From 47ce8a968844eeb061d95eb4533e2dbf807ec079 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gordan=20Neki=C4=87?=
 <48327736+gnekich@users.noreply.github.com>
Date: Mon, 22 Dec 2025 19:50:36 +0100
Subject: [PATCH] =?UTF-8?q?fix:=20:bug:=20fix=20the=20utf8ToBase64=5F=20im?=
 =?UTF-8?q?plementation=20to=20mitigate=20maximum=20s=E2=80=A6=20(#32817)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* fix: :bug: fix the utf8ToBase64_ implementation to mitigate maximum stack error for big scriptlets, resolves issue 51448

* docs: :memo: update comment
---
 .../brave_adblock_browser_proxy.ts                     | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/browser/resources/settings/default_brave_shields_page/brave_adblock_browser_proxy.ts b/browser/resources/settings/default_brave_shields_page/brave_adblock_browser_proxy.ts
index 7922cfe6234..7fab1fe0d7f 100644
--- a/browser/resources/settings/default_brave_shields_page/brave_adblock_browser_proxy.ts
+++ b/browser/resources/settings/default_brave_shields_page/brave_adblock_browser_proxy.ts
@@ -146,7 +146,15 @@ export class BraveAdblockBrowserProxyImpl implements BraveAdblockBrowserProxy {
 
   private utf8ToBase64_ (str: string) {
     const uint8Array = new TextEncoder().encode(str)
-    const base64String = btoa(String.fromCharCode(...uint8Array))
+    let binaryString = ''
+    const chunkSize = 1024
+    for (let i = 0; i < uint8Array.length; i += chunkSize) {
+      const chunk = uint8Array.slice(i, i + chunkSize)
+      binaryString += String.fromCharCode(...chunk)
+    }
+    const base64String = btoa(binaryString)
+    // Replace with uint8Array.toBase64() when TypeScript adds support for 
+    // toBase64 method.
     return base64String
   }