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lib/socket_recv_operation.cpp

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+///////////////////////////////////////////////////////////////////////////////
+// Copyright (c) Lewis Baker
+// Licenced under MIT license. See LICENSE.txt for details.
+///////////////////////////////////////////////////////////////////////////////
+
+#include <cppcoro/net/socket_recv_operation.hpp>
+#include <cppcoro/net/socket.hpp>
+
+#if CPPCORO_OS_WINNT
+# include <WinSock2.h>
+# include <WS2tcpip.h>
+# include <MSWSock.h>
+# include <Windows.h>
+
+bool cppcoro::net::socket_recv_operation_impl::try_start(
+	cppcoro::detail::win32_overlapped_operation_base& operation) noexcept
+{
+	// Need to read this flag before starting the operation, otherwise
+	// it may be possible that the operation will complete immediately
+	// on another thread and then destroy the socket before we get a
+	// chance to read it.
+	const bool skipCompletionOnSuccess = m_socket.skip_completion_on_success();
+
+	DWORD numberOfBytesReceived = 0;
+	DWORD flags = 0;
+	int result = ::WSARecv(
+		m_socket.native_handle(),
+		reinterpret_cast<WSABUF*>(&m_buffer),
+		1, // buffer count
+		&numberOfBytesReceived,
+		&flags,
+		operation.get_overlapped(),
+		nullptr);
+	if (result == SOCKET_ERROR)
+	{
+		int errorCode = ::WSAGetLastError();
+		if (errorCode != WSA_IO_PENDING)
+		{
+			// Failed synchronously.
+			operation.m_errorCode = static_cast<DWORD>(errorCode);
+			operation.m_numberOfBytesTransferred = numberOfBytesReceived;
+			return false;
+		}
+	}
+	else if (skipCompletionOnSuccess)
+	{
+		// Completed synchronously, no completion event will be posted to the IOCP.
+		operation.m_errorCode = ERROR_SUCCESS;
+		operation.m_numberOfBytesTransferred = numberOfBytesReceived;
+		return false;
+	}
+
+	// Operation will complete asynchronously.
+	return true;
+}
+
+
+void cppcoro::net::socket_recv_operation_impl::cancel(
+	cppcoro::detail::win32_overlapped_operation_base& operation) noexcept
+{
+	(void)::CancelIoEx(
+		reinterpret_cast<HANDLE>(m_socket.native_handle()),
+		operation.get_overlapped());
+}
+
+#endif