SignalWaitinfo(), SignalWaitinfo_r()

Select a pending signal


#include <sys/neutrino.h>

int SignalWaitinfo( const sigset_t* set,
                    siginfo_t* info );

int SignalWaitinfo_r( const sigset_t* set,
                      siginfo_t* info );


A pointer to a sigset_t object that specifies the signals you want to wait for.
NULL, or a pointer to a siginfo_t structure where the function can store information about the signal.



Use the -l c option to qcc to link against this library. This library is usually included automatically.


The SignalWaitinfo() and SignalWaitinfo_r() kernel calls select the pending signal from the set specified by set. If no signal in set is pending at the time of the call, the thread blocks until one or more signals in set become pending or until interrupted by an unblocked, caught signal.

These functions are identical except in the way they indicate errors. See the Returns section for details.

  • Instead of using these kernel calls directly, consider calling sigwaitinfo().
  • If you don't block the signals before calling this function, there's a race condition in that a signal can be delivered just before the call is made, causing the call to block, which you might not want it to do. Note that simply blocking a signal is insufficient, as there's still a race condition where the signal is delivered just before the call to block it is handled. You could do the following:
    1. Install a signal handler that sets a flag.
    2. Block the signal.
    3. Check if the flag is set.
    4. Call SignalWaitinfo().

If the info argument isn't NULL, information on the selected signal is stored there as follows:

siginfo_t member Description
si_signo Selected signal number
si_code Signal code
si_value Signal value

If, while SignalWaitinfo() is waiting, a caught signal occurs that isn't blocked, the signal handler is invoked and SignalWaitinfo() is interrupted with an error of EINTR.

Blocking states

The calling thread blocks waiting for a signal.


A signal number. If an error occurs:


The call was interrupted by a signal.
A fault occurred when the kernel tried to access the buffers provided.
A kernel timeout unblocked the call. See TimerTimeout().


QNX Neutrino

Cancellation point Yes
Interrupt handler No
Signal handler Yes
Thread Yes