lookupss.c

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/* $Id: lookupss.c 37828 2008-12-03 17:32:36Z dgorbachev $
 *
 * COPYRIGHT:       See COPYING in the top level directory
 * PROJECT:         ReactOS system libraries
 * FILE:            lib/smlib/lookupss.c
 */
#include "precomp.h"

#define NDEBUG
#include <debug.h>

/**********************************************************************
 * NAME                         EXPORTED
 *  SmLookupSubsystem/6
 *
 * DESCRIPTION
 *  Read from the registry key
 *  \Registry\SYSTEM\CurrentControlSet\Control\Session Manager\Subsystems
 *  the value which name is Name.
 *
 * ARGUMENTS
 *  Name: name of the program to run, that is a value's name in
 *        the SM registry key Subsystems;
 *  Data: what the registry gave back for Name;
 *  DataLength: how much Data the registry returns;
 *  DataType: what is Data?
 *  Environment: set it if you want this function to use it
 *        to possibly expand Data before giving it back; if set
 *        to NULL, no expansion will be performed.
 */
NTSTATUS WINAPI
SmLookupSubsystem (IN     PWSTR   Name,
           IN OUT PWSTR   Data,
           IN OUT PULONG  DataLength,
           IN OUT PULONG  DataType,
           IN     PVOID   Environment OPTIONAL)
{
    NTSTATUS           Status = STATUS_SUCCESS;
    UNICODE_STRING     usKeyName = { 0, 0, NULL };
    OBJECT_ATTRIBUTES  Oa = {0};
    HANDLE             hKey = (HANDLE) 0;

    DPRINT("SM: %s(Name='%S') called\n", __FUNCTION__, Name);
    /*
     * Prepare the key name to scan and
     * related object attributes.
     */
    RtlInitUnicodeString (& usKeyName,
        L"\\Registry\\Machine\\SYSTEM\\CurrentControlSet\\Control\\Session Manager\\SubSystems");

    InitializeObjectAttributes (& Oa,
                    & usKeyName,
                    OBJ_CASE_INSENSITIVE,
                    NULL,
                    NULL);
    /*
     * Open the key. This MUST NOT fail, if the
     * request is for a legitimate subsystem.
     */
    Status = NtOpenKey (& hKey,
                  MAXIMUM_ALLOWED,
                  & Oa);
    if(NT_SUCCESS(Status))
    {
        UNICODE_STRING usValueName = { 0, 0, NULL };
        PWCHAR         KeyValueInformation = NULL;
        ULONG          KeyValueInformationLength = 1024;
        ULONG          ResultLength = 0L;
        PKEY_VALUE_PARTIAL_INFORMATION kvpi = NULL;

        KeyValueInformation = RtlAllocateHeap (RtlGetProcessHeap(),
                               0,
                               KeyValueInformationLength);
        if (NULL == KeyValueInformation)
        {
            return STATUS_NO_MEMORY;
        }
        kvpi = (PKEY_VALUE_PARTIAL_INFORMATION) KeyValueInformation;
        RtlInitUnicodeString (& usValueName, Name);
        Status = NtQueryValueKey (hKey,
                      & usValueName,
                      KeyValuePartialInformation,
                      KeyValueInformation,
                      KeyValueInformationLength,
                      & ResultLength);
        if(NT_SUCCESS(Status))
        {
            DPRINT("nkvpi.TitleIndex = %ld\n", kvpi->TitleIndex);
            DPRINT("kvpi.Type        = %ld\n", kvpi->Type);
            DPRINT("kvpi.DataLength  = %ld\n", kvpi->DataLength);

            if((NULL != Data) && (NULL != DataLength) && (NULL != DataType))
            {
                *DataType = kvpi->Type;
                if((NULL != Environment) && (REG_EXPAND_SZ == *DataType))
                {
                    UNICODE_STRING Source;
                    PWCHAR         DestinationBuffer = NULL;
                    UNICODE_STRING Destination;
                    ULONG          Length = 0;

                    DPRINT("SM: %s: value will be expanded\n", __FUNCTION__);

                    DestinationBuffer = RtlAllocateHeap (RtlGetProcessHeap(),
                                         0,
                                         (2 * KeyValueInformationLength));
                    if (NULL == DestinationBuffer)
                    {
                        Status = STATUS_NO_MEMORY;
                    }
                    else
                    {
                        Source.Length        = kvpi->DataLength;
                        Source.MaximumLength = kvpi->DataLength;
                        Source.Buffer        = (PWCHAR) & kvpi->Data;

                        Destination.Length        = 0;
                        Destination.MaximumLength = (2 * KeyValueInformationLength);
                        Destination.Buffer        = DestinationBuffer;

                        Status = RtlExpandEnvironmentStrings_U (Environment,
                                            & Source,
                                            & Destination,
                                            & Length);
                        if(NT_SUCCESS(Status))
                        {
                            *DataLength = min(*DataLength, Destination.Length);
                            RtlCopyMemory (Data, Destination.Buffer, *DataLength);
                        }
                        RtlFreeHeap (RtlGetProcessHeap(), 0, DestinationBuffer);
                    }
                }else{
                    DPRINT("SM: %s: value won't be expanded\n", __FUNCTION__);
                    *DataLength = min(*DataLength, kvpi->DataLength);
                    RtlCopyMemory (Data, & kvpi->Data, *DataLength);
                }
                *DataType = kvpi->Type;
            }else{
                DPRINT1("SM: %s: Data or DataLength or DataType is NULL!\n", __FUNCTION__);
                Status = STATUS_INVALID_PARAMETER;
            }
        }else{
            DPRINT1("%s: NtQueryValueKey failed (Status=0x%08lx)\n", __FUNCTION__, Status);
        }
        RtlFreeHeap (RtlGetProcessHeap(), 0, KeyValueInformation);
        NtClose (hKey);
    }else{
        DPRINT1("%s: NtOpenKey failed (Status=0x%08lx)\n", __FUNCTION__, Status);
    }
    return Status;
}

/* EOF */