procmgr_event_notify()

Arguments:

flags

A bitwise OR of the type of events that you want to be notified of, or 0 to unarm the sigevent. The event types include:

• PROCMGR_EVENT_CONFSTR
• PROCMGR_EVENT_CONTIG_ALLOC_FAIL
• PROCMGR_EVENT_DAEMON_DEATH
• PROCMGR_EVENT_PATHSPACE
• PROCMGR_EVENT_PROCESS_CREATE
• PROCMGR_EVENT_PROCESS_DEATH
• PROCMGR_EVENT_SYNC
• PROCMGR_EVENT_SYSCONF
• PROCMGR_EVENT_TOD

For more information, see Event types, below.

event

A pointer to a sigevent structure that specifies how you want to be notified.

Library:

libc

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

Description:

The procmgr_event_notify() function requests that the process manager notify the caller of the system-wide events identified by the given flags. The application must register the event by calling MsgRegisterEvent() with SYSMGR_COID passed as the connection ID (coid).

To remove the current notification request, pass a value of 0 for flags.

Event types

The following event types are defined in <sys/procmgr.h>:

PROCMGR_EVENT_CONFSTR

A process set a configuration string.

PROCMGR_EVENT_CONTIG_ALLOC_FAIL

An attempt to allocate contiguous memory failed.

PROCMGR_EVENT_DAEMON_DEATH

A process in session 1 died. This event is most useful for watching for the death of daemon processes that use procmgr_daemon() to put themselves in session 1 as well as close and redirect file descriptors. As a result of this closing and redirecting, the death of daemons is difficult to detect otherwise.

PROCMGR_EVENT_PATHSPACE

A resource manager added or removed an entry (i.e., mountpoint) to or from the pathname space. This is generally associated with resource manager calls to resmgr_attach() and resmgr_detach(). Terminating a resource manager process also generates this event if the mountpoints haven't been detached.

PROCMGR_EVENT_PROCESS_CREATE

A new process has been created.

PROCMGR_EVENT_PROCESS_DEATH

A process died.

PROCMGR_EVENT_SYNC

A process called sync() to synchronize the filesystems.

PROCMGR_EVENT_SYSCONF

A process set a system configuration string.

PROCMGR_EVENT_TOD

A process changed the time of day by calling ClockTime() or clock_settime().

If you set SIGEV_FLAG_UPDATEABLE in the hidden bits in the sigevent structure, the kernel provides some additional information in the sigev_value member:

The code for generating the hash of the pathname is as follows:

static unsigned pathspace_hash( const unsigned char *str ) {

    unsigned hash, x;

    for (x = hash = 0 ; *str ; ++str) {
        hash = (hash << 4) + *str;
        if ((x = hash & 0xf0000000u) != 0) {
            hash ^= (x >> 24);
            hash &= ~x;
        }
    }
    // Modification from standard ELFHash so that client can tell that the
    // sigev_value field contains a hash if it's non-zero
    return hash | 0x80000000u;

}

Returns:

-1 on error (errno is set); any other value indicates success.

Examples:

/*
 * This code demonstrates procmgr_event_notify() with the PROCMGR_EVENT_PROCESS_DEATH
 * flag, which allows you to be notified if any process in session 1 dies.
 */
#include <ctype.h>
#include <devctl.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/neutrino.h>
#include <sys/procfs.h>
#include <sys/procmgr.h>

#define PROCESS_DIED_CODE   (_PULSE_CODE_MINAVAIL + 1)

int main( int argc, char **argv )
{
    int chid, coid, rc;
    struct sigevent event;
    struct _pulse msg;

    chid = ChannelCreate( _NTO_CHF_PRIVATE );
    if (0 > chid) {
        fprintf( stderr, "ChannelCreate() failed : %s", strerror(errno) );
        exit( EXIT_FAILURE );
    }

    coid = ConnectAttach( 0, 0, chid, _NTO_SIDE_CHANNEL, _NTO_COF_CLOEXEC );
    if (0 > coid) {
        fprintf( stderr, "ConnectAttach() failed : %s", strerror(errno) );
        exit( EXIT_FAILURE );
    }

    SIGEV_PULSE_INIT( &event, coid, SIGEV_PULSE_PRIO_INHERIT, PROCESS_DIED_CODE, 0 );
    SIGEV_MAKE_UPDATEABLE( &event );

    if (0 != MsgRegisterEvent( &event, SYSMGR_COID )) {
        fprintf( stderr, "MsgRegisterEvent() failed : %s", strerror(errno) );
        exit( EXIT_FAILURE );
    }
    /*
     * Ask to be notified via a pulse whenever a process dies
     */
    if (procmgr_event_notify( PROCMGR_EVENT_PROCESS_DEATH, &event ) == -1) {
        fprintf( stderr, "procmgr_event_notify() failed : %s", strerror(errno) );
        exit( EXIT_FAILURE );
    }

    for(;;) {
        rc = MsgReceivePulse( chid, &msg, sizeof(msg), NULL );
        if (rc == -1) {
            fprintf( stderr, "MsgReceivePulse() failed : %s", strerror(errno) );
            exit( EXIT_FAILURE );
        }

        switch(msg.code) {
            case PROCESS_DIED_CODE:
                printf( "process pid:%i is no longer running\n", msg.value.sival_int );
                break;
        }
    }
    return 0;
}

Classification:

QNX OS