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Sftp file stream should consider negative offsets in Seek #1020

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Sftp file stream should consider negative offsets in Seek #1020

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5bf54bd
fix sftp file stream to consider negative offsets in Seek()
S-Jindal Oct 25, 2022
7a0f567
remove unwatned changes
S-Jindal Oct 25, 2022
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40 changes: 24 additions & 16 deletions src/Renci.SshNet/Sftp/SftpFileStream.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
#if FEATURE_TAP
using System.Threading.Tasks;
#endif
using System.Reflection;
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What's this for?

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Dummy change, will remove it


namespace Renci.SshNet.Sftp
{
Expand Down Expand Up @@ -283,8 +284,8 @@ internal SftpFileStream(ISftpSession session, string path, FileMode mode, FileAc
// that ensures we always receive or send the max. number of bytes in a single SSH_FXP_READ
// or SSH_FXP_WRITE message

_readBufferSize = (int) session.CalculateOptimalReadLength((uint) bufferSize);
_writeBufferSize = (int) session.CalculateOptimalWriteLength((uint) bufferSize, _handle);
_readBufferSize = (int)session.CalculateOptimalReadLength((uint)bufferSize);
_writeBufferSize = (int)session.CalculateOptimalWriteLength((uint)bufferSize, _handle);

if (mode == FileMode.Append)
{
Expand Down Expand Up @@ -381,7 +382,7 @@ internal static async Task<SftpFileStream> OpenAsync(ISftpSession session, strin
await session.RequestCloseAsync(handle, cancellationToken).ConfigureAwait(false);
}
catch
{
{
// The original exception is presumably more informative, so we just ignore this one.
}
throw;
Expand Down Expand Up @@ -509,7 +510,7 @@ public override int Read(byte[] buffer, int offset, int count)
var bytesAvailableInBuffer = _bufferLen - _bufferPosition;
if (bytesAvailableInBuffer <= 0)
{
var data = _session.RequestRead(_handle, (ulong) _position, (uint) _readBufferSize);
var data = _session.RequestRead(_handle, (ulong)_position, (uint)_readBufferSize);

if (data.Length == 0)
{
Expand Down Expand Up @@ -726,7 +727,7 @@ public override int ReadByte()
// Read more data into the internal buffer if necessary.
if (_bufferPosition >= _bufferLen)
{
var data = _session.RequestRead(_handle, (ulong) _position, (uint) _readBufferSize);
var data = _session.RequestRead(_handle, (ulong)_position, (uint)_readBufferSize);
if (data.Length == 0)
{
// We've reached EOF.
Expand Down Expand Up @@ -783,6 +784,8 @@ public override long Seek(long offset, SeekOrigin origin)
return _position;
}

var attributes = (SftpFileAttributes)null;

// The behaviour depends upon the read/write mode.
if (_bufferOwnedByWrite)
{
Expand All @@ -798,15 +801,16 @@ public override long Seek(long offset, SeekOrigin origin)
newPosn = _position + offset;
break;
case SeekOrigin.End:
var attributes = _session.RequestFStat(_handle, false);
newPosn = attributes.Size - offset;
attributes = _session.RequestFStat(_handle, false);
newPosn = attributes.Size + offset;
break;
}

if (newPosn == -1)
if (newPosn == -1 || (attributes != null && newPosn > attributes.Size))
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seeking past the end of file when writing is valid, it's a way to extend the file size.

{
throw new EndOfStreamException("End of stream.");
}

_position = newPosn;
}
else
Expand All @@ -829,7 +833,7 @@ public override long Seek(long offset, SeekOrigin origin)
if (newPosn >= (_position - _bufferPosition) &&
newPosn < (_position - _bufferPosition + _bufferLen))
{
_bufferPosition = (int) (newPosn - (_position - _bufferPosition));
_bufferPosition = (int)(newPosn - (_position - _bufferPosition));
_position = newPosn;
return _position;
}
Expand All @@ -849,12 +853,16 @@ public override long Seek(long offset, SeekOrigin origin)
newPosn = _position + offset;
break;
case SeekOrigin.End:
var attributes = _session.RequestFStat(_handle, false);
newPosn = attributes.Size - offset;
if (attributes == null)
{
attributes = _session.RequestFStat(_handle, false);
}

newPosn = attributes.Size + offset;
break;
}

if (newPosn < 0)
if (newPosn < 0 || (attributes != null && newPosn > attributes.Size))
{
throw new EndOfStreamException();
}
Expand Down Expand Up @@ -974,7 +982,7 @@ public override void Write(byte[] buffer, int offset, int count)
{
using (var wait = new AutoResetEvent(false))
{
_session.RequestWrite(_handle, (ulong) _position, buffer, offset, tempLen, wait);
_session.RequestWrite(_handle, (ulong)_position, buffer, offset, tempLen, wait);
}
}
else
Expand All @@ -996,7 +1004,7 @@ public override void Write(byte[] buffer, int offset, int count)
{
using (var wait = new AutoResetEvent(false))
{
_session.RequestWrite(_handle, (ulong) (_position - _bufferPosition), GetOrCreateWriteBuffer(), 0, _bufferPosition, wait);
_session.RequestWrite(_handle, (ulong)(_position - _bufferPosition), GetOrCreateWriteBuffer(), 0, _bufferPosition, wait);
}

_bufferPosition = 0;
Expand Down Expand Up @@ -1106,7 +1114,7 @@ public override void WriteByte(byte value)
{
using (var wait = new AutoResetEvent(false))
{
_session.RequestWrite(_handle, (ulong) (_position - _bufferPosition), writeBuffer, 0, _bufferPosition, wait);
_session.RequestWrite(_handle, (ulong)(_position - _bufferPosition), writeBuffer, 0, _bufferPosition, wait);
}

_bufferPosition = 0;
Expand Down Expand Up @@ -1192,7 +1200,7 @@ private void FlushWriteBuffer()
{
using (var wait = new AutoResetEvent(false))
{
_session.RequestWrite(_handle, (ulong) (_position - _bufferPosition), _writeBuffer, 0, _bufferPosition, wait);
_session.RequestWrite(_handle, (ulong)(_position - _bufferPosition), _writeBuffer, 0, _bufferPosition, wait);
}

_bufferPosition = 0;
Expand Down