From 9ce90cdf8ce29db737e1494bfe36ee54e748cc93 Mon Sep 17 00:00:00 2001
From: The6P4C <watsonjcampbell@gmail.com>
Date: Fri, 29 Sep 2017 08:05:15 +1000
Subject: [PATCH] Refactor SystemTimeUtils and add exception to SetSystemTime

---
 ThunderboltTimeSync/FormMain.cs        | 17 ++++----
 ThunderboltTimeSync/SystemTimeUtils.cs | 57 +++++++++++++++-----------
 2 files changed, 42 insertions(+), 32 deletions(-)

diff --git a/ThunderboltTimeSync/FormMain.cs b/ThunderboltTimeSync/FormMain.cs
index 36c71d3..9d6b913 100644
--- a/ThunderboltTimeSync/FormMain.cs
+++ b/ThunderboltTimeSync/FormMain.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Diagnostics;
-using System.Security.Principal;
 using System.Windows.Forms;
 
 namespace ThunderboltTimeSync {
@@ -19,12 +18,16 @@ namespace ThunderboltTimeSync {
 
 			InitializeComponent();
 
-			Debug.WriteLine(SystemTimeUtils.GetTime().ToString("yyyy-MM-ddTHH:mm:ssK.ffff"));
-			SystemTimeUtils.SetTime(new DateTime(
-				2000, 1, 1,
-				10, 0, 0, 0
-			));
-			Debug.WriteLine(SystemTimeUtils.GetTime().ToString("yyyy-MM-ddTHH:mm:ssK.ffff"));
+			Debug.WriteLine(SystemTimeUtils.GetSystemTime().ToString("yyyy-MM-ddTHH:mm:ssK.ffff"));
+			try {
+				SystemTimeUtils.SetSystemTime(new DateTime(
+					2000, 1, 1,
+					10, 0, 0, 0
+				));
+			} catch (SystemTimeUtils.SystemTimeException stEx) {
+				Debug.WriteLine(string.Format("Setting system time failed: \"{0}\"", stEx.Message));
+			}
+			Debug.WriteLine(SystemTimeUtils.GetSystemTime().ToString("yyyy-MM-ddTHH:mm:ssK.ffff"));
 		}
 	}
 }
diff --git a/ThunderboltTimeSync/SystemTimeUtils.cs b/ThunderboltTimeSync/SystemTimeUtils.cs
index 2578850..4573c11 100644
--- a/ThunderboltTimeSync/SystemTimeUtils.cs
+++ b/ThunderboltTimeSync/SystemTimeUtils.cs
@@ -1,36 +1,43 @@
 using System;
-using System.Diagnostics;
 using System.Runtime.InteropServices;
 
 namespace ThunderboltTimeSync {
 	class SystemTimeUtils {
-		[StructLayout(LayoutKind.Sequential)]
-		private struct SYSTEMTIME {
-			public short wYear;
-			public short wMonth;
-			public short wDayOfWeek;
-			public short wDay;
-			public short wHour;
-			public short wMinute;
-			public short wSecond;
-			public short wMilliseconds;
-		};
+		public class SystemTimeException : Exception {
+			public SystemTimeException(int hresult) : base(string.Format("The system time could not be set (HRESULT 0x{1:X8}).", hresult)) {
+				HResult = hresult;
+			}
+		}
 
-		[DllImport("kernel32.dll")]
-		private static extern uint GetLastError();
+		private class WindowsAPI {
+			[StructLayout(LayoutKind.Sequential)]
+			public struct SYSTEMTIME {
+				public short wYear;
+				public short wMonth;
+				public short wDayOfWeek;
+				public short wDay;
+				public short wHour;
+				public short wMinute;
+				public short wSecond;
+				public short wMilliseconds;
+			};
 
-		[DllImport("kernel32.dll", SetLastError = true)]
-		private static extern bool SetSystemTime(ref SYSTEMTIME lpSystemTime);
+			[DllImport("kernel32.dll")]
+			public static extern int GetLastError();
 
-		[DllImport("kernel32.dll")]
-		private static extern void GetSystemTime(ref SYSTEMTIME lpSystemTime);
+			[DllImport("kernel32.dll", SetLastError = true)]
+			public static extern bool SetSystemTime(ref SYSTEMTIME lpSystemTime);
+
+			[DllImport("kernel32.dll")]
+			public static extern void GetSystemTime(ref SYSTEMTIME lpSystemTime);
+		}
 
 		/// <summary>
 		/// Sets the system time.
 		/// </summary>
 		/// <param name="dateTime">The date and time to set the system clock to.</param>
-		public static void SetTime(DateTime dateTime) {
-			SYSTEMTIME systemTime = new SYSTEMTIME();
+		public static void SetSystemTime(DateTime dateTime) {
+			WindowsAPI.SYSTEMTIME systemTime = new WindowsAPI.SYSTEMTIME();
 
 			systemTime.wYear = (short) dateTime.Year;
 			systemTime.wMonth = (short) dateTime.Month;
@@ -41,10 +48,10 @@ namespace ThunderboltTimeSync {
 			systemTime.wSecond = (short) dateTime.Second;
 			systemTime.wMilliseconds = (short) dateTime.Millisecond;
 
-			bool setSucceeded = SetSystemTime(ref systemTime);
+			bool setSucceeded = WindowsAPI.SetSystemTime(ref systemTime);
 
 			if (!setSucceeded) {
-				Debug.WriteLine(string.Format("Call failed: error = {0}", GetLastError()));
+				throw new SystemTimeException(WindowsAPI.GetLastError());
 			}
 		}
 
@@ -52,9 +59,9 @@ namespace ThunderboltTimeSync {
 		/// Retrieves the current system time.
 		/// </summary>
 		/// <returns>The current system time.</returns>
-		public static DateTime GetTime() {
-			SYSTEMTIME systemTime = new SYSTEMTIME();
-			GetSystemTime(ref systemTime);
+		public static DateTime GetSystemTime() {
+			WindowsAPI.SYSTEMTIME systemTime = new WindowsAPI.SYSTEMTIME();
+			WindowsAPI.GetSystemTime(ref systemTime);
 
 			DateTime systemDateTime = new DateTime(
 				systemTime.wYear, systemTime.wMonth, systemTime.wDay,