FltAllocateFileLock function (fltkernel.h)

Article
03/23/2023

The FltAllocateFileLock routine allocates and initializes a new FILE_LOCK structure.

Syntax

PFILE_LOCK FLTAPI FltAllocateFileLock(
  [in, optional] PFLT_COMPLETE_LOCK_CALLBACK_DATA_ROUTINE CompleteLockCallbackDataRoutine,
  [in, optional] PUNLOCK_ROUTINE                          UnlockRoutine
);

Parameters

[in, optional] CompleteLockCallbackDataRoutine

Pointer to a PFLT_COMPLETE_LOCK_CALLBACK_DATA_ROUTINE-typed callback routine to be called when an IRP_MJ_LOCK_CONTROL request is completed. This parameter is optional and can be NULL.

[in, optional] UnlockRoutine

Pointer to a PUNLOCK_ROUTINE-typed callback routine to be called when the byte range is unlocked. This parameter is optional and can be NULL.

Return value

FltAllocateFileLock returns a pointer to the newly allocated FILE_LOCK structure.

Remarks

FltAllocateFileLock allocates a new FILE_LOCK structure from paged pool and initializes it.

The returned FILE_LOCK structure can be used to lock a byte range in a file by calling FltProcessFileLock.

When the FILE_LOCK structure is no longer needed, it can be uninitialized by calling FltUninitializeFileLock. The uninitialized FILE_LOCK structure can then be initialized for reuse by calling FltInitializeFileLock.

To free an initialized FILE_LOCK structure, call FltFreeFileLock.

When the CallbackData parameter passed to FltProcessFileLock represents a fast I/O operation, the callback specified in CompleteLockCallbackDataRoutine is not invoked. Only when the I/O operation in CallbackData is an IRP, and CompleteLockCallbackDataRoutine is not NULL, will the callback routine be called.

Requirements

Requirement	Value
Minimum supported client	Windows XP SP2
Minimum supported server	Windows Server 2003 SP1
Target Platform	Universal
Header	fltkernel.h (include Fltkernel.h)
Library	FltMgr.lib
IRQL	<= APC_LEVEL