Question

Microsoft Office documents, im my case: PowerPoint presentations, can have restricted permissions. How can I find out, programmatically, which permissions my code has on a given document?

All I can find on MSDN on this topic is this:
http://msdn.microsoft.com/en-us/library/aa432118.aspx

If I run the following code, I get a list of users that have permissions on the given document:

Sub test()
    Dim perm As Office.Permission
    Set perm = ActivePresentation.Permission
    Debug.Print "Enabled=" & perm.Enabled
    If perm.Enabled Then
        Debug.Print "PermissionFromPolicy=" & perm.PermissionFromPolicy
        Debug.Print "PolicyName='" & perm.PolicyName & "'"
        Debug.Print "PolicyDescription='" & perm.PolicyDescription & "'"
        Dim uperm As Office.UserPermission
        For Each uperm In perm
            Debug.Print uperm.UserId & ", " & uperm.Permission
        Next uperm
    End If
End Sub

Sample output:

Enabled=True
PermissionFromPolicy=False
PolicyName='Do Not Distribute'
PolicyDescription='Permission is currently restricted. Only specified users can access this content.'
[e-mail], 64
[e-mail], 33
[e-mail], 33

The “Permission” is a bitmap the definition for which I found in Microsoft’s public COM header files:

enum MsoPermission
{
  msoPermissionView = 1,
  msoPermissionRead = 1,
  msoPermissionEdit = 2,
  msoPermissionSave = 4,
  msoPermissionExtract = 8,
  msoPermissionChange = 15,
  msoPermissionPrint = 16,
  msoPermissionObjModel = 32,
  msoPermissionFullControl = 64,
  msoPermissionAllCommon = 127
};

Still, this does not tell me which particular permissions my code has. If I only knew who I am (in terms of a UserPermission.UserId), I could look up my permissions in the Permission object. But I cannot find that bit of information. What am I missing?

There are known ways to obtain the Windows user name (the login name for the current user on that Windows machine). Unfortunately, this is not the user id that is checked against when PowerPoint decides which permissions I have on the document. To emphasize: PowerPoint provides a UI that lets me change “who I am” at run time. Obviously, this does not change the login use name (i.e., the name returned by ADVAPI). The user names PowerPoint is referring to, are identified/authorized via Microsoft’s Passport.

Thanks in advance!
Volker

Answer 1

Today I received an additional answer from Microsoft (still regarding SRQ091221600157) which actually seems to solve the problem, at least in my particular instance. This approach still smells like work-around and there is no documentation that would confirm that it actually works, but it seems plausible enough and withstands some ad-hoc tests. And, it feels much less patchy than any other work-around I came up with. It goes like this:

Only users with msoPermissionFullControl can see permissions of other users (undocumented assumption). Thus, if a user does not have msoPermissionFullControl, the Permission collection contains exactly one item and this item reflects the current user’s permissions. If the permission collection contains multiple items, this means that the current user must have msoPermissionFullControl. Also, the current user must be visible in the Permission collection, but there is still no way to find out which of the identities in the Permission collection represents the current user.