public static void SaveMD5Stream(AlternateDataStreamInfo md5StreamInfo, byte[] fileHash, DateTime fileWriteTimeUtc)
{
FileStream md5Stream = md5StreamInfo.OpenWrite();
MD5Descriptor descriptor = new MD5Descriptor();
descriptor.FileHash = fileHash;
descriptor.FileWriteTimeUtc = fileWriteTimeUtc;
descriptor.WriteToStream(md5Stream);
md5Stream.Close();
}
public static MD5StreamStatus TestMD5Stream(FileInfo fileInfo)
{
byte[] fileHash = GetFileHash(fileInfo.FullName);
AlternateDataStreamInfo md5StreamInfo = FileSystem.GetAlternateDataStream(fileInfo, MD5StreamName);
if (md5StreamInfo.Exists)
{
Stream md5Stream = md5StreamInfo.OpenRead();
MD5Descriptor descriptor = MD5Descriptor.ReadFromStream(md5Stream);
if (descriptor == null)
{
return(MD5StreamStatus.Invalid);
}
if (DateTime.Equals(fileInfo.LastWriteTimeUtc, descriptor.FileWriteTimeUtc))
{
if (ByteUtils.AreByteArraysEqual(fileHash, descriptor.FileHash))
{
return(MD5StreamStatus.Correct);
}
else
{
return(MD5StreamStatus.Incorrect);
}
}
else // file was updated since MD5 was stored
{
SaveMD5Stream(md5StreamInfo, fileHash, fileInfo.LastWriteTimeUtc);
// We revert to the last write time before the ADS was written
File.SetLastWriteTimeUtc(fileInfo.FullName, fileInfo.LastWriteTimeUtc);
return(MD5StreamStatus.Updated);
}
}
else
{
SaveMD5Stream(md5StreamInfo, fileHash, fileInfo.LastWriteTimeUtc);
// We revert to the last write time before the ADS was written
File.SetLastWriteTimeUtc(fileInfo.FullName, fileInfo.LastWriteTimeUtc);
return(MD5StreamStatus.Created);
}
}
/// <summary>
/// Will return null if descriptor is invalid
/// </summary>
public static MD5Descriptor ReadFromStream(Stream stream)
{
Dictionary <string, string> properties;
try
{
properties = ReadProperties(stream);
}
catch (ArgumentException)
{
return(null);
}
if (properties == null)
{
return(null);
}
if (properties.ContainsKey("MD5") && properties.ContainsKey("FileWriteTimeUtc"))
{
MD5Descriptor descriptor = new MD5Descriptor();
string md5String = properties["MD5"];
string fileWriteTimeUtcString = properties["FileWriteTimeUtc"];
try
{
descriptor.FileHash = HexStringToBytes(md5String);
descriptor.FileWriteTimeUtc = DateTime.Parse(fileWriteTimeUtcString, CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal);
}
catch
{
return(null);
}
return(descriptor);
}
return(null);
}
