Retroactively fix files uploaded while finfo was broken/missing

See https://www.woltlab.com/community/thread/312697/

Author: dtdesign

wcfsetup/install/files/lib/system/worker/FileRebuildDataWorker.class.php

@@ -2,10 +2,12 @@
 
 namespace wcf\system\worker;
 
+use wcf\data\file\File;
 use wcf\data\file\FileEditor;
 use wcf\data\file\FileList;
 use wcf\system\file\processor\exception\DamagedImage;
 use wcf\system\file\processor\FileProcessor;
+use wcf\util\FileUtil;
 
 use function wcf\functions\exception\logThrowable;
 
@@ -45,6 +47,8 @@ public function execute()
     {
         parent::execute();
 
+        $this->fixMimeType();
+
         $damagedFileIDs = [];
         foreach ($this->objectList as $file) {
             try {
@@ -61,4 +65,92 @@ public function execute()
             FileEditor::deleteAll($damagedFileIDs);
         }
     }
+
+    private function fixMimeType(): void
+    {
+        $reloadFiles = false;
+        foreach ($this->objectList as $file) {
+            // Workaround for images that have been detected but failed to
+            // determine their dimensions.
+            $isImageWithoutDimensions = $file->isImage() && $file->width === null;
+
+            if ($file->mimeType !== 'application/octet-stream' && !$isImageWithoutDimensions) {
+                continue;
+            }
+
+            $mimeType = FileUtil::getMimeType($file->getPathname());
+            if ($file->mimeType === $mimeType && !$isImageWithoutDimensions) {
+                continue;
+            }
+
+            // When the mime type was incorrectly detected before, for example,
+            // because fileinfo was not present or malfunctioning, the physical
+            // location of the file may be incorrect.
+            //
+            // The location is determined by the safe file extension, anything
+            // that ends in `.bin` is piped through PHP instead of being served
+            // through the web server directly.
+            $previousFileExtension = File::getSafeFileExtension($file->mimeType, $file->filename);
+            $detectedFileExtension = File::getSafeFileExtension($mimeType, $file->filename);
+
+            $width = $height = null;
+            if (\str_starts_with($mimeType, 'image/')) {
+                $data = @\getimagesize($file->getPathname());
+                if ($data === null) {
+                    // Treat broken images as binary files.
+                    $mimeType === 'application/octet-stream';
+                    $detectedFileExtension = 'bin';
+
+                    if ($file->mimeType === $mimeType) {
+                        continue;
+                    }
+                } else {
+                    $width = $data[0];
+                    $height = $data[1];
+                }
+            }
+
+            if ($previousFileExtension !== $detectedFileExtension) {
+                $path = $this->getPath($file->fileHash, $detectedFileExtension);
+                FileUtil::makePath($path);
+
+                \rename(
+                    $file->getPathname(),
+                    $path . \sprintf(
+                        '%d-%s.%s',
+                        $file->fileID,
+                        $file->fileHash,
+                        $detectedFileExtension,
+                    ),
+                );
+            }
+
+            (new FileEditor($file))->update([
+                'fileExtension' => $detectedFileExtension,
+                'mimeType' => $mimeType,
+                'width' => $width,
+                'height' => $height,
+            ]);
+
+            $reloadFiles = true;
+        }
+
+        if ($reloadFiles) {
+            $this->objectList->readObjects();
+        }
+    }
+
+    private function getPath(string $fileHash, string $fileExtension): string
+    {
+        $folderA = \substr($fileHash, 0, 2);
+        $folderB = \substr($fileHash, 2, 2);
+        $isStaticFile = $fileExtension !== 'bin';
+
+        return \sprintf(
+            '_data/%s/files/%s/%s/',
+            $isStaticFile ? 'public' : 'private',
+            $folderA,
+            $folderB,
+        );
+    }
 }