Modify access time of Windows read only file through WSL - windows

Question

I have a read-only file, say samp.txt and I run the following on PowerShell:
> $file = Get-Item .\samp.txt
> $file.LastAccessTime = (get-date)
we get: "Access to the path 'G:\Study_Material\Coding\samp.txt' is denied."
Now before we proceed, look at the access time:
> $file.LastAccessTime will be
Sunday, December 30, 2018 11:02:49 PM
Now we open WSL and do: $ touch samp.txt
Back to PowerShell we do:
> $file = Get-Item .\samp.txt
> $file.LastAccessTime
we get:
Sunday, December 30, 2018 11:19:16 PM
Thus it has been modified with no elevated privileges.
Now my question: How is it possible to mimic this action in PowerShell alone without removing the ReadOnly tag by modifying the $file.Attributes.

Answer 1

When dealing with ReadOnly files, you cannot simply change the LastAccessTime.
(see the comments by eryksun ).
In order to have it work in PowerShell, you need to first remove the ReadOnly flag from the file's attributes, do the change and reset the ReadOnly flag like so:
$file = Get-Item .\samp.txt -Force
# test if the ReadOnly flag on the file is set
if ($file.Attributes -band 1) {
# remove the ReadOnly flag from the file. (FILE_ATTRIBUTE_READONLY = 1)
$file.Attributes = $file.Attributes -bxor 1
# or use: $file | Set-ItemProperty -Name IsReadOnly -Value $false
$file.LastAccessTime = (Get-Date)
# reset the ReadOnly flag
$file.Attributes = $file.Attributes -bxor 1
# or use: $file | Set-ItemProperty -Name IsReadOnly -Value $true
}
else {
# the file is not ReadOnly, so just do the 'touch' on the LastAccessTime
$file.LastAccessTime = (Get-Date)
}
You can read all about file attributes and their numeric values here