I have a DivisionByZeroError due to a null value in the division

[mmanzano]

This line is protecting us from 0.0 value but not for null values. Is there a reason to not think about an scenario where $rightValue could be null?

https://github.com/dompdf/dompdf/blob/e83283715efe39806b64d3bdae7974d4400f711a/src/Css/Style.php#L1355

I have problems due to that when I use tailwind in order to styling a document. In my end when I remove the line @tailwind components the issue is gone so I don't know if something is wrong in Tailwind. I've tried to change the condition to $rightValue === null || $rightValue === 0.0 and it works. Could I make a PR with this?. I'm asking because maybe I'm missing something. I don't want to do the PR without explaining my reasoning before.

[bsweeney]

Pull requests are always welcome. It would help diagnose the issue to know what from the CSS is causing the issue, but if you are unable to identify it I might be able to do so if you provide some sample code.

[mmanzano]

I leave here a repo where you can reproduce the error:

https://github.com/mmanzano/dompdf-issue-3530

The problematic CSS is in this file:

https://github.com/mmanzano/dompdf-issue-3530/blob/main/resources/views/pdf.blade.php

If I'm not wrong, It's something related with the calc in the padding-bottom of the .aspect-w-x css classes.

I left in the readme some instructions in order to reproduce the exception in a computer without php installed (just in case). Let me know if you need more directions:

https://github.com/mmanzano/dompdf-issue-3530/blob/main/README.md

Thanks for your answer. :+1:

[mmanzano]

@bsweeney did you have time to take a look into the issue? :heart:

[bsweeney]

I have not had a chance to look into it yet. I can confirm this is happening. Looks like the calc function is running even though the variable hasn't been set. Additionally, the calc isn't re-run later once the variable is set. I'll see if I can figure out how to address (besides adding a null check).

[bsweeney]

So, there are two issues here:

1. Attempting to compute a calculation where one side is null. I think if either side of the calculation is null we should not perform the calculation.
2. Unsupported selectors. Dompdf doesn't yet support selectors with escaped characters. The problematic variable is set by the selector .aspect-w-1\.41. The "." is supposed to represent a literal period in the selector, but Dompdf doesn't currently understand escaped characters. As a result, this selector actually is taken to represent as an element with two classes applied: "aspect-w-1" and "41".

I should be able to address both issues in the next release. In the meantime, I believe if you just replace the escaped characters (e.g., change the class to something like aspect-w-1_41) then your document should render without errors.