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Implement our own (probably crappy) seeking mechanism for network streams which do not support it

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This commit is contained in:
Michael Becker 2014-11-17 15:56:57 -05:00
parent 4f5f99bfcf
commit 7ae6a1762b
1 changed files with 69 additions and 12 deletions
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81
CSharp/Plugins/UniversalEditor.Plugins.Web/Accessors/HTTPAccessor.cs
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@ -26,36 +26,48 @@ namespace UniversalEditor.Accessors
private System.Net.HttpWebRequest http = null;
private System.IO.Stream mvarStream = null;
private long mvarLength = 0;
public override long Length
{
get
{
if (mvarStream == null) throw new InvalidOperationException("Please open before looking");
return mvarStream.Length;
return mvarLength;
}
set
{
if (mvarStream == null) throw new InvalidOperationException("Please open before looking");
mvarStream.SetLength(value);
throw new InvalidOperationException();
}
}
private long mvarPosition = 0;
private byte[] mvarBuffer = new byte[0];
protected override long GetPosition()
{
if (mvarStream == null) throw new InvalidOperationException("Please open before looking");
return mvarStream.Position;
return mvarPosition;
}
public override void Seek(long length, IO.SeekOrigin position)
{
System.IO.SeekOrigin position1 = System.IO.SeekOrigin.Begin;
switch (position)
{
case IO.SeekOrigin.Begin: position1 = System.IO.SeekOrigin.Begin; break;
case IO.SeekOrigin.Current: position1 = System.IO.SeekOrigin.Current; break;
case IO.SeekOrigin.End: position1 = System.IO.SeekOrigin.End; break;
case IO.SeekOrigin.Begin:
{
mvarPosition = length;
break;
}
case IO.SeekOrigin.Current:
{
mvarPosition += length;
break;
}
case IO.SeekOrigin.End:
{
mvarPosition = mvarLength - length;
break;
}
}
mvarStream.Seek(length, position1);
}
protected override void OpenInternal()
@ -63,9 +75,20 @@ namespace UniversalEditor.Accessors
if (http != null) throw new InvalidOperationException("Please close before opening");
http = (HttpWebRequest)WebRequest.Create(mvarFileName);
WebResponse resp = http.GetResponse();
string contentLength = resp.Headers[HttpResponseHeader.ContentLength];
long contentLengthL = 0;
if (Int64.TryParse(contentLength, out contentLengthL))
{
mvarLength = contentLengthL;
}
mvarBuffer = new byte[mvarLength];
mvarStream = resp.GetResponseStream();
}
private long mvarActualPosition = 0;
protected override void CloseInternal()
{
if (http == null) throw new InvalidOperationException("Please open before closing");
@ -83,8 +106,42 @@ namespace UniversalEditor.Accessors
}
protected override int ReadInternal(byte[] buffer, int start, int count)
{
if (mvarStream == null) throw new InvalidOperationException("Please open before reading");
return mvarStream.Read(buffer, start, count);
if (mvarPosition < mvarActualPosition)
{
// count of bytes available to be read from the buffer, starting at
// current position
long bufferAvailableCount = (mvarActualPosition - mvarPosition);
// count of bytes that will be read from the buffer for this read
// operation
long bufferCount = Math.Min(count, bufferAvailableCount);
// count of bytes that will be read from the stream for this read
// operation
long newCount = (count - bufferAvailableCount);
// total count of bytes to be read from both buffer and stream
long realCount = bufferCount + newCount;
byte[] newBuffer = new byte[newCount];
int readFromStream = mvarStream.Read(newBuffer, 0, (int)newCount);
Array.Copy(newBuffer, 0, mvarBuffer, (int)(start + bufferCount), newCount);
Array.Copy(mvarBuffer, mvarPosition, buffer, start, realCount);
return (int)realCount;
}
else if (mvarPosition == mvarActualPosition)
{
if (mvarStream == null) throw new InvalidOperationException("Please open before reading");
int realCount = mvarStream.Read(buffer, start, count);
Array.Copy(buffer, 0, mvarBuffer, mvarPosition, realCount);
mvarActualPosition += realCount;
mvarPosition += count;
return realCount;
}
return -1;
}
}
}