Util/XdgMime.cs

   1 //
   2 // XdgMime.cs
   3 //
   4 // Copyright (C) 2006 Debajyoti Bera
   5 //
   6
   7 //
   8 // Permission is hereby granted, free of charge, to any person obtaining a
   9 // copy of this software and associated documentation files (the "Software"),
  10 // to deal in the Software without restriction, including without limitation
  11 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12 // and/or sell copies of the Software, and to permit persons to whom the
  13 // Software is furnished to do so, subject to the following conditions:
  14 //
  15 // The above copyright notice and this permission notice shall be included in
  16 // all copies or substantial portions of the Software.
  17 //
  18 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24 // DEALINGS IN THE SOFTWARE.
  25 //
  26
  27
  28 using System;
  29 using System.IO;
  30 using System.Runtime.InteropServices;
  31 using System.Text;
  32
  33 namespace Beagle.Util {
  34         public class XdgMime {
  35
  36                 [DllImport ("libbeagleglue")]
  37                 static extern IntPtr xdg_mime_get_mime_type_for_file (string file_path, IntPtr optional_stat_info);
  38
  39                 public static string GetMimeType (string file_path)
  40                 {
  41                         string mime_type = Marshal.PtrToStringAnsi (xdg_mime_get_mime_type_for_file (file_path, (IntPtr) null));
  42
  43                         if (mime_type != "application/octet-stream")
  44                                 return mime_type;
  45
  46                         // xdgmime recognizes most files without extensions as
  47                         // application/octet-stream.  Check the first 256 bytes
  48                         // to see if it's really plain text.
  49                         if (ValidateUTF8 (file_path))
  50                                 return "text/plain";
  51                         else
  52                                 return mime_type;
  53                 }
  54
  55                 private static UTF8Encoding validating_encoding = new UTF8Encoding (true, true);
  56
  57                 private static bool ValidateUTF8 (string file_path)
  58                 {
  59                         FileStream fs;
  60
  61                         try {
  62                                 fs = new FileStream (file_path, FileMode.Open, FileAccess.Read, FileShare.Read);
  63                         } catch (IOException) {
  64                                 return false;
  65                         }
  66
  67                         byte[] byte_buf = new byte [256];
  68                         char[] char_buf = new char [256];
  69
  70                         int buf_length = fs.Read (byte_buf, 0, 256);
  71
  72                         fs.Close ();
  73
  74                         if (buf_length == 0)
  75                                 return false; // Don't treat empty files as text/plain
  76
  77                         Decoder d = validating_encoding.GetDecoder ();
  78
  79                         try {
  80                                 d.GetChars (byte_buf, 0, buf_length, char_buf, 0);
  81
  82                                 // FIXME: UTF8 allows control characters in a file.
  83                                 // Should we allow control characters in a text file?
  84                         } catch (ArgumentException ex) {
  85                                 return false;
  86                         }
  87
  88                         return true;
  89                 }
  90         }
  91 }