io_flush_buffer_sync 1037 io.c               VALUE result = io_flush_buffer_sync(arg);
io_flush_buffer_sync 1050 io.c               return rb_thread_io_blocking_region(io_flush_buffer_sync, fptr, fptr->fd);
io_flush_buffer_sync 4221 io.c           	    if ((int)io_flush_buffer_sync(fptr) < 0 && NIL_P(err))