beagled/FileAttributesStore_ExtendedAttribute.cs

   1 //
   2 // FileAttributesStore_ExtendedAttribute.cs
   3 //
   4 // Copyright (C) 2004 Novell, Inc.
   5 //
   6
   7 //
   8 // Permission is hereby granted, free of charge, to any person obtaining a copy
   9 // of this software and associated documentation files (the "Software"), to deal
  10 // in the Software without restriction, including without limitation the rights
  11 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12 // copies of the Software, and to permit persons to whom the Software is
  13 // furnished to do so, subject to the following conditions:
  14 //
  15 // The above copyright notice and this permission notice shall be included in all
  16 // 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 FROM,
  23 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  24 // SOFTWARE.
  25 //
  26
  27 using System;
  28 using System.IO;
  29
  30 using Beagle.Util;
  31
  32 namespace Beagle.Daemon {
  33
  34         public class FileAttributesStore_ExtendedAttribute : IFileAttributesStore {
  35
  36                 public static bool Disable = false;
  37
  38                 private string index_fingerprint;
  39
  40                 public FileAttributesStore_ExtendedAttribute (string index_fingerprint)
  41                 {
  42                         this.index_fingerprint = index_fingerprint;
  43                 }
  44
  45                 // Version history:
  46                 // 1: Original
  47                 // 2: Replace LastIndexedTime with LastAttrTime
  48                 const int EA_VERSION = 2;
  49
  50                 // FIXME: We should probably serialize the data into a lump and attach
  51                 // it to just one EA.  The current method has an inherent race condition:
  52                 // if the file changes out from under us mid-Read or mid-Write, all sorts
  53                 // of weirdness could ensue.
  54
  55                 const string fingerprint_attr = "Fingerprint";
  56                 const string unique_id_attr = "Uid";
  57                 const string last_mtime_attr = "MTime";
  58                 const string last_attrtime_attr = "AttrTime";
  59                 const string filter_attr = "Filter";
  60
  61                 public FileAttributes Read (string path)
  62                 {
  63                         if (Disable)
  64                                 return null;
  65
  66                         try {
  67                                 string tmp;
  68                                 tmp = ExtendedAttribute.Get (path, fingerprint_attr);
  69                                 if (tmp == null
  70                                     || int.Parse (tmp.Substring (0, 2)) != EA_VERSION
  71                                     || (index_fingerprint != null && tmp.Substring (3) != index_fingerprint))
  72                                         return null;
  73
  74                                 FileAttributes attr = new FileAttributes ();
  75
  76                                 string uid_str = ExtendedAttribute.Get (path, unique_id_attr);
  77                                 attr.UniqueId = GuidFu.FromShortString (uid_str);
  78
  79                                 attr.Path = path;
  80                                 attr.LastWriteTime = StringFu.StringToDateTime (ExtendedAttribute.Get (path, last_mtime_attr));
  81
  82                                 attr.LastAttrTime = StringFu.StringToDateTime (ExtendedAttribute.Get (path, last_attrtime_attr));
  83
  84                                 tmp = ExtendedAttribute.Get (path, filter_attr);
  85                                 if (tmp != null) {
  86                                         attr.FilterVersion = int.Parse (tmp.Substring (0, 3));
  87                                         attr.FilterName = tmp.Substring (4);
  88                                 }
  89
  90                                 return attr;
  91
  92                         } catch (Exception e) {
  93                                 //Logger.Log.Debug ("Caught exception reading EAs from {0}", path);
  94                                 //Logger.Log.Debug (e);
  95                                 // FIXME: Do something smarter with the exception.
  96                                 return null;
  97                         }
  98                 }
  99
 100                 public bool Write (FileAttributes attr)
 101                 {
 102                         if (Disable)
 103                                 return false;
 104
 105                         try {
 106                                 string tmp;
 107
 108                                 tmp = String.Format ("{0:00} {1}", EA_VERSION, index_fingerprint);
 109                                 ExtendedAttribute.Set (attr.Path, fingerprint_attr, tmp);
 110
 111                                 // Try to read the EA we just set.  If we
 112                                 // can't, they won't be much use to us --- so
 113                                 // just return false.
 114                                 string what_we_just_wrote;
 115                                 try {
 116                                         what_we_just_wrote = ExtendedAttribute.Get (attr.Path, fingerprint_attr);
 117                                 } catch (Exception ex) {
 118                                         return false;
 119                                 }
 120                                 if (what_we_just_wrote != tmp)
 121                                         return false;
 122
 123                                 ExtendedAttribute.Set (attr.Path, unique_id_attr, GuidFu.ToShortString (attr.UniqueId));
 124                                 ExtendedAttribute.Set (attr.Path, last_mtime_attr,
 125                                                        StringFu.DateTimeToString (attr.LastWriteTime));
 126
 127                                 if (attr.HasFilterInfo) {
 128                                         tmp = String.Format ("{0:000} {1}", attr.FilterVersion, attr.FilterName);
 129                                         ExtendedAttribute.Set (attr.Path, filter_attr, tmp);
 130                                 }
 131
 132                                 // This has to be the last thing we write out, to get LastAttrTime as close
 133                                 // to the ctime as possible.
 134                                 attr.LastAttrTime = DateTime.UtcNow;
 135                                 ExtendedAttribute.Set (attr.Path, last_attrtime_attr,
 136                                                        StringFu.DateTimeToString (attr.LastAttrTime));
 137
 138                                 return true;
 139                         } catch (IOException e) {
 140                                 // An IOException here probably means that we don't have the right
 141                                 // permissions to set the EAs.  We just fail silently and return false rather
 142                                 // than spewing a bunch of scary exceptions.
 143                                 //Logger.Log.Debug (e);
 144                                 return false;
 145                         } catch (Exception e) {
 146                                 Logger.Log.Debug (e, "Caught exception writing EAs to {0}", attr.Path);
 147                                 // FIXME: Do something smarter with the exception.
 148                                 return false;
 149                         }
 150                 }
 151
 152                 public void Drop (string path)
 153                 {
 154                         if (Disable)
 155                                 return;
 156
 157                         try {
 158                                 ExtendedAttribute.Remove (path, fingerprint_attr);
 159                                 ExtendedAttribute.Remove (path, unique_id_attr);
 160                                 ExtendedAttribute.Remove (path, last_mtime_attr);
 161                                 ExtendedAttribute.Remove (path, last_attrtime_attr);
 162                                 ExtendedAttribute.Remove (path, filter_attr);
 163
 164                         } catch (Exception e) {
 165                                 // FIXME: Do something smarter with the exception.
 166                         }
 167                 }
 168
 169                 // There are no transactions for EAs
 170
 171                 public void BeginTransaction ()
 172                 { }
 173
 174                 public void CommitTransaction ()
 175                 { }
 176
 177         }
 178 }