System.Web.HttpRequest.MakeInputStream C# (CSharp) Method

		void MakeInputStream ()
		{
			if (input_stream != null)
				return;

			if (worker_request == null) {
				input_stream = new MemoryStream (new byte [0], 0, 0, false, true);
				DoFilter (new byte [1024]);
				return;
			}

			//
			// Use an unmanaged memory block as this might be a large
			// upload
			//
			int content_length = ContentLength;
			int content_length_kb = content_length / 1024;
			HttpRuntimeSection config = HttpRuntime.Section;
			if (content_length_kb > config.MaxRequestLength)
				throw HttpException.NewWithCode (400, "Upload size exceeds httpRuntime limit.", WebEventCodes.RuntimeErrorPostTooLarge);

			int total = 0;
			byte [] buffer;
			buffer = worker_request.GetPreloadedEntityBody ();
			// we check the instance field 'content_length' here, not the local var.
			if (this.content_length <= 0 || worker_request.IsEntireEntityBodyIsPreloaded ()) {
				if (buffer == null || content_length == 0) {
					input_stream = new MemoryStream (new byte [0], 0, 0, false, true);
				} else {
					input_stream = new MemoryStream (buffer, 0, buffer.Length, false, true);
				}
				DoFilter (new byte [1024]);
				return;
			}

			if (buffer != null)
				total = buffer.Length;

			if (content_length > 0 && content_length_kb >= config.RequestLengthDiskThreshold) {
				// Writes the request to disk
				total = Math.Min (content_length, total);
				request_file = GetTempStream ();
				Stream output = request_file;
				if (total > 0)
					output.Write (buffer, 0, total);

				if (total < content_length) {
					buffer = new byte [Math.Min (content_length, INPUT_BUFFER_SIZE)];
					do {
						int n;
						int min = Math.Min (content_length - total, INPUT_BUFFER_SIZE);
						n = worker_request.ReadEntityBody (buffer, min);
						if (n <= 0)
							break;
						output.Write (buffer, 0, n);
						total += n;
					} while (total < content_length);
				}

				request_file.SetReadOnly ();
				input_stream = request_file;
			} else if (content_length > 0) {
				// Buffers the request in an IntPtrStream
				total = Math.Min (content_length, total);
				IntPtr content = Marshal.AllocHGlobal (content_length);
				if (content == (IntPtr) 0)
					throw HttpException.NewWithCode (
						String.Format ("Not enough memory to allocate {0} bytes.", content_length),
						WebEventCodes.WebErrorOtherError);

				if (total > 0)
					Marshal.Copy (buffer, 0, content, total);

				if (total < content_length) {
					buffer = new byte [Math.Min (content_length, INPUT_BUFFER_SIZE)];
					do {
						int n;
						int min = Math.Min (content_length - total, INPUT_BUFFER_SIZE);
						n = worker_request.ReadEntityBody (buffer, min);
						if (n <= 0)
							break;
						Marshal.Copy (buffer, 0, (IntPtr) ((long)content + total), n);
						total += n;
					} while (total < content_length);
				}

				input_stream = new IntPtrStream (content, total);
			} else {
				// Buffers the request in a MemoryStream or writes to disk if threshold exceeded
				MemoryStream ms = new MemoryStream ();
				Stream output = ms;
				if (total > 0)
					ms.Write (buffer, 0, total);

				buffer = new byte [INPUT_BUFFER_SIZE];
				long maxlength = config.MaxRequestLength * 1024L;
				long disk_th = config.RequestLengthDiskThreshold * 1024L;
				int n;
				while (true) {
					n = worker_request.ReadEntityBody (buffer, INPUT_BUFFER_SIZE);
					if (n <= 0)
						break;
					total += n;
					if (total < 0 || total > maxlength)
						throw HttpException.NewWithCode (400, "Upload size exceeds httpRuntime limit.", WebEventCodes.RuntimeErrorPostTooLarge);

					if (ms != null && total > disk_th) {
						// Swith to on-disk file.
						request_file = GetTempStream ();
						ms.WriteTo (request_file);
						ms = null;
						output = request_file;
					}
					output.Write (buffer, 0, n);
				}

				if (ms != null) {
					input_stream = new MemoryStream (ms.GetBuffer (), 0, (int) ms.Length, false, true);
				} else {
					request_file.SetReadOnly ();
					input_stream = request_file;
				}
			}
			DoFilter (buffer);

			if (total < content_length)
				throw HttpException.NewWithCode (411, "The request body is incomplete.", WebEventCodes.WebErrorOtherError);
		}
#endif