fix for HTCache organisation that may have caused unlimited grow of the cache

appeared only for tree-caches

git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@4433 6c8d7289-2bf4-0310-a012-ef5d649a1542

source/de/anomic/plasma/plasmaHTCache.java

@@ -809,11 +809,13 @@ public final class plasmaHTCache {
     
     
     /**
-     * This is a helper funktion that extracts the Hash from the filename
+     * This is a helper function that extracts the Hash from the filename
      */
     public static String getHash(final File f) {
         if ((!f.isFile()) || (f.getPath().indexOf("hash") < 0)) return null;
-        String hexHash = f.getName().substring(0,18);
+        String name = f.getName();
+        if (name.length() < 18) return null; // not a hash file name
+        String hexHash = name.substring(0,18);
         if (hexHash.indexOf('.') >= 0) return null;
         try {
             String hash = kelondroBase64Order.enhancedCoder.encode(serverCodings.decodeHex(hexHash));