYSTEM,
useropen: Option<unsafe extern "C" fn(_: *const i8, _: *mut u32, _: *mut *mut c_void, _: *mut c_void) -> FMOD_RESULT>,
userclose: Option<unsafe extern "C" fn(_: *mut c_void, _: *mut c_void) -> FMOD_RESULT>,
userread: Option<unsafe extern "C" fn(_: *mut c_void, _: *mut c_void, _: u32, _: *mut u32, _: *mut c_void) -> FMOD_RESULT>,
userseek: Option<unsafe extern "C" fn(_: *mut c_void, _: u32, _: *mut c_void) -> FMOD_RESULT>,
) -> FMOD_RESULT