cCDROMdriveletter

1.2.0

DSCResources/cCDROMdriveletter/cCDROMdriveletter.psm1

function Get-TargetResource
{
    [CmdletBinding()]
    [OutputType([System.Collections.Hashtable])]
    param
    (
        # specify the drive letter as a single letter, optionally include the colon
        [parameter(Mandatory = $true)]
        [System.String]
        $DriveLetter
    )

    # allow use of drive letter without colon
    $DriveLetter = $DriveLetter[0] + ":"

    Write-Verbose "Using Get-CimInstance to get the cdrom drives in the system"
    try {
        $currentDriveLetter = (Get-CimInstance -ClassName WIn32_cdromdrive | Where-Object {
                                    $_.Caption -ne "Microsoft Virtual DVD-ROM"
                                    }
                               ).Drive
    }
    catch
    {
        Write-Verbose "Without a cdrom drive in the system, this resource has nothing to do."
        $Ensure = 'Present'
    }

    # check if $driveletter is the location of the CD drive
    if ($currentDriveLetter -eq $DriveLetter)
    {
        Write-Verbose "cdrom is currently set to $DriveLetter as requested"
        $Ensure = 'Present'
    }
    else
    {
        Write-Verbose "cdrom is currently set to $currentDriveLetter, not $DriveLetter as requested"
        $Ensure = 'Absent'
    }

    $returnValue = @{
    DriveLetter = $currentDriveLetter
    Ensure = $Ensure
    }

    $returnValue

}


function Set-TargetResource
{
    [CmdletBinding(SupportsShouldProcess=$True,
                   ConfirmImpact="Low")]
    param
    (
        # specify the drive letter as a single letter, optionally include the colon
        [parameter(Mandatory = $true)]
        [System.String]
        $DriveLetter,

        [ValidateSet("Present","Absent")]
        [System.String]
        $Ensure = "Present"
    )

    # allow use of drive letter without colon
    $DriveLetter = $DriveLetter[0] + ":"

    # Get the current drive letter corresponding to the virtual cdrom drive
    # the Caption and DeviceID properties are used to avoid mounted ISO images
    # with the Device ID, we look for the length of the string after the final backslash (crude, but appears to work so far)

    # Example DeviceID for a virtual drive in a Hyper-V VM - SCSI\CDROM&VEN_MSFT&PROD_VIRTUAL_DVD-ROM\000006
    # Example DeviceID for a mounted ISO in a Hyper-V VM - SCSI\CDROM&VEN_MSFT&PROD_VIRTUAL_DVD-ROM\2&1F4ADFFE&0&000002
    $currentDriveLetter = (Get-CimInstance -ClassName win32_cdromdrive | Where-Object {
                        -not (
                                $_.Caption -eq "Microsoft Virtual DVD-ROM" -and
                                ($_.DeviceID.Split("\")[-1]).Length -gt 10
                             )
                        }
                   ).Drive
    
    Write-Verbose "The current drive letter is $currentDriveLetter, attempting to set to $driveletter"

    # assuming a drive letter is found
    if ($currentDriveLetter)
    {
        # get the volume corresponding to the drive letter, and set the drive letter of this volume to $DriveLetter
        if ($PSCmdlet.ShouldProcess("Setting cdrom drive letter to $DriveLetter")) {
            Get-CimInstance -ClassName Win32_Volume -Filter "DriveLetter = '$currentDriveLetter'" | 
            Set-CimInstance -Property @{ DriveLetter="$DriveLetter"}
        }
    }
}


function Test-TargetResource
{
    [CmdletBinding()]
    [OutputType([System.Boolean])]
    param
    (
        # specify the drive letter as a single letter, optionally include the colon
        [parameter(Mandatory = $true)]
        [System.String]
        $DriveLetter,

        [ValidateSet("Present","Absent")]
        [System.String]
        $Ensure
    )

    # allow use of drive letter without colon
    $DriveLetter = $DriveLetter[0] + ":"

    # is there a cdrom
    $cdrom = Get-CimInstance -ClassName WIn32_cdromdrive -Property Id
    # what type of drive is attached to $driveletter
    $volumeDriveType = Get-CimInstance -ClassName Win32_Volume -Filter "DriveLetter = '$DriveLetter'" -Property DriveType
    
    if ($Ensure -eq 'Present')
    {
        # check there is a cdrom
        if ($cdrom)
        {
            Write-Verbose ("cdrom found with device id: " + $cdrom.id)
            if ($volumeDriveType) {
                Write-Verbose ("volume with driveletter $driveletter is type " + $volumeDriveType.DriveType + " (5 is a cdrom drive).")
            }
            else {
                Write-Verbose ("there doesn't appear to be a driveletter $driveletter")
            }            
            # return true if the requested volume is a cdrom
            $result = [System.Boolean]($volumeDriveType.DriveType -eq 5)
        }
        else { 
            # return true if there is no cdrom - can't set what isn't there!
            Write-Verbose ("No cdrom found.")
            $result = $true 
        }
    }
    # $Ensure -eq 'Absent', do nothing
    else { 
        Write-Verbose 'When $Ensure is set to Absent this resource does nothing.'
        $result = $true 
    }
          
    $result

}


Export-ModuleMember -Function *-TargetResource