Q218965: HOWTO: Obtain the Owner of a File on Windows NT
Article: Q218965
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:4.0,5.0,6.0; winnt:3.5,3.51,4.0
Operating System(s):
Keyword(s): kbAPI kbKernBase kbOSWinNT kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpDSVB kbCodeSnippet
Last Modified: 05-JUN-2001
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The information in this article applies to:
- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0
- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0
- the operating system: Microsoft Windows NT, versions 3.5, 3.51, 4.0
- the operating system: Microsoft Windows 2000
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SUMMARY
=======
Retrieving the owner of a file requires obtaining the security descriptor for
the file, then using the security descriptor to get a pointer to the owner's
Security Identifier (SID). Finally, you use the owner's SID to obtain the owner
and domain name of the file.
This article provides a Visual Basic sample code that obtains the owner of a file
on Microsoft Windows NT.
MORE INFORMATION
================
The following sample code retrieves the owner of the file notepad.exe, which is
located in the default Windows folder.
NOTE: If the file is on an NTFS partition, this code returns the assigned owner
of the file, but if it is on a FAT partition, the owner will be "Everyone".
1. Start a new Visual Basic Standard EXE project. Form1 is created by default.
2. Place a command button (Command1) on Form1.
3. Paste the following code into the General Declarations section of Form1:
Option Explicit
Private Declare Function GetFileSecurity Lib "advapi32.dll" _
Alias "GetFileSecurityA" ( _
ByVal lpFileName As String, _
ByVal RequestedInformation As Long, _
pSecurityDescriptor As Byte, _
ByVal nLength As Long, _
lpnLengthNeeded As Long _
) As Long
Private Declare Function GetSecurityDescriptorOwner Lib "advapi32.dll" _
(pSecurityDescriptor As Any, _
pOwner As Long, _
lpbOwnerDefaulted As Long) As Long
Private Declare Function LookupAccountSid Lib "advapi32.dll" _
Alias "LookupAccountSidA" ( _
ByVal lpSystemName As String, _
ByVal Sid As Long, _
ByVal name As String, _
cbName As Long, _
ByVal ReferencedDomainName As String, _
cbReferencedDomainName As Long, _
peUse As Long) As Long
Private Declare Function GetWindowsDirectory Lib "kernel32" _
Alias "GetWindowsDirectoryA" ( _
ByVal lpBuffer As String, _
ByVal nSize As Long) As Long
Private Const OWNER_SECURITY_INFORMATION = &H1
Private Const ERROR_INSUFFICIENT_BUFFER = 122&
Private Const MAX_PATH = 255
Sub Command1_Click()
Dim szfilename As String ' File name to retrieve the owner for
Dim bSuccess As Long ' Status variable
Dim sizeSD As Long ' Buffer size to store Owner's SID
Dim pOwner As Long ' Pointer to the Owner's SID
Dim name As String ' Name of the file owner
Dim domain_name As String ' Name of the first domain for the owner
Dim name_len As Long ' Required length for the owner name
Dim domain_len As Long ' Required length for the domain name
Dim sdBuf() As Byte ' Buffer for Security Descriptor
Dim nLength As Long ' Length of the Windows Directory
Dim deUse As Long ' Pointer to a SID_NAME_USE enumerated
' type indicating the type of the account
' Initialize some required variables.
bSuccess = 0
name = ""
domain_name = ""
name_len = 0
domain_len = 0
pOwner = 0
szfilename = Space(MAX_PATH)
' Obtain the path to the Windows Directory and use the notepad.exe file
' as it should be on the system.
nLength = GetWindowsDirectory(szfilename, Len(szfilename))
If nLength = 0 Then
MsgBox "Unable to Obtain the Windows Directory"
End If
szfilename = Left$(szfilename, nLength) & "\notepad.exe"
' Call GetFileSecurity the first time to obtain the size of the
' buffer required for the Security Descriptor.
bSuccess = GetFileSecurity( _
szfilename, _
OWNER_SECURITY_INFORMATION, _
0, _
0&, _
sizeSD)
If (bSuccess = 0) And _
(Err.LastDllError <> ERROR_INSUFFICIENT_BUFFER) Then
MsgBox "GetLastError returned : " & Err.LastDllError
End If
' Create a buffer of the required size and call GetFileSecurity again.
ReDim sdBuf(0 To sizeSD - 1) As Byte
' Fill the buffer with the security descriptor of the object specified
' by the szfilename parameter. The calling process must have the right
' to view the specified aspects of the object's security status.
bSuccess = GetFileSecurity( _
szfilename, _
OWNER_SECURITY_INFORMATION, _
sdBuf(0), _
sizeSD, _
sizeSD)
If (bSuccess <> 0) Then
' Obtain the owner's SID from the Security Descriptor.
'
bSuccess = GetSecurityDescriptorOwner(sdBuf(0), pOwner, 0&)
If (bSuccess = 0) Then
MsgBox "GetLastError returned : " & Err.LastDllError
End If
' Retrieve the name of the account and the name of the first
' domain on which this SID is found. Passes in the Owner's SID
' obtained previously. Call LookupAccountSid twice, the first time
' to obtain the required size of the owner and domain names.
bSuccess = LookupAccountSid(vbNullString, pOwner, name, name_len, _
domain_name, domain_len, deUse)
If (bSuccess = 0) And _
(Err.LastDllError <> ERROR_INSUFFICIENT_BUFFER) Then
MsgBox "GetLastError returned : " & Err.LastDllError
End If
' Allocate the required space in the name and domain_name string
' variables. Allocate 1 byte less to avoid the appended NULL character.
'
name = Space(name_len - 1)
domain_name = Space(domain_len - 1)
' Call LookupAccountSid again to actually fill in the name of the owner
' and the first domain.
'
bSuccess = LookupAccountSid(vbNullString, pOwner, name, name_len, _
domain_name, domain_len, deUse)
If bSuccess = 0 Then
MsgBox "GetLastError returned : " & Err.LastDllError
End If
MsgBox "The Owner of " & szfilename & " is " & name
End If
End Sub
4. Press F5 to run the application and then click Command1 to display the owner
of the file.
Additional query words:
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Keywords : kbAPI kbKernBase kbOSWinNT kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpDSVB kbCodeSnippet
Technology : kbOSWin2000 kbVBSearch kbAudDeveloper kbOSWinSearch kbOSWinNT350 kbOSWinNT400 kbOSWinNT351 kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600 kbVB400Search kbVB400 kbOSWinNTSearch
Version : WINDOWS:4.0,5.0,6.0; winnt:3.5,3.51,4.0
Issue type : kbhowto
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