filediskreadwrite.c

操作系统的一些有用的题目

#include <ntddk.h>
#include "ntifs.h"

NTSTATUS
FileDiskReadWrite (
    IN PDEVICE_OBJECT   DeviceObject,
    IN PIRP             Irp
    )
{
    PDEVICE_EXTENSION   device_extension;
    PIO_STACK_LOCATION  io_stack;

    device_extension = (PDEVICE_EXTENSION) DeviceObject->DeviceExtension;

    if (!device_extension->media_in_device)
    {
        Irp->IoStatus.Status = STATUS_NO_MEDIA_IN_DEVICE;
		//STATUS_NO_MEDIA_IN_DEVICE在ntstatus.h中定义为((NTSTATUS)0xC0000013L)
        Irp->IoStatus.Information = 0;

        IoCompleteRequest(Irp, IO_NO_INCREMENT);

        return STATUS_NO_MEDIA_IN_DEVICE;
    }//清空设备类型

    io_stack = IoGetCurrentIrpStackLocation(Irp);

    if (io_stack->Parameters.Read.Length == 0)
    {
        Irp->IoStatus.Status = STATUS_SUCCESS;
        Irp->IoStatus.Information = 0;

        IoCompleteRequest(Irp, IO_NO_INCREMENT);

        return STATUS_SUCCESS;
    }
	//完成对Irp的处理
    IoMarkIrpPending(Irp);
	//改变文件链表
    ExInterlockedInsertTailList(
        &device_extension->list_head,
        &Irp->Tail.Overlay.ListEntry,
        &device_extension->list_lock
        );

    KeSetEvent(
        &device_extension->request_event,
        (KPRIORITY) 0,
        FALSE
        );

    return STATUS_PENDING;
	//STATUS_PENDING在ntstatus.h中定义为((NTSTATUS)0x00000103L)
}