NTFS JunctionPoints with PB ?

[Ari Savola]

Hi folks,

as I would like to create some junction points to solve one specific disk space (/usability) problem, I would like to know if you have any experience with these ?

This is what I have now to play with, but it will fail even at the CreateFile call (at least )

(.. I can't use the code tags here because of the "//?/" string??.. so an attachment is provided)

Please, if you know how to make this example work, tell me.

Oh, in the MakeJunction call the 1st parameter is the new junction name (should not exist before hand? I don't know yet if it will override..) and the 2nd is an existing folder name.

cheers.. aSa C[_]

[José Roca]

I can't use the code tags here because of the "//?/" string??.. so an attachment is provided

Check the "Disable smilies in text" option.

#COMPILE EXE
#DIM ALL

#INCLUDE "Win32API.inc"
#INCLUDE "WINIOCTL.INC"

%TMN_REPARSE_DATA_BUFFER_HEADER_SIZE = 8

GLOBAL szBuffer AS ASCIIZ * %MAX_PATH*2

' Since MS apparently removed this struct (and its documentation) from
' the W2k SDK, but still refer to it in 'winioctl.h' for the specific
' IOCTLs, I decided to rename it and make it available.
' I've made some modifications to this one for easier access.
'
' Structure for FSCTL_SET_REPARSE_POINT, FSCTL_GET_REPARSE_POINT, and
' FSCTL_DELETE_REPARSE_POINT.
' This version of the reparse data buffer is only for Microsoft tags.

TYPE TMN_REPARSE_DATA_BUFFER
	 ReparseTag AS LONG
	 ReparseDataLength AS INTEGER
	 Reserved AS INTEGER
	 ' IO_REPARSE_TAG_MOUNT_POINT specifics follow
	 SubstituteNameOffset AS INTEGER
	 SubstituteNameLength AS INTEGER
	 PrintNameOffset AS INTEGER
	 PrintNameLength AS INTEGER
	 'PathBuffer AS STRING PTR
	 'PathBuffer AS INTEGER PTR
	 PathBuffer AS ASCIIZ PTR
END TYPE

_______________________________________________________________


FUNCTION PBMAIN () AS LONG

	IF ISFALSE(MakeJunction("C:\1JUNCTION","C:\ADOBEAPP\FONTSYS")) THEN
		MSGBOX "nononous"
	ELSE
		MSGBOX "YEShh"
	END IF

END FUNCTION

_______________________________________________________________


FUNCTION MakeJunction(strJunctionDir AS STRING, strDestDir AS STRING) AS LONG
	LOCAL lngDirHandle, lngRet, lngBytes AS LONG
	LOCAL nDestMountPointBytes AS INTEGER
	LOCAL szNewJunctionName AS ASCIIZ * %MAX_PATH
	LOCAL szDestinationDir AS ASCIIZ * %MAX_PATH
	LOCAL rdbBuffer AS TMN_REPARSE_DATA_BUFFER

	FUNCTION = 1

	szNewJunctionName = "\\?\" & strJunctionDir & $NUL

'  lngDirHandle = CreateFile("\\?\" & strJunctionDir & CHR(0), %OF_READWRITE, 0, BYVAL 0&, _
'                          %OPEN_EXISTING, %FILE_FLAG_BACKUP_SEMANTICS OR %FILE_FLAG_OPEN_REPARSE_POINT, 0)

	lngDirHandle = CreateFile(szNewJunctionName, BYVAL %GENERIC_READ OR %GENERIC_WRITE, BYVAL 0, BYVAL 0&, _
													BYVAL %OPEN_EXISTING, BYVAL %FILE_FLAG_BACKUP_SEMANTICS OR %FILE_FLAG_OPEN_REPARSE_POINT, BYVAL 0)

	IF lngDirHandle = -1 THEN
		'PrintError
		FUNCTION = 0
		EXIT FUNCTION
	END IF

	szDestinationDir = "\??\" & strDestDir & $NUL

	nDestMountPointBytes = (LEN(szDestinationDir) - 1) * 2

	rdbBuffer.ReparseTag = %IO_REPARSE_TAG_MOUNT_POINT
	rdbBuffer.ReparseDataLength = nDestMountPointBytes + 12
	rdbBuffer.Reserved = 0
	rdbBuffer.SubstituteNameOffset = 0
	rdbBuffer.SubstituteNameLength = nDestMountPointBytes
	rdbBuffer.PrintNameOffset = nDestMountPointBytes + 2
	rdbBuffer.PrintNameLength = 0
	'rdbBuffer.PathBuffer = StringToIntArray(strDestinationDir)
	szBuffer = UCODE$(szDestinationDir)
	rdbBuffer.PathBuffer = VARPTR(szBuffer)

	lngRet = DeviceIoControl(lngDirHandle, %FSCTL_SET_REPARSE_POINT, rdbBuffer, rdbBuffer.ReparseDataLength + _
													%TMN_REPARSE_DATA_BUFFER_HEADER_SIZE, BYVAL 0&, 0, lngBytes, BYVAL 0&)

	IF lngRet = 0 THEN
		'PrintError
		FUNCTION = 0
	END IF

	CloseHandle lngDirHandle

END FUNCTION

[José Roca]

The last parameter in the TMN_REPARSE_DATA_BUFFER structure isn't a pointer, but a variable-length unicode string.

You can declare PathBuffer AS STRING * [enough number of characters to hold the string].

Or you can do something like this:

TYPE TMN_REPARSE_DATA_BUFFER
	 ReparseTag AS LONG
	 ReparseDataLength AS WORD
	 Reserved AS WORD
	 ' IO_REPARSE_TAG_MOUNT_POINT specifics follow
	 SubstituteNameOffset AS WORD
	 SubstituteNameLength AS WORD
	 PrintNameOffset AS WORD
	 PrintNameLength AS WORD
END TYPE

rdbBuffer.ReparseTag = %IO_REPARSE_TAG_MOUNT_POINT
rdbBuffer.ReparseDataLength = nDestMountPointBytes + 12
rdbBuffer.Reserved = 0
rdbBuffer.SubstituteNameOffset = 0
rdbBuffer.SubstituteNameLength = nDestMountPointBytes
rdbBuffer.PrintNameOffset = nDestMountPointBytes + 2
rdbBuffer.PrintNameLength = 0

DIM strBuffer AS STRING
strBuffer = rdbBuffer & UCODE$(szDestinationDir & $NUL)
lngRet = DeviceIoControl(lngDirHandle, %FSCTL_SET_REPARSE_POINT, BYVAL STRPTR(strBuffer), rdbBuffer.ReparseDataLength + _
													%TMN_REPARSE_DATA_BUFFER_HEADER_SIZE, BYVAL 0&, 0, lngBytes, BYVAL 0&)

[Ari Savola]

a-haa. Thank You for such a simple solution for the problematic code tagging. Couldn't have thought of that by myself.

That last parameter was problematic for me to understand correctly, but my intension was to "trial and error" it if nothing else.. but I haven't been able to reach that code part yet as the CreateFile() is not working and I don't know yet why. Thank you for good examples, they will be appreciated.

I have tried to avoid API calls as I know a zit about them. (well I don't call myself a Windows programmer either..)

thank you.. aSa C[_]

[Michael Mattias]

>CreateFile() is not working and I don't know yet why.

lngDirHandle = CreateFile(szNewJunctionName, BYVAL %GENERIC_READ OR %GENERIC_WRITE, BYVAL 0, BYVAL 0&, _ 
              BYVAL %OPEN_EXISTING, _
              BYVAL %FILE_FLAG_BACKUP_SEMANTICS OR %FILE_FLAG_OPEN_REPARSE_POINT, BYVAL 0)
[COLOR="Red"]LastError = GetLastError()[/COLOR]
IF lngDirHandle = -1 THEN        '   INVALID_HANDLE_VALUE 
   Msg = SystemErrorMessageText (LastError) 
   PRINT Msg
   'PrintError


....

FUNCTION SystemErrorMessageText (BYVAL ECode AS LONG) AS STRING
  LOCAL Buffer AS ASCIIZ * 255
  FormatMessage %FORMAT_MESSAGE_FROM_SYSTEM, BYVAL %NULL, _ 
       ECode, %NULL, buffer, SIZEOF(buffer), BYVAL %NULL

  FUNCTION = FORMAT$(ECode, "##### ") & Buffer

END FUNCTION

Try that.

MCM

[Ari Savola]

Well, I'm puzzled. I added the code MCM suggested, thank you, and I got no.2: "The system cannot find the file specified". I don't think you're supposed to manually create a directory there (?), so there has to be something wrong with the parameters (??). And the "Adobe directory" does exist with a file in it.

cheers.. aSa C[_]

.....

Seems that you really NEED to create a directory for the "mount". But that "PathBuffer" is still a problem: "The data present in the reparse point buffer is invalid". I have tried with both "PathBuffer as STRING * %MAX_PATH*2" and with that funny looking "TYPE + string data" combo.

In C++ this TYPE is defined as:

 
struct TMN_REPARSE_DATA_BUFFER  {
  DWORD ReparseTag;
  WORD ReparseDataLength;
  WORD Reserved;
  // IO_REPARSE_TAG_MOUNT_POINT specifics follow
  WORD SubstituteNameOffset;
  WORD SubstituteNameLength;
  WORD PrintNameOffset;
  WORD PrintNameLength;
  WCHAR PathBuffer[1];
};

That "PathBuffer" definition is a little bit hard for me to understand clearly.

cheers.. aSa C[_]

[Kev Peel]

If the type can be extended then PathBuffer is just two bytes (or one UNICODE character), you can pass a pointer to this around but when referencing it fully you would need to use something like PEEK$/POKE$/MoveMemory.

This is really like the BITMAPINFO structure with the color array.

[Ari Savola]

This is the working version

Thank you for your kind help. With that even I was able to "fix" this skeleton.

Here's the working, similar code:

 
#COMPILE EXE
#DIM ALL
 
#INCLUDE "Win32API.inc"
#INCLUDE "WINIOCTL.INC"
 
%TMN_REPARSE_DATA_BUFFER_HEADER_SIZE = 8
 
' Since MS apparently removed this struct (and its documentation) from
' the W2k SDK, but still refer to it in 'winioctl.h' for the specific
' IOCTLs, I decided to rename it and make it available.
' I've made some modifications to this one for easier access.
'
' Structure for FSCTL_SET_REPARSE_POINT, FSCTL_GET_REPARSE_POINT, and
' FSCTL_DELETE_REPARSE_POINT.
' This version of the reparse data buffer is only for Microsoft tags.
TYPE TMN_REPARSE_DATA_BUFFER
   ReparseTag AS LONG
   ReparseDataLength AS WORD
   Reserved AS WORD
   ' IO_REPARSE_TAG_MOUNT_POINT specifics follow
   SubstituteNameOffset AS WORD
   SubstituteNameLength AS WORD
   PrintNameOffset AS WORD
   PrintNameLength AS WORD
   'WCHAR PathBuffer[1];
END TYPE
'You NEED to add PathBuffer data AFTER this struct with this type of TYPE definition!
_______________________________________________________________
 
FUNCTION PBMAIN () AS LONG
 
  ' The 1st parameter is the new junction point name, the 2nd is the folder path the junction point is pointing to
  ' Junction point must have an existing folder with the same same as the junction point has (here C:\1JUNCTION must exist)
  IF ISFALSE(MakeJunction("C:\1JUNCTION","C:\ADOBEAPP\FONTSYS")) THEN
    MSGBOX "nononous"
  ELSE
    MSGBOX "YEShh"
  END IF
 
END FUNCTION
_______________________________________________________________
 
FUNCTION MakeJunction(strJunctionDir AS STRING, strDestDir AS STRING) AS LONG
  LOCAL lngDirHandle, lngRet, lngBytes, LastError AS LONG
  LOCAL nDestMountPointBytes AS INTEGER
  LOCAL strNewJunctionName, strDestinationDir, strBuffer AS STRING
  LOCAL rdbBuffer AS TMN_REPARSE_DATA_BUFFER
 
  FUNCTION = 1
 
  lngDirHandle = CreateFile("\\?\" & strJunctionDir & $NUL, BYVAL %GENERIC_READ OR %GENERIC_WRITE, BYVAL 0, BYVAL 0&, _
                BYVAL %OPEN_EXISTING, BYVAL %FILE_FLAG_BACKUP_SEMANTICS OR %FILE_FLAG_OPEN_REPARSE_POINT, BYVAL 0)
  IF lngDirHandle = -1 THEN        ' %INVALID_HANDLE_VALUE
    'PrintError
    MSGBOX SystemErrorMessageText(GetLastError())
    FUNCTION = 0
    EXIT FUNCTION
  END IF
 
  strDestinationDir = "\??\" & strDestDir & $NUL
  nDestMountPointBytes = (LEN(strDestinationDir)-1)*2
 
  rdbBuffer.ReparseTag = %IO_REPARSE_TAG_MOUNT_POINT
  rdbBuffer.ReparseDataLength = nDestMountPointBytes+12
  rdbBuffer.Reserved = 0
  rdbBuffer.SubstituteNameOffset = 0
  rdbBuffer.SubstituteNameLength = nDestMountPointBytes
  rdbBuffer.PrintNameOffset = nDestMountPointBytes+2
  rdbBuffer.PrintNameLength = 0
 
  strBuffer = rdbBuffer & UCODE$(strDestinationDir)
 
  lngRet = DeviceIoControl(lngDirHandle, %FSCTL_SET_REPARSE_POINT, BYVAL STRPTR(strBuffer), rdbBuffer.ReparseDataLength + _
   %TMN_REPARSE_DATA_BUFFER_HEADER_SIZE, BYVAL 0&, 0, lngBytes, BYVAL 0&)
  IF lngRet = 0 THEN
    'PrintError
    MSGBOX SystemErrorMessageText(GetLastError())
    FUNCTION = 0
  END IF
 
  CloseHandle lngDirHandle
 
END FUNCTION
_______________________________________________________________
 
FUNCTION SystemErrorMessageText(BYVAL ECode AS LONG) AS STRING
  LOCAL Buffer AS ASCIIZ*255
 
  FormatMessage %FORMAT_MESSAGE_FROM_SYSTEM, BYVAL %NULL, ECode, %NULL, buffer, SIZEOF(buffer), BYVAL %NULL
  FUNCTION = FORMAT$(ECode, "##### ") & Buffer
 
END FUNCTION

cheers.. aSa C[_]

PS. @José
"Disable smileys in text" did not solve the problem with this code sample for me. I HAD to highlight that \\?\ string and click the "Remove link" button + "Automatically parse links" in text is also off. Life is funny if you could always be a bystander ; )