Split-CommandLine.ps1

<#
.Synopsis
	Parse command-line arguments using Win32 API CommandLineToArgvW function.

.Link
	http://edgylogic.com/blog/powershell-and-external-commands-done-right/

.Description
	This is the Cmdlet version of the code from the article http://edgylogic.com/blog/powershell-and-external-commands-done-right.
	It can parse command-line arguments using Win32 API function CommandLineToArgvW . 

.Parameter CommandLine
	This parameter is optional.

	A string representing the command-line to parse. If not specified, the command-line of the current PowerShell host is used.

.Example
	Split-CommandLine

		Description
		-----------
		Get the command-line of the current PowerShell host, parse it and return arguments.

.Example
	Split-CommandLine -CommandLine '"c:\windows\notepad.exe" test.txt'

		Description
		-----------
		Parse user-specified command-line and return arguments.

.Example
    '"c:\windows\notepad.exe" test.txt',  '%SystemRoot%\system32\svchost.exe -k LocalServiceNetworkRestricted' | Split-CommandLine

		Description
		-----------
		Parse user-specified command-line from pipeline input and return arguments.

.Example
    Get-WmiObject Win32_Process -Filter "Name='notepad.exe'" | Split-CommandLine

		Description
		-----------
		Parse user-specified command-line from property name of the pipeline object and return arguments.
#>
function Split-CommandLine
{
    [CmdletBinding()]
    Param
    (
        [Parameter(Mandatory=$false, ValueFromPipeline=$true, ValueFromPipelineByPropertyName=$true, Position=0)]
        [ValidateNotNullOrEmpty()]
        [string]$CommandLine
    )

    Begin
    {
        $Kernel32Definition = @'
            [DllImport("kernel32")]
            public static extern IntPtr GetCommandLineW();
            [DllImport("kernel32")]
            public static extern IntPtr LocalFree(IntPtr hMem);
'@
        $Kernel32 = Add-Type -MemberDefinition $Kernel32Definition -Name 'Kernel32' -Namespace 'Win32' -PassThru

        $Shell32Definition = @'
            [DllImport("shell32.dll", SetLastError = true)]
            public static extern IntPtr CommandLineToArgvW(
                [MarshalAs(UnmanagedType.LPWStr)] string lpCmdLine,
                out int pNumArgs);
'@
        $Shell32 = Add-Type -MemberDefinition $Shell32Definition -Name 'Shell32' -Namespace 'Win32' -PassThru

        if(!$CommandLine)
        {
            $CommandLine = [System.Runtime.InteropServices.Marshal]::PtrToStringUni($Kernel32::GetCommandLineW())
        }
    }

    Process
    {
        $ParsedArgCount = 0
        $ParsedArgsPtr = $Shell32::CommandLineToArgvW($CommandLine, [ref]$ParsedArgCount)

        Try
        {
            $ParsedArgs = @();

            0..$ParsedArgCount | ForEach-Object {
                $ParsedArgs += [System.Runtime.InteropServices.Marshal]::PtrToStringUni(
                    [System.Runtime.InteropServices.Marshal]::ReadIntPtr($ParsedArgsPtr, $_ * [IntPtr]::Size)
                )
            }
        }
        Finally
        {
            $Kernel32::LocalFree($ParsedArgsPtr) | Out-Null
        }

        $ret = @()

        # -lt to skip the last item, which is a NULL ptr
        for ($i = 0; $i -lt $ParsedArgCount; $i += 1) {
            $ret += $ParsedArgs[$i]
        }

        return $ret
    }
}