GetStringValue silently fails

Gerry Hickman

2009-04-15 13:22:22 UTC

Hi,

The two keys you have chosen for the test are not going to be available
on many computers. How about testing with

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
REG_SZ, LegalNoticeCaption
REG_SZ, LegalNoticeText

On my system (Vista) they are both empty string values.

I notice something very strange in your test; you appear to be getting
the same "corrupt" value of FFE869 in _both_ calls??

Post by Josh
I have a VBScript (see below) that uses GetStringValue to read two
values from the local registry. Both of these values are REG_SZ and
their value is "" (empty string). If I run a single instance of the

cscript //nologo scan.vbs

printSeparatorFile=, typeName=String, rval=0, err=0
System.EnterpriseServices.Thunk.dll=, typeName=String, rval=0, err=0
But every once in a while, the value is reported to be a sequence of 3
unprintable bytes even though the call to GetStringValue returns 0 and
Err.Number is 0. In other words, the call silently fails with a
corrupt value.

cscript //nologo scan.vbs

printSeparatorFile=FFE869, typeName=String, rval=0, err=0
System.EnterpriseServices.Thunk.dll=FFE869, typeName=String, rval=0,
err=0
I can cause this to happen almost immediately by calling the script
from a batch file, and running two instances of the batch file (see
below) concurrently. Once in this state, it usually stays there until
I restart the WMI service. Though sometimes it seems to clear up on
its own.
I have only seen this problem with some registry values of type REG_SZ
whose value is "".
I have also run regmon 7.03 (sysinternals) to see if other processes
are accessing these registry keys & values, but it only reports
wmiprvse.exe. Interestingly, regmon shows that QueryValue returns the
correct value "", in other words, WMI is receiving the correct value,
but there is a disconnect between WMI and my VBScript.
10.14105988 wmiprvse.exe:3728 OpenKey HKLM\SOFTWARE\Microsoft\Ole
\NONREDIST SUCCESS Access: 0x1
10.14108276 wmiprvse.exe:3728 QueryValue HKLM\SOFTWARE\Microsoft\Ole
\NONREDIST\System.EnterpriseServices.Thunk.dll SUCCESS ""
10.14109898 wmiprvse.exe:3728 QueryValue HKLM\SOFTWARE\Microsoft\Ole
\NONREDIST\System.EnterpriseServices.Thunk.dll SUCCESS ""
10.14112854 wmiprvse.exe:3728 QueryKey HKLM\SOFTWARE\Microsoft\Ole
\NONREDIST ACCESS VIOLATION
10.14114475 wmiprvse.exe:3728 CloseKey HKLM\SOFTWARE\Microsoft\Ole
\NONREDIST SUCCESS
I'm running on XP SP2. I've tried rebooting, but I get the same
result.
Any suggestions?
TIA,
Josh
--------------------------------------------------------------------------------------------------------------
Batch File
--------------------------------------------------------------------------------------------------------------
FOR /L %%G IN (1,1,1000) DO cscript //nologo scan.vbs
--------------------------------------------------------------------------------------------------------------
scan.vbs
--------------------------------------------------------------------------------------------------------------
Const HKEY_LOCAL_MACHINE = &H80000002
Set objReg=GetObject("winmgmts:{impersonationLevel=impersonate}!\\.
\root\default:StdRegProv")
If Err.Number <> 0 Then
WScript.Echo "Failed to connect"
WScript.Quit 1
End If
GetValue HKEY_LOCAL_MACHINE, "SOFTWARE\Microsoft\Windows NT
\CurrentVersion\Print\Printers\Dell Laser Printer
M5200\DsSpooler","printSeparatorFile"
GetValue HKEY_LOCAL_MACHINE, "SOFTWARE\Microsoft\Ole
\NONREDIST","System.EnterpriseServices.Thunk.dll"
WScript.Quit 0
Function GetValue(hive, key, name)
Dim value
Dim strValue
rval = objReg.GetStringValue(hive, key, name, value)
num = Err.Number
strValue = ToHex(Trim(value))
WScript.Echo " " & name & "=" & strValue & ", typeName=" & TypeName
(value) & ", rval=" & CStr(rval) & ", err=" & CStr(num)
End Function
Function ToHex( strLine )
iLen = Len(strLine)
strEscaped = ""
If ( iLen > 0 ) Then
For i = 1 To iLen
s = Mid(strLine, i, 1)
h = Hex(AscW(s))
If Len(h) = 1 Then
strEscaped = strEscaped & "0"
End If
strEscaped = strEscaped & h
Next
End If
ToHex = strEscaped
End Function

--
Gerry Hickman (London UK)