package Linux::FANotify;
use strict;
use warnings;
use Linux::FANotify::LowLevel ':constants',':functions';
use POSIX qw();
use Data::Printer;

my $fan_fd = perl_fanotify_init(0,0);

warn "fan fd: $fan_fd $!";
my $fan_fh;open($fan_fh,'<&=',$fan_fd);

my $ret = perl_fanotify_mark(
    $fan_fd,
    CONST_mark_add,# | CONST_mark_mount,
    CONST_open | CONST_close | CONST_event_on_child,
    0, '/tmp');
if ($ret < 0) {
    die "WTF? $ret";
}

my $buffer;#=perl_memalign(4096,8192);

sub program_for_pid {
    my ($pid) = @_;

    my $ret = "<unknown program ($pid)>";

    open my $fh,'<',"/proc/$pid/cmdline" or return $ret;

    my $cmdline = do { local $/;<$fh> };chomp $cmdline;

    return $cmdline || $ret;
}

sub print_event {
    my ($ev) = @_;

    my $procname = program_for_pid($ev->{pid});
    my $filename = readlink "/proc/self/fd/".$ev->{fd};
    $filename ||= "<unknown file ($ev->{fd})>";
    my $mask = $ev->{mask};

    print "$procname ($mask) $filename\n";
    POSIX::close($ev->{fd});
}

while (1) {
    my $len = sysread($fan_fh,$buffer,8192,0);
    my $ret = unpack_events($buffer);

    for my $ev (@$ret) {
        print_event($ev);
    }
}

close $fan_fh;