private void ConvertFromBase64(Span <byte> tmpBuffer, Span <byte> outputBuffer, out int consumed, out int written)
{
int bytesToTransform = _inputIndex + tmpBuffer.Length;
Debug.Assert(bytesToTransform >= 4);
byte[]? transformBufferArray = null;
Span <byte> transformBuffer = stackalloc byte[StackAllocSize];
if (bytesToTransform > StackAllocSize)
{
transformBuffer = transformBufferArray = CryptoPool.Rent(bytesToTransform);
}
// Copy _inputBuffer to transformBuffer and append tmpBuffer
Debug.Assert(_inputIndex < _inputBuffer.Length);
_inputBuffer.AsSpan(0, _inputIndex).CopyTo(transformBuffer);
tmpBuffer.CopyTo(transformBuffer.Slice(_inputIndex));
// Save data that won't be transformed to _inputBuffer, so it can be transformed later
_inputIndex = bytesToTransform & 3; // bit hack for % 4
bytesToTransform -= _inputIndex; // only transform up to the next multiple of 4
Debug.Assert(_inputIndex < _inputBuffer.Length);
tmpBuffer.Slice(tmpBuffer.Length - _inputIndex).CopyTo(_inputBuffer);
transformBuffer = transformBuffer.Slice(0, bytesToTransform);
OperationStatus status = Base64.DecodeFromUtf8(transformBuffer, outputBuffer, out consumed, out written);
if (status == OperationStatus.Done)
{
Debug.Assert(consumed == bytesToTransform);
}
else
{
Debug.Assert(status == OperationStatus.InvalidData);
ThrowHelper.ThrowBase64FormatException();
}
ReturnToCryptoPool(transformBufferArray, transformBuffer.Length);
}
public int TransformBlock(byte[] inputBuffer, int inputOffset, int inputCount, byte[] outputBuffer, int outputOffset)
{
ThrowHelper.ValidateTransformBlock(inputBuffer, inputOffset, inputCount);
int inputBlocks = Math.DivRem(inputCount, InputBlockSize, out int inputRemainder);
if (inputBlocks == 0)
{
ThrowHelper.ThrowArgumentOutOfRange(ThrowHelper.ExceptionArgument.inputCount);
}
if (outputBuffer == null)
{
ThrowHelper.ThrowArgumentNull(ThrowHelper.ExceptionArgument.outputBuffer);
}
if (inputRemainder != 0)
{
ThrowHelper.ThrowArgumentOutOfRange(ThrowHelper.ExceptionArgument.inputCount);
}
int requiredOutputLength = checked (inputBlocks * OutputBlockSize);
if (requiredOutputLength > outputBuffer.Length - outputOffset)
{
ThrowHelper.ThrowArgumentOutOfRange(ThrowHelper.ExceptionArgument.outputBuffer);
}
Span <byte> input = inputBuffer.AsSpan(inputOffset, inputCount);
Span <byte> output = outputBuffer.AsSpan(outputOffset, requiredOutputLength);
OperationStatus status = Base64.EncodeToUtf8(input, output, out int consumed, out int written, isFinalBlock: false);
Debug.Assert(status == OperationStatus.Done);
Debug.Assert(consumed == input.Length);
Debug.Assert(written == output.Length);
return(written);
}