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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
#if DEBUG
#define TRACE
#endif
//
//
// Description:
// Downloader for downloading resources from the Internet in byte ranges using .NET
// web requests. This class is used by ByteWrapper (unmanaged code) to make additional
// web requests other than through WININET
using System.Collections;
using System.ComponentModel; // For Win32Exception
using System.Globalization;
using System.IO;
using System.Net;
using System.Net.Cache; // For RequestCachePolicy
using System.Runtime.InteropServices; // For Marshal
using System.Threading; // For Mutex
using Microsoft.Win32.SafeHandles;
using MS.Internal.PresentationCore;
namespace MS.Internal.IO.Packaging
{
/// <summary>
/// Downloader for byte range requests
/// </summary>
/// <remarks>
/// For now, we will only process one batch of requests at a time. We will most likely
/// want to spin multiple threads and do multiple batches at a time in the future
/// </remarks>
internal class ByteRangeDownloader : IDisposable
{
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
/// <summary>
/// Constructor for ByteRangeDownloader - for UrlMon usage
/// </summary>
/// <param name="eventHandle">event to signal when new data is available in tempStream</param>
/// <param name="requestedUri">uri we should make requests to</param>
/// <param name="tempFileName">temp file to write to</param>
internal ByteRangeDownloader(Uri requestedUri, string tempFileName, SafeWaitHandle eventHandle)
: this(requestedUri, eventHandle)
{
ArgumentNullException.ThrowIfNull(tempFileName);
if (tempFileName.Length <= 0)
{
throw new ArgumentException(SR.InvalidTempFileName, "tempFileName");
}
_tempFileStream = File.Open(tempFileName, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite);
}
/// <summary>
/// Constructor for ByteRangeDownloader - used by NetStream who owns the tempStream
/// </summary>
/// <param name="eventHandle">event to signal when new data is available in tempStream</param>
/// <param name="fileMutex">mutex to synchronize access to tempStream</param>
/// <param name="requestedUri">uri we should make requests to</param>
/// <param name="tempStream">stream to write data to</param>
internal ByteRangeDownloader(Uri requestedUri, Stream tempStream, SafeWaitHandle eventHandle, Mutex fileMutex)
: this(requestedUri, eventHandle)
{
Debug.Assert(fileMutex != null, "FileMutex must be a valid mutex");
Debug.Assert(tempStream != null, "ByteRangeDownloader requires a stream to write to");
_tempFileStream = tempStream;
_fileMutex = fileMutex;
}
#endregion Constructors
//------------------------------------------------------
//
// Interfaces
//
//------------------------------------------------------
#region IDisposable
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this); // not strictly necessary, but if we ever have a subclass with a finalizer, this will be more efficient
}
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
lock (_syncObject)
{
if (!_disposed)
{
try
{
// if there is no mutex, then we own the stream and we should close it
if (FileMutex == null && _tempFileStream != null)
{
_tempFileStream.Close();
}
}
finally
{
_requestedUri = null;
_byteRangesInProgress = null;
_requestsOnWait = null;
_byteRangesAvailable = null;
_tempFileStream = null;
_eventHandle = null;
_proxy = null;
_credentials = null;
_cachePolicy = null;
_disposed = true;
}
}
}
}
}
#endregion IDisposable
//------------------------------------------------------
//
// Internal Methods
//
//------------------------------------------------------
#region Internal Methods
/// <summary>
/// Get the byte ranges that are downloaded
/// </summary>
/// <returns>byte ranges that are downloaded; byteRanges is one dimensional
/// array consisting pairs of offset and length</returns>
internal int[,] GetDownloadedByteRanges()
{
int[,] byteRanges = null;
// The worker thread will never call dispose nor this method; no need lock
CheckDisposed();
lock (_syncObject)
{
CheckErroredOutCondition();
int rangeCount = _byteRangesAvailable.Count / 2;
// The worker thread will update the bytes downloaded; need to lock
byteRanges = new int[rangeCount, 2];
for (int i = 0; i < rangeCount; ++i)
{
byteRanges[i, Offset_Index] = (int)_byteRangesAvailable[(i * 2) + Offset_Index];
byteRanges[i, Length_Index] = (int)_byteRangesAvailable[(i * 2) + Length_Index];
}
_byteRangesAvailable.Clear();
}
return byteRanges;
}
/// <summary>
/// Make byte range request
/// </summary>
/// <param name="byteRanges">byte ranges to be downloaded; byteRanges is two dimensional
/// array consisting pairs of offset and length</param>
internal void RequestByteRanges(int[,] byteRanges)
{
// The worker thread will never call dispose nor this method; no need to lock
CheckDisposed();
ArgumentNullException.ThrowIfNull(byteRanges);
CheckTwoDimensionalByteRanges(byteRanges);
// When multiple byte ranges are requested through one HttpWebRequest, the current HttpWebResponse
// returns a stream with headers which has to be manually parsed. At this point, we decided to
// make only one byte range request at a time
// At this point, none of the callers of this class will make more than one range
// So, we will assert if more than one byte range request is made
Debug.Assert(byteRanges.GetLength(0) == 1, "We don't support a request with multiple byte ranges");
_firstRequestMade = true;
// If there is no request in progress, start the request process; otherwise put it in the wait queue
lock (_syncObject)
{
CheckErroredOutCondition();
// _byteRangeInprogress can be cleared out from the worker thread and this method can be called
// from the caller thread; need to lock
if (_byteRangesInProgress == null)
{
_webRequest = CreateHttpWebRequest(byteRanges);
_byteRangesInProgress = byteRanges;
_webRequest.BeginGetResponse(ResponseCallback, this);
}
else // cannot make request yet, put the request in the wait queue
{
// Lazy Init
if (_requestsOnWait == null)
{
// there are currently only ever two of these (one pair)
// so optimize
_requestsOnWait = new ArrayList(2);
}
for (int i = 0; i < byteRanges.GetLength(0); ++i)
{
// Add requests to the wait queue
_requestsOnWait.Add((int) byteRanges[i, Offset_Index]);
_requestsOnWait.Add((int) byteRanges[i, Length_Index]);
}
}
}
}
/// <summary>
/// Convert bytes ranges from one dimensional array (pairs of offset and length)
/// to two dimensional array
/// </summary>
/// <param name="inByteRanges">byteRanges in one dimensional array consisting pairs of offset and length</param>
/// <returns>byteRanges in two dimensional array consisting pairs of offset and length</returns>
static internal int[,] ConvertByteRanges(int[] inByteRanges)
{
CheckOneDimensionalByteRanges(inByteRanges);
int[,] outByteRanges = new int[(inByteRanges.Length / 2),2];
for (int i=0, j=0; i < inByteRanges.Length; ++i, ++j)
{
outByteRanges[j,Offset_Index] = inByteRanges[i];
outByteRanges[j,Length_Index] = inByteRanges[i+1];
++i;
}
return outByteRanges;
}
/// <summary>
/// Convert bytes ranges from two dimensional array (paris of offiset and length)
/// to one dimensional array
/// </summary>
/// <param name="inByteRanges">byteRanges in two dimensional array consisting pairs of offset and length</param>
/// <returns>byteRanges in one dimensional array consisting pairs of offset and length</returns>
static internal int[] ConvertByteRanges(int[,] inByteRanges)
{
// Normallly we will check the input from the caller
// but in our scenario, the two dimensional array is always generated by ByteRangeDownloader
// No need to check
#if DEBUG
CheckTwoDimensionalByteRanges(inByteRanges);
#endif
int[] outByteRanges = new int[inByteRanges.Length];
for (int i=0, j=0; i < inByteRanges.GetLength(0); ++i, ++j)
{
outByteRanges[j] = inByteRanges[i, Offset_Index];
outByteRanges[++j] = inByteRanges[i, Length_Index];
}
return outByteRanges;
}
#endregion Internal Methods
//------------------------------------------------------
//
// Internal Properties
//
//------------------------------------------------------
#region Internal Properties
/// <summary>
/// Proxy for all requests to ByteRangeDownloader
/// </summary>
internal IWebProxy Proxy
{
set
{
CheckDisposed();
ArgumentNullException.ThrowIfNull(value);
if (!_firstRequestMade)
{
_proxy = value;
}
else // Once first request is made it cannot change
{
throw new InvalidOperationException(SR.RequestAlreadyStarted);
}
}
}
/// <summary>
/// Authentication information for all requests to ByteRangeDownloader
/// </summary>
internal ICredentials Credentials
{
set
{
CheckDisposed();
_credentials = value;
}
}
/// <summary>
/// Cache Policy for all requests to ByteRangeDownloader
/// </summary>
internal RequestCachePolicy CachePolicy
{
set
{
CheckDisposed();
if (!_firstRequestMade)
{
_cachePolicy = value;
}
else // Once first request is made it cannot cahnge
{
throw new InvalidOperationException(SR.RequestAlreadyStarted);
}
}
}
/// <summary>
/// OS synchronization object use to synchronize access to the temp file - if null, no sync is needed
/// </summary>
internal Mutex FileMutex
{
get
{
CheckDisposed();
return _fileMutex;
}
}
/// <summary>
/// Returns true if any request errored out
/// </summary>
internal bool ErroredOut
{
get
{
CheckDisposed();
lock (_syncObject)
{
return _erroredOut;
}
}
}
#endregion Internal Properties
//------------------------------------------------------
//
// Private Classes
//
//------------------------------------------------------
//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
#region Private Methods
/// <summary>
/// Check if the object is disposed
/// </summary>
/// <remarks>this._disposed is not changed by a thread while another thread is calling this function</remarks>
private void CheckDisposed()
{
if (_disposed)
{
throw new ObjectDisposedException(null, SR.ByteRangeDownloaderDisposed);
}
}
/// <summary>
/// Constructor for ByteRangeDownloader
/// </summary>
private ByteRangeDownloader(Uri requestedUri, SafeWaitHandle eventHandle)
{
ArgumentNullException.ThrowIfNull(requestedUri);
// Ensure uri is correct scheme (http or https) Do case-sensitive comparison since Uri.Scheme contract is to return in lower case only.
if (!string.Equals(requestedUri.Scheme, Uri.UriSchemeHttp, StringComparison.Ordinal) && !string.Equals(requestedUri.Scheme, Uri.UriSchemeHttps, StringComparison.Ordinal))
{
throw new ArgumentException(SR.InvalidScheme, "requestedUri");
}
ArgumentNullException.ThrowIfNull(eventHandle);
if (eventHandle.IsInvalid || eventHandle.IsClosed)
{
throw new ArgumentException(SR.InvalidEventHandle, "eventHandle");
}
_requestedUri = requestedUri;
_eventHandle = eventHandle;
}
/// <summary>
/// Check if it has been errored out from the worker thread and re-throw the exception that was
/// thrown from the worker thread
/// </summary>
/// <remarks>No need to lock in this function since the caller always locks before making this call</remarks>
private void CheckErroredOutCondition()
{
if (_erroredOut)
{
throw new InvalidOperationException(SR.ByteRangeDownloaderErroredOut, _erroredOutException);
}
}
/// <summary>
/// Download the requested bytes
/// </summary>
private HttpWebRequest CreateHttpWebRequest(int[,] byteRanges)
{
HttpWebRequest request;
// Create the request object
request = (HttpWebRequest)WpfWebRequestHelper.CreateRequest(_requestedUri);
request.ProtocolVersion = HttpVersion.Version11;
request.Method = "GET";
// Set the Proxy to Empty one; If we don't set this to empty one, it will try to find one for us
// and ends up triggering JScript in another assembly. This will throw PolicyException since the JScript
// dll doesn't have execution right. This is a bug in CLR; supposed to be fixed later
// Future work: Need to keep consistent HTTP stack with the WININET one (e.g. authentication, proxy, cookies)
// IWebProxy emptyProxy = GlobalProxySelection.GetEmptyWebProxy();
// request.Proxy = emptyProxy;
request.Proxy = _proxy;
request.Credentials = _credentials;
request.CachePolicy = _cachePolicy;
// Add byte ranges (to header)
for (int i = 0; i < byteRanges.GetLength(0); ++i)
{
request.AddRange(byteRanges[i,Offset_Index],
byteRanges[i,Offset_Index] + byteRanges[i,Length_Index] - 1);
}
return request;
}
/// <summary>
/// Raise Win32 events informing a client that the requested bytes are available or it errored out
/// </summary>
/// <param name="throwExceptionOnError">indicates if an exception to be thrown on fail to set event</param>
/// <remarks></remarks>
private void RaiseEvent(bool throwExceptionOnError)
{
if (_eventHandle != null && !_eventHandle.IsInvalid && !_eventHandle.IsClosed)
{
if (MS.Win32.UnsafeNativeMethods.SetEvent(_eventHandle) == 0)
{
if (throwExceptionOnError)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
}
}
}
/// <summary>
/// ResponseCallBack
/// </summary>
/// <param name="ar">async result</param>
/// <remarks>static method not necessary</remarks>
private void ResponseCallback(IAsyncResult ar)
{
HttpWebResponse webResponse = null;
lock (_syncObject)
{
try
{
if (_disposed)
{
return;
}
// The caller thread can dispose this class and the worker thread need to check the disposed
// condition; need to lock
// If disposed, there is nothing to handle
webResponse = (HttpWebResponse)WpfWebRequestHelper.EndGetResponse(_webRequest, ar);
// If it is not partial content, no need to look further
if (webResponse.StatusCode == HttpStatusCode.PartialContent)
{
//
// Check for few conditions
//
// Get the header and make sure that it was indeed the byte range response
int beginOffset = _byteRangesInProgress[0, Offset_Index];
int endOffset = beginOffset+ _byteRangesInProgress[0,Length_Index] - 1;
// HttpWebRequest in the current CLR does not allow multiple byte range requests.
// At this point, none of the callers of this class will make more than one range at a time
// So, we should not receive any response with more than one range returned
// When multiple byte ranges requests are support in HttpWebRequest eventually,
// there is a question on how to handle multipart response (Content-Type=multipart/byteranges)
// At this point we only need to handle one byte range response (Content-Range header) only
// Request was successful
// Note: endOffset could be trimmed offset in the case where the response didn't
// satisfy the entire request
if (CheckContentRange(webResponse.Headers, beginOffset, ref endOffset))
{
// Write out the bytes to the temp file
if (WriteByteRange(webResponse, beginOffset, endOffset - beginOffset + 1))
{
// The range is downloaded successfully; add it to the list
_byteRangesAvailable.Add(beginOffset);
_byteRangesAvailable.Add(endOffset - beginOffset + 1);
}
else
_erroredOut = true;
}
else
{
_erroredOut = true;
_erroredOutException = new NotSupportedException(SR.ByteRangeRequestIsNotSupported);
}
}
else
{
_erroredOut = true;
}
}
catch (Exception e) // catch (and re-throw) exceptions so we can inform the other thread
{
_erroredOut = true;
_erroredOutException = e;
throw;
}
catch // catch (and re-throw) all kinds of exceptions so we can inform the other thread
{
// inform other thread of error condition
_erroredOut= true;
_erroredOutException = null;
throw;
}
finally
{
if (webResponse != null)
{
webResponse.Close();
}
// bytes requested are downloaded or errored out
// inform the caller that these ranges are available
RaiseEvent(!_erroredOut);
}
// If we haven't errored out already, process the next batch
if (!_erroredOut)
{
ProcessWaitQueue();
}
}
}
/// <summary>
/// Shared code for mutex and non-mutex to call
/// </summary>
private bool Write(Stream s, int offset, int length)
{
int readBytes;
// Process the data chunk at a time (Size of the data that can be processed one time is WriteBufferSize)
_tempFileStream.Seek(offset, SeekOrigin.Begin);
while (length > 0)
{
// Read in the data into the buffer
readBytes = s.Read(_buffer, 0, WriteBufferSize);
if (readBytes == 0)
break;
// Write it out
_tempFileStream.Write(_buffer, 0, readBytes);
length -= readBytes;
}
if (length != 0)
return false;
_tempFileStream.Flush();
return true;
}
/// <summary>
/// Write out the downloaded byte ranges to the temp file
/// </summary>
/// <param name="response">Http web response</param>
/// <param name="offset">Offset of the byte range</param>
/// <param name="length">Length of the byte range</param>
/// <returns>True if it is successfully written out</returns>
private bool WriteByteRange(HttpWebResponse response, int offset, int length)
{
bool result = false;
// Get the downloaded stream
using (Stream s = response.GetResponseStream())
{
if (_buffer == null)
{
_buffer = new byte[WriteBufferSize];
}
// mutex available?
if (_fileMutex != null)
{
// use it
try
{
// block until temp file is available
_fileMutex.WaitOne();
lock (PackagingUtilities.IsolatedStorageFileLock)
{
result = Write(s, offset, length);
}
}
finally
{
_fileMutex.ReleaseMutex();
}
}
else
result = Write(s, offset, length);
}
return result;
}
/// <summary>
/// Process the requests that are in the wait queue
/// </summary>
/// <remarks>This is only called from ResponseCallback which synchronize the call</remarks>
private void ProcessWaitQueue()
{
// There is other requests waiting in the queue; Process those
if (_requestsOnWait != null && _requestsOnWait.Count > 0)
{
// _byteRangesInProgress is already allocated and can be reused
_byteRangesInProgress[0,Offset_Index] = (int) _requestsOnWait[Offset_Index];
_byteRangesInProgress[0,Length_Index] = (int) _requestsOnWait[Length_Index];
_requestsOnWait.RemoveRange(0, 2);
_webRequest = CreateHttpWebRequest(_byteRangesInProgress);
_webRequest.BeginGetResponse(ResponseCallback, this);
}
else
{
// If there is nothing more to process in the wait queue, clear out
// _byteRangesInProgress so that subsequent byte range requests can be made
_byteRangesInProgress = null;
}
}
/// <summary>
/// Check if the given byte ranges follows correct format
/// 1) number of items in the array should be even number (It should be one dimensional array consisting pairs
/// of offset and length
/// 2) offset cannot be less than 0
/// 3) length cannot be less than equal to 0
/// </summary>
/// <param name="byteRanges">Byte ranges to be checked</param>
/// <returns>True if the byte ranges are in correct format</returns>
static private void CheckOneDimensionalByteRanges(int[] byteRanges)
{
// The byteRanges should never be less; perf optimization
if (byteRanges.Length < 2 || (byteRanges.Length % 2) != 0)
{
throw new ArgumentException(SR.Format(SR.InvalidByteRanges, "byteRanges"));
}
for (int i = 0; i < byteRanges.Length; i++)
{
if (byteRanges[i] < 0 || byteRanges[i+1] <= 0)
{
throw new ArgumentException(SR.Format(SR.InvalidByteRanges, "byteRanges"));
}
i++;
}
}
/// <summary>
/// Check if the given byte ranges follows correct format
/// 1) array should consist pairs of offset and length
/// 2) offset cannot be less than 0
/// 3) length cannot be less than equal to 0
/// </summary>
/// <param name="byteRanges">Byte ranges to be checked</param>
/// <returns>True if the byte ranges are in correct format</returns>
static private void CheckTwoDimensionalByteRanges(int[,] byteRanges)
{
if (byteRanges.GetLength(0) <= 0 || byteRanges.GetLength(1) != 2)
{
throw new ArgumentException(SR.Format(SR.InvalidByteRanges, "byteRanges"));
}
for (int i = 0; i < byteRanges.GetLength(0); ++i)
{
if (byteRanges[i,Offset_Index] < 0 || byteRanges[i,Length_Index] <= 0)
{
throw new ArgumentException(SR.Format(SR.InvalidByteRanges, "byteRanges"));
}
}
}
/// <summary>
/// Check if the some of byte range request is satisfied by the given response
/// This method make sure of the following:
/// 1) It contains Content-Range field
/// 2) Content-Range follows the format defined in RFC2616
/// a. it should be in the form of "bytes 0-499/1234" or "bytes 0-499/*"
/// b. it should not be "bytes */*" or "*/1234"
/// c. last-byte-pos must not be less than its first byte pos
/// 3) Ignore the response that does not conform to condition #1 and #2
/// </summary>
/// <param name="responseHeaders">collection of headers returned with WebResponse</param>
/// <param name="beginOffset">first byte pos the requested byte range</param>
/// <param name="endOffset">last byte pos the requested byte range</param>
/// <returns>False if the response contains invalid Content-Range field
/// or none of bytes requested is included in the response.
/// True if the some bytes of the requested bytes are included in the response.</returns>
static private bool CheckContentRange(WebHeaderCollection responseHeaders, int beginOffset, ref int endOffset)
{
String contentRange = responseHeaders[ContentRangeHeader];
// No Content-Range (condition #1)
if (contentRange == null)
{
return false;
}
contentRange = contentRange.ToUpperInvariant();
// No Content-Range (condition #1)
if (contentRange.Length == 0
|| !contentRange.StartsWith(ByteRangeUnit, StringComparison.Ordinal))
{
return false;
}
// ContentRange: BYTES XXX-YYY/ZZZ
int index = contentRange.IndexOf('-');
if (index == -1)
{
return false;
}
// Get the first byte offset of the range (XXX)
int firstByteOffset = Int32.Parse(contentRange.AsSpan(ByteRangeUnit.Length,
index - ByteRangeUnit.Length),
NumberStyles.None, NumberFormatInfo.InvariantInfo);
ReadOnlySpan<char> contentRangeSpan = contentRange.AsSpan(index + 1);
// ContentRange: YYY/ZZZ
index = contentRangeSpan.IndexOf('/');
if (index == -1)
{
return false;
}
// Get the last byte offset of the range (YYY)
int lastByteOffset = Int32.Parse(contentRangeSpan.Slice(0, index), NumberStyles.None, NumberFormatInfo.InvariantInfo);
// Get the instance length
// ContentRange: ZZZ
contentRangeSpan = contentRangeSpan.Slice(index + 1);
if (!contentRangeSpan.Equals("*", StringComparison.Ordinal))
{
// Note: for firstByteOffset and lastByteOffset, we are using Int32.Parse to make sure Int32.Parse to throw
// if it is not an integer or the integer is bigger than Int32 since HttpWebRequest.AddRange
// only supports Int32
// Once HttpWebRequest.AddRange start supporting Int64 we should change it to Int64 and long
Int32.Parse(contentRangeSpan, NumberStyles.None, NumberFormatInfo.InvariantInfo);
}
// The response is considered to be successful if
// the last byte offset is greater than the first offset of the response
// and the response range satisfies some or all of the requested range
// However, we don't want to deal with the situation where the first byte of the response is not the beginning
// of the requested range
bool successful = (firstByteOffset <= lastByteOffset
&& beginOffset == firstByteOffset);
// Check if the response didn't satisfy the end part of the requested range
if (successful && lastByteOffset < endOffset)
{
endOffset = lastByteOffset;
}
return successful;
}
#endregion Private Methods
//------------------------------------------------------
//
// Private Properties
//
//------------------------------------------------------
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
#region Private Fields
private bool _firstRequestMade;
private bool _disposed;
private Object _syncObject = new Object();
private bool _erroredOut;
private Exception _erroredOutException;
private Uri _requestedUri; // url to be downloaded
private RequestCachePolicy _cachePolicy;
private IWebProxy _proxy;
private ICredentials _credentials;
private CookieContainer _cookieContainer = new CookieContainer(1);
private SafeWaitHandle _eventHandle; // event handle which needs to be raised to inform the caller that
// the requested bytes are available
private Mutex _fileMutex; // object controlling synchronization on the temp file - if this is null, we own the stream
private System.IO.Stream _tempFileStream; // stream to write to
private ArrayList _byteRangesAvailable = new ArrayList(2); // byte ranges that are downloaded
private ArrayList _requestsOnWait; // List of byte ranges requested need to be processed
private int[,] _byteRangesInProgress;
private HttpWebRequest _webRequest;
private byte[] _buffer; // Buffer used for writing out the downloaded bytes to temp file
private const int WriteBufferSize = 4096; // Buffer size for writing out to the temp file
private const int TimeOut = 5000;
private const int Offset_Index = 0;
private const int Length_Index = 1;
private const String ByteRangeUnit = "BYTES ";
private const String ContentRangeHeader = "Content-Range";
#endregion Private Fields
}
}
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