Bug in file handling

cache.php assumes fopen always succeeds, this is not the case.

A basic patch to add error handling:

--- cache.php.orig   2013-08-12 21:01:51.304559847 +0000
+++ cache.php   2013-08-12 21:01:30.613445609 +0000
@@ -249,6 +249,10 @@ function hyper_cache_write(&$data) {
         if ($data['gz']) unset($data['html']);
     }
     $file = fopen($hc_file, 'w');
+    if (!$file) {
+        error_log("Failed to open cache file '$hc_file'");
+        return;
+    }
     fwrite($file, serialize($data));
     fclose($file);

http://wordpress.org/plugins/hyper-cache/