Windows2000/private/ntos/ex/exinfo.c

/*++

Copyright (c) 1989  Microsoft Corporation

Module Name:

    exinfo.c

Abstract:

    This module implements the NT set anmd query system information services.

Author:

    Ken Reneris (kenr) 19-July-1994

Environment:

    Kernel mode only.

Revision History:

--*/

#include "exp.h"

#if _PNP_POWER_
#if defined(ALLOC_PRAGMA)
#pragma alloc_text(PAGE, ExpCheckSystemInformation)
#pragma alloc_text(PAGE, ExpCheckSystemInfoWork)
#endif // _PNP_POWER_

VOID
ExpCheckSystemInformation (
    PVOID       Context,
    PVOID       InformationClass,
    PVOID       Argument2
    )
/*++

Routine Description:

    Callback function invoked when something in the system information
    may have changed.

Arguments:

    Context - Where invoked from.

    InformationClass - which class for the given context was set
        (ignored for now)

    Argument2

Return Value:

--*/
{
    ExQueueWorkItem (&ExpCheckSystemInfoWorkItem, DelayedWorkQueue);
}


VOID
ExpCheckSystemInfoWork (
    IN PVOID Context
    )
/*++

Routine Description:

    Verifies registery data for various system information classes
    is up to date.

Arguments:

Return Value:

--*/
{
    static struct {
        SYSTEM_INFORMATION_CLASS         InformationLevel;
        ULONG                            BufferSize;
    } RegistryInformation[] = {
        SystemBasicInformation,          sizeof (SYSTEM_BASIC_INFORMATION),
        SystemPowerInformation,          sizeof (SYSTEM_POWER_INFORMATION),
        SystemProcessorSpeedInformation, sizeof (SYSTEM_PROCESSOR_SPEED_INFORMATION),
        0,                               0
    };

    struct {
        KEY_VALUE_PARTIAL_INFORMATION   Key;
        union {
            SYSTEM_BASIC_INFORMATION BasicInformation;
            SYSTEM_POWER_INFORMATION PowerSettings;
            SYSTEM_PROCESSOR_SPEED_INFORMATION  ProcessorSpeed;
        };
    } RegistryBuffer, QueryBuffer;

    ULONG               Index, BufferSize, disposition, length;
    NTSTATUS            Status;
    OBJECT_ATTRIBUTES   objectAttributes;
    UNICODE_STRING      unicodeString, ValueString;
    HANDLE              CurrentControlSet, SystemInformation, LevelInformation;
    LARGE_INTEGER       Interval;
    BOOLEAN             Rescan;
    WCHAR               wstr[10];

    PAGED_CODE();


    // Only one worked needed at a time needed to update the SystemInformation
    // data in the registry


    if (InterlockedIncrement (&ExpCheckSystemInfoBusy) != 0) {
        return ;
    }

    RtlInitUnicodeString (&ValueString,  ExpWstrSystemInformationValue);


    // Open CurrentControlSet


    InitializeObjectAttributes( &objectAttributes, &CmRegistryMachineSystemCurrentControlSet, OBJ_CASE_INSENSITIVE, NULL, NULL );
    Status = NtOpenKey (&CurrentControlSet, KEY_READ | KEY_WRITE, &objectAttributes );
    if (NT_SUCCESS(Status)) {

        // Open SystemInformation


        RtlInitUnicodeString( &unicodeString, ExpWstrSystemInformation );
        InitializeObjectAttributes( &objectAttributes, &unicodeString, OBJ_CASE_INSENSITIVE, CurrentControlSet, NULL );
        Status = NtCreateKey ( &SystemInformation, KEY_READ | KEY_WRITE, &objectAttributes, 0, NULL, REG_OPTION_VOLATILE, &disposition );
        NtClose (CurrentControlSet);
    }

    if (!NT_SUCCESS(Status)) {
        InterlockedDecrement (&ExpCheckSystemInfoBusy);
        return ;
    }


    // Loop and check SystemInformation data in registry


    do {
        Rescan = FALSE;


        // Wait a moment


        Interval.QuadPart = -3000000;
        KeDelayExecutionThread (KernelMode, FALSE, &Interval);


        // For now just check each SystemInformation level and update
        // any level which is out of date


        for (Index=0; RegistryInformation[Index].BufferSize; Index++) {


            // Initialize registry data buffer


            BufferSize = RegistryInformation[Index].BufferSize;
            RtlZeroMemory (RegistryBuffer.Key.Data, BufferSize);


            // Open appropiate SystemInformation level key
            swprintf (wstr, L"%d", RegistryInformation[Index].InformationLevel);
            RtlInitUnicodeString (&unicodeString, wstr);
            InitializeObjectAttributes( &objectAttributes, &unicodeString, OBJ_CASE_INSENSITIVE, SystemInformation, NULL );
            Status = NtCreateKey ( &LevelInformation, KEY_READ | KEY_WRITE, &objectAttributes, 0, NULL, REG_OPTION_VOLATILE, &disposition );

            // If key opened, read current data value from the registry
            if (NT_SUCCESS(Status)) {
                NtQueryValueKey (LevelInformation, &ValueString, KeyValuePartialInformation, &RegistryBuffer.Key, sizeof (RegistryBuffer), &length);
            }

            // Query current SystemInformation data
            Status = NtQuerySystemInformation (RegistryInformation[Index].InformationLevel, &QueryBuffer.Key.Data, BufferSize, NULL);

            // Check if current SystemInformation matches the registry
            // information
            if (NT_SUCCESS(Status)  && !RtlEqualMemory (RegistryBuffer.Key.Data, QueryBuffer.Key.Data, BufferSize) ) {
                // Did not match - update registry to current SystemInfomration
                Status = NtSetValueKey (LevelInformation, &ValueString, 0L, REG_BINARY, QueryBuffer.Key.Data, BufferSize);

                // Make notificant that this information level has changed
                ExNotifyCallback (ExCbSetSystemInformation, (PVOID) RegistryInformation[Index].InformationLevel, (PVOID) NULL);
            }


            // Close this InformatiobLevel and check the next one


            NtClose (LevelInformation);
        }


        // If no Rescan, remove our count from the busy flag


        if (!Rescan &&
            InterlockedDecrement (&ExpCheckSystemInfoBusy) >= 0) {


            // Some other worker thread attempted to perform a scan.  Reset
            // counter to 1 and loop


            ExInterlockedExchangeUlong ((PULONG) &ExpCheckSystemInfoBusy, 0, &ExpCheckSystemInfoLock);
            Rescan = TRUE;
        }

    } while (Rescan);


    // Cleanup


    NtClose (SystemInformation);
}

#endif  // _PNP_POWER_