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; WinIoCtl.h
;
#FILE_DEVICE_FILE_SYSTEM         = $00000009
#METHOD_BUFFERED                 = 0
#FILE_ANY_ACCESS                 = 0
#FILE_SPECIAL_ACCESS             = (#FILE_ANY_ACCESS)

Macro CTL_CODE( DeviceType, Function, Method, Access )
  (((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2) | (Method))
EndMacro

#FSCTL_SET_REPARSE_POINT         = CTL_CODE(#FILE_DEVICE_FILE_SYSTEM, 41, #METHOD_BUFFERED, #FILE_SPECIAL_ACCESS)
#FSCTL_GET_REPARSE_POINT         = CTL_CODE(#FILE_DEVICE_FILE_SYSTEM, 42, #METHOD_BUFFERED, #FILE_ANY_ACCESS)
#FSCTL_DELETE_REPARSE_POINT      = CTL_CODE(#FILE_DEVICE_FILE_SYSTEM, 43, #METHOD_BUFFERED, #FILE_SPECIAL_ACCESS)

; Winbase.h
;
#FILE_FLAG_OPEN_REPARSE_POINT    = $00200000

; WinNT.h
;
#IO_REPARSE_TAG_MOUNT_POINT  = $A0000003       
#IO_REPARSE_TAG_HSM          = $C0000004       
#IO_REPARSE_TAG_HSM2         = $80000006       
#IO_REPARSE_TAG_SIS          = $80000007       
#IO_REPARSE_TAG_DFS          = $8000000A       
#IO_REPARSE_TAG_SYMLINK      = $A000000C       
#IO_REPARSE_TAG_DFSR         = $80000012


; From Windows Driver Kit.
; http://msdn.microsoft.com/en-us/library/ms791514.aspx
;
Structure SymbolicLinkReparseBuffer
  SubstituteNameOffset.w
  SubstituteNameLength.w
  PrintNameOffset.w
  PrintNameLength.w
  Flags.l
  PathBuffer.w[1]
EndStructure

Structure MountPointReparseBuffer
  SubstituteNameOffset.w
  SubstituteNameLength.w
  PrintNameOffset.w
  PrintNameLength.w
  PathBuffer.w[1]
EndStructure

Structure GenericReparseBuffer
  DataBuffer.b[1]
EndStructure

Structure REPARSE_DATA_BUFFER
  ReparseTag.l
  ReparseDataLength.w
  Reserved.w
  StructureUnion
    SymbolicLinkReparseBuffer.SymbolicLinkReparseBuffer
    MountPointReparseBuffer.MountPointReparseBuffer
    GenericReparseBuffer.GenericReparseBuffer
  EndStructureUnion
EndStructure




; Tries to follow a directory link on Windows Vista (should also work for files)
;
; - If the directory is no link, the result is the original directory
; - If the target cannot be read, the result is ""
;
Procedure.s GetDirectoryTarget(Directory$)
  Protected TokenHandle, BufferSize, hDirectory, BytesReturned.l
  Protected Privileges.TOKEN_PRIVILEGES
  Protected *Buffer.REPARSE_DATA_BUFFER
  Protected Result$ = ""

  ; Check if the directory is a reparse point (link or mount point)
  ;
  If GetFileAttributes_(@Directory$) & #FILE_ATTRIBUTE_REPARSE_POINT

    ; The backup privilege is required to open a directory for io queries
    ; So try to set it on our process token. (usually it should be set already)
    ;
    If OpenProcessToken_(GetCurrentProcess_(), #TOKEN_ADJUST_PRIVILEGES, @TokenHandle)
      Privileges\PrivilegeCount = 1
      Privileges\Privileges[0]\Attributes = #SE_PRIVILEGE_ENABLED
    
      If LookupPrivilegeValue_(#Null, @"SeBackupPrivilege", @Privileges\Privileges[0]\Luid)       
        AdjustTokenPrivileges_(TokenHandle, #False, @Privileges, SizeOf(TOKEN_PRIVILEGES), #Null, #Null)
      EndIf    
      CloseHandle_(TokenHandle)
    EndIf
    
    ; Open the directory
    ;   Have to pass 0 as access right (not #GENERIC_READ), as it fails otherwise
    ;   http://www.codeproject.com/KB/vista/Windows_Vista.aspx
    ;
    hDirectory = CreateFile_(@Directory$, 0, #FILE_SHARE_READ|#FILE_SHARE_WRITE, #Null, #OPEN_EXISTING, #FILE_FLAG_OPEN_REPARSE_POINT | #FILE_FLAG_BACKUP_SEMANTICS, #Null)
    If hDirectory <> #INVALID_HANDLE_VALUE
    
      ; Allocate a buffer for the io query. 1000 bytes should be enough for the real path (in unicode)
      ;
      BufferSize = SizeOf(REPARSE_DATA_BUFFER) + 1000
      *Buffer = AllocateMemory(BufferSize)
      
      If *Buffer
        
        ; Query the directory for reparse point information
        ;
        If DeviceIoControl_(hDirectory, #FSCTL_GET_REPARSE_POINT, #Null, 0, *Buffer, BufferSize, @BytesReturned, #Null) <> 0
        
          ; Check the kind of reparse point (device drivers can create their own tags, so this is important)
          ; The "& $FFFFFFFF" is for 64bit, as the tags are negative when interpreted as quads
          ;
          If *Buffer\ReparseTag & $FFFFFFFF = #IO_REPARSE_TAG_MOUNT_POINT

            ; Read the result. The offset and length are in bytes. PeekS needs length in characters
            ;
            Result$ = PeekS(@*Buffer\MountPointReparseBuffer\PathBuffer[0] + *Buffer\MountPointReparseBuffer\SubstituteNameOffset, *Buffer\MountPointReparseBuffer\SubstituteNameLength / 2, #PB_Unicode)

          ElseIf *Buffer\ReparseTag & $FFFFFFFF = #IO_REPARSE_TAG_SYMLINK
          
            Result$ = PeekS(@*Buffer\SymbolicLinkReparseBuffer\PathBuffer[0] + *Buffer\SymbolicLinkReparseBuffer\SubstituteNameOffset, *Buffer\SymbolicLinkReparseBuffer\SubstituteNameLength / 2, #PB_Unicode)

          EndIf
        
        EndIf     
      
        FreeMemory(*Buffer)
      EndIf
    
      CloseHandle_(hDirectory)
    EndIf
  
  Else
  
    ; It is not a reparse point, so return the original path
    ;
    Result$ = Directory$
    
  EndIf
  
  ; Since the result is a unicode directory name, it can have the "\??\" prefix which allows a length of 32767 characters.
  ;
  If Left(Result$, 4) = "\??\"
    Result$ = Right(Result$, Len(Result$)-4)
  EndIf

  ProcedureReturn Result$
EndProcedure



; ----------------------------------------------------------------------------


Directory$ = "C:\Documents and Settings\"

Debug "Testing: " + Directory$
Debug "Target: " + GetDirectoryTarget(Directory$)