jrdeinhard has asked for the wisdom of the Perl Monks concerning the following question:

Hello, I'm trying to webify a windows event log script. This script works fine when run from a command line on the server running IIS, but when run as a CGI using CGI.PM it returns the following error: Bad file descriptor at C:\Inetpub\wwwroot\cgi-bin\login.pl line 99. 
line 99:
    $EventLog->GetOldest(\$first) || die $!;

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I believe this is might be a permissions problem but not sure where to look anyone have any ideas? Thanks in advance! Subroutine: 
sub server_events {
    print_header();
    print"<h2>SysAdmin Tools v0.1 (beta) </h2>\n";
    my $servername = $q->param('servername') || 'localhost';
    my $eventtype  = $q->param('eventtype') || 'System';
    my $eventquan  = $q->param('eventquan') || '10';
    print qq{<b>$servername is Server </b><br>};
    print qq{<b>$eventtype is Event Type </b><br>};
    print qq{<b>$eventquan is Event Quantity </b><br>};
    my ($EventLog, $count, $first, $key);
    $first = $count = 0;
    my $event={
    'Source'              => NULL,
    'Computer'            => NULL,
    'Length'              => NULL,
    'Category'            => NULL,
    'RecordNumber'        => NULL,
    'TimeGenerated'       => NULL,
    'Timewritten'         => NULL,
    'EventID'             => NULL,
    'EventType'           => NULL,
    'ClosingRecordNumber' => NULL,
    'Strings'             => NULL,
    'Data',               => NULL,
    };
    $EventLog = new Win32::EventLog( "$eventtype","$servername" ) || d
+ie $!;
    $EventLog->GetOldest(\$first) || die $!;
    $EventLog->GetNumber(\$count) || die $!;
    $EventLog->Read((EVENTLOG_SEEK_READ | EVENTLOG_BACKWARDS_READ),$fi
+rst+$count,$event);
    for my $i ($first+$count-$eventquan+1..$first+$count)
    {
    $EventLog->Read((EVENTLOG_SEQUENTIAL_READ|EVENTLOG_BACKWARDS_READ)
+,0,$event);
    my ($sec,$min,$hour,$mday,$mon,$year,$sday,$yday,$isdst) = localti
+me($event->{'TimeGenerated'});
    print sprintf("%15s -> %02d\-%02d\-%02d, %02d:%02d\n",'timestamp',
+$year,$mon+1,$mday,$hour,$min);

    #to get a readable EventId
    $event->{'EventID'} = $event->{'EventID'} & 0xffff;

    foreach $key ('RecordNumber','Category','Source','EventID', 'Event
+Type', 'Strings', 'Data')
        {
        print sprintf( "%15s -> %s\n",$key, $event->{$key} );
        print "<br>"
        }

    print "\n<br>";
    }

}

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Replies are listed 'Best First'.
Re: win32::eventlog file descriptor errors on IIS Server ($^E)
by tye (Sage) on May 15, 2007 at 20:56 UTC

    Where did you read that $! would hold useful information about errors from Win32::EventLog ? You should check $^E instead (not that the module documentation bothers to tell you this). And testing shows that Win32::EventLog->new() doesn't return a false value for failure, *sigh*. So change your code to something more like: 

        $EventLog= Win32::EventLog->new( "$eventtyp­e", "$serve­rname" )
        or  die $^E;
    die $^E
        if  ! $EventLog->{handle};
    $EventLog->GetOldest( \$first )
        or  die $^E;

    [download]

    And you'll probably see that you don't have privilege to read remote event logs from the security context of a CGI script (since Win32 CGI scripts are usually run in a security context that has no access to Win32 network resources).

    I suspect there is a FAQ on how to access network resources from an IIS script that you could find.

    - tye        

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[d/l]
[select]
      Thanks, I set up the IIS directory where I'm executing my CGI scripts to run as an anonymous user where the anon is a network admin. Everything is working great now! Also appreciatted the tip on $^E, being new to perl I'm not totally up on some all of the built-in's! -Jeff
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Re: win32::eventlog file descriptor errors on IIS Server
by thezip (Vicar) on May 15, 2007 at 20:09 UTC

    Updated:

    Yes, your privileges will be entirely different on the command-line than when the webserver runs it...



    This advice is garbage... so please excuse the noise:

    You might want to do a check for file existence and then complain when it fails. You'll want to explicitly declare the filename (ie. fullpath/filename).

    Maybe the webserver is looking in a different path than when you run it on the command line?

    Where do you want *them* to go today?
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