PowerShell script for deleting files with otherwise invalid filenames

DeleteAnyFile.ps1

param([String]$filename)

$signature = @' 
[DllImport("kernel32.dll", ExactSpelling=true, CharSet=CharSet.Unicode, SetLastError=true)]
public static extern uint DeleteFileW( 
    string lpFileName); 
'@

$type = $null
try
{
    $type = [DeleteAnyFile.Win32Utils]
}
catch 
{
}

if ($type -eq $null)
{
    $type = Add-Type -MemberDefinition $signature `
        -Name Win32Utils -Namespace DeleteAnyFile `
        -Using System.Text -PassThru 
}

function MakeLongPath([string]$path)
{
    if ($path.StartsWith("\") -eq !$path.StartsWith("\\") )
    {
        $pwdRoot = [System.IO.Path]::GetPathRoot((pwd).ProviderPath)
        $path = [System.IO.Path]::Combine($pwdRoot, $path.Substring(1))
    }
    elseif (![System.IO.Path]::IsPathRooted($path))
    {
        $path = [System.IO.Path]::Combine((pwd).ProviderPath, $path)
    }

    if ($path.StartsWith("\\?\"))
    {
        $f = $path
    }
    elseif ($path.StartsWith("\\"))
    {
        $f = "\\?\UNC\"+$path.Substring(2)
    }
    elseif ($path.Length -ge 2 -and $path[1] -eq ":")
    {
        $f = "\\?\$path"
    }

    $parts = $f.Split("\")
    $pathStack = [System.Collections.Generic.Stack[String]]::new()
    foreach ($part in $parts)
    {
        if ($part -eq ".")
        {
            continue
        }
        elseif ($part -eq "..")
        {
            $pathStack.Pop() > $null
        }
        else
        {
            $pathStack.Push($part)
        }
    }

    return [String]::Join('\', [System.Linq.Enumerable]::Reverse($pathStack))
}

if ($type::DeleteFileW((MakeLongPath $filename)) -eq 0)
{
    throw [System.ComponentModel.Win32Exception]([System.Runtime.InteropServices.Marshal]::GetLastWin32Error())
}