Prepare wpiutil for merge into allwpilib.

wpiutil/src/main/native/cpp/tcpsockets/SocketError.cpp

@@ -0,0 +1,40 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2015-2018 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "tcpsockets/SocketError.h"
+
+#ifdef _WIN32
+#include <winsock2.h>
+#else
+#include <cerrno>
+#include <cstring>
+#endif
+
+namespace wpi {
+
+int SocketErrno() {
+#ifdef _WIN32
+  return WSAGetLastError();
+#else
+  return errno;
+#endif
+}
+
+std::string SocketStrerror(int code) {
+#ifdef _WIN32
+  LPSTR errstr = nullptr;
+  FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, 0,
+                code, 0, (LPSTR)&errstr, 0, 0);
+  std::string rv(errstr);
+  LocalFree(errstr);
+  return rv;
+#else
+  return std::strerror(code);
+#endif
+}
+
+}  // namespace wpi