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Crash/Exception due to invalid CSS parsing
Description
Given SVG input file with CSS polyline{ fill: none; }; ellipse{ stroke:url(#colorForest); fill: none; stroke-width: 4; };
This code https://github.com/svg-net/SVG/blob/master/Source/SvgDocument.cs#L490
parses the CSS and returns 3! rules, even though there are only two.
First rule the polyline
Second rule the ellipse
Third rule Selector null and Value null, triggering a null reference exception at:
rule.Selector
https://github.com/svg-net/SVG/blob/master/Source/SvgDocument.cs#L499
Using this CSS: polyline{ fill: none; }; ellipse{ stroke:url(#colorForest); fill: none; stroke-width: 4; }
Fixes the issue. Its technically a problem with the ExCSS parser thing, and not SVG itself.
Example data
Used Versions
Running at commit c4e83167c6adfb8d6770eb109d1a03dd656096c2 from 20th jan 2021
@dedmen
What do you expect from this issue ?
Please specify the correct CSS as below.
polyline{ fill: none; } ellipse{ stroke:url(#colorForest); fill: none; stroke-width: 4; }
Now:
Input: polyline{ fill: none; }; ellipse{ stroke:url(#colorForest); fill: none; stroke-width: 4; };
Output: 1 rule for polyline, 1 rule for ellipse, 1 rule for null
Input: polyline{ fill: none; }; ellipse{ stroke:url(#colorForest); fill: none; stroke-width: 4; }
Output: 1 rule for polyline, 1 rule for ellipse
Expected:
Input: polyline{ fill: none; }; ellipse{ stroke:url(#colorForest); fill: none; stroke-width: 4; };
Output: 1 rule for polyline, 1 rule for ellipse
Input: polyline{ fill: none; }; ellipse{ stroke:url(#colorForest); fill: none; stroke-width: 4; }
Output: 1 rule for polyline, 1 rule for ellipse
The semicolon at the end shouldn't cause the CSS parser to output a null rule, and trigger a NullReferenceException
Fixes the issue. Its technically a problem with the ExCSS parser thing, and not SVG itself.
As you said, it depends on behavior of ExCSS library.
However, even major browsers(Edge, Firefox, Chrome) make an error for this semicolon issue.
(sample HTML)
<html>
<meta charset="UTF-8">
<head>
<style type="text/css">
p {line-height:1.5;};
p {color:blue;}
</style>
</head>
<body>
<p>This is CSS test.</p>
</body>
</html>
For reference, the latest ExCSS gives the following results. Output: 1 rule for polyline