context: //
  // Copy.cs: Task that can copy files
  //
  // Author:
  //   Marek Sieradzki (marek.sieradzki@gmail.com)
  //
  // (C) 2005 Marek Sieradzki
  //
  // Permission is hereby granted, free of charge, to any person obtaining
  // a copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to
  // permit persons to whom the Software is furnished to do so, subject to
  // the following conditions:
  //
  // The above copyright notice and this permission notice shall be
  // included in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  using System;
  using System.Collections;
  using System.Collections.Generic;
  using System.IO;
  using Microsoft.Build.Framework;
  using Microsoft.Build.Utilities;
  
  namespace Microsoft.Build.Tasks {
  	public class Copy : TaskExtension {
  	
  		ITaskItem[]	copiedFiles;
  		ITaskItem[]	destinationFiles;
  		ITaskItem	destinationFolder;
  		bool		skipUnchangedFiles;
  		ITaskItem[]	sourceFiles;
  		bool		overwriteReadOnlyFiles;
  		
  		public Copy ()
  		{
  		}
  
  		public override bool Execute ()
  		{
  			if (sourceFiles.Length == 0)
  				// nothing to copy!
  				return true;
  
  			try {
  				List <ITaskItem> temporaryCopiedFiles = new List <ITaskItem> ();
  			
  				if (sourceFiles != null && destinationFiles != null &&
  					sourceFiles.Length != destinationFiles.Length) {
  					Log.LogError ("Number of source files is different than number of destination files.");
  					return false;
  				}
  
  				if (destinationFiles != null && destinationFolder != null) {
  					Log.LogError ("You must specify only one attribute from DestinationFiles and DestinationFolder");
  					return false;
  				}
  
  				if (destinationFiles != null && destinationFiles.Length > 0) {
  					for (int i = 0; i < sourceFiles.Length; i ++) {
  						ITaskItem sourceItem = sourceFiles [i];
  						ITaskItem destinationItem = destinationFiles [i];
  						string sourceFile = sourceItem.GetMetadata ("FullPath");
  						string destinationFile = destinationItem.GetMetadata ("FullPath");
  
  						if (!File.Exists (sourceFile)) {
  							Log.LogError ("Cannot copy {0} to {1}, as the source file doesn't exist.", sourceFile, destinationFile);
  							continue;
  						}
  
  						if (!skipUnchangedFiles || HasFileChanged (sourceFile, destinationFile))
  							CopyFile (sourceFile, destinationFile, true);
  
  						sourceItem.CopyMetadataTo (destinationItem);
  						temporaryCopiedFiles.Add (destinationItem);
  					}
  					
  				} else if (destinationFolder != null) {
  					List<ITaskItem> temporaryDestinationFiles = new List<ITaskItem> ();
  					string destinationDirectory = destinationFolder.GetMetadata ("FullPath");
  					bool directoryCreated = CreateDirectoryIfRequired (destinationDirectory);
  					
  					foreach (ITaskItem sourceItem in sourceFiles) {
  						string sourceFile = sourceItem.GetMetadata ("FullPath");
  						string filename = sourceItem.GetMetadata ("Filename") + sourceItem.GetMetadata ("Extension");
  						string destinationFile = Path.Combine (destinationDirectory,filename);
  
  						if (!File.Exists (sourceFile)) {
  							Log.LogError ("Cannot copy {0} to {1}, as the source file doesn't exist.", sourceFile, destinationFile);
  							continue;
  						}
  
  						if (!skipUnchangedFiles || directoryCreated ||
  							HasFileChanged (sourceFile, destinationFile))
  							CopyFile (sourceFile, destinationFile, false);
  
  						temporaryCopiedFiles.Add (new TaskItem (
  								Path.Combine (destinationFolder.GetMetadata ("Identity"), filename),
  								sourceItem.CloneCustomMetadata ()));
  
  						temporaryDestinationFiles.Add (new TaskItem (
  								Path.Combine (destinationFolder.GetMetadata ("Identity"), filename),
  								sourceItem.CloneCustomMetadata ()));
  					}
  					destinationFiles = temporaryDestinationFiles.ToArray ();
  				} else {
  					Log.LogError ("You must specify DestinationFolder or DestinationFiles attribute.");
  					return false;
  				}
  				
  				copiedFiles = temporaryCopiedFiles.ToArray ();
  
  				return !Log.HasLoggedErrors;
  			}
  			catch (Exception ex) {
  				Log.LogErrorFromException (ex);
  				return false;
  			}
  		}
  
  		[Output]
  		public ITaskItem[] CopiedFiles {
  			get {
  				return copiedFiles;
  			}
  		}
  
  		[Output]
  		public ITaskItem[] DestinationFiles {
  			get {
  				return destinationFiles;
  			}
  			set {
  				destinationFiles = value;
  			}
  		}
  
  		public ITaskItem DestinationFolder {
  			get {
  				return destinationFolder;
  			}
  			set {
  				destinationFolder = value;
  			}
  		}
  
  		public bool SkipUnchangedFiles {
  			get {
  				return skipUnchangedFiles;
  			}
  			set {
  				skipUnchangedFiles = value;
  			}
  		}
  
  #if NET_3_5
  		public bool OverwriteReadOnlyFiles {
  			get {
  				return overwriteReadOnlyFiles;
  			}
  			set {
  				overwriteReadOnlyFiles = value;
  			}
  		}
  #endif
  
  		[Required]
  		public ITaskItem[] SourceFiles {
  			get {
  				return sourceFiles;
  			}
  			set {
  				sourceFiles = value;
  			}
  		}
  
  		// returns whether directory was created or not
  		bool CreateDirectoryIfRequired (string name)
  		{
  			if (Directory.Exists (name))
  				return false;
  
  			Log.LogMessage ("Creating directory '{0}'", name);
  			Directory.CreateDirectory (name);
  			return true;
  		}
  
  		void CopyFile (string source, string dest, bool create_dir)
  		{
  			if (create_dir)
  				CreateDirectoryIfRequired (Path.GetDirectoryName (dest));
  			if (overwriteReadOnlyFiles)
  				ClearReadOnlyAttribute (dest);
  			Log.LogMessage ("Copying file from '{0}' to '{1}'", source, dest);
  			if (String.Compare (source, dest) != 0) {
  				// Ensure that we delete the destination file first so that if the file is already
  				// opened via mmap we do not screw up the data for the process which has the file open
  				// Fixes https://bugzilla.xamarin.com/show_bug.cgi?id=9146
  				if (!HasReadOnlyAttribute (dest))
  					File.Delete (dest);
  
gt: 				File.Copy (source, dest, true);