io_wait(3) - Linux man page
Name
io_wait - wait for eventsSyntax
#include <io.h>void io_wait();
Description
io_wait pays attention to timeouts: if a descriptor reaches its timeout, and the program is interested in reading or writing that descriptor, io_wait will return promptly.
Under some circumstances, io_wait will return even though no interesting descriptors are ready. Do not assume that a descriptor is ready merely because io_wait has returned.
io_wait is not interrupted by the delivery of a signal. Programs that expect interruption are unreliable: they will block if the same signal is delivered a moment before io_wait. The correct way to handle signals is with the self-pipe trick.