trigger a rescan when trying to fopen a file that exists in cache but not on disk

Signed-off-by: Robin Appelman <robin@icewind.nl>

lib/private/Files/Storage/Local.php

@@ -166,6 +166,9 @@ class Local extends \OC\Files\Storage\Common {
 	public function stat($path) {
 		$fullPath = $this->getSourcePath($path);
 		clearstatcache(true, $fullPath);
+		if (!file_exists($fullPath)) {
+			return false;
+		}
 		$statResult = @stat($fullPath);
 		if (PHP_INT_SIZE === 4 && $statResult && !$this->is_dir($path)) {
 			$filesize = $this->filesize($path);
@@ -388,11 +391,15 @@ class Local extends \OC\Files\Storage\Common {
 	}
 
 	public function fopen($path, $mode) {
+		$sourcePath = $this->getSourcePath($path);
+		if (!file_exists($sourcePath) && $mode === 'r') {
+			return false;
+		}
 		$oldMask = umask($this->defUMask);
 		if (($mode === 'w' || $mode === 'w+') && $this->unlinkOnTruncate) {
 			$this->unlink($path);
 		}
-		$result = fopen($this->getSourcePath($path), $mode);
+		$result = @fopen($sourcePath, $mode);
 		umask($oldMask);
 		return $result;
 	}

lib/private/Files/View.php

@@ -1001,7 +1001,17 @@ class View {
 			$this->logger->info('Trying to open a file with a mode other than "r" or "w" can cause severe performance issues with some backends', ['app' => 'core']);
 		}
 
-		return $this->basicOperation('fopen', $path, $hooks, $mode);
+		$handle = $this->basicOperation('fopen', $path, $hooks, $mode);
+		if (!is_resource($handle) && $mode === 'r') {
+			// trying to read a file that isn't on disk, check if the cache is out of sync and rescan if needed
+			$mount = $this->getMount($path);
+			$internalPath = $mount->getInternalPath($this->getAbsolutePath($path));
+			$storage = $mount->getStorage();
+			if ($storage->getCache()->inCache($internalPath) && !$storage->file_exists($path)) {
+				$this->writeUpdate($storage, $internalPath);
+			}
+		}
+		return $handle;
 	}
 
 	/**