[转]IoCompleteRequest函数源码

/*
 * @implemented
 */
VOID
FASTCALL
IofCompleteRequest(IN PIRP Irp,
                   IN CCHAR PriorityBoost)
{
    PIO_STACK_LOCATION StackPtr, LastStackPtr;
    PDEVICE_OBJECT DeviceObject;
    PFILE_OBJECT FileObject;
    PETHREAD Thread;
    NTSTATUS Status;
    PMDL Mdl, NextMdl;
    ULONG MasterCount;
    PIRP MasterIrp;
    ULONG Flags;
    NTSTATUS ErrorCode = STATUS_SUCCESS;
    IOTRACE(IO_IRP_DEBUG,
            "%s - Completing IRP %p\n",
            __FUNCTION__,
            Irp);

    /* Make sure this IRP isn't getting completed twice or is invalid */
    if ((Irp->CurrentLocation) > (Irp->StackCount + 1))
    {
        /* Bugcheck */
        KeBugCheckEx(MULTIPLE_IRP_COMPLETE_REQUESTS, (ULONG_PTR)Irp, 0, 0, 0);
    }

    /* Some sanity checks */
    ASSERT(Irp->Type == IO_TYPE_IRP);
    ASSERT(!Irp->CancelRoutine);
    ASSERT(Irp->IoStatus.Status != STATUS_PENDING);
    ASSERT(Irp->IoStatus.Status != (NTSTATUS)0xFFFFFFFF);

    /* Get the last stack */
    LastStackPtr = (PIO_STACK_LOCATION)(Irp + 1);//这里
    if (LastStackPtr->Control & SL_ERROR_RETURNED)
    {
        /* Get the error code */
        ErrorCode = PtrToUlong(LastStackPtr->Parameters.Others.Argument4);
    }

    /*
     * Start the loop with the current stack and point the IRP to the next stack
     * and then keep incrementing the stack as we loop through. The IRP should
     * always point to the next stack location w.r.t the one currently being
     * analyzed, so completion routine code will see the appropriate value.
     * Because of this, we must loop until the current stack location is +1 of
     * the stack count, because when StackPtr is at the end, CurrentLocation is +1.
     */
    for (StackPtr = IoGetCurrentIrpStackLocation(Irp),
         Irp->CurrentLocation++,
         Irp->Tail.Overlay.CurrentStackLocation++;
         Irp->CurrentLocation <= (Irp->StackCount + 1);
         StackPtr++,
         Irp->CurrentLocation++,
         Irp->Tail.Overlay.CurrentStackLocation++)
    {
        /* Set Pending Returned */
        Irp->PendingReturned = StackPtr->Control & SL_PENDING_RETURNED;

        /* Check if we failed */
        if (!NT_SUCCESS(Irp->IoStatus.Status))
        {
            /* Check if it was changed by a completion routine */
            if (Irp->IoStatus.Status != ErrorCode)
            {
                /* Update the error for the current stack */
                ErrorCode = Irp->IoStatus.Status;
                StackPtr->Control |= SL_ERROR_RETURNED;
                LastStackPtr->Parameters.Others.Argument4 = UlongToPtr(ErrorCode);
                LastStackPtr->Control |= SL_ERROR_RETURNED;
            }
        }

        /* Check if there is a Completion Routine to Call */
        if ((NT_SUCCESS(Irp->IoStatus.Status) &&
             (StackPtr->Control & SL_INVOKE_ON_SUCCESS)) ||
            (!NT_SUCCESS(Irp->IoStatus.Status) &&
             (StackPtr->Control & SL_INVOKE_ON_ERROR)) ||
            (Irp->Cancel &&
             (StackPtr->Control & SL_INVOKE_ON_CANCEL)))
        {
            /* Clear the stack location */
            IopClearStackLocation(StackPtr);

            /* Check for highest-level device completion routines */
            if (Irp->CurrentLocation == (Irp->StackCount + 1))
            {
                /* Clear the DO, since the current stack location is invalid */
                DeviceObject = NULL;
            }
            else
            {
                /* Otherwise, return the real one */
                DeviceObject = IoGetCurrentIrpStackLocation(Irp)->DeviceObject;
            }

            /* Call the completion routine */
            Status = StackPtr->CompletionRoutine(DeviceObject,
                                                 Irp,
                                                 StackPtr->Context);

            /* Don't touch the Packet in this case, since it might be gone! */
            if (Status == STATUS_MORE_PROCESSING_REQUIRED) return;
        }
        else
        {
            /* Otherwise, check if this is a completed IRP */
            if ((Irp->CurrentLocation <= Irp->StackCount) &&
                (Irp->PendingReturned))
            {
                /* Mark it as pending */
                IoMarkIrpPending(Irp);
            }

            /* Clear the stack location */
            IopClearStackLocation(StackPtr);
        }
    }

    /* Check if the IRP is an associated IRP */
    if (Irp->Flags & IRP_ASSOCIATED_IRP)
    {
        /* Get the master IRP and count */
        MasterIrp = Irp->AssociatedIrp.MasterIrp;
        MasterCount = InterlockedDecrement(&MasterIrp->AssociatedIrp.IrpCount);

        /* Free the MDLs */
        for (Mdl = Irp->MdlAddress; Mdl; Mdl = NextMdl)
        {
            /* Go to the next one */
            NextMdl = Mdl->Next;
            IoFreeMdl(Mdl);
        }

        /* Free the IRP itself */
        IoFreeIrp(Irp);

        /* Complete the Master IRP */
        if (!MasterCount) IofCompleteRequest(MasterIrp, PriorityBoost);
        return;
    }

    /* We don't support this yet */
    ASSERT(Irp->IoStatus.Status != STATUS_REPARSE);

    /* Check if we have an auxiliary buffer */
    if (Irp->Tail.Overlay.AuxiliaryBuffer)
    {
        /* Free it */
        ExFreePool(Irp->Tail.Overlay.AuxiliaryBuffer);
        Irp->Tail.Overlay.AuxiliaryBuffer = NULL;
    }

    /* Check if this is a Paging I/O or Close Operation */
    if (Irp->Flags & (IRP_PAGING_IO | IRP_CLOSE_OPERATION))
    {
        /* Handle a Close Operation or Sync Paging I/O */
        if (Irp->Flags & (IRP_SYNCHRONOUS_PAGING_IO | IRP_CLOSE_OPERATION))
        {
            /* Set the I/O Status and Signal the Event */
            Flags = Irp->Flags & (IRP_SYNCHRONOUS_PAGING_IO | IRP_PAGING_IO);
            *Irp->UserIosb = Irp->IoStatus;
            KeSetEvent(Irp->UserEvent, PriorityBoost, FALSE);

            /* Free the IRP for a Paging I/O Only, Close is handled by us */
            if (Flags) IoFreeIrp(Irp);
        }
        else
        {
#if 0
            /* Page 166 */
            KeInitializeApc(&Irp->Tail.Apc
                            &Irp->Tail.Overlay.Thread->Tcb,
                            Irp->ApcEnvironment,
                            IopCompletePageWrite,
                            NULL,
                            NULL,
                            KernelMode,
                            NULL);
            KeInsertQueueApc(&Irp->Tail.Apc,
                             NULL,
                             NULL,
                             PriorityBoost);
#else
            /* Not implemented yet. */
            DPRINT1("Not supported!\n");
            while (TRUE);
#endif
        }

        /* Get out of here */
        return;
    }

    /* Unlock MDL Pages, page 167. */
    Mdl = Irp->MdlAddress;
    while (Mdl)
    {
    MmUnlockPages(Mdl);
        Mdl = Mdl->Next;
    }

    /* Check if we should exit because of a Deferred I/O (page 168) */
    if ((Irp->Flags & IRP_DEFER_IO_COMPLETION) && !(Irp->PendingReturned))
    {
        /*
         * Return without queuing the completion APC, since the caller will
         * take care of doing its own optimized completion at PASSIVE_LEVEL.
         */
        return;
    }

    /* Get the thread and file object */
    Thread = Irp->Tail.Overlay.Thread;
    FileObject = Irp->Tail.Overlay.OriginalFileObject;

    /* Make sure the IRP isn't canceled */
    if (!Irp->Cancel)
    {
        /* Initialize the APC */
        KeInitializeApc(&Irp->Tail.Apc,
                        &Thread->Tcb,
                        Irp->ApcEnvironment,
                        IopCompleteRequest,
                        NULL,
                        NULL,
                        KernelMode,
                        NULL);

        /* Queue it */
        KeInsertQueueApc(&Irp->Tail.Apc,
                         FileObject,
                         NULL, /* This is used for REPARSE stuff */
                         PriorityBoost);
    }
    else
    {
        /* The IRP just got canceled... does a thread still own it? */
        if (Thread)
        {
            /* Yes! There is still hope! Initialize the APC */
            KeInitializeApc(&Irp->Tail.Apc,
                            &Thread->Tcb,
                            Irp->ApcEnvironment,
                            IopCompleteRequest,
                            NULL,
                            NULL,
                            KernelMode,
                            NULL);

            /* Queue it */
            KeInsertQueueApc(&Irp->Tail.Apc,
                             FileObject,
                             NULL, /* This is used for REPARSE stuff */
                             PriorityBoost);
        }
        else
        {
            /* Nothing left for us to do, kill it */
            ASSERT(Irp->Cancel);
            IopCleanupIrp(Irp, FileObject);
        }
    }
}