1 /*
   2  * Copyright (c) 2008, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.nio.fs;
  27 
  28 import java.nio.file.Path;
  29 import java.io.IOException;
  30 import java.security.AccessController;
  31 import java.security.PrivilegedAction;
  32 
  33 /**
  34  * File type detector that uses the GNOME I/O library to guess the
  35  * MIME type of a file.
  36  */
  37 
  38 public class GnomeFileTypeDetector
  39     extends AbstractFileTypeDetector
  40 {
  41     // true if GIO is available
  42     private final boolean gioAvailable;
  43 
  44     public GnomeFileTypeDetector() {
  45         gioAvailable = initializeGio();
  46     }
  47 
  48     @Override
  49     public String implProbeContentType(Path obj) throws IOException {
  50         if (!gioAvailable)
  51             return null;
  52         if (!(obj instanceof UnixPath))
  53             return null;
  54 
  55         UnixPath path = (UnixPath)obj;
  56         NativeBuffer buffer = NativeBuffers.asNativeBuffer(path.getByteArrayForSysCalls());
  57         try {
  58             // GIO may access file so need permission check
  59             path.checkRead();
  60             byte[] type = probeGio(buffer.address());
  61             return (type == null) ? null : Util.toString(type);
  62         } finally {
  63             buffer.release();
  64         }
  65 
  66     }
  67 
  68     // GIO
  69     private static native boolean initializeGio();
  70     private static native byte[] probeGio(long pathAddress);
  71 
  72     static {
  73         AccessController.doPrivileged(new PrivilegedAction<>() {
  74             public Void run() {
  75                 System.loadLibrary("nio");
  76                 return null;
  77         }});
  78     }
  79 }