Split-Path gets error if drive doesn't exist locally

Split-Path gets error if drive doesn't exist locally by Stephen Mills

Closed

as Fixed

Type:	Bug
ID:	499194
Opened:	10/21/2009 11:50:26 AM
Access Restriction:	Public

Workaround(s)

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User(s) can reproduce this bug

If you have a path that you want to split that was generated on a remote system, Split-Path will generate an error unless you have the same drive letter on your local system. If you leave out the drive letter and ":", then it works as expected, except you no longer have a reference to the drive letter. Since it doesn't validate any other part of the path, it shouldn't validate the drive letter existing either.

Details (expand)

Always Happens

I don't know if this issue existed previously

Use PowerShell V2 RC on Windows XP
Execute:
Split-Path -Path 'T:\Backups\2009\10\DBBackup.BAK' -Leaf
Results:
Split-Path : Cannot find drive. A drive with the name 'T' does not exist.
At line:1 char:11
+ Split-Path <<<< -Path 'T:\Backups\2009\DBBackup.BAK'
+ CategoryInfo : ObjectNotFound: (T:String) [Split-Path], DriveNotFoundException
+ FullyQualifiedErrorId : DriveNotFound,Microsoft.PowerShell.Commands.SplitPathCommand

As long as the path has a valid format, it should split it as if the drive letter did exist.

Execute:
Split-Path -Path 'T:\Backups\2009\10\DBBackup.BAK' -Leaf
Results:
DBBackup.BAK

or
Execute:
Split-Path -Path 'T:\Backups\2009\10\DBBackup.BAK' -Parent
Results:
DBBackup.BAK
T:\Backups\2009\10

0 attachments

I can reproduce the problem in Powershell 2.0:

Split-Path : Cannot find drive. A drive with the name 'D' does not exist.
+ CategoryInfo : ObjectNotFound: (D:String) [Split-Path], DriveNotFoundException
+ FullyQualifiedErrorId : DriveNotFound,Microsoft.PowerShell.Commands.SplitPathCommand

This is strange, I assumed Split-Path didn't hit the file system, and got the error above.

An ugly but robust work-a-round is to use [System.IO.Path]::GetDirectoryName, or [System.IO.Path]::GetFileName if you're using the -Leaf option. Those functions don't hit the local file system, and I assumed Split-Path used these functions internally.

This is a dangerous bug which can surprise everyone when you least expect it. Even when using a single computer the drive configuration can change.

Lesson: Don't use Split-Path in ANY powershell code, use the [System.IO.Path] functions instead. Can we have some feedback if this will be fixed in Powershell 2.0 at all?