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private static extern bool SetFileInformationByHandle(SafeHandle hFile, FileInformationClass FileInformationClass, ref FileInformation FileInformation, Int32 dwBufferSize);
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SetFileInformationByHandle(fileStream.SafeFileHandle, FileInformationClass.FileDispositionInfo, ref FileInformation, Marshal.SizeOf(FileInformation.FILE_DISPOSITION_INFO));
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SetFileInformationByHandle(fileStream.SafeFileHandle, FileInformationClass.FileEndOfFileInfo, ref FileInformation, Marshal.SizeOf(FileInformation.FILE_END_OF_FILE_INFO));
