/// <summary>
/// Returns MD5 hash of filter expression
/// </summary>
/// <returns>MD5 hash of filter expression</returns>
public string GetFilterHash()
{
var hash = MD5HashHelper.GetHash(new[] { First.GetFilterHash(), Second.GetFilterHash() });
return(Utility.ByteArrayAsHexString(hash));
}
/// <summary>
/// Initialize list of modified files / folder for each volume
/// </summary>
/// <param name="emitFilter"></param>
/// <param name="fileAttributeFilter"></param>
/// <param name="skipFilesLargerThan"></param>
/// <param name="prevJournalData"></param>
/// <returns></returns>
private Dictionary <string, VolumeData> Initialize(IFilter emitFilter, FileAttributes fileAttributeFilter, long skipFilesLargerThan,
IEnumerable <USNJournalDataEntry> prevJournalData)
{
if (prevJournalData == null)
{
throw new UsnJournalSoftFailureException(Strings.USNHelper.PreviousBackupNoInfo);
}
var result = new Dictionary <string, VolumeData>();
// get hash identifying current source filter / sources configuration
// ReSharper disable once PossibleMultipleEnumeration
var configHash = Utility.Utility.ByteArrayAsHexString(MD5HashHelper.GetHash(new string[] {
emitFilter == null ? string.Empty : emitFilter.ToString(),
string.Join("; ", m_sources),
fileAttributeFilter.ToString(),
skipFilesLargerThan.ToString()
}));
// create lookup for journal data
var journalDataDict = prevJournalData.ToDictionary(data => data.Volume);
// iterate over volumes
foreach (var sourcesPerVolume in SortByVolume(m_sources))
{
if (m_token.IsCancellationRequested)
{
break;
}
var volume = sourcesPerVolume.Key;
var volumeSources = sourcesPerVolume.Value;
var volumeData = new VolumeData
{
Volume = volume,
JournalData = null
};
result[volume] = volumeData;
try
{
// prepare journal data entry to store with current fileset
var journal = new USNJournal(volume);
var nextData = new USNJournalDataEntry
{
Volume = volume,
JournalId = journal.JournalId,
NextUsn = journal.NextUsn,
ConfigHash = configHash
};
// add new data to result set
volumeData.JournalData = nextData;
// only use change journal if:
// - journal ID hasn't changed
// - nextUsn isn't zero (we use this as magic value to force a rescan)
// - the configuration (sources or filters) hasn't changed
if (!journalDataDict.TryGetValue(volume, out var prevData))
{
throw new UsnJournalSoftFailureException(Strings.USNHelper.PreviousBackupNoInfo);
}
if (prevData.JournalId != nextData.JournalId)
{
throw new UsnJournalSoftFailureException(Strings.USNHelper.JournalIdChanged);
}
if (prevData.NextUsn == 0)
{
throw new UsnJournalSoftFailureException(Strings.USNHelper.NextUsnZero);
}
if (prevData.ConfigHash != nextData.ConfigHash)
{
throw new UsnJournalSoftFailureException(Strings.USNHelper.ConfigHashChanged);
}
var changedFiles = new HashSet <string>(Utility.Utility.ClientFilenameStringComparer);
var changedFolders = new HashSet <string>(Utility.Utility.ClientFilenameStringComparer);
// obtain changed files and folders, per volume
foreach (var source in volumeSources)
{
if (m_token.IsCancellationRequested)
{
break;
}
foreach (var entry in journal.GetChangedFileSystemEntries(source, prevData.NextUsn))
{
if (m_token.IsCancellationRequested)
{
break;
}
if (entry.Item2.HasFlag(USNJournal.EntryType.File))
{
changedFiles.Add(entry.Item1);
}
else
{
changedFolders.Add(Util.AppendDirSeparator(entry.Item1));
}
}
}
// At this point we have:
// - a list of folders (changedFolders) that were possibly modified
// - a list of files (changedFiles) that were possibly modified
//
// With this, we need still need to do the following:
//
// 1. Simplify the folder list, such that it only contains the parent-most entries
// (eg. { "C:\A\B\", "C:\A\B\C\", "C:\A\B\D\E\" } => { "C:\A\B\" }
volumeData.Folders = Utility.Utility.SimplifyFolderList(changedFolders).ToList();
// 2. Our list of files may contain entries inside one of the simplified folders (from step 1., above).
// Since that folder is going to be fully scanned, those files can be removed.
// Note: it would be wrong to use the result from step 2. as the folder list! The entries removed
// between 1. and 2. are *excluded* folders, and files below them are to be *excluded*, too.
volumeData.Files =
new HashSet <string>(Utility.Utility.GetFilesNotInFolders(changedFiles, volumeData.Folders));
// Record success for volume
volumeData.IsFullScan = false;
}
catch (Exception e)
{
// full scan is required this time (eg. due to missing journal entries)
volumeData.Exception = e;
volumeData.IsFullScan = true;
volumeData.Folders = new List <string>();
volumeData.Files = new HashSet <string>();
// use original sources
foreach (var path in volumeSources)
{
var isFolder = path.EndsWith(Util.DirectorySeparatorString, StringComparison.Ordinal);
if (isFolder)
{
volumeData.Folders.Add(path);
}
else
{
volumeData.Files.Add(path);
}
}
}
}
return(result);
}