How to specify custom COM enum as PowerShell method parameter - powershell

Question

How can I create a reference for a enum declared inside a COM object to pass to a method that requires it? Specifically, there is a method SetHomeDir on a 3rd-party COM object that takes in an enum as the only parameter. The definition that parameter expects is basically:
typedef enum
{
abFalse = 0,
abTrue = 1,
abInherited = -2
} SFTPAdvBool;
It appears to be defined somewhere in the COM object, but not as an object that I can create with New-Object. I have tried the following and they all give the same MX Error: 7 response:
$obj.SetHomeDir($true)
$obj.SetHomeDir(1)
$obj.SetHomeDir([Object]1)
$obj.SetHomeDir([Int16]1)
Exception calling "SetHomeDir" with "1" argument(s): "MX Error: 7 (00000007)"
Here are the results from trying some other approaches:
PS C:\> New-Object -ComObject SFTPCOMINTERFACELib.SFTPAdvBool
New-Object : Cannot load COM type SFTPCOMINTERFACELib.SFTPAdvBool.
PS C:\> [SFTPAdvBool]::abTrue
Unable to find type [SFTPAdvBool]:
make sure that the assembly containing this type is loaded.
PS C:\> [SFTPCOMINTERFACELib.SFTPAdvBool]::abTrue
Unable to find type [SFTPCOMINTERFACELib.SFTPAdvBool]:
make sure that the assembly containing this type is loaded.
The method signature that COM exposes to PowerShell looks like this:
PS C:\> $user.SetHomeDir
MemberType : Method
OverloadDefinitions : {void SetHomeDir (SFTPAdvBool)}
TypeNameOfValue : System.Management.Automation.PSMethod
Value : void SetHomeDir (SFTPAdvBool)
Name : SetHomeDir
IsInstance : True
Note: This is running under PowerShell 2.0 on Windows Server 2008 R2, but I would consider upgrading the Windows Management Framework to a newer version if necessary.
Update: Here is a screenshot from the Visual Studio object explorer, in case that offers up any clues.

Answer 1

We ended up using a compiled C# interop wrapper around the COM object. I was able to specify an int as the parameter and just used a case statement to pass the correct value from the enum. As far as I can tell there isn't a way to do this directly from Powershell and requires wrapping the COM object in managed code.
We have opened a dialog with Globalscape and hopefully this will be something they address in a future release.

Answer 2

We can try to fool the com object by creating the enum on your own and pass it to the function:
If you can upgrade to Powershell 5 try (in Powershell - enum is a new keyword in ver 5):
Enum SFTPAdvBool
{
abFalse = 0
abTrue = 1
abInherited = -2
}
And call:
$obj.SetHomeDir([SFTPAdvBool]::abTrue)
for anything older than PS 5 you can try:
$code = #"
namespace SFTPCOMINTERFACELib {
public enum SFTPAdvBool {
abFalse = 0,
abTrue = 1,
abInherited = -2
}
}
"#
Add-Type -TypeDefinition $code -Language CSharpVersion3
And call:
$obj.SetHomeDir([SFTPCOMINTERFACELib.SFTPAdvBool]::abTrue)
This will basically create a C# enum and will add it as a type into Powershell.

Answer 3

PowerShell v2.0 is archaic at this point, but it shouldn't be stopping you here. SFTPAdvBool appears to be from the GlobalScape EFT Server COM API, so that's what I'm assuming.
The issue is that you need a value of type SFTPAdvBool, according to the C# scripting examples (See ConfigureUser.cs for one use). For a .Net object, you'd define that as [SFTPAdvBool]::abTrue or [SFTPCOMINTERFACELib.SFTPAdvBool]::abTrue, but I'm not sure if that will work. I've not worked with COM enums in PowerShell before. You might need New-Object -ComObject SFTPCOMINTERFACELib.SFTPAdvBool or some variant.
If nothing works, you could use VBScript, or C#, or contact GlobalScape in the hopes they join the 21st century and drop COM, or use WinSCP's .Net library... but I'm betting you can't since you're working someplace that paid for EFT Server.

Answer 4

There are some hints in their knowledge base that the library doesn't always work correctly out of process, so that would apply remotely, or when using the 32-bit library from a 64-bit process.
For example:
http://forums.globalscape.com/PrintTopic38567.aspx
The solution would be to use the 32-bit powershell in C:\Windows\SysWOW64\WindowsPowerShell\ If you need to call that remotely you may have to do it explicitly using the & operator.