Registry provider: key names "." and ".." aren't supported in PS drive paths due to filesystem-like path normalization

[mklement0]

If you use a path with a key literally named . or .. that is based on one of the registry drive provider's drives such as HKCU:, these names are currently misinterpreted as referring to the current and parent "directory" respectively, as in the filesystem.

The workaround is to use a provider-native path via the registry:: prefix.

If it's too late to change this behavior and perhaps people rely on it, expecting filesystem-analogous behavior, the pitfall - and workaround - should be documented.

Note that creating a key named . is not a hypothetical example; you need it to define a file type for extension-less file names, for instance (HKEY_CLASSES_ROOT\.)

Steps to reproduce (on Windows)

Note: The same applies analogously to a key literally named '..'.

# A path to a key named "."
$regPathPS = 'HKCU:\_tmp\.'
# Equivalent provider-native path.
$regPathProviderNative = 'registry::HKEY_CURRENT_USER\_tmp\.'

# Create the key using the provider-native path
# - which is currently the only option.
$null = New-Item -Force $regPathProviderNative

# Try to retrieve the new key using the PS drive notation.
# This currently retrieves 'HKCU:\_tmp' instead, i.e., the
# *parent* path, because the "." is misinterpreted as a reference to
# the "directory" HKCU:\_tmp
try {

  (Get-Item -LiteralPath $regPathPS).PSChildName | Should -Be '.'

} finally {
  # Clean up.
  Remove-Item -Recurse -LiteralPath (Split-Path -Path $regPathPS)
}

Expected behavior

The test should pass.

Actual behavior

The test fails:

...
Strings differ at index 0.
Expected: '.'
But was:  '_tmp'
...

Environment data

PowerShell Core 6.2.0 / Windows PowerShell v5.1

[kvprasoon]

Is the problem is in Get-Item ? It get the proper childname using Get-ChildItem

[mklement0]

@kvprasoon, no: Get-ChildItem is equally affected.

It only works incidentally in this scenario: it still targets only registry::HKEY_CURRENT_USER\_tmp and enumerates its children - the only one of which happens to be . in the test above; if you create a sibling key, say, registry::HKEY_CURRENT_USER\_tmp\foo, you'll see that Get-ChildItem HKCU:\_tmp\. enumerates them both.

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has not had any activity in 6 months, if this is a bug please try to reproduce on the latest version of PowerShell and reopen a new issue and reference this issue if this is still a blocker for you.

[microsoft-github-policy-service]

This issue has been marked as "No Activity" as there has been no activity for 6 months. It has been closed for housekeeping purposes.