not \fICURLIOCMD_RESTARTREAD\fP.
The \fIclientp\fP argument to the callback is set with the
-\fICURLOPT_IOCTLDATA(3)\fP option.
+\fUICURLOPT_IOCTLDATA(3)\fP option.
This option is deprecated! Do not use it. Use \fICURLOPT_SEEKFUNCTION(3)\fP
instead to provide seeking! If \fICURLOPT_SEEKFUNCTION(3)\fP is set, this