SendDownStreamIrp 函式

本主題中提供的函式程式碼範例 SendDownStreamIrp 示範如何實作驅動程式提供的函式，以將同步 IOCTL 要求傳送至 ACPI 驅動程式。 函 SendDownStreamIrp 式可用來傳送 IOCTL_ACPI_EVAL_METHOD 要求、 IOCTL_ACPI_EVAL_METHOD_EX 要求或 IOCTL_ACPI_ENUM_CHILDREN 要求。

本節中包含的函式範例程式碼 SendDownStreamIrp 會執行下列作業順序：

• 建立事件物件。

• 呼叫 IoBuildDeviceIoControlRequest 以建立 IOCTL 要求。

• 呼叫 IoCallDriver 以傳送 IOCTL 要求。

• 等候 ACPI 驅動程式發出事件物件的訊號，這表示要求已完成。

• 將要求的狀態傳回給呼叫端。

NTSTATUS
SendDownStreamIrp(
    IN PDEVICE_OBJECT   Pdo,
    IN ULONG            Ioctl,
    IN PVOID            InputBuffer,
    IN ULONG            InputSize,
    IN PVOID            OutputBuffer,
    IN ULONG            OutputSize
)
/*
Routine Description:
    General-purpose function called to send a request to the PDO. 
    The IOCTL argument accepts the control method being passed down
    by the calling function

    This subroutine is only valid for the IOCTLS other than ASYNC EVAL. 

Parameters:
    Pdo             - the request is sent to this device object
    Ioctl           - the request - specified by the calling function
    InputBuffer     - incoming request
    InputSize       - size of the incoming request
    OutputBuffer    - the answer
    OutputSize      - size of the answer buffer

Return Value:
    NT Status of the operation
*/
{
    IO_STATUS_BLOCK     ioBlock;
    KEVENT              myIoctlEvent;
    NTSTATUS            status;
    PIRP                irp;

    // Initialize an event to wait on
    KeInitializeEvent(&myIoctlEvent, SynchronizationEvent, FALSE);

    // Build the request
    irp = IoBuildDeviceIoControlRequest(
        Ioctl, 
        Pdo,
        InputBuffer,
        InputSize,
        OutputBuffer,
        OutputSize,
        FALSE,
        &myIoctlEvent,
        &ioBlock);

    if (!irp) {
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    // Pass request to Pdo, always wait for completion routine
    status = IoCallDriver(Pdo, irp);

    if (status == STATUS_PENDING) {
        // Wait for the IRP to be completed, and then return the status code
        KeWaitForSingleObject(
            &myIoctlEvent,
            Executive,
            KernelMode,
            FALSE,
            NULL);

        status = ioBlock.Status;
    }

    return status;
}