private static async Task <Stream> TrimStreamInternal(
Stream stream,
HttpRange originalRange,
ContentRange?receivedRange,
// iv or nonce in stream could have already been trimmed during decryption
int alreadyTrimmedOffsetAmount,
bool async,
CancellationToken cancellationToken)
{
// retrim start of stream to original requested location
// keeping in mind whether we already trimmed due to an IV or nonce
int gap = (int)(originalRange.Offset - (receivedRange?.Start ?? 0)) - alreadyTrimmedOffsetAmount;
int read = 0;
while (gap > read)
{
int toRead = gap - read;
// throw away initial bytes we want to trim off; stream cannot seek into future
if (async)
{
read += await stream.ReadAsync(new byte[toRead], 0, toRead, cancellationToken).ConfigureAwait(false);
}
else
{
read += stream.Read(new byte[toRead], 0, toRead);
}
}
if (originalRange.Length.HasValue)
{
stream = WindowStream.GetWindow(stream, originalRange.Length.Value);
}
return(stream);
}
private static async Task <Stream> TrimStreamInternal(
Stream stream,
HttpRange originalRange,
ContentRange?receivedRange,
bool pulledOutIV,
bool async,
CancellationToken cancellationToken)
{
// retrim start of stream to original requested location
// keeping in mind whether we already pulled the IV out of the stream as well
int gap = (int)(originalRange.Offset - (receivedRange?.Start ?? 0))
- (pulledOutIV ? Constants.ClientSideEncryption.EncryptionBlockSize : 0);
int read = 0;
while (gap > read)
{
int toRead = gap - read;
// throw away initial bytes we want to trim off; stream cannot seek into future
if (async)
{
read += await stream.ReadAsync(new byte[toRead], 0, toRead, cancellationToken).ConfigureAwait(false);
}
else
{
read += stream.Read(new byte[toRead], 0, toRead);
}
}
if (originalRange.Length.HasValue)
{
stream = new WindowStream(stream, originalRange.Length.Value);
}
return(stream);
}
