wdm/PortEnum.c

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/*
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 *  Copyright 2004 Spiro Trikaliotis
 *
 */

#include <initguid.h>
#include <wdm.h>

#define PENUMERATE_DEFINED 
typedef struct ENUMERATE_WDM *PENUMERATE; 
#include "cbm_driver.h"

typedef
struct ENUMERATE_WDM
{
    PWSTR SymbolicLinkList;

    PWSTR CurrentSymbolicLink;
} ENUMERATE, *PENUMERATE;


NTSTATUS
ParPortEnumerateOpen(PENUMERATE *EnumStruct)
{
    PENUMERATE enumStruct;
    NTSTATUS ntStatus;

    FUNC_ENTER();

    // Allocate memory for the enumStruct

    DBG_IRQL( < DISPATCH_LEVEL);
    enumStruct = ExAllocatePoolWithTag(PagedPool, 
        sizeof(ENUMERATE), MTAG_SENUMERATE);

    if (enumStruct)
    {
        // Mark: We did not yet enumerate the first entry

        enumStruct->CurrentSymbolicLink = NULL;

        // Get every device which implementes our interface

        DBG_IRQL( == PASSIVE_LEVEL);
        ntStatus = IoGetDeviceInterfaces(&GUID_PARALLEL_DEVICE,
            NULL, // no pdo given
            0,
            &enumStruct->SymbolicLinkList);
    }
    else 
    {
        ntStatus = STATUS_INSUFFICIENT_RESOURCES;
    }

    // didn't we succeed? Then return with the correct value

    if (!NT_SUCCESS(ntStatus))  
    {
        // We had a problem obtaining the devices which implement the
        // parallel port interface, thus, fail this function

        if (enumStruct)
        {
            // Free the enumStruct

            DBG_IRQL( < DISPATCH_LEVEL);
            ExFreePool(enumStruct);

            enumStruct = NULL;
        }
    }

    *EnumStruct = enumStruct;

    FUNC_LEAVE_NTSTATUS(ntStatus);
}

NTSTATUS
ParPortEnumerate(PENUMERATE EnumStruct, PCWSTR *DriverName)
{
    FUNC_ENTER();

    DBG_ASSERT(EnumStruct != NULL);
    DBG_ASSERT(EnumStruct->SymbolicLinkList != NULL);

    // Advance EnumStruct->CurrentSymbolicLink to the next entry

    if (EnumStruct->CurrentSymbolicLink == NULL)
    {
        // we just started enumerating, get the first entry

        EnumStruct->CurrentSymbolicLink = EnumStruct->SymbolicLinkList;
    }
    else
    {
        // advance to the next entry

        EnumStruct->CurrentSymbolicLink += wcslen(EnumStruct->CurrentSymbolicLink)+1;
    }

    // Give the next driver name to the caller

    *DriverName = EnumStruct->CurrentSymbolicLink;

    FUNC_LEAVE_NTSTATUS((**DriverName) ? STATUS_SUCCESS : STATUS_NO_MORE_ENTRIES);
}

VOID
ParPortEnumerateClose(PENUMERATE EnumStruct)
{
    FUNC_ENTER();

    DBG_ASSERT(EnumStruct != NULL);
    DBG_ASSERT(EnumStruct->SymbolicLinkList != NULL);

    // Free both allocated buffers

    DBG_IRQL( < DISPATCH_LEVEL);
    ExFreePool(EnumStruct->SymbolicLinkList);
    ExFreePool(EnumStruct);

    DBGDO(EnumStruct = NULL;)

    FUNC_LEAVE();
}

NTSTATUS 
CbmOpenDeviceRegistryKey(IN PDEVICE_OBJECT a, IN ULONG b, IN ACCESS_MASK c, OUT PHANDLE d)
{
    FUNC_ENTER();

    FUNC_LEAVE_NTSTATUS(IoOpenDeviceRegistryKey(a, b, c, d));
}