708 lines
15 KiB
C
708 lines
15 KiB
C
/*++
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Copyright (c) 1989 Microsoft Corporation
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Module Name:
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eventpr.c
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Abstract:
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This module implements the executive event pair object. Functions
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are provided to create, open, waitlow, waithi, setlow, sethi,
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sethiwaitlo, setlowaithi.
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Author:
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Mark Lucovsky (markl) 18-Oct-1990
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Environment:
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Kernel mode only.
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Revision History:
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--*/
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#include "exp.h"
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// Define performance counters.
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ULONG EvPrSetHigh = 0;
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ULONG EvPrSetLow = 0;
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// Address of event pair object type descriptor.
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POBJECT_TYPE ExEventPairObjectType;
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// Structure that describes the mapping of generic access rights to object
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// specific access rights for event pair objects.
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GENERIC_MAPPING ExpEventPairMapping = {
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STANDARD_RIGHTS_READ |
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SYNCHRONIZE,
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STANDARD_RIGHTS_WRITE |
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SYNCHRONIZE,
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STANDARD_RIGHTS_EXECUTE |
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SYNCHRONIZE,
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EVENT_PAIR_ALL_ACCESS
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};
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(INIT, ExpEventPairInitialization)
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#pragma alloc_text(PAGE, NtCreateEventPair)
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#pragma alloc_text(PAGE, NtOpenEventPair)
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#pragma alloc_text(PAGE, NtWaitLowEventPair)
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#pragma alloc_text(PAGE, NtWaitHighEventPair)
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#pragma alloc_text(PAGE, NtSetLowWaitHighEventPair)
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#pragma alloc_text(PAGE, NtSetHighWaitLowEventPair)
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#pragma alloc_text(PAGE, NtSetHighEventPair)
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#pragma alloc_text(PAGE, NtSetLowEventPair)
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#endif
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BOOLEAN
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ExpEventPairInitialization (
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)
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/*++
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Routine Description:
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This function creates the event pair object type descriptor at system
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initialization and stores the address of the object type descriptor
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in global storage.
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Arguments:
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None.
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Return Value:
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A value of TRUE is returned if the event pair object type descriptor is
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successfully initialized. Otherwise a value of FALSE is returned.
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--*/
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{
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OBJECT_TYPE_INITIALIZER ObjectTypeInitializer;
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ULONG Offset = 0;
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NTSTATUS Status;
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UNICODE_STRING TypeName;
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// Initialize string descriptor.
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RtlInitUnicodeString(&TypeName, L"EventPair");
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// Create event object type descriptor.
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RtlZeroMemory(&ObjectTypeInitializer, sizeof(ObjectTypeInitializer));
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ObjectTypeInitializer.Length = sizeof(ObjectTypeInitializer);
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ObjectTypeInitializer.InvalidAttributes = OBJ_OPENLINK;
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ObjectTypeInitializer.GenericMapping = ExpEventPairMapping;
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ObjectTypeInitializer.PoolType = NonPagedPool;
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ObjectTypeInitializer.DefaultNonPagedPoolCharge = sizeof(EEVENT_PAIR);
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ObjectTypeInitializer.ValidAccessMask = EVENT_PAIR_ALL_ACCESS;
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ObjectTypeInitializer.UseDefaultObject = TRUE;
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Status = ObCreateObjectType(&TypeName,
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&ObjectTypeInitializer,
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(PSECURITY_DESCRIPTOR)NULL,
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&ExEventPairObjectType);
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// If the event pair object type descriptor was successfully created, then
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// return a value of TRUE. Otherwise return a value of FALSE.
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return (BOOLEAN)(NT_SUCCESS(Status));
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}
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NTSTATUS
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NtCreateEventPair (
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OUT PHANDLE EventPairHandle,
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IN ACCESS_MASK DesiredAccess,
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IN POBJECT_ATTRIBUTES ObjectAttributes OPTIONAL
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)
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/*++
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Routine Description:
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This function creates an event pair object, sets it initial state,
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and opens a handle to the object with the specified desired access.
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Arguments:
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EventPairHandle - Supplies a pointer to a variable that will receive the
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event pair object handle.
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DesiredAccess - Supplies the desired types of access for the event
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pair object.
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ObjectAttributes - Supplies a pointer to an object attributes
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structure.
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Return Value:
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TBS
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--*/
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{
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PEEVENT_PAIR EventPair;
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HANDLE Handle;
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KPROCESSOR_MODE PreviousMode;
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NTSTATUS Status;
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// Establish an exception handler, probe the output handle address, and
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// attempt to create an event object. If the probe fails, then return the
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// exception code as the service status. Otherwise return the status value
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// returned by the object insertion routine.
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try {
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// Get previous processor mode and probe output handle address if
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// necessary.
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PreviousMode = KeGetPreviousMode();
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if (PreviousMode != KernelMode) {
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ProbeForWriteHandle(EventPairHandle);
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}
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// Allocate event object.
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Status = ObCreateObject(PreviousMode,
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ExEventPairObjectType,
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ObjectAttributes,
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PreviousMode,
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NULL,
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sizeof(EEVENT_PAIR),
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0,
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0,
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(PVOID *)&EventPair);
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// If the event pair object was successfully allocated, then
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// initialize the event pair object and attempt to insert the
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// event pair object in the current process' handle table.
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if (NT_SUCCESS(Status)) {
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KeInitializeEventPair(&EventPair->KernelEventPair);
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Status = ObInsertObject((PVOID)EventPair,
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NULL,
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DesiredAccess,
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0,
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(PVOID *)NULL,
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&Handle);
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// If the event pair object was successfully inserted in the
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// current process' handle table, then attempt to write the
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// event pair object handle value. If the write attempt
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// fails, then do not report an error. When the caller
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// attempts to access the handle value, an access violation
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// will occur.
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if (NT_SUCCESS(Status)) {
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try {
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*EventPairHandle = Handle;
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} except(ExSystemExceptionFilter()) {
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}
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}
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}
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// If an exception occurs during the probe of the output handle address,
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// then always handle the exception and return the exception code as the
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// status value.
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} except (ExSystemExceptionFilter()) {
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return GetExceptionCode();
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}
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// Return service status.
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return Status;
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}
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NTSTATUS
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NtOpenEventPair(
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OUT PHANDLE EventPairHandle,
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IN ACCESS_MASK DesiredAccess,
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IN POBJECT_ATTRIBUTES ObjectAttributes
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)
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/*++
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Routine Description:
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This function opens a handle to an event pair object with the specified
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desired access.
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Arguments:
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EventPairHandle - Supplies a pointer to a variable that will receive
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the event pair object handle.
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DesiredAccess - Supplies the desired types of access for the event
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pair object.
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ObjectAttributes - Supplies a pointer to an object attributes structure.
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Return Value:
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TBS
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--*/
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{
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HANDLE Handle;
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KPROCESSOR_MODE PreviousMode;
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NTSTATUS Status;
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// Establish an exception handler, probe the output handle address, and
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// attempt to open the event object. If the probe fails, then return the
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// exception code as the service status. Otherwise return the status value
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// returned by the object open routine.
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try {
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// Get previous processor mode and probe output handle address
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// if necessary.
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PreviousMode = KeGetPreviousMode();
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if (PreviousMode != KernelMode) {
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ProbeForWriteHandle(EventPairHandle);
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}
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// Open handle to the event pair object with the specified
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// desired access.
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Status = ObOpenObjectByName(ObjectAttributes,
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ExEventPairObjectType,
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PreviousMode,
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NULL,
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DesiredAccess,
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NULL,
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&Handle);
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// If the open was successful, then attempt to write the event
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// pair object handle value. If the write attempt fails, then do
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// not report an error. When the caller attempts to access the
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// handle value, an access violation will occur.
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if (NT_SUCCESS(Status)) {
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try {
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*EventPairHandle = Handle;
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} except(ExSystemExceptionFilter()) {
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}
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}
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// If an exception occurs during the probe of the output event handle,
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// then always handle the exception and return the exception code as the
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// status value.
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} except (ExSystemExceptionFilter()) {
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return GetExceptionCode();
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}
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// Return service status.
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return Status;
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}
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NTSTATUS
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NtWaitLowEventPair(
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IN HANDLE EventPairHandle
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)
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/*++
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Routine Description:
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This function waits on the low event of an event pair object.
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Arguments:
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EventPairHandle - Supplies a handle to an event pair object.
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Return Value:
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TBS
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--*/
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{
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PEEVENT_PAIR EventPair;
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KPROCESSOR_MODE PreviousMode;
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NTSTATUS Status;
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// Reference event pair object by handle.
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PreviousMode = KeGetPreviousMode();
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Status = ObReferenceObjectByHandle(EventPairHandle,
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SYNCHRONIZE,
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ExEventPairObjectType,
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PreviousMode,
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(PVOID *)&EventPair,
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NULL);
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// If the reference was successful, then wait on the Low event
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// of the event pair.
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if (NT_SUCCESS(Status)) {
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Status = KeWaitForLowEventPair(&EventPair->KernelEventPair,
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PreviousMode,
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FALSE,
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NULL);
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ObDereferenceObject(EventPair);
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}
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// Return service status.
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return Status;
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}
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NTSTATUS
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NtWaitHighEventPair(
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IN HANDLE EventPairHandle
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)
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/*++
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Routine Description:
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This function waits on the high event of an event pair object.
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Arguments:
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EventPairHandle - Supplies a handle to an event pair object.
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Return Value:
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TBS
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--*/
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{
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PEEVENT_PAIR EventPair;
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KPROCESSOR_MODE PreviousMode;
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NTSTATUS Status;
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// Reference event pair object by handle.
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PreviousMode = KeGetPreviousMode();
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Status = ObReferenceObjectByHandle(EventPairHandle,
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SYNCHRONIZE,
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ExEventPairObjectType,
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PreviousMode,
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(PVOID *)&EventPair,
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NULL);
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// If the reference was successful, then wait on the Low event
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// of the event pair.
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if (NT_SUCCESS(Status)) {
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Status = KeWaitForHighEventPair(&EventPair->KernelEventPair,
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PreviousMode,
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FALSE,
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NULL);
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ObDereferenceObject(EventPair);
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}
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// Return service status.
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return Status;
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}
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NTSTATUS
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NtSetLowWaitHighEventPair(
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IN HANDLE EventPairHandle
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)
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/*++
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Routine Description:
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This function sets the low event of an event pair and then
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waits on the high event of an event pair object.
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Arguments:
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EventPairHandle - Supplies a handle to an event pair object.
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Return Value:
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TBS
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--*/
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{
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PEEVENT_PAIR EventPair;
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KPROCESSOR_MODE PreviousMode;
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NTSTATUS Status;
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// Reference event pair object by handle.
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PreviousMode = KeGetPreviousMode();
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Status = ObReferenceObjectByHandle(EventPairHandle,
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SYNCHRONIZE,
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ExEventPairObjectType,
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PreviousMode,
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(PVOID *)&EventPair,
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NULL);
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// If the reference was successful, then wait on the Low event
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// of the event pair.
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if (NT_SUCCESS(Status)) {
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EvPrSetLow++;
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Status = KeSetLowWaitHighEventPair(&EventPair->KernelEventPair,
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PreviousMode);
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ObDereferenceObject(EventPair);
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}
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// Return service status.
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return Status;
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}
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NTSTATUS
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NtSetHighWaitLowEventPair(
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IN HANDLE EventPairHandle
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)
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/*++
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Routine Description:
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This function sets the high event of an event pair and then
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waits on the low event of an event pair object.
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Arguments:
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EventPairHandle - Supplies a handle to an event pair object.
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Return Value:
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TBS
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--*/
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{
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PEEVENT_PAIR EventPair;
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KPROCESSOR_MODE PreviousMode;
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NTSTATUS Status;
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// Reference event pair object by handle.
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PreviousMode = KeGetPreviousMode();
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Status = ObReferenceObjectByHandle(EventPairHandle,
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SYNCHRONIZE,
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ExEventPairObjectType,
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PreviousMode,
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(PVOID *)&EventPair,
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NULL);
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// If the reference was successful, then wait on the Low event
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// of the event pair.
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if (NT_SUCCESS(Status)) {
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EvPrSetHigh++;
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Status = KeSetHighWaitLowEventPair(&EventPair->KernelEventPair,
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PreviousMode);
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ObDereferenceObject(EventPair);
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}
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// Return service status.
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return Status;
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}
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NTSTATUS
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NtSetLowEventPair(
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IN HANDLE EventPairHandle
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)
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/*++
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Routine Description:
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This function sets the low event of an event pair object.
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Arguments:
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EventPairHandle - Supplies a handle to an event pair object.
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Return Value:
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TBS
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--*/
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{
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PEEVENT_PAIR EventPair;
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KPROCESSOR_MODE PreviousMode;
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NTSTATUS Status;
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// Reference event pair object by handle.
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PreviousMode = KeGetPreviousMode();
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Status = ObReferenceObjectByHandle(EventPairHandle,
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SYNCHRONIZE,
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ExEventPairObjectType,
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PreviousMode,
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(PVOID *)&EventPair,
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NULL);
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// If the reference was successful, then wait on the Low event
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// of the event pair.
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if (NT_SUCCESS(Status)) {
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EvPrSetLow++;
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KeSetLowEventPair(&EventPair->KernelEventPair,
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EVENT_PAIR_INCREMENT,FALSE);
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ObDereferenceObject(EventPair);
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}
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// Return service status.
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return Status;
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}
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NTSTATUS
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NtSetHighEventPair(
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IN HANDLE EventPairHandle
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)
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/*++
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Routine Description:
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This function sets the high event of an event pair object.
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Arguments:
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EventPairHandle - Supplies a handle to an event pair object.
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Return Value:
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TBS
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--*/
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{
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PEEVENT_PAIR EventPair;
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KPROCESSOR_MODE PreviousMode;
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NTSTATUS Status;
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// Reference event pair object by handle.
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PreviousMode = KeGetPreviousMode();
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Status = ObReferenceObjectByHandle(EventPairHandle,
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SYNCHRONIZE,
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ExEventPairObjectType,
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PreviousMode,
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(PVOID *)&EventPair,
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NULL);
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// If the reference was successful, then wait on the Low event
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// of the event pair.
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if (NT_SUCCESS(Status)) {
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EvPrSetHigh++;
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KeSetHighEventPair(&EventPair->KernelEventPair,
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EVENT_PAIR_INCREMENT,FALSE);
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ObDereferenceObject(EventPair);
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}
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// Return service status.
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return Status;
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}
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