private void ReadTextCache()
{
byte[] bytes = new byte[4];
// Read from the file till the end
while (fileStream.Position < fileStream.Length)
{
// Remember the log item start position in the file
int pos = (int)fileStream.Position;
// Read the item type and length
if (fileStream.Read(bytes, 0, bytes.Length) < bytes.Length)
{
throw new FormatException("Invalid log file to append to. Log item header too short.");
}
// Parse type and length data
FieldLogItemType type = (FieldLogItemType)((bytes[0] & 0xF0) >> 4);
bytes[0] = (byte)(bytes[0] & 0x0F);
if (BitConverter.IsLittleEndian)
{
Array.Reverse(bytes);
}
int length = BitConverter.ToInt32(bytes, 0);
// Check whether this is a text item
if (type == FieldLogItemType.StringData)
{
// Read the item and add it to the text cache
byte[] stringBytes = new byte[length];
if (fileStream.Read(stringBytes, 0, length) < length)
{
throw new FormatException("Invalid log file to append to. Text log item shorter than indicated.");
}
// Parse the text data
string str = Encoding.UTF8.GetString(stringBytes);
// Add text to the cache
textCache[str] = pos;
}
else
{
// Seek over the item and verify that it worked
long expected = fileStream.Position + length;
if (fileStream.Seek(length, SeekOrigin.Current) != expected)
{
throw new FormatException("Invalid log file to append to. Log item shorter than indicated.");
}
}
}
}
/// <summary>
/// Reads a log item from the log file.
/// </summary>
/// <param name="reader">Log file reader.</param>
/// <param name="type">The type of log item to read.</param>
/// <returns>The read log item.</returns>
internal static FieldLogItem Read(FieldLogFileReader reader, FieldLogItemType type)
{
switch (type)
{
case FieldLogItemType.Text:
return(FieldLogTextItem.Read(reader));
case FieldLogItemType.Data:
return(FieldLogDataItem.Read(reader));
case FieldLogItemType.Exception:
return(FieldLogExceptionItem.Read(reader));
case FieldLogItemType.Scope:
case FieldLogItemType.RepeatedScope:
return(FieldLogScopeItem.Read(reader, type == FieldLogItemType.RepeatedScope));
}
throw new ArgumentException("Unsupported log item type (" + (int)type + ")");
}
/// <summary>
/// Sets the type of the item to write.
/// </summary>
/// <param name="itemType">Log item type.</param>
internal void SetItemType(FieldLogItemType itemType)
{
this.itemType = (byte)itemType;
}
/// <summary>
/// Sets the type of the item to write.
/// </summary>
/// <param name="itemType">Log item type.</param>
internal void SetItemType(FieldLogItemType itemType)
{
this.itemType = (byte)itemType;
}
/// <summary>
/// Reads a log item from the log file.
/// </summary>
/// <param name="reader">Log file reader.</param>
/// <param name="type">The type of log item to read.</param>
/// <returns>The read log item.</returns>
internal static FieldLogItem Read(FieldLogFileReader reader, FieldLogItemType type)
{
switch (type)
{
case FieldLogItemType.Text:
return FieldLogTextItem.Read(reader);
case FieldLogItemType.Data:
return FieldLogDataItem.Read(reader);
case FieldLogItemType.Exception:
return FieldLogExceptionItem.Read(reader);
case FieldLogItemType.Scope:
case FieldLogItemType.RepeatedScope:
return FieldLogScopeItem.Read(reader, type == FieldLogItemType.RepeatedScope);
}
throw new ArgumentException("Unsupported log item type (" + (int)type + ")");
}
