Add deploy directory detection (#1400)

Add Filesystem class for java and namespace methods for C++ for detecting deploy location.

wpilibc/src/main/native/include/frc/Filesystem.h

@@ -0,0 +1,45 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <wpi/SmallVector.h>
+
+#include "frc/RobotBase.h"
+
+namespace frc {
+namespace filesystem {
+
+/**
+ * Obtains the current working path that the program was launched with.
+ * This is analogous to the `pwd` command on unix.
+ *
+ * @param result The result of the current working path lookup.
+ */
+void GetLaunchDirectory(wpi::SmallVectorImpl<char>& result);
+
+/**
+ * Obtains the operating directory of the program. On the roboRIO, this
+ * is /home/lvuser. In simulation, it is where the simulation was launched
+ * from (`pwd`).
+ *
+ * @param result The result of the operating directory lookup.
+ */
+void GetOperatingDirectory(wpi::SmallVectorImpl<char>& result);
+
+/**
+ * Obtains the deploy directory of the program, which is the remote location
+ * src/main/deploy is deployed to by default. On the roboRIO, this is
+ * /home/lvuser/deploy. In simulation, it is where the simulation was launched
+ * from, in the subdirectory "deploy" (`pwd`/deploy).
+ *
+ * @param result The result of the operating directory lookup
+ */
+void GetDeployDirectory(wpi::SmallVectorImpl<char>& result);
+
+}  // namespace filesystem
+}  // namespace frc