[-] Fixes a race condition

Fixes a race condition leading to file coruption and PHP crashes when
writing the cache index file.

Handles concurrency properly by using a temporary file and an atomic
rename() instead of file_put_contents(), which is not atomic, on a
file which is potentially accessed by many processes at the same time

classes/Autoload.php

@@ -136,27 +136,13 @@ class Autoload
 		}
 		else
 		{
-			// Let's write index content in cache file
-			// In order to be sure that this file is correctly written, a check is done on the file content
-			$loop_protection = 0;
-			do
-			{
-				$integrity_is_ok = false;
-				file_put_contents($filename, $content, LOCK_EX);
-				if ($loop_protection++ > 10)
-					break;
-
-				// If the file content end with PHP tag, integrity of the file is ok
-				if (preg_match('#\?>\s*$#', file_get_contents($filename)))
-					$integrity_is_ok = true;
-			}
-			while (!$integrity_is_ok);
-
-			if (!$integrity_is_ok)
-			{
-				file_put_contents($filename, '<?php return array(); ?>', LOCK_EX);
-				// Cannot use PrestaShopException in this context
-				die('Your file '.$filename.' is corrupted. Please remove this file, a new one will be regenerated automatically');
+			$filename_tmp = tempnam(dirname($filename), basename($filename.'.'));
+			if($filename_tmp !== FALSE and file_put_contents($filename_tmp, $content, LOCK_EX) !== FALSE) {
+				rename($filename_tmp, $filename);
+			} else {
+				// $filename_tmp couldn't be written. $filename should be there anyway (even if outdated),
+				// no need to die.
+				error_log('Cannot write temporary file '.$filename_tmp);
 			}
 		}