// -------------------------------------------------------------------------------------------
/// <summary>
/// Gives, in a target byte array, another one readed from a stream, until consume a number of bytes or before some marks.
/// Return the index of the found mark or -1 if the consumable bytes limit was reached.
/// For efficiency, this capture is divided in two types...
/// One simple, applicable to any underlying Stream, for when the marks only have one byte of lenght,
/// and other complex for when the marks are of greater lenght (in that case the Stream must support Seek).
/// </summary>
public static int CaptureStreamReaderSegment(ref byte[] TargetSegment, BinaryReader TorrentReader, int BytesNumberLimit, params byte[][] LimitMarks)
{
if (BytesNumberLimit < 1 || LimitMarks.GetLength(0) < 1)
{
throw new UsageAnomaly("Limits for stream reading are not well established.", new DataWagon("BytesNumberLimit", BytesNumberLimit)
.Add("LimitMarks", LimitMarks));
}
// Note: It could be validated that each LimitMarks item is a byte array and not a null reference,
// but that is omitted to avoid performance impact.
int MarksCount = LimitMarks.GetLength(0);
int Ind = 0;
int MarksMaxLength = 0;
// Next, the lenght of the marks are determined
bool MarksAreShort = true;
for (Ind = 0; Ind < MarksCount; Ind++)
{
if (LimitMarks[Ind].Length > 1)
{
MarksAreShort = false;
if (LimitMarks[Ind].Length > MarksMaxLength)
{
MarksMaxLength = LimitMarks[Ind].Length;
}
}
}
if (MarksMaxLength > LimitMarkMaxLength)
{
throw new UsageAnomaly("Segment limit marks exceeds the limit established at " + LimitMarkMaxLength.ToString() + ".", MarksMaxLength);
}
if (MarksAreShort) // Simple implementation, applicable to any stream
{
return(CaptureSegmentWithSimpleStreamReader(ref TargetSegment, TorrentReader, BytesNumberLimit, LimitMarks));
}
// Complex implementetion, only applicable for seek-capable streams.
if (!TorrentReader.BaseStream.CanSeek)
{
throw new UsageAnomaly("A seek capable Stream is required when exists limit marks with more than one byte.", TorrentReader.BaseStream);
}
return(CaptureSegmentWithComplexStreamReader(ref TargetSegment, TorrentReader, BytesNumberLimit, MarksMaxLength, LimitMarks));
}
// -------------------------------------------------------------------------------------------
/// <summary>
/// Gives, in a target byte array, another one readed from a stream, until consume a number of bytes or before some marks conformed by more than one byte.
/// Return the index of the found mark or -1 if the consumable bytes limit was reached.
/// </summary>
private static int CaptureSegmentWithComplexStreamReader(ref byte[] TargetSegment, BinaryReader TorrentReader, int BytesNumberLimit,
int MarksMaxLength, params byte[][] LimitMarks)
{
int CaptureEndingCause = -1;
int MarksCount = LimitMarks.GetLength(0);
SimpleList <byte[]> Parts = new SimpleList <byte[]>();
byte[] Part = new byte[0];
int ConsumedBytesCount = 0;
int ConsumedBytesTotal = 0;
int FoundedPosition = 0;
int Pos = 0;
while ((ConsumedBytesCount = (Part = TorrentReader.ReadBytes(BLOCK_SIZE_TINY)).Length) > 0)
{
ConsumedBytesTotal += ConsumedBytesCount;
Pos = -1;
foreach (byte[] Mark in LimitMarks)
{
Pos++;
if ((FoundedPosition = Search(Part, Mark)) >= 0)
{
CaptureEndingCause = Pos;
TorrentReader.BaseStream.Seek((Part.Length - (FoundedPosition + Mark.Length)) * -1, SeekOrigin.Current);
Part = ExtractSegment(Part, 0, FoundedPosition);
break;
}
}
if (FoundedPosition >= 0)
{
Parts.Add(Part);
break;
}
if (ConsumedBytesTotal >= BytesNumberLimit)
{
throw new UsageAnomaly("Stream has been readed/consumed until reach the " + BytesNumberLimit.ToString() + " bytes limit.",
new DataWagon("ConsumedBytesCount", ConsumedBytesCount));
}
if (ConsumedBytesCount == BLOCK_SIZE_TINY)
{
Part = ExtractSegment(Part, 0, Part.Length - MarksMaxLength);
}
Parts.Add(Part);
// If less than the expected bytes were read, then means the stream's end was reached.
if (ConsumedBytesCount < BLOCK_SIZE_TINY)
{
break;
}
TorrentReader.BaseStream.Seek(MarksMaxLength * -1, SeekOrigin.Current);
}
TargetSegment = new byte[((BLOCK_SIZE_TINY - MarksMaxLength) * (Parts.Count - 1)) + Part.Length];
Pos = 0;
foreach (byte[] Fragment in Parts)
{
CopyByteArray(TargetSegment, Fragment, Pos, (byte)0, false);
Pos += Fragment.Length;
}
return(CaptureEndingCause);
}
// -------------------------------------------------------------------------------------------
/// <summary>
/// Gives, in a target byte array, another one readed from a stream, until consume a number of bytes or before some marks conformed by only one byte.
/// Return the index of the found mark or -1 if the consumable bytes limit was reached.
/// </summary>
private static int CaptureSegmentWithSimpleStreamReader(ref byte[] TargetSegment, BinaryReader TorrentReader, int BytesNumberLimit,
params byte[][] LimitMarks)
{
int CaptureEndingCause = -1;
int MarksCount = LimitMarks.GetLength(0);
int Ind = 0;
int Pos = 0;
int ConsumedBytesCount = 0;
bool FoundedMark = false;
byte Atom = 0;
SimpleList <byte[]> Parts = new SimpleList <byte[]>();
byte[] Part = new byte[0];
int PartBytesCount = 0;
Parts.Add(Part);
try
{
while (ConsumedBytesCount < BytesNumberLimit)
{
Atom = TorrentReader.ReadByte();
ConsumedBytesCount++;
FoundedMark = false;
for (Ind = 0; Ind < MarksCount; Ind++)
{
if (Atom == LimitMarks[Ind][0])
{
FoundedMark = true;
CaptureEndingCause = Ind;
break;
}
}
if (FoundedMark)
{
break;
}
if (PartBytesCount == BLOCK_SIZE_TINY)
{
Part = new byte[BLOCK_SIZE_TINY];
PartBytesCount = 0;
Parts.Add(Part);
}
Part[PartBytesCount] = Atom;
PartBytesCount++;
}
throw new UsageAnomaly("Stream has been readed/consumed until reach the " + BytesNumberLimit.ToString() + " bytes limit.",
new DataWagon("ConsumedBytesCount", ConsumedBytesCount));
}
#pragma warning disable 168
catch (EndOfStreamException Anomaly)
{ // The possible end of the stream is expected.
};
#pragma warning restore 168
TargetSegment = new byte[(BLOCK_SIZE_TINY * (Parts.Count - 1)) + PartBytesCount];
Ind = 0;
Pos = 0;
foreach (byte[] Fragment in Parts)
{
Ind++;
CopyByteArray(TargetSegment, (Ind < Parts.Count ? Fragment : BytesHandling.ExtractSegment(Fragment, 0, PartBytesCount)), Pos, (byte)0, false);
Pos += BLOCK_SIZE_TINY;
}
return(CaptureEndingCause);
}
