ZwQueryValueKey function (wdm.h)
The ZwQueryValueKey routine returns a value entry for a registry key.
Syntax
NTSYSAPI NTSTATUS ZwQueryValueKey(
[in] HANDLE KeyHandle,
[in] PUNICODE_STRING ValueName,
[in] KEY_VALUE_INFORMATION_CLASS KeyValueInformationClass,
[out, optional] PVOID KeyValueInformation,
[in] ULONG Length,
[out] PULONG ResultLength
);
Parameters
[in] KeyHandle
Handle to the key to read value entries from. This handle is created by a successful call to ZwCreateKey or ZwOpenKey.
[in] ValueName
Pointer to the name of the value entry to obtain data for.
[in] KeyValueInformationClass
A KEY_VALUE_INFORMATION_CLASS value that determines the type of information returned in the KeyValueInformation buffer.
[out, optional] KeyValueInformation
Pointer to a caller-allocated buffer that receives the requested information.
[in] Length
Specifies the size, in bytes, of the KeyValueInformation buffer.
[out] ResultLength
Pointer to a variable that receives the size, in bytes, of the key information. If the ZwQueryValueKey routine returns STATUS_SUCCESS, callers can use the value of this variable to determine the amount of data returned. If the routine returns STATUS_BUFFER_OVERFLOW or STATUS_BUFFER_TOO_SMALL, callers can use the value of this variable to determine the size of buffer required to hold the key information.
Return value
ZwQueryValueKey returns STATUS_SUCCESS on success, or the appropriate error code on failure. Possible error code values include:
| Return code | Description |
|---|---|
| STATUS_OBJECT_NAME_NOT_FOUND | The registry value was not available. |
| STATUS_BUFFER_OVERFLOW | The buffer supplied is too small, and only partial data has been written to the buffer. ResultLength is set to the minimum size required to hold the requested information. |
| STATUS_BUFFER_TOO_SMALL | The buffer supplied is too small, and no data has been written to the buffer. ResultLength is set to the minimum size required to hold the requested information. |
| STATUS_INVALID_PARAMETER | The KeyInformationClass parameter is not a valid KEY_VALUE_INFORMATION_CLASS value. |
Remarks
The KeyHandle passed to ZwQueryValueKey must have been opened with KEY_QUERY_VALUE access. This is accomplished by passing KEY_QUERY_VALUE, KEY_READ, or KEY_ALL_ACCESS as the DesiredAccess parameter to ZwCreateKey or ZwOpenKey.
For more information about working with registry keys, see Using the Registry in a Driver.
If the call to this function occurs in user mode, you should use the name "NtQueryValueKey" instead of "ZwQueryValueKey". For calls from kernel-mode drivers, the NtXxx and ZwXxx versions of a Windows Native System Services routine can behave differently in the way that they handle and interpret input parameters. For more information about the relationship between the NtXxx and ZwXxx versions of a routine, see Using Nt and Zw Versions of the Native System Services Routines.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Universal |
| Header | wdm.h (include Wdm.h, Ntddk.h, Ntifs.h) |
| Library | NtosKrnl.lib |
| DLL | NtosKrnl.exe |
| IRQL | PASSIVE_LEVEL |
| DDI compliance rules | HwStorPortProhibitedDDIs(storport), IrqlZwPassive(wdm), PowerIrpDDis(wdm), ZwRegistryCreate(storport), ZwRegistryCreate(storport), ZwRegistryCreate(wdm), ZwRegistryOpen(storport), ZwRegistryOpen(storport), ZwRegistryOpen(wdm) |
See also
Using Nt and Zw Versions of the Native System Services Routines