Mybb: PHP 7 / undefined constant THIS_SCRIPT

[frostschutz]

Message
Use of undefined constant THIS_SCRIPT - assumed 'THIS_SCRIPT' (this will throw an error in a future version of PHP)

Someone reported this issue with my plugin ( https://github.com/frostschutz/MyBB-Google-SEO/issues/60 ). And here I am, shamelessly trying to offload this issue onto you guys.

Usually THIS_SCRIPT is defined by MyBB at the very top of the file like this:

https://github.com/mybb/mybb/blob/feature/showthread.php#L12

define('THIS_SCRIPT', 'showthread.php');

and then global.php is loaded afterwards

https://github.com/mybb/mybb/blob/feature/showthread.php#L28

require_once "./global.php";

And then various things check THIS_SCRIPT for various reasons. This is a problem if THIS_SCRIPT is undefined, so global.php ALSO defines THIS_SCRIPT:

https://github.com/mybb/mybb/blob/feature/global.php#L32-L35

if(!defined('THIS_SCRIPT'))
{
    define('THIS_SCRIPT', '');
}

Now why is that a problem with my plugin? Well, it only happens after the plugin was loaded, because there is all sorts of stuff in global.php before THIS_SCRIPT was redefined to empty string. In particular, init.php is loaded first so THIS_SCRIPT is undefined in init.php and dependencies such as plugins.

https://github.com/mybb/mybb/blob/feature/global.php#L17-18

// Load main MyBB core file which begins all of the magic
require_once $working_dir.'/inc/init.php';

The issue in my plugin would be resolved nicely if MyBB could move the THIS_SCRIPT empty string fallback to the very top of global.php.

Otherwise I'd have to do what the example plugin does....

https://github.com/mybb/mybb/blob/feature/inc/plugins/hello.php#L19

if(defined('THIS_SCRIPT'))

i.e. explicitely check if it's defined first before using it anywhere - but it seems like it should be defined more or less globally (and it's already the case, just not in the early loading phase for plugins) and a lot of other code also simply assumes it's there.

What do you think?

[frostschutz]

Or perhaps that fallback should be moved to init.php as that is where also other things are defined globally (MYBB_ROOT, TIME_NOW).

There should be no downsides to this change unless there is someone explicitely checking for THIS_SCRIPT nonexistence

if(!defined(THIS_SCRIPT)) { do_something_great(); } /* would no longer work */

but I think it's unlikely for anyone to do that

[euantorano]

I’d vote for moving the fallback to init.php personally, given it’s used almost everywhere. I don’t think there would be any adverse affects caused by the change either.

On 4 Feb 2018, at 13:51, Andreas Klauer [e-mail] wrote:

Or perhaps that fallback should be moved to init.php as that is where also other things are defined globally (MYBB_ROOT, TIME_NOW).

There should be no downsides to this change unless there is someone explicitely checking for THIS_SCRIPT nonexistence

if(!defined(THIS_SCRIPT)) { do_something_great(); } /* would no longer work */
but I think it's unlikely for anyone to do that

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[labrocca]

What about changing it to

if(!defined('THIS_SCRIPT'))
{
define('THIS_SCRIPT', 'unknown');
}

[dragonexpert]

I definitely agree with moving it to init.php. I have multiple plugins that I otherwise have to do additional coding to check for it.

[AlekzNet]

Any progress on that? adding the check&set in init.php helps for to get the forum work without errors, but the admin interface still throws errors.

[euantorano]

I've assigned it to 1.8.16, but we don't have a PR yet.

[effone]

I support what @labrocca suggested, to define fallback value to 'unknown'. If someone explicitely checking for THIS_SCRIPT nonexistence he can just query the value to be 'unknown' or not.

But again if anywhere other place inside MyBB; this kind of explicit check is already in place that should be modified too.