Skip to content

fix: preg_replace backreference corruption in preload head injection #7

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
SamJUK merged 1 commit into from
Jul 15, 2026
Merged

fix: preg_replace backreference corruption in preload head injection #7

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 2 additions & 2 deletions Observer/ResponseBefore.php
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -21,9 +21,9 @@ public function execute(\Magento\Framework\Event\Observer $observer)
}

$response = $observer->getEvent()->getData('response');
$response->setBody(preg_replace(
$response->setBody(preg_replace_callback(
'/<head.*?>/',
"<head>
fn() => "<head>
<!-- SamJUK_FetchPriority:preload -->
{$this->getPreloadsHTML()}
<!-- / SamJUK_FetchPriority::preload -->",
Expand Down
27 changes: 27 additions & 0 deletions Test/Unit/Observer/ResponseBeforeTest.php
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -158,6 +158,33 @@ public function testModifiesResponseInFrontendAreaWithLinks(): void
$this->subject->execute($this->observerMock);
}

/**
* Test that hrefs containing "$" + digits (e.g. "/img$1.jpg") are not corrupted.
* preg_replace() treats $0-$99 in its replacement argument as backreferences
* regardless of source; preg_replace_callback() does not have this problem.
*/
public function testDoesNotCorruptHrefsContainingDollarDigitSequences(): void
{
$linkMock = $this->createMock(LinkInterface::class);
$linkMock->method('getAttrs')->willReturn(['rel' => 'preload', 'href' => '/img$1.jpg']);

$this->appStateMock->method('getAreaCode')->willReturn(Area::AREA_FRONTEND);
$this->linkStoreMock->method('get')->willReturn([$linkMock]);

$this->secureHtmlRendererMock->method('renderTag')
->willReturn('<link rel="preload" href="/img$1.jpg">');

$this->responseMock->method('getBody')->willReturn(self::SAMPLE_RESPONSE_HTML);

$this->responseMock->expects($this->once())
->method('setBody')
->with($this->callback(function ($body) {
return str_contains($body, '/img$1.jpg');
}));

$this->subject->execute($this->observerMock);
}

/**
* Test that only the first <head> tag is replaced.
*/
Expand Down
Loading