Code:
/ DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Core / System / Windows / Media / Imaging / BitmapDownload.cs / 3 / BitmapDownload.cs
//------------------------------------------------------------------------------ // Microsoft Avalon // Copyright (c) Microsoft Corporation // // File: BitmapDownload.cs // //----------------------------------------------------------------------------- #pragma warning disable 1634, 1691 // Allow suppression of certain presharp messages using System; using System.IO; using System.Collections.Generic; using System.Collections; using System.ComponentModel; using System.ComponentModel.Design.Serialization; using System.Reflection; using System.Threading; using System.Windows.Threading; using MS.Internal; using System.Diagnostics; using System.Windows.Media; using System.Globalization; using System.Security; using System.Security.Permissions; using System.Runtime.InteropServices; using System.Windows.Media.Animation; using System.Windows.Media.Composition; using System.Windows.Media.Imaging; using MS.Win32.PresentationCore; using MS.Internal.AppModel; using MS.Internal.PresentationCore; using SR=MS.Internal.PresentationCore.SR; using SRID=MS.Internal.PresentationCore.SRID; using System.Net; using System.Net.Cache; using System.Text; using MS.Win32; namespace System.Windows.Media.Imaging { #region QueueEntry /// /// QueueEntry /// internal struct QueueEntry { internal Listdecoders; internal Uri inputUri; internal Stream inputStream; internal Stream outputStream; internal string streamPath; internal byte[] readBuffer; internal long contentLength; internal string contentType; internal int lastPercent; internal WebRequest webRequest; } #endregion #region BitmapDownload /// /// The BitmapDownload class provides a way to download streams off-thread to /// a cache /// internal static class BitmapDownload { /// /// Critical: This code initializes critical member queue /// TreatAsSafe: This code does not expose the critical data /// [SecurityCritical,SecurityTreatAsSafe] static BitmapDownload() { _waitEvent = new AutoResetEvent(false); _workQueue = Queue.Synchronized(new Queue()); _uriTable = Hashtable.Synchronized(new Hashtable()); _readCallback = new AsyncCallback(ReadCallback); _responseCallback = new AsyncCallback(ResponseCallback); _thread = new Thread(new ThreadStart(DownloadThreadProc)); _syncLock = new object(); } #region Methods /// /// Begin a download /// ////// Critical: This code elevates to create a file and initiate download /// [SecurityCritical] internal static void BeginDownload( BitmapDecoder decoder, Uri uri, RequestCachePolicy uriCachePolicy, Stream stream ) { lock (_thread) { if (!_thread.IsAlive) { _thread.IsBackground = true; _thread.Start(); } } QueueEntry entry; // If there is already a download for this uri, just add the decoder to the list if (uri != null) { lock (_syncLock) { if (_uriTable[uri] != null) { entry = (QueueEntry)_uriTable[uri]; entry.decoders.Add(decoder); return; } } } entry = new QueueEntry(); entry.decoders = new List(); lock (_syncLock) { entry.decoders.Add(decoder); } entry.inputUri = uri; entry.inputStream = stream; string cacheFolder = MS.Win32.WinInet.InternetCacheFolder.LocalPath; string pathToUse = null; bool passed = false; (new FileIOPermission(FileIOPermissionAccess.Read | FileIOPermissionAccess.Write | FileIOPermissionAccess.Append, cacheFolder)).Assert(); // BlessedAssert try { // Try creating a file 10000 (arbitrary) times for (int i = 0; i < 10000; i++) { pathToUse = cacheFolder + (new Random().Next(10000, Int32.MaxValue)).ToString(CultureInfo.InvariantCulture); if (!File.Exists(pathToUse)) { try { entry.outputStream = new FileStream( pathToUse, FileMode.CreateNew, FileAccess.ReadWrite ); entry.streamPath = pathToUse; passed = true; break; } catch(Exception e) { if (CriticalExceptions.IsCriticalException(e)) { throw; } continue; } } } } finally { FileIOPermission.RevertAssert(); } if (!passed) { throw new IOException(SR.Get(SRID.Image_CannotCreateTempFile)); } entry.readBuffer = new byte[READ_SIZE]; entry.contentLength = -1; entry.contentType = string.Empty; entry.lastPercent = 0; // Add the entry to the table if we know the uri if (uri != null) { lock (_syncLock) { _uriTable[uri] = entry; } } if (stream == null) { bool fElevate = false; if (uri.Scheme == Uri.UriSchemeHttp || uri.Scheme == Uri.UriSchemeHttps) { SecurityHelper.BlockCrossDomainForHttpsApps(uri); // In this case we first check to see if the consumer has media permissions for // safe media (Site of Origin + Cross domain), if it // does we assert and run the code that requires the assert if (SecurityHelper.CallerHasMediaPermission(MediaPermissionAudio.NoAudio, MediaPermissionVideo.NoVideo, MediaPermissionImage.SafeImage)) { fElevate = true; } } // This is the case where we are accessing an http image from an http site and we have media permission if (fElevate) { (new WebPermission(NetworkAccess.Connect, BindUriHelper.UriToString(uri))).Assert(); // BlessedAssert } try { entry.webRequest = WpfWebRequestHelper.CreateRequest(uri); if (uriCachePolicy != null) { entry.webRequest.CachePolicy = uriCachePolicy; } } finally { if(fElevate) { WebPermission.RevertAssert(); } } entry.webRequest.BeginGetResponse(_responseCallback, entry); } else { _workQueue.Enqueue(entry); // Signal _waitEvent.Set(); } } /// /// Thread Proc /// /// /// Critical: This code accesses the queue, extracts entries and reads content /// TreatAsSafe: This code does not expose the queue and the read from the stream are sent to a callback. /// [SecurityCritical,SecurityTreatAsSafe] internal static void DownloadThreadProc() { Queue workQueue = _workQueue; for (;;) { _waitEvent.WaitOne(); while (workQueue.Count != 0) { QueueEntry entry = (QueueEntry)workQueue.Dequeue(); #pragma warning disable 6500 // Catch all exceptions and marshal them to the correct thread try { IAsyncResult result = entry.inputStream.BeginRead( entry.readBuffer, 0, READ_SIZE, _readCallback, entry ); } catch (Exception e) { MarshalException(entry, e); } #pragma warning restore 6500 } } } /// /// Response callback ////// Critical: This code accesses the queue and also calls into WebRequest methods /// [SecurityCritical] private static void ResponseCallback(IAsyncResult result) { QueueEntry entry = (QueueEntry)result.AsyncState; #pragma warning disable 6500 // Catch all exceptions and marshal them to the correct thread try { WebResponse response = WpfWebRequestHelper.EndGetResponse(entry.webRequest, result); entry.inputStream = response.GetResponseStream(); entry.contentLength = response.ContentLength; entry.contentType = response.ContentType; entry.webRequest = null; // GC the WebRequest _workQueue.Enqueue(entry); // Signal _waitEvent.Set(); } catch(Exception e) { MarshalException(entry, e); } #pragma warning restore 6500 } /// /// Read callback /// ////// Critical: This code accesses the queue /// [SecurityCritical] private static void ReadCallback(IAsyncResult result) { QueueEntry entry = (QueueEntry)result.AsyncState; int bytesRead = 0; #pragma warning disable 6500 try { bytesRead = entry.inputStream.EndRead(result); } catch(Exception e) { MarshalException(entry, e); } #pragma warning restore 6500 if (bytesRead == 0) { entry.outputStream.Flush(); entry.outputStream.Seek(0, SeekOrigin.Begin); lock (_syncLock) { // Fire download progress & completion event for each decoder foreach (LateBoundBitmapDecoder decoder in entry.decoders) { // // Marshal events to UI thread // MarshalEvents( decoder, new DispatcherOperationCallback(decoder.ProgressCallback), 100 ); MarshalEvents( decoder, new DispatcherOperationCallback(decoder.DownloadCallback), entry.outputStream ); } } // Delete entry from uri table if (entry.inputUri != null) { lock (_syncLock) { _uriTable[entry.inputUri] = null; } } } else { entry.outputStream.Write(entry.readBuffer, 0, bytesRead); if (entry.contentLength > 0) { int percentComplete = (int)Math.Floor(100.0 * (double)entry.outputStream.Length / (double)entry.contentLength); // Only raise if percentage went up by ~1% (ie value changed). if (percentComplete != entry.lastPercent) { // Update last value entry.lastPercent = percentComplete; lock (_syncLock) { // Fire download progress event for each decoder foreach (LateBoundBitmapDecoder decoder in entry.decoders) { // // Marshal events to UI thread // MarshalEvents( decoder, new DispatcherOperationCallback(decoder.ProgressCallback), percentComplete ); } } } } _workQueue.Enqueue(entry); _waitEvent.Set(); } } /// /// Marshals a call to the Dispatcher thread /// private static void MarshalEvents( LateBoundBitmapDecoder decoder, DispatcherOperationCallback doc, object arg ) { Dispatcher dispatcher = decoder.Dispatcher; if (dispatcher != null) { dispatcher.BeginInvoke(DispatcherPriority.Normal, doc, arg); } else { // Decoder seems to be thread free. This is probably bad Debug.Assert(false); } } /// /// Marshal an exception to the Dispatcher thread /// private static void MarshalException( QueueEntry entry, Exception e ) { lock (_syncLock) { // Fire download completion event for each decoder foreach (LateBoundBitmapDecoder decoder in entry.decoders) { MarshalEvents( decoder, new DispatcherOperationCallback(decoder.ExceptionCallback), e ); } if (entry.inputUri != null) { lock (_syncLock) { _uriTable[entry.inputUri] = null; } } } } #endregion #region Data Members /// Thread event internal static AutoResetEvent _waitEvent = new AutoResetEvent(false); /// Work Queue ////// Critical: This element holds data that is obtained under an elevation /// [SecurityCritical] internal static Queue _workQueue; /// Uri hash table internal static Hashtable _uriTable; /// Read callback internal static AsyncCallback _readCallback; /// Response callback internal static AsyncCallback _responseCallback; /// Thread object private static Thread _thread; /// lock object private static object _syncLock; /// Default async read size private const int READ_SIZE = 1024; #endregion } #endregion } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. 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