pinvoke.net: Edit: secur32.GetUserNameEx

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@pinvoke=http://pinvoke.net/$$$.htm

Summary: Gets the name of the user or other security principal associated with the calling thread.

!!!!C# Signature:
 public enum ExtendedNameFormat
 {
     /// <summary>
     /// An unknown name type.
     /// </summary>
     NameUnknown = 0,
 
     /// <summary>
     /// The fully qualified distinguished name
     /// (for example, CN=Jeff Smith,OU=Users,DC=Engineering,DC=Microsoft,DC=Com).
     /// </summary>
     NameFullyQualifiedDN = 1,
 
     /// <summary>
     /// A legacy account name (for example, Engineering\JSmith).
     /// The domain-only version includes trailing backslashes (\\).
     /// </summary>
     NameSamCompatible = 2,
 
     /// <summary>
     /// A "friendly" display name (for example, Jeff Smith).
     /// The display name is not necessarily the defining relative distinguished name (RDN).
     /// </summary>
     NameDisplay = 3,
 
     /// <summary>
     /// A GUID string that the IIDFromString function returns
     /// (for example, {4fa050f0-f561-11cf-bdd9-00aa003a77b6}).
     /// </summary>
     NameUniqueId = 6,
 
     /// <summary>
     /// The complete canonical name (for example, engineering.microsoft.com/software/someone).
     /// The domain-only version includes a trailing forward slash (/).
     /// </summary>
     NameCanonical = 7,
 
     /// <summary>
     /// The user principal name (for example, someone@example.com).
     /// </summary>
     NameUserPrincipal = 8,
 
     /// <summary>
     /// The same as NameCanonical except that the rightmost forward slash (/)
     /// is replaced with a new line character (\n), even in a domain-only case
     /// (for example, engineering.microsoft.com/software\nJSmith).
     /// </summary>
     NameCanonicalEx = 9,
 
     /// <summary>
     /// The generalized service principal name
     /// (for example, www/www.microsoft.com@microsoft.com).
     /// </summary>
     NameServicePrincipal = 10,
 
     /// <summary>
     /// The DNS domain name followed by a backward-slash and the SAM user name.
     /// </summary>
     NameDnsDomain = 12
 }

[DllImport("secur32.dll", CharSet=CharSet.Auto, SetLastError=true)]
 public static extern int GetUserNameEx (ExtendedNameFormat nameFormat,
    StringBuilder userName, ref int userNameSize);
!!!!VB Signature:
 Declare Function GetUserNameEx Lib "secur32.dll" (nameFormat As Integer, _
   userName As StringBuilder, ByRef userNameSize As Integer) As Integer
!!!!User-Defined Types:
None.

!!!!Notes:
This may be required because System.Environment.UserDomainName is broken.  If the local machine has a user account that is the same name as a logged in domain user (machineName\bob & domainName\bob) UserDomainName returns the machine name, not the domain name.

!!!!Tips & Tricks:
Please add some!

!!!!Sample Code:
 public class Sample
 {
      enum EXTENDED_NAME_FORMAT
      {
         NameUnknown = 0, 
         NameFullyQualifiedDN = 1, 
         NameSamCompatible = 2, 
         NameDisplay = 3, 
         NameUniqueId = 6, 
         NameCanonical = 7, 
         NameUserPrincipal = 8, 
         NameCanonicalEx = 9, 
         NameServicePrincipal = 10, 
         NameDnsDomain = 12
      }

[DllImport("secur32.dll", CharSet=CharSet.Auto)]
      public static extern int GetUserNameEx (int nameFormat, StringBuilder userName, ref int userNameSize);

public String GetUserDomain()
      {
         if (Environment.OSVersion.Platform != PlatformID.Win32NT)
            return null;

StringBuilder userName = new StringBuilder(1024);
         int userNameSize = userName.Capacity;

if(0 != GetUserNameEx((int)EXTENDED_NAME_FORMAT.NameSamCompatible, userName, ref userNameSize))
         {
            string[] nameParts = userName.ToString().Split('\\');
            if (2 != nameParts.Length) return null;
            return nameParts[0];
         }

return null;
      }
 }

!!!!VB

public class Sample

Declare Function GetUserNameExA Lib "secur32.dll" (ByVal nameFormat As Integer, _
  ByVal userName As System.Text.StringBuilder, ByRef userNameSize As Integer) As Integer

' GetUserNameExA for ANSI 
 ' GetUserNameExW for UNICODE

Public Enum EXTENDED_NAME_FORMAT
        NameUnknown = 0
        NameFullyQualifiedDN = 1
        NameSamCompatible = 2
        NameDisplay = 3
        NameUniqueId = 6
        NameCanonical = 7
        NameUserPrincipal = 8
        NameCanonicalEx = 9
        NameServicePrincipal = 10
        NameDnsDomain = 12
    End Enum

Public Function GetUserName() As String

Dim UserName As New System.Text.StringBuilder(1024)
        Dim userNameSize As Integer = UserName.Capacity

If Environment.OSVersion.Platform <> PlatformID.Win32NT Then
            Return ""
        End If

If GetUserNameExA(EXTENDED_NAME_FORMAT.NameSamCompatible, UserName, userNameSize) <> 0 Then

Dim NameParts() As String = UserName.ToString().Split("\")
            If NameParts.Length <> 2 Then
                Return ""
            End If

Return NameParts(1)

Else
            Return ""

End If

End Function

End Class

!!!!Alternative Managed API:
System.Environment.UserName@msdn
System.Environment.UserDomainName@msdn

Documentation: GetUserNameEx@msdn on MSDN