System.Net.Security.SslStreamInternal.ReadByte C# (CSharp) Method

        internal int ReadByte()
        {
            if (Interlocked.Exchange(ref _nestedRead, 1) == 1)
            {
                throw new NotSupportedException(SR.Format(SR.net_io_invalidnestedcall, "ReadByte", "read"));
            }

            // If there's any data in the buffer, take one byte, and we're done.
            try
            {
                if (InternalBufferCount > 0)
                {
                    int b = InternalBuffer[InternalOffset];
                    SkipBytes(1);
                    return b;
                }
            }
            finally
            {
                // Regardless of whether we were able to read a byte from the buffer,
                // reset the read tracking.  If we weren't able to read a byte, the
                // subsequent call to Read will set the flag again.
                _nestedRead = 0;
            }

            // Otherwise, fall back to reading a byte via Read, the same way Stream.ReadByte does.
            // This allocation is unfortunate but should be relatively rare, as it'll only occur once
            // per buffer fill internally by Read.
            byte[] oneByte = new byte[1];
            int bytesRead = Read(oneByte, 0, 1);
            Debug.Assert(bytesRead == 0 || bytesRead == 1);
            return bytesRead == 1 ? oneByte[0] : -1;
        }