public override ValueTask WriteAsync(ReadOnlyMemory <byte> buffer, CancellationToken cancellationToken = default)
{
long writeOffset = CanSeek ? Interlocked.Add(ref _filePosition, buffer.Length) - buffer.Length : -1;
(SafeFileHandle.OverlappedValueTaskSource? vts, int errorCode) = RandomAccess.QueueAsyncWriteFile(_fileHandle, buffer, writeOffset, cancellationToken);
return(vts != null
? new ValueTask(vts, vts.Version)
: (errorCode == 0) ? ValueTask.CompletedTask : ValueTask.FromException(HandleIOError(writeOffset, errorCode)));
}
private unsafe ValueTask WriteAsyncInternal(ReadOnlyMemory <byte> source, CancellationToken cancellationToken)
{
if (!CanWrite)
{
ThrowHelper.ThrowNotSupportedException_UnwritableStream();
}
long positionBefore = _filePosition;
if (CanSeek)
{
// When using overlapped IO, the OS is not supposed to
// touch the file pointer location at all. We will adjust it
// ourselves, but only in memory. This isn't threadsafe.
_filePosition += source.Length;
UpdateLengthOnChangePosition();
}
(SafeFileHandle.ValueTaskSource? vts, int errorCode) = RandomAccess.QueueAsyncWriteFile(_fileHandle, source, positionBefore, cancellationToken);
return(vts != null
? new ValueTask(vts, vts.Version)
: (errorCode == 0) ? ValueTask.CompletedTask : ValueTask.FromException(HandleIOError(positionBefore, errorCode)));
}
