public static void SetQuickHash(FileItem file)
{
if (file.Size > 0)
{
//fast random byte checking
using (var stream = File.OpenRead(file.FileName))
{
var length = stream.Length;
var tags = new byte[3];
//first byte
stream.Seek(0, SeekOrigin.Begin);
tags[0] = (byte)stream.ReadByte();
//middle byte, we need it especially for xml like files
if (length > 1)
{
stream.Seek(stream.Length / 2, SeekOrigin.Begin);
tags[1] = (byte)stream.ReadByte();
}
//last byte
if (length > 2)
{
stream.Seek(0, SeekOrigin.End);
tags[2] = (byte)stream.ReadByte();
}
file.QuickHash = HashTool.GetHashText(tags);
}
}
}
private string AddToQuickHash(FileItem fileItem)
{
// for empty files, do not hash
fileItem.QuickHash = fileItem.Size == 0 ? "" : HashTool.QuickHashFile(fileItem.FileName);
if (_sameQuickHashGroups.ContainsKey(fileItem.QuickHash))
{
if (_sameQuickHashGroups[fileItem.QuickHash].Files.Count == 1 &&
string.IsNullOrEmpty(_sameQuickHashGroups[fileItem.QuickHash].Files[0].FullHash))
{
// quickhash in group, so no fullhash comparison done. Create one now
var prevFileItem = _sameQuickHashGroups[fileItem.QuickHash].Files[0];
AddToFullHash(prevFileItem);
_duplicates++;
//Log(string.Format("{0}, {1}, {2}", _fileNo, _duplicates, _sameFullHashGroups.Count));
}
_sameQuickHashGroups[fileItem.QuickHash].Files.Add(fileItem);
// This fileSize exists, so check on existing full hash
return(AddToFullHash(fileItem));
}
else
{
// quickhash did not exist, so no duplicate file
_sameQuickHashGroups.Add(fileItem.QuickHash, new SameQuickHashGroup());
_sameQuickHashGroups[fileItem.QuickHash].Files.Add(fileItem);
return(null);
}
}
public static bool IsDuplicate(string fileName1, string fileName2)
{
if (new FileInfo(fileName1).Length != new FileInfo(fileName2).Length)
{
return(false);
}
if (HashTool.QuickHashFile(fileName1) != HashTool.QuickHashFile(fileName2))
{
return(false);
}
return(HashTool.HashFile(fileName1) == HashTool.HashFile(fileName2));
}
private string AddToFullHash(FileItem fileItem)
{
// for small files, the full hash is same as quickhash
fileItem.FullHash = fileItem.Size < 4 ? fileItem.QuickHash : HashTool.HashFile(fileItem.FileName);
if (_sameFullHashGroups.ContainsKey(fileItem.FullHash))
{
// fullhash exists, so duplicate file
_sameFullHashGroups[fileItem.FullHash].Files.Add(fileItem);
return(fileItem.FullHash);
}
else
{
// fullhash did not exist, so no duplicate file
_sameFullHashGroups.Add(fileItem.FullHash, new SameFullHashGroup());
_sameFullHashGroups[fileItem.FullHash].Files.Add(fileItem);
return(null);
}
}
// ******** Private functions ****** /
private string GetHash(string fileName)
{
var fileInfo = new FileInfo(fileName);
// Add all files in groups based on size
if (!_sameSizeGroups.ContainsKey(fileInfo.Length))
{
return(null);
}
if (_sameSizeGroups[fileInfo.Length].Files.Count == 1 &&
string.IsNullOrEmpty(_sameSizeGroups[fileInfo.Length].Files[0].QuickHash))
{
// Single file in group, so no quickhash comparison done. Create one now
var prevFileItem = _sameSizeGroups[fileInfo.Length].Files[0];
AddToQuickHash(prevFileItem);
}
var quickHash = HashTool.QuickHashFile(fileName);
if (!_sameQuickHashGroups.ContainsKey(quickHash))
{
return(null);
}
if (_sameQuickHashGroups[quickHash].Files.Count == 1 &&
string.IsNullOrEmpty(_sameQuickHashGroups[quickHash].Files[0].FullHash))
{
// quickhash in group, but no fullhash comparison done. Create one now
var prevFileItem = _sameQuickHashGroups[quickHash].Files[0];
AddToFullHash(prevFileItem);
}
var fullHash = HashTool.HashFile(fileName);
if (!_sameFullHashGroups.ContainsKey(fullHash))
{
return(null);
}
return(fullHash);
//return !_sameFullHashGroups.ContainsKey(fullHash) ? null : fullHash;
}
