键盘过滤驱动勘误《寒江独钓》

Keydata=Irp->AssociatedIrp.SystemBuffer;
numKeys=Irp->IoStatus.Information / Sizeof(KEYBOARD_INPUT_DATA);
for ( i=0;i<numKeys;i++)
{
    DbgPrint(("numKeys : %d ",numKeys));
    DbgPrint(("Scan code : %x ",KeyData->MakeCode));
    DbgPrint(("%s\n",KeyData->Flags? "up":"down"));
    MyPrintKeyStroke((UCHAR)KeyData->MakeCode);

    if (KeyData->MakeCode==CAPS_LOCK)
    {
        KeyData->MakeCode=LCONTROL;
    }
}

以上是书上的源代码，整个循环体只遍历了第一个结构体，后面的并没有进行操作，虽然有个循环但是并没有什么实质的作用，正确的遍历代码应该是下面的样子。程序代码所在页面Page-73

Keydata=Irp->AssociatedIrp.SystemBuffer;
numKeys=Irp->IoStatus.Information / Sizeof(KEYBOARD_INPUT_DATA);
for ( i=0;i<numKeys;i++,numKeys++)
{
    DbgPrint(("numKeys : %d ",numKeys));
    DbgPrint(("Scan code : %x ",KeyData->MakeCode));
    DbgPrint(("%s\n",KeyData->Flags? "up":"down"));
    MyPrintKeyStroke((UCHAR)KeyData->MakeCode);

    if (KeyData->MakeCode==CAPS_LOCK)
    {
        KeyData->MakeCode=LCONTROL;
    }
}