Proper usage of kqueue?

26 Jun 2007

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Hi guys,

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>
#define NUMBER_OF_CHANGES 2
int main( int argc, char *argv[] ) {
    int fd, queue_id, ev;
    struct kevent changelist[ NUMBER_OF_CHANGES ];
    struct kevent eventlist[ NUMBER_OF_CHANGES ];
    struct timespec * timeout = NULL;
    if( argc != 2 ) {
        fprintf( stderr, "usage: %s [directory]\n", argv[ 0 ] );
        return EXIT_FAILURE;
    }
    printf( "Observing %s\n", argv[ 1 ] );
    queue_id = kqueue();
    if( queue_id < 0 ) {
        perror( "kqueue" );
        return EXIT_FAILURE;
    }
    fd = open( argv[ 1 ], O_RDONLY );
    if( fd < 0 ) {
        perror( "open" );
        return EXIT_FAILURE;
    }
    for( ;; ) {
        ev = kevent( queue_id, changelist, 2, eventlist, 2, timeout );
        printf( "We have %d events registered.\n", ev );
        if( ev < 0 ) {
            perror( "kevent" );
            continue;
        }
        if( eventlist[ 0 ].fflags & NOTE_DELETE ) {
            printf( "File deleted.\n" );
            break;
        }
        if( eventlist[ 0 ].fflags & NOTE_ATTRIB ) {
            printf( "File attributes modified.\n" );
        }
        if( eventlist[ 1 ].fflags & NOTE_FORK ) {
            printf( "launchd forked.\n" );
        }
        if( eventlist[ 1 ].fflags & NOTE_EXIT ) {
            printf( "forked process exited.\n" );
        }
        if( eventlist[ 1 ].fflags & NOTE_EXEC ) {
            printf( "launchd exec'ed.\n" );
        }
        if( eventlist[ 1 ].fflags & NOTE_TRACKERR ) {
            printf( "eeps, not enough resources.\n" );
        }
        if( eventlist[ 1 ].fflags & NOTE_CHILD ) {
            printf( "\tParentPID: %d\n", eventlist[ 1 ].data );
        }
        if( eventlist[ 1 ].fflags & NOTE_TRACK ) {
            printf( "NOTE_TRACK returned from parent.\n" );
        }
    }
    close( queue_id );
    close( fd );
    return EXIT_SUCCESS;
}

Thanks,
Will Johansson
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I'm trying to play around with kqueue and learning it. Right now I'm
trying to see how I can register both VNODE and PROC for use with one
single kqueue. However, I've had two kernel panics this morning.
First kernel panics I've had on my MacBook since I bought it. I'm
suspecting something's up possibly with my code. If anyone would look
at my code below and comment about it, that'd be appreciated!
    EV_SET( &changelist[ 0 ], fd, EVFILT_VNODE, EV_ADD | EV_ONESHOT,
NOTE_DELETE | NOTE_EXTEND | NOTE_WRITE | NOTE_ATTRIB, 0, 0 );

    EV_SET( &changelist[ 1 ], 1, EVFILT_PROC, EV_ADD | EV_ONESHOT,
NOTE_EXIT | NOTE_FORK | NOTE_EXEC | NOTE_TRACK, 0, 0 );
        if( eventlist[ 0 ].fflags & NOTE_EXTEND || eventlist
[ 0 ].fflags & NOTE_WRITE ) {

            printf( "File modified.\n" );

        }
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