sigevent

Structure that describes an event

Synopsis:

#include <sys/siginfo.h>

union sigval {
    int         sival_int;
    void       *sival_ptr;
};

The sigevent structure is complicated; see below.

Description:

This structure describes an event. The int sigev_notify member indicates how the notification is to occur, as well as which of the other members are used:

The <sys/siginfo.h> file also defines some macros to make initializing the sigevent structure easier. All the macros take a pointer to a sigevent structure as their first argument, event, and set the sigev_notify member to the appropriate value.

SIGEV_INTR

Raise an interrupt. No other fields in the structure are used.

The initialization macro is:

SIGEV_INTR_INIT( event )

SIGEV_NONE

Don't send any notification. No other fields in the structure are used.

The initialization macro is:

SIGEV_NONE_INIT( event )

SIGEV_PULSE

Send a pulse. The following fields are used:

int sigev_coid

The connection ID. This should be attached to the channel with which the pulse will be received.

short sigev_priority

The priority of the pulse.

short sigev_code

A code to be interpreted by the pulse handler. Although sigev_code can be any 8-bit signed value, programs should avoid sigev_code values less than zero in order to avoid conflict with kernel or QNX manager generated pulse codes. These codes all start with _PULSE_CODE_ and are defined in <sys/neutrino.h>. A safe range of pulse values is _PULSE_CODE_MINAVAIL to _PULSE_CODE_MAXAVAIL.

void *sigev_value.sival_ptr

A 32-bit value to be interpreted by the pulse handler.

The initialization macro is:

SIGEV_PULSE_INIT( event, coid, priority, code, value )

SIGEV_SIGNAL

Send a signal to a process. The following fields are used:

int sigev_signo

The signal to raise. This must be in the range from 1 through NSIG - 1.

The initialization macro is:

SIGEV_SIGNAL_INIT( event, signal )

If you need to set the sigev_value for a SIGEV_SIGNAL event (for example if SA_SIGINFO is set), you'll have to initialize the sigevent structure manually.

SIGEV_SIGNAL_CODE

This is similar to SIGEV_SIGNAL, except that SIGEV_SIGNAL_CODE also includes a value and a code. The following fields are used:

int sigev_signo

The signal to raise. This must be in the range from 1 through NSIG - 1.

short sigev_code

A code to be interpreted by the signal handler. This must be in the range from SI_MINAVAIL through SI_MAXAVAIL.

void *sigev_value.sival_ptr

A 32-bit value to be interpreted by the signal handler.

The initialization macro is:

SIGEV_SIGNAL_CODE_INIT( event, signal, value, code )

SIGEV_SIGNAL_THREAD

Send a signal to a specific thread. The following fields are used:

int sigev_signo

The signal to raise. This must be in the range from 1 through NSIG - 1.

short sigev_code

A code to be interpreted by the signal handler. This must be in the range from SI_MINAVAIL through SI_MAXAVAIL.

void *sigev_value.sival_ptr

A 32-bit value to be interpreted by the signal handler.

The initialization macro is:

SIGEV_SIGNAL_THREAD_INIT( event, signal, value, code )

SIGEV_THREAD

Create a new thread.

We don't recommend using this type of event. Pulses are more efficient.

The following fields are used:

void (*sigev_notify_function) (union sigval)

A pointer to the function to be notified.

pthread_attr *sigev_notify_attributes

A pointer to thread attributes. This must be NULL, or point to a structure initialized by pthread_attr_init() at the time of delivery.

void *sigev_value.sival_ptr

A value that's to be passed to the notification function.

The initialization macro is:

SIGEV_THREAD_INIT( event, fn, value, attr )

SIGEV_UNBLOCK

Force a thread to become unblocked. No other fields in the structure are used.

The initialization macro is:

SIGEV_UNBLOCK_INIT( event )

Classification:

QNX 6

See also:

ds_create(), InterruptAttach(), InterruptAttachEvent(), iofunc_notify(), iofunc_notify_trigger(), ionotify(), lio_listio(), mq_notify(), MsgDeliverEvent(), procmgr_event_notify(), TimerCreate(), timer_create(), TimerInfo(), TimerTimeout(), timer_timeout()

"Neutrino IPC" in the Neutrino microkernel chapter of the System Architecture guide