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//------------------------------------------------------------------------------
// 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;
using Microsoft.Win32.SafeHandles;
namespace System.Windows.Media.Imaging
{
#region QueueEntry
///
/// QueueEntry
///
internal class QueueEntry
{
internal List<WeakReference> decoders;
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
{
/// <SecurityNote>
/// Critical: This code initializes critical member queue
/// TreatAsSafe: This code does not expose the critical data
/// </SecurityNote>
[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
///
/// <SecurityNote>
/// Critical: This code elevates to create a file and initiate download.
/// UnmanagedCode permission is asserted to allow the creation
/// of a FileStream from a handle obtained by CreateFile.
/// </SecurityNote>
[SecurityCritical]
internal static void BeginDownload(
BitmapDecoder decoder,
Uri uri,
RequestCachePolicy uriCachePolicy,
Stream stream
)
{
lock (_syncLock)
{
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(new WeakReference(decoder));
return;
}
}
}
entry = new QueueEntry();
entry.decoders = new List<WeakReference>();
lock (_syncLock)
{
entry.decoders.Add(new WeakReference(decoder));
}
entry.inputUri = uri;
entry.inputStream = stream;
string cacheFolder = MS.Win32.WinInet.InternetCacheFolder.LocalPath;
bool passed = false;
new SecurityPermission(SecurityPermissionFlag.UnmanagedCode).Assert(); // BlessedAssert
try
{
// Get the file path
StringBuilder tmpFileName = new StringBuilder(NativeMethods.MAX_PATH);
MS.Win32.UnsafeNativeMethods.GetTempFileName(cacheFolder, "WPF", 0, tmpFileName);
try
{
string pathToUse = tmpFileName.ToString();
SafeFileHandle fileHandle = MS.Win32.UnsafeNativeMethods.CreateFile(
pathToUse,
NativeMethods.GENERIC_READ | NativeMethods.GENERIC_WRITE, /* dwDesiredAccess */
0, /* dwShare */
null, /* lpSecurityAttributes */
NativeMethods.CREATE_ALWAYS, /* dwCreationDisposition */
NativeMethods.FILE_ATTRIBUTE_TEMPORARY |
NativeMethods.FILE_FLAG_DELETE_ON_CLOSE, /* dwFlagsAndAttributes */
IntPtr.Zero /* hTemplateFile */
);
if (fileHandle.IsInvalid)
{
throw new Win32Exception();
}
entry.outputStream = new FileStream(fileHandle, FileAccess.ReadWrite);
entry.streamPath = pathToUse;
passed = true;
}
catch(Exception e)
{
if (CriticalExceptions.IsCriticalException(e))
{
throw;
}
}
}
finally
{
SecurityPermission.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
///
/// <SecurityNote>
/// 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.
/// </SecurityNote>
[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
{
entry.inputStream.BeginRead(
entry.readBuffer,
0,
READ_SIZE,
_readCallback,
entry
);
}
catch (Exception e)
{
MarshalException(entry, e);
}
finally
{
//
// This method never exits, and 'entry' is _not_ scoped
// to the while loop, so if we don't null entry out it will
// be rooted while _waitEvent.WaitOne() blocks.
//
entry = null;
}
#pragma warning restore 6500
}
}
}
///
/// Response callback
/// <SecurityNote>
/// Critical: This code accesses the queue and also calls into WebRequest methods
/// </SecurityNote>
[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
///
/// <SecurityNote>
/// Critical: This code accesses the queue
/// </SecurityNote>
[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)
{
//
// We're done reading from the input stream.
//
entry.inputStream.Close();
entry.inputStream = null;
//
// We're done writing to the output stream. Make sure everything
// is written to disk.
//
entry.outputStream.Flush();
entry.outputStream.Seek(0, SeekOrigin.Begin);
lock (_syncLock)
{
// Fire download progress & completion event for each decoder
foreach (WeakReference decoderReference in entry.decoders)
{
LateBoundBitmapDecoder decoder = decoderReference.Target as LateBoundBitmapDecoder;
if (decoder != null)
{
//
// 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 (WeakReference decoderReference in entry.decoders)
{
LateBoundBitmapDecoder decoder = decoderReference.Target as LateBoundBitmapDecoder;
if (decoder != null)
{
//
// 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 (WeakReference decoderReference in entry.decoders)
{
LateBoundBitmapDecoder decoder = decoderReference.Target as LateBoundBitmapDecoder;
if (decoder != null)
{
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
/// <SecurityNote>
/// Critical: This element holds data that is obtained under an elevation
/// </SecurityNote>
[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
}
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