Invalid File Handle with SP4 Nwrdr.sys

• Microsoft Windows NT Server version 3.51

SYMPTOMS

The following message occurs in File Manager when you attempt to browse directories on a Novell NetWare 3.11 or 3.12 server volume:

   Invalid File Handle

CAUSE

A check was put into the Service Pack 4 version of Client Services for NetWare (CSNW) because of the possibility of a NetWare Server assigning a duplicate directory handle. This fix caused a regression in Windows NT because it did not differentiate between directory handles and print queue IDs.

RESOLUTION

Check each Volume Control Block (VCB) to determine whether it is a print queue or not before invalidating the handles.

MORE INFORMATION

CSNW uses a single DWORD union to represent directory-specific or printer- specific information in its record of a mapping, or Volume Control Block (VCB). The value in the union depends on the resource type for that VCB; the resource type can be either print or disk. The fix for duplicate directory handle assignment did not check the resource type. Therefore a print queue ID of 0xf903004f would also appear to represent a directory handle of 0x3, because the second byte in the union represents a directory handle if the resource type is disk.

In the example above, if a disk resource mapping results in a NetWare server allocating a Directory Handle of 3, then both the new directory handle and the second byte of the existing print queue ID would be invalidated with an FF(-1). Subsequent commands sent to the NetWare server, using FF for a file handle, result in the Invalid File Handle message and the remapping of the Disk resource connection. This invalidation also has the effect of changing the print queue ID. This causes print failures, because it is likely that the resulting print queue ID the client attempts to use does not exist.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.51 with Service Pack 4. This problem was corrected in the latest Windows NT 3.51 U.S. Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K