Wildcard character in registry paths results in "Illegal characters in path." #4704

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1. Ilya (iSazonov)

   added

   WG-Engine-Providersbuilt-in PowerShell providers such as FileSystem, Certificates, Registry, etc.built-in PowerShell providers such as FileSystem, Certificates, Registry, etc.

   Issue-Questionideally support can be provided via other mechanisms, but sometimes folks do open an issue to get aideally support can be provided via other mechanisms, but sometimes folks do open an issue to get a

   on Aug 30, 2017
2. mklement0 commented on Aug 30, 2017

   

   Michael Klement (mklement0)

   on Aug 30, 2017

   Last edited by mklement0

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   You did hit a bug, but there are two important asides:

   You should always use -LiteralPath to prevent (potentially unwanted) wildcard matching:

   Remove-Item -LiteralPath "HKCU:\Software\Classes\*\shell\"

   Positionally, your argument binds to -Path, which performs wildcard matching, which would delete the shell subkeys of all subkeys of HKCU:\Software\Classes.

   Also, there is no escaping of wildcard expressions; "HKCU:\Software\Classes\``*\shell\" tries to match HKCU:\Software\Classes\`*\shell\ as a pattern, which is not the intent.

   The only way to suppress wildcard matching is to use -LiteralPath.
3. mklement0 commented on Aug 30, 2017

   

   Michael Klement (mklement0)

   on Aug 30, 2017

   Last edited by mklement0

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   A test case to demonstrate the problem succinctly:

   # Note that paths passed to New-Item are *always* interpreted as literals paths.
   # (Its -Path parameter is the equivalent of the -LiteralPath parameter in the Get-* and Remove-* cmdlets.)
   New-Item -Force HKCU:\_tmp\*\sub, HKCU:\_tmp\foo\sub
   
   # -LiteralPath: Should only delete the key with the *literal* "*" in its path.
   Remove-Item -LiteralPath HKCU:\_tmp\*\sub\
   
   # -Path (implied by positional use: should apply wildcard matching and delete
   # the "sub"  subkeys of ALL "HKCU:\_tmp" subkeys.
   Remove-Item HKCU:\_tmp\*\sub\
   
   Remove-Item -Recurse HKCU:\_tmp

   Currently, the first 2 Remove-Item calls fail with Illegal characters in path.

   Note that the commands fail on Windows PowerShell too, but quietly.
4. jared-is-ray commented on Aug 30, 2017

   

   Jared Ray (jared-is-ray)

   on Aug 30, 2017

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   Thank you very much for quick response and for the tip on -LiteralPath, I was unaware of this option.

   One other note on where I got HKCU:\Software\Classes\``*\shell\ from: as part of my debugging, I was trying to cd into the path with the "*" key in it. It seems that cd does expand the wildcard. I was able to prevent the expansion of the wildcard and cd into the path with no problem when I escaped the backtick. I assumed this was because it might be getting passed to some code downstream that turns the backtick into an actual escape sequence. I have no idea if this is related, but perhaps it gives a little more info on the bug.

   With unescaped wildcard:

   cd "HKCU:\Software\Classes\*\shell\" 
   cd : Cannot set the location because path 'HKCU:\Software\Classes\*\shell\' resolved to multiple containers. You can only the set location to a
   single container at a time.
   At line:1 char:1
   + cd "HKCU:\Software\Classes\*\shell\"
   + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       + CategoryInfo          : InvalidArgument: (:) [Set-Location], PSArgumentException
       + FullyQualifiedErrorId : Argument,Microsoft.PowerShell.Commands.SetLocationCommand

   With escaped backtick:

   cd "HKCU:\Software\Classes\``*\shell\" 
   pwd
   
   Path
   ----
   HKCU:\Software\Classes\*\shell\
5. mklement0 commented on Aug 30, 2017

   

   Michael Klement (mklement0)

   on Aug 30, 2017

   Last edited by mklement0

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   Jared Ray (@jared-is-ray):

   The escaping trick is intriguing - I would not expect that to work, and, bizarrely, it even works with two backticks (but no more):

   # Inexplicably works even with *2* (effective) backticks.
   cd "HKCU:\Software\Classes\````*\shell\" # same as: 'HKCU:\Software\Classes\``*\shell\'

   Again, however, -LiteralPath is the right solution:

   cd -LiteralPath HKCU:\Software\Classes\*\shell\
6. mklement0 commented on Sep 1, 2017

   

   Michael Klement (mklement0)

   on Sep 1, 2017

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   Jared Ray (@jared-is-ray):

   My bad: You can escape wildcard patterns, and what you tried should have worked, after all.

   > [System.Management.Automation.WildcardPattern]::Escape('HKCU:\Software\Classes\*\shell\')
   HKCU:\Software\Classes\`*\shell\

   • I still puzzled by the escaping with two ` (effective) instances, however, given the following:

   [System.Management.Automation.WildcardPattern]::Unescape('``*')
   `*   # !! 1 ` retained, as expected.

   • Given that it's easy to get the escaping wrong manually and it is cumbersome to apply it programmatically, escaping is best reserved for cases where you have a wildcard expression in which you must escape parts as literals; in other words: if you know that your path is meant to be taken literally, -LiteralPath is the simple and robust choice.
7. Steve Lee (SteveL-MSFT)

   self-assigned this

   on Sep 19, 2017
8. Steve Lee (SteveL-MSFT)

   added

   Issue-BugIssue has been identified as a bug in the productIssue has been identified as a bug in the product

   and removed

   Issue-Questionideally support can be provided via other mechanisms, but sometimes folks do open an issue to get aideally support can be provided via other mechanisms, but sometimes folks do open an issue to get a

   on Sep 19, 2017
9. Aditya Patwardhan (adityapatwardhan)

   closed this as completedin #4866on Sep 25, 2017
10. Ilya (iSazonov)

    added

    Resolution-FixedThe issue is fixed.The issue is fixed.

    on Sep 26, 2017