RtlEnumerateGenericTableAvl function (ntddk.h)

Article
02/28/2023

The RtlEnumerateGenericTableAvl routine is used to enumerate the elements in a generic table.

Syntax

NTSYSAPI PVOID RtlEnumerateGenericTableAvl(
  [in] PRTL_AVL_TABLE Table,
  [in] BOOLEAN        Restart
);

Parameters

[in] Table

A pointer to the generic table (RTL_AVL_TABLE). The table must have been initialized by calling RtlInitializeGenericTableAvl.

[in] Restart

Set to TRUE if the enumeration is to start at the first element in the table. Set to FALSE if resuming the enumeration from a previous call.

To enumerate all elements in the table, use RtlEnumerateGenericTableAvl as follows:

for (p = RtlEnumerateGenericTableAvl ( Table, TRUE );
     p != NULL;
     p = RtlEnumerateGenericTableAvl ( Table, FALSE )) {
        // Process the element pointed to by p
}

Return value

RtlEnumerateGenericTableAvl returns a pointer to the next element, if one exists. If there are no more elements in the table, RtlEnumerateGenericTableAvl returns NULL.

Remarks

Callers of the Rtl..GenericTableAvl routines are responsible for exclusively synchronizing access to the generic table. An exclusive fast mutex is the most efficient synchronization mechanism to use for this purpose.

By default, the operating system uses splay trees to implement generic tables, but the RtlEnumerateGenericTableAvl routine only works with Adelson-Velsky/Landis (AVL) trees. To configure the generic table routines to use AVL trees instead of splay trees in your driver, insert the following define statement in a common header file before including Ntddk.h:

#define RTL_USE_AVL_TABLES 0

If RTL_USE_AVL_TABLES is not defined, you must use the AVL form of the generic table routines. For example, use the RtlEnumerateGenericTableAvl routine instead of RtlEnumerateGenericTable. In the call to RtlEnumerateGenericTableAvl, the caller must pass a RTL_AVL_TABLE table structure rather than RTL_GENERIC_TABLE.

Callers of RtlEnumerateGenericTableAvl must be running at IRQL < DISPATCH_LEVEL if the caller-allocated memory for the generic table is pageable.

Requirements

Requirement	Value
Target Platform	Universal
Header	ntddk.h (include Ntddk.h, Ntifs.h, Fltkernel.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	IRQL < DISPATCH_LEVEL (see Remarks section)