NTSTATUS NTAPI NtReleaseMutant	(	IN HANDLE	MutantHandle,
		IN PLONG PreviousCount	OPTIONAL
	)
Definition at line 295 of file mutant.c.
{
    PKMUTANT Mutant;
    KPROCESSOR_MODE PreviousMode = ExGetPreviousMode();
    NTSTATUS Status;
    PAGED_CODE();
    DPRINT("NtReleaseMutant(MutantHandle 0x%p PreviousCount 0x%p)\n",
            MutantHandle,
            PreviousCount);

     /* Check if we were called from user-mode */
    if ((PreviousCount) && (PreviousMode != KernelMode))
    {
        /* Entry SEH Block */
        _SEH2_TRY
        {
            /* Make sure the state pointer is valid */
            ProbeForWriteLong(PreviousCount);
        }
        _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
        {
            /* Return the exception code */
            _SEH2_YIELD(return _SEH2_GetExceptionCode());
        }
        _SEH2_END;
    }

    /* Open the Object */
    Status = ObReferenceObjectByHandle(MutantHandle,
                                       MUTANT_QUERY_STATE,
                                       ExMutantObjectType,
                                       PreviousMode,
                                       (PVOID*)&Mutant,
                                       NULL);

    /* Check for Success and release if such */
    if (NT_SUCCESS(Status))
    {
        /*
         * Release the mutant. doing so might raise an exception which we're
         * required to catch!
         */
        _SEH2_TRY
        {
            /* Release the mutant */
            LONG Prev = KeReleaseMutant(Mutant,
                                        MUTANT_INCREMENT,
                                        FALSE,
                                        FALSE);

            /* Return the previous count if requested */
            if (PreviousCount) *PreviousCount = Prev;
        }
        _SEH2_EXCEPT(ExSystemExceptionFilter())
        {
            /* Get the exception code */
            Status = _SEH2_GetExceptionCode();
        }
        _SEH2_END;

        /* Dereference it */
        ObDereferenceObject(Mutant);
    }

    /* Return Status */
    return Status;
}
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