From ae059387855f71567ad0bb8e24dbefb830b6c624 Mon Sep 17 00:00:00 2001
From: Jaifroid <egk10@cam.ac.uk>
Date: Sun, 6 Dec 2020 21:47:13 +0000
Subject: [PATCH] Fix catastrophic backtracking

Former-commit-id: b6d4ec6664991164989bc4a809cf13c945adb006 [formerly add1f091841cf936e5e5a02ee7e8d99e9d0b6c57 [formerly 2f34f011c2b41a5501dcb6cfc8e3710ba1d21d80]]
Former-commit-id: 28999c62eedfd9966726e4f34b97716e392cf32d
Former-commit-id: b3202981b0ee58f9dc6b35252849e0d4fdb87c54
---
 www/js/app.js | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/www/js/app.js b/www/js/app.js
index 1eb36aab..b8afb0bb 100644
--- a/www/js/app.js
+++ b/www/js/app.js
@@ -3078,23 +3078,25 @@ define(['jquery', 'zimArchiveLoader', 'uiUtil', 'util', 'cache', 'images', 'cook
                 /[^\\](\$\$?)((?:\\\$|(?!\1)[\s\S])+)\1/.test(htmlArticle) : false;
             //Replace all TeX SVGs with MathJax scripts
             if (params.useMathJax) {
-                htmlArticle = htmlArticle.replace(/<img\s+(?=[^>]+?math-fallback-image)[^>]*?alt\s*=\s*(['"])((?:[^"']|(?!\1)[\s\S])+)[^>]+>/ig,
-                    function (p0, p1, math) {
-                        // Remove any rogue ampersands in MathJax due to double escaping (by Wikipedia)
-                        math = math.replace(/&amp;/g, '&');
-                        // Change any mbox commands to fbox (because KaTeX doesn't support mbox)
-                        math = math.replace(/mbox{/g, 'fbox{');
-                        return '<script type="math/tex">' + math + '</script>';
-                    });
                 // Deal with any newer MathML blocks
                 htmlArticle = htmlArticle.replace(/(<math\b[^>]+alttext=(["']))((?:[^"']|[\s\S](?!\2))+?)(\2(?:[^<]|<(?!\/math))+(?:[^<]|<(?!img))+)<img\b[^>]+?class=["'][^"']*?mwe-math-fallback-image[^>]+>/ig,
-                    function (_p0, p1, _p2, math, p4) {
-                        // Remove any rogue ampersands in MathJax due to double escaping (by Wikipedia)
-                        math = math.replace(/&amp;/g, '&');
-                        // Change any mbox commands to fbox (because KaTeX doesn't support mbox)
-                        math = math.replace(/mbox{/g, 'fbox{');
-                        return p1 + math + p4 + '<script type="math/tex">' + math + '</script>';
-                    });
+                function (_p0, p1, _p2, math, p4) {
+                    // Remove any rogue ampersands in MathJax due to double escaping (by Wikipedia)
+                    math = math.replace(/&amp;/g, '&');
+                    // Change any mbox commands to fbox (because KaTeX doesn't support mbox)
+                    math = math.replace(/mbox{/g, 'fbox{');
+                    return p1 + math + p4 + '<script type="math/tex">' + math + '</script>';
+                });
+                // Older math blocks
+                htmlArticle = htmlArticle.replace(/<img\s+(?=[^>]+?math-fallback-image)[^>]*?alt\s*=\s*(['"])((?:[^"']|(?!\1)[\s\S])+)[^>]+>/ig,
+                function (p0, p1, math) {
+                    // Remove any rogue ampersands in MathJax due to double escaping (by Wikipedia)
+                    math = math.replace(/&amp;/g, '&');
+                    // Change any mbox commands to fbox (because KaTeX doesn't support mbox)
+                    math = math.replace(/mbox{/g, 'fbox{');
+                    return '<script type="math/tex">' + math + '</script>';
+                });
+                
             }
 
             params.containsMathTex = params.useMathJax ? /<script\s+type\s*=\s*['"]\s*math\/tex\s*['"]/i.test(htmlArticle) : false;