SVGReader: Detect CSS animated SVGs

This does a string check on animated and @keyframe in style elements
for SVGs. If there is a match it will treat this SVG as animated.

While in theory this could be a false positive, without fulling
parsing the CSS, the chances of that seem minor and there are no
real negative consequences either.

Bug: T332790
Change-Id: I4b8b0781e8f9135d9ab856f3ec06f5a76c66c9a8

includes/media/SVGReader.php

@@ -282,6 +282,16 @@ class SVGReader {
 					}
 				}
 				switch ( $this->reader->localName ) {
+					case 'style':
+						$styleContents = $this->reader->readString();
+						if (
+							str_contains( $styleContents, 'animated' ) ||
+							str_contains( $styleContents, '@keyframes' )
+						) {
+							$this->debug( "HOUSTON WE HAVE ANIMATION" );
+							$this->metadata['animated'] = true;
+						}
+						break;
 					case 'script':
 						// Normally we disallow files with
 						// <script>, but its possible

tests/phpunit/data/media/css-animated.svg

@@ -0,0 +1,17 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" viewBox="0 0 100 100">
+	<defs>
+		<style>
+			@keyframes spin {
+				0% { transform: rotate(0deg); }
+				100% { transform: rotate(360deg); }
+			}
+			svg {
+				animation: spin 5s linear infinite;
+			}
+			.acircle {
+				opacity: 0.65;
+			}
+		</style>
+	</defs>
+	<circle class="acircle" cx="40" cy="40" r="30" stroke="red" fill="none"/>
+</svg>

tests/phpunit/includes/media/SVGReaderTest.php

@@ -141,6 +141,17 @@ class SVGReaderTest extends \MediaWikiIntegrationTestCase {
 					'translations' => []
 				],
 			],
+			[
+				"$base/css-animated.svg",
+				[
+					'width' => 100,
+					'height' => 100,
+					'originalWidth' => '100',
+					'originalHeight' => '100',
+					'animated' => true,
+					'translations' => []
+				],
+			],
 		];
 	}