/// <summary>
/// Reads the metadata from a message file.
/// </summary>
/// <param name="msgID">The message ID.</param>
/// <param name="path">Fully qualified path to the message file.</param>
/// <returns>The <see cref="QueuedMsgInfo" />.</returns>
internal QueuedMsgInfo ReadMessageMetadata(Guid msgID, string path)
{
QueuedMsgInfo msgInfo;
int cbBody;
byte[] md5Hash;
long savePos;
using (var fsMsg = new EnhancedFileStream(path, FileMode.Open, FileAccess.ReadWrite))
{
try
{
// Read the message file header
if (fsMsg.ReadInt32() != MsgMagic) // Magic Number
{
throw new Exception();
}
if (fsMsg.ReadInt32() != 0) // Format Version
{
throw new Exception();
}
fsMsg.ReadInt32(); // Reserved
// Verify that the MD5 hash saved in then file matches the
// hash computed for the remainder of the file as it exists
// right now.
md5Hash = fsMsg.ReadBytes(MD5Hasher.DigestSize);
savePos = fsMsg.Position;
if (!Helper.ArrayEquals(md5Hash, MD5Hasher.Compute(fsMsg, fsMsg.Length - fsMsg.Position)))
{
throw new FormatException(string.Format("Message file [{0}] is corrupt. MD5 digests do not match.", path));
}
fsMsg.Position = savePos;
// Skip over the message body data
cbBody = fsMsg.ReadInt32();
fsMsg.Position = fsMsg.Position + cbBody;
// Read the metadata and add the provider specific information
msgInfo = new QueuedMsgInfo(fsMsg.ReadString16());
msgInfo.PersistID = msgInfo.ID;
msgInfo.ProviderData = path;
return(msgInfo);
}
catch
{
throw new FormatException(string.Format("Bad message file [{0}].", path));
}
}
}
private OperationLogMode mode; // The current mode
/// <summary>
/// Opens or creates a file operation log file.
/// </summary>
/// <param name="path">The path to the log file.</param>
/// <param name="transactionID">The log's transaction <see cref="Guid" />.</param>
/// <remarks>
/// New logs will be created in <see cref="OperationLogMode.Undo" /> mode.
/// </remarks>
public FileOperationLog(string path, Guid transactionID)
{
this.path = Path.GetFullPath(path);
this.file = new EnhancedFileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite);
if (file.Length == 0)
{
// Initialize a new file
file.WriteInt32(Magic);
file.WriteInt32(0);
file.WriteInt32(0);
file.WriteInt32((int)OperationLogMode.Undo);
file.WriteBytesNoLen(transactionID.ToByteArray());
file.Flush();
}
else
{
// Open an existing file.
try
{
if (file.ReadInt32() != Magic || // Magic number
file.ReadInt32() != 0)
{ // Format Versopn
throw new Exception();
}
file.ReadInt32(); // Reserved
switch (file.ReadInt32()) // Mode
{
case (int)OperationLogMode.Undo:
mode = OperationLogMode.Undo;
break;
case (int)OperationLogMode.Redo:
mode = OperationLogMode.Redo;
break;
default:
throw new Exception();
}
this.transactionID = new Guid(file.ReadBytes(16));
if (transactionID != this.transactionID)
{
throw new Exception();
}
}
catch
{
throw new TransactionException(CorruptMsg);
}
}
}
//---------------------------------------------------------------------
// Static members
/// <summary>
/// Verifies that a log file is not corrupt.
/// </summary>
/// <param name="path">The path to the log file.</param>
/// <param name="transactionID">Returns as the file's transaction <see cref="Guid" />.</param>
/// <returns><c>true</c> if the log file is valid, <c>false</c> if it is corrupt.</returns>
public static bool Validate(string path, out Guid transactionID)
{
int cb;
try
{
using (var file = new EnhancedFileStream(path, FileMode.Open, FileAccess.ReadWrite))
{
if (file.ReadInt32() != Magic || // Magic number
file.ReadInt32() != 0)
{ // Format Versopn
throw new Exception();
}
switch (file.ReadInt32()) // Mode
{
case (int)OperationLogMode.Undo:
case (int)OperationLogMode.Redo:
break;
default:
throw new Exception();
}
file.ReadInt32(); // Reserved
transactionID = new Guid(file.ReadBytes(16));
while (!file.Eof)
{
if (file.ReadInt32() != Magic)
{
throw new Exception();
}
cb = file.ReadInt32();
if (cb < 0 || cb + file.Position > file.Length)
{
throw new Exception();
}
file.Position += cb;
}
return(true);
}
}
catch
{
transactionID = Guid.Empty;
return(false);
}
}