From cdf4931171694ed5b2c4396cda4458342971770b Mon Sep 17 00:00:00 2001
From: Gregor Harlan <mail@gh01.de>
Date: Mon, 31 Aug 2026 15:49:48 +0200
Subject: [PATCH] fix: avoid "No clang found" when the clang cache is deleted
 by a parallel request

`rex_clang::checkCache()` checked the cache file with `is_file()` and read it
afterwards. If a parallel request cleared the cache in between, the read failed
silently, `rex_file::getCache()` returned its empty default and the clang list
stayed empty for the whole request - which surfaces as `LogicException: No clang
found.` in `getStartId()`, and as silently wrong results in `exists()`/`getAll()`.

Read the file first and fall back to a freshly generated cache if the result is
empty. `rex_clang_service::generateCache()` now returns the generated data, so
the fallback does not have to read the file again and cannot lose the same race.
---
 redaxo/src/core/lib/clang/clang.php   | 10 +++++++---
 redaxo/src/core/lib/clang/service.php |  4 +++-
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/redaxo/src/core/lib/clang/clang.php b/redaxo/src/core/lib/clang/clang.php
index 6e6ee84359..6501aaec8d 100644
--- a/redaxo/src/core/lib/clang/clang.php
+++ b/redaxo/src/core/lib/clang/clang.php
@@ -243,10 +243,14 @@ private static function checkCache()
         }
 
         $file = rex_path::coreCache('clang.cache');
-        if (!is_file($file)) {
-            rex_clang_service::generateCache();
+        $cache = rex_file::getCache($file);
+
+        // deliberately no is_file() check: a parallel cache clear could delete the file between check and read
+        if (!$cache) {
+            $cache = rex_clang_service::generateCache();
         }
-        foreach (rex_file::getCache($file) as $id => $data) {
+
+        foreach ($cache as $id => $data) {
             $clang = new self();
             $clang->id = (int) $id;
             $clang->priority = (int) $data['priority'];
diff --git a/redaxo/src/core/lib/clang/service.php b/redaxo/src/core/lib/clang/service.php
index a704314e27..ac361ab506 100644
--- a/redaxo/src/core/lib/clang/service.php
+++ b/redaxo/src/core/lib/clang/service.php
@@ -127,7 +127,7 @@ public static function deleteCLang($id)
      * Schreibt Spracheigenschaften in die Datei include/clang.php.
      *
      * @throws rex_exception
-     * @return void
+     * @return array<int, array<string, scalar|null>>
      */
     public static function generateCache()
     {
@@ -146,5 +146,7 @@ public static function generateCache()
         if (!rex_file::putCache($file, $clangs)) {
             throw new rex_exception('Clang cache file could not be generated');
         }
+
+        return $clangs;
     }
 }