io_block - switch to blocking I/O

       io_block puts UNIX descriptor fd into ``blocking mode.''

       File  descriptors are normally in blocking mode, except if they come from accept() or io_accept() and the
       listening socket was in non-blocking mode.

       io_block - switch to blocking I/O

io_nonblock(3)

                                                                                                     io_block(3)

#include<libowfat/io.h>

       void io_block(int64 fd);