[HttpFoundation] use atomic writes in MockFileSessionStorage

Author: nicolas-grekas

Session/Storage/MockFileSessionStorage.php

@@ -103,7 +103,10 @@ public function save()
 
         try {
             if ($data) {
-                file_put_contents($this->getFilePath(), serialize($data));
+                $path = $this->getFilePath();
+                $tmp = $path.bin2hex(random_bytes(6));
+                file_put_contents($tmp, serialize($data));
+                rename($tmp, $path);
             } else {
                 $this->destroy();
             }
@@ -123,8 +126,11 @@ public function save()
      */
     private function destroy(): void
     {
-        if (is_file($this->getFilePath())) {
+        set_error_handler(static function () {});
+        try {
             unlink($this->getFilePath());
+        } finally {
+            restore_error_handler();
         }
     }
 
@@ -141,8 +147,14 @@ private function getFilePath(): string
      */
     private function read(): void
     {
-        $filePath = $this->getFilePath();
-        $this->data = is_readable($filePath) && is_file($filePath) ? unserialize(file_get_contents($filePath)) : [];
+        set_error_handler(static function () {});
+        try {
+            $data = file_get_contents($this->getFilePath());
+        } finally {
+            restore_error_handler();
+        }
+
+        $this->data = $data ? unserialize($data) : [];
 
         $this->loadSession();
     }