NTSTATUS
NtSetEvent (
IN HANDLE EventHandle,
OUT PLONG PreviousState OPTIONAL
)
/*++
Routine Description:
This function sets an event object to a Signaled state and attempts to
satisfy as many waits as possible.
Arguments:
EventHandle - Supplies a handle to an event object.
PreviousState - Supplies an optional pointer to a variable that will
receive the previous state of the event object.
Return Value:
TBS
--*/
{
PVOID Event;
KPROCESSOR_MODE PreviousMode;
LONG State;
NTSTATUS Status;
//
// Establish an exception handler, probe the previous state address if
// specified, reference the event object, and set the event object. If
// the probe fails, then return the exception code as the service status.
// Otherwise return the status value returned by the reference object by
// handle routine.
//
try {
//
// Get previous processor mode and probe previous state address
// if necessary.
//
PreviousMode = KeGetPreviousMode();
if ((PreviousMode != KernelMode) && (ARGUMENT_PRESENT(PreviousState))) {
ProbeForWriteLong(PreviousState);
}
//
// Reference event object by handle.
//
Status = ObReferenceObjectByHandle(EventHandle,
EVENT_MODIFY_STATE,
ExEventObjectType,
PreviousMode,
&Event,
NULL);
//
// If the reference was successful, then set the event object to the
// Signaled state, dereference event object, and write the previous
// state value if specified. If the write of the previous state fails,
// then do not report an error. When the caller attempts to access the
// previous state value, an access violation will occur.
//
if (NT_SUCCESS(Status)) {
State = KeSetEvent((PKEVENT)Event, ExpEventBoost, FALSE);
ObDereferenceObject(Event);
if (ARGUMENT_PRESENT(PreviousState)) {
try {
*PreviousState = State;
}
except(ExSystemExceptionFilter()) {
}
}
}
//
// If an exception occurs during the probe of the previous state, then
// always handle the exception and return the exception code as the status
// value.
//
} except(ExSystemExceptionFilter()) {
return GetExceptionCode();
}
//
// Return service status.
//
return Status;
}
NTSTATUS
NtReleaseMutant (
IN HANDLE MutantHandle,
OUT PLONG PreviousCount OPTIONAL
)
/*++
Routine Description:
This function releases a mutant object.
Arguments:
Mutant - Supplies a handle to a mutant object.
PreviousCount - Supplies an optional pointer to a variable that will
receive the previous mutant count.
Return Value:
TBS
--*/
{
LONG Count;
PVOID Mutant;
KPROCESSOR_MODE PreviousMode;
NTSTATUS Status;
//
// Establish an exception handler, probe the previous count address if
// specified, reference the mutant object, and release the mutant object.
// If the probe fails, then return the exception code as the service
// status. Otherwise return the status value returned by the reference
// object by handle routine.
//
try {
//
// Get previous processor mode and probe previous count address
// if necessary.
//
PreviousMode = KeGetPreviousMode();
if ((PreviousMode != KernelMode) && (ARGUMENT_PRESENT(PreviousCount))) {
ProbeForWriteLong(PreviousCount);
}
//
// Reference mutant object by handle.
//
// Note that the desired access is specified as zero since only the
// owner can release a mutant object.
//
Status = ObReferenceObjectByHandle(MutantHandle,
0,
ExMutantObjectType,
PreviousMode,
&Mutant,
NULL);
//
// If the reference was successful, then release the mutant object. If
// an exception occurs because the caller is not the owner of the mutant
// object, then dereference mutant object and return the exception code
// as the service status. Otherise write the previous count value if
// specified. If the write of the previous count fails, then do not
// report an error. When the caller attempts to access the previous
// count value, an access violation will occur.
//
if (NT_SUCCESS(Status)) {
try {
Count = KeReleaseMutant((PKMUTANT)Mutant, MUTANT_INCREMENT, FALSE, FALSE);
ObDereferenceObject(Mutant);
if (ARGUMENT_PRESENT(PreviousCount)) {
try {
*PreviousCount = Count;
} except(ExSystemExceptionFilter()) {
}
}
//
// If an exception occurs because the caller is not the owner of
// the mutant object, then always handle the exception, dereference
// the mutant object, and return the exception code as the status
// value.
//
} except(ExSystemExceptionFilter()) {
ObDereferenceObject(Mutant);
return GetExceptionCode();
}
}
//
// If an exception occurs during the probe of the previous count, then
// always handle the exception and return the exception code as the status
// value.
//
} except(ExSystemExceptionFilter()) {
return GetExceptionCode();
}
//
// Return service status.
//
return Status;
}
