bug fix in <NtFile>.Read(<length>), null is not 0 in RunFileCallSync

[bravosierra99]

This is the error I was getting
`
$file = Get-NtFile <some_path> -win32path
$file.read(5)
Exception calling "Read" with "1" argument(s): "(0xC000000D) - An invalid parameter was passed to a service or
function."
At line:1 char:187

• ... t-NtFile C:\Users\ben\Documents\desktop.ini -Win32Path; $file.read(3)

•                                                         ~~~~~~~~~~~~~
  

  • CategoryInfo : NotSpecified: (:) [], MethodInvocationException
  • FullyQualifiedErrorId : NtException
    `

I'm not a c# person and I didn't dive into if there are underlying problems beyond where I made my fix. While I would have expected null and 0 to be the same, they don't appear to be so I just made the lowest level fix that made sense to me.

let me know if you have any questions.

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[bravosierra99]

added CLA

[tyranid]

Thanks for that, however the behavior is intentional. By default the code opens the file in asynchronous mode. In this mode the kernel does not track the current position of the file pointer so you must always explicitly specify the offset you want to read the bytes from. The reason there's a difference between null and 0 is in synchronous mode you don't need to specify the offset at all. That parameter is optional so it's okay to pass null, however you can specify it if you wanted to. For async you must specify the offset regardless, but the Read method does not try and help you here as it doesn't even know what offset you want to read from.

Therefore you'd need to do one of two things to correctly read data, either pass the position e.g. $file.Read(5, 0) or open the file in synchronous mode e.g. $file = Get-NtFile <some path> -Win32Path -Options SynchronousIoNonAlert -Access GenericAll,Synchronize

[bravosierra99]

Got it! Thanks for the response! Sorry!