Implement basic cache purge (issue #178)

index.php

@@ -23,6 +23,22 @@ if (!extension_loaded('openssl'))
 ini_set('user_agent', 'Mozilla/5.0 (X11; Linux x86_64; rv:30.0) Gecko/20121202 Firefox/30.0 (rss-bridge/0.1; +https://github.com/sebsauvage/rss-bridge)');
 // -------
 
+// cache file purge - delete cache files older than 24 hours
+$cacheTimeLimit = time() - 60*60*24 ;
+$cachePath = 'cache';
+$cacheIterator = new RecursiveIteratorIterator(
+  new RecursiveDirectoryIterator($cachePath),
+  RecursiveIteratorIterator::CHILD_FIRST
+);
+foreach ($cacheIterator as $cacheFile) {
+   if (in_array($cacheFile->getBasename(), array('.', '..')))
+      continue;
+   elseif ($cacheFile->isFile()) {
+      if( filemtime($cacheFile->getPathname()) < $cacheTimeLimit )
+         unlink( $cacheFile->getPathname() );
+      }
+}
+
 // default whitelist
 $whitelist_file = './whitelist.txt';
 $whitelist_default = array(