Avoid problems saving files (with safe saving enabled) when the same project is also open in Visual Studio

src/Main/Base/Project/Util/NativeMethods.cs

@@ -17,6 +17,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.ComponentModel;
 using System.IO;
 using System.Runtime.InteropServices;
 using System.Security;
@@ -122,6 +123,39 @@ namespace ICSharpCode.SharpDevelop
 		}
 		#endregion
 		
+		
+		#region SetFileTime
+		[StructLayout(LayoutKind.Sequential)]
+		struct FILETIME
+		{
+			internal uint ftTimeLow;
+			internal uint ftTimeHigh;
+
+			public FILETIME(long fileTime)
+			{
+				unchecked {
+    				this.ftTimeLow = (uint)fileTime;
+    				this.ftTimeHigh = (uint)(fileTime >> 32);
+				}
+			}
+		}
+		
+		[DllImport("kernel32.dll", SetLastError = true)]
+		[return: MarshalAs(UnmanagedType.Bool)]
+		unsafe static extern bool SetFileTime(SafeFileHandle hFile, FILETIME* creationTime, FILETIME* lastAccessTime, FILETIME* lastWriteTime);
+		
+		/// <summary>
+		/// Update the file times on the given file handle.
+		/// </summary>
+		public unsafe static void SetFileCreationTime(SafeFileHandle hFile, DateTime creationTime)
+		{
+		    FILETIME fileCreationTime = new FILETIME(creationTime.ToFileTimeUtc());
+			if (!SetFileTime(hFile, &fileCreationTime, null, null)) {
+				throw new Win32Exception(Marshal.GetLastWin32Error());
+			}
+		}
+		#endregion
+		
 		#region Get OEM Encoding
 		[DllImport("kernel32.dll")]
 		static extern int GetOEMCP();

src/Main/Base/Project/Workbench/File/OpenedFile.cs

@@ -230,6 +230,14 @@ namespace ICSharpCode.SharpDevelop.Workbench
 			bool safeSaving = SD.FileService.SaveUsingTemporaryFile && File.Exists(FileName);
 			string saveAs = safeSaving ? FileName + ".bak" : FileName;
 			using (FileStream fs = new FileStream(saveAs, FileMode.Create, FileAccess.Write)) {
+			    if (safeSaving) {
+					// Copy creation time from source file
+					// Because setting the time requires opening the file for write access,
+					// we can't use System.IO.File.SetCreationTimeUtc for this, as it would open the file twice,
+					// which causes problems when another process is monitoring the directory
+					// and reading our new file as soon as we're done writing.
+					NativeMethods.SetFileCreationTime(fs.SafeFileHandle, File.GetCreationTimeUtc(FileName));
+				}
 				if (currentView != null) {
 					SaveCurrentViewToStream(fs);
 				} else {
@@ -237,7 +245,7 @@ namespace ICSharpCode.SharpDevelop.Workbench
 				}
 			}
 			if (safeSaving) {
-				DateTime creationTime = File.GetCreationTimeUtc(FileName);
+				// TODO: we should probably use Win32 MoveFileEx to atomically move while replacing the old file
 				File.Delete(FileName);
 				try {
 					File.Move(saveAs, FileName);
@@ -247,7 +255,6 @@ namespace ICSharpCode.SharpDevelop.Workbench
 					System.Threading.Thread.Sleep(250);
 					File.Move(saveAs, FileName);
 				}
-				File.SetCreationTimeUtc(FileName, creationTime);
 			}
 			IsDirty = false;
 		}