windows的磁盤操作之一——基本概念 (1)

　　最近項目中需要在windows系統下與磁盤打交道，用了一個禮拜時間，弄懂了一些基本的概念，記錄于此，并以項目中的部分代碼作為范例。
　　首先說明一點，本文中使用的不是cmd命令行，基于以下幾點原因：
　　1.在C/C++中調用系統命令會存在處理的種種不方便，需要大量額外的代碼去分析命令執行結果。
　　2.windows命令行遠不如linux的shell來的強大。
　　3.效率。
　　當然，如果不考慮編碼，僅作為系統下一種應用工具的話，DiskPart是既安全又便利的選擇。
　　我們先來看幾個主要的使用頻繁的函數。
　　在windows下與磁盤打交道最主要的API就是DeviceIoControl了，以下是從MSDN中直接拷貝出來的對該函數的說明。此函數確實太重要也太強大了，建議大家耐著性子先將它的說明看完，當然，本文后續例子中會大量用到此函數，可隨時返回此節參閱。
　　DeviceIoControl Function
　　Sends a control code directly to a specified device driver, causing the corresponding device to perform the corresponding operation.
　　BOOL WINAPI DeviceIoControl（
　　__in          HANDLE hDevice,
　　__in          DWORD dwIoControlCode,
　　__in          LPVOID lpInBuffer,
　　__in          DWORD nInBufferSize,
　　__out         LPVOID lpOutBuffer,
　　__in          DWORD nOutBufferSize,
　　__out         LPDWORD lpBytesReturned,
　　__in          LPOVERLAPPED lpOverlapped
　　）;
　　Parameters
　　hDevice
　　A handle to the device on which the operation is to be performed. The device is typically a volume, directory, file, or stream. To retrieve a device handle, use the CreateFile function. For more information, see Remarks.
　　dwIoControlCode
　　The control code for the operation. This value identifies the specific operation to be performed and the type of device on which to perform it.
　　For a list of the control codes, see Remarks. The documentation for each control code provides usage details for the lpInBuffer, nInBufferSize, lpOutBuffer, and nOutBufferSize parameters.
　　lpInBuffer
　　A pointer to the input buffer that contains the data required to perform the operation. The format of this data depends on the value of the dwIoControlCode parameter.
　　This parameter can be NULL if dwIoControlCode specifies an operation that does not require input data.
　　nInBufferSize
　　The size of the input buffer, in bytes.
　　lpOutBuffer
　　A pointer to the output buffer that is to receive the data returned by the operation. The format of this data depends on the value of the dwIoControlCode parameter.
　　This parameter can be NULL if dwIoControlCode specifies an operation that does not return data.
　　nOutBufferSize
　　The size of the output buffer, in bytes.
　　lpBytesReturned
　　A pointer to a variable that receives the size of the data stored in the output buffer, in bytes.
　　If the output buffer is too small to receive any data, the call fails, GetLastError returns ERROR_INSUFFICIENT_BUFFER, and lpBytesReturned is zero.
　　If the output buffer is too small to hold all of the data but can hold some entries, some drivers will return as much data as fits. In this case, the call fails, GetLastError returns ERROR_MORE_DATA, and lpBytesReturned indicates the amount of data received. Your application should call DeviceIoControl again with the same operation, specifying a new starting point.
　　If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation returns no output data and lpOutBuffer is NULL, DeviceIoControl makes use of lpBytesReturned. After such an operation, the value of lpBytesReturned is meaningless.
　　If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this parameter is not NULL and the operation returns data, lpBytesReturned is meaningless until the overlapped operation has completed. To retrieve the number of bytes returned, call GetOverlappedResult. If hDevice is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.
　　lpOverlapped
　　A pointer to an OVERLAPPED structure.
　　If hDevice was opened without specifying FILE_FLAG_OVERLAPPED, lpOverlapped is ignored.
　　If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, the operation is performed as an overlapped （asynchronous） operation. In this case, lpOverlapped must point to a valid OVERLAPPED structure that contains a handle to an event object. Otherwise, the function fails in unpredictable ways.
　　For overlapped operations, DeviceIoControl returns immediately, and the event object is signaled when the operation has been completed. Otherwise, the function does not return until the operation has been completed or an error occurs.
　　Return Value
　　If the operation completes successfully, the return value is nonzero.
　　If the operation fails or is pending, the return value is zero. To get extended error information, call GetLastError.
　　Remarks
　　To retrieve a handle to the device, you must call the CreateFile function with either the name of a device or the name of the driver associated with a device. To specify a device name, use the following format:
　　\\.\DeviceName
　　DeviceIoControl can accept a handle to a specific device. For example, to open a handle to the logical drive A: with CreateFile, specify \\.\a:. Alternatively, you can use the names \\.\PhysicalDrive0, \\.\PhysicalDrive1, and so on, to open handles to the physical drives on a system.
　　You should specify the FILE_SHARE_READ and FILE_SHARE_WRITE access flags when calling CreateFile to open a handle to a device driver. However, when you open a communications resource, such as a serial port, you must specify exclusive access. Use the other CreateFile parameters as follows when opening a device handle:
　　·         The fdwCreate parameter must specify OPEN_EXISTING.
　　·         The hTemplateFile parameter must be NULL.
　　·         The fdwAttrsAndFlags parameter can specify FILE_FLAG_OVERLAPPED to indicate that the returned handle can be used in overlapped （asynchronous） I/O operations.
　　Requirements
　　Client
　　Requires Windows Vista, Windows XP, Windows 2000 Professional, or Windows NT Workstation.
　　Server
　　Requires Windows Server 2008, Windows Server 2003, Windows 2000 Server, or Windows NT Server.
　　Header
　　Declared in Winbase.h; include Windows.h.
　　Library
　　Use Kernel32.lib.
　　DLL
　　Requires Kernel32.dll.
　　該函數實現對設備的訪問，包括獲取信息，發送命令，交換數據等。可以利用該接口函數向指定的設備驅動發送正確的控制碼及數據，分析它的響應，執行程序設計人員想要的功能。磁盤操作只是它強大功能中的一小部分。
　　該函數最重要的兩個參數是hDevice和dwIoControlCode.
　　控制碼dwIoControlCode決定了操作類型，與磁盤相關的控制碼有
　　IOCTL_DISK_CREATE_DISK    利用CREATE_DISK結構中的信息對指定磁盤和磁盤分區進行初始化。
　　IOCTL_DISK_DELETE_DRIVE_LAYOUT    從主引導記錄中刪除引導信息，所以磁盤將會被從頭到尾的格式化。扇區0中的分區信息也就不復存在了。
　　IOCTL_DISK_FORMAT_TRACKS    格式化指定的、連續的軟盤磁道。如果需要更多的功能請使用IOCTL_DISK_FORMAT_TRACKS_EX。
　　IOCTL_DISK_FORMAT_TRACKS_EX    格式化指定的、連續的軟盤磁道。
　　IOCTL_DISK_GET_CACHE_INFORMATION    返回磁盤的高速緩存配置數據
　　IOCTL_DISK_GET_DRIVE_GEOMETRY_EX    返回物理磁盤的擴展信息。包括：類型、柱面數量、每柱面磁道數、每磁道扇區數和每扇區字節數等。
　　IOCTL_DISK_GET_DRIVE_LAYOUT_EX    返回各分區的擴展信息以及這些分區的特性。更多信息請參照DRIVE_LAYOUT_INFORMATION_EX結構。
　　IOCTL_DISK_GET_LENGTH_INFO    返回指定磁盤/卷/分區的大小信息
　　IOCTL_DISK_GET_PARTITION_INFO_EX    返回指定分區的擴展信息。包括：分區類型、大小和種類。更多信息請參照PARTITION_INFORMATION_EX結構。
　　IOCTL_DISK_GROW_PARTITION    擴大指定分區。
　　IOCTL_DISK_IS_WRITABLE    確定指定磁盤是否可寫。
　　IOCTL_DISK_PERFORMANCE    啟用并獲取磁盤性能統計
　　IOCTL_DISK_PERFORMANCE_OFF    關閉磁盤性能統計
　　IOCTL_DISK_REASSIGN_BLOCKS    使磁盤設備影射一塊區域做為它的備用存儲塊公用池（spare block pool）。
　　IOCTL_DISK_SET_CACHE_INFORMATION    設置磁盤的配置信息
　　IOCTL_DISK_SET_DRIVE_LAYOUT_EX    根據給定的磁盤信息對磁盤進行分區。
　　IOCTL_DISK_SET_PARTITION_INFO_EX    設置指定分區的分區信息。包括AT和EFI （Extensible Firmware Interface）分區的布局信息。
　　IOCTL_DISK_UPDATE_PROPERTIES    使緩沖的分區表無效并重新獲取一份。
　　IOCTL_DISK_VERIFY    對指定磁盤進行邏輯格式化
　　另一個參數hDevice指向要操作的設備句柄，調用函數CreateFile獲得。CreateFile函數原型為
　　HANDLE WINAPI CreateFile（
　　__in          LPCTSTR lpFileName,
　　__in          DWORD dwDesiredAccess,
　　__in          DWORD dwShareMode,
　　__in          LPSECURITY_ATTRIBUTES lpSecurityAttributes,
　　__in          DWORD dwCreationDisposition,
　　__in      

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