最近專案中需要在windows系統下與磁碟打交道，用了一個禮拜時間，弄懂了一些基本的概念，記錄於此，並以專案中的部分程式碼作為範例。

首先說明一點，本文中使用的不是cmd命令列，基於以下幾點原因：

1．在C/C++中呼叫系統命令會存在處理的種種不方便，需要大量額外的程式碼去分析命令執行結果。

2．windows命令列遠不如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式。

在windows下與磁碟打交道最主要的API就是DeviceIoControl了，以下是從MSDN中直接拷貝出來的對該函式的說明。此函式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，本文後續例子中會大量用到此函式，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.

該函式實現對裝置的訪問，包括獲取資訊，傳送命令，交換資料等。可以利用該介面函式向指定的裝置驅動傳送正確的控制碼及資料，分析它的響應，執行程式設計人員想要的功能。磁碟操作只是它強大功能中的一小部分。

該函式最重要的兩個引數是hDevice和dwIoControlCode.

控制碼dwIoControlCode決定了操作型別，與磁碟相關的控制碼有

IOCTL_DISK_CREATE_DISK    利用CREATE_DISK結構中的資訊對指定磁碟和磁碟分割槽進行初始化。

IOCTL_DISK_DELETE_DRIVE_LAYOUT    從主引導記錄中刪除引導資訊，所以磁碟將會被從頭到尾的格式化。扇區0中的分割槽資訊也就不復存在了。

IOCTL_DISK_FORMAT_TRACKS    格式化指定的、連續的軟盤磁軌。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、連續的軟盤磁軌。

IOCTL_DISK_GET_CACHE_INFORMATION    返回磁碟的快取記憶體配置資料

IOCTL_DISK_GET_DRIVE_GEOMETRY_EX    返回物理磁碟的擴充套件資訊。包括：型別、柱面數量、每柱面磁軌數、每磁軌扇區數和每扇區位元組數等。

IOCTL_DISK_GET_DRIVE_LAYOUT_EX    返回各分割槽的擴充套件資訊以及這些分割槽的特性。更多資訊請參照DRIVE_LAYOUT_INFORMATION_EX結構。

IOCTL_DISK_GET_LENGTH_INFO    返回指定磁碟/卷/分割槽的大小資訊

IOCTL_DISK_GET_PARTITION_INFO_EX    返回指定分割槽的擴充套件資訊。包括：分割槽型別、大小和種類。更多資訊請參照PARTITION_INFORMATION_EX結構。

IOCTL_DISK_GROW_PARTITION    擴大指定分割槽。

IOCTL_DISK_IS_WRITABLE    確定指定磁碟是否可寫。

IOCTL_DISK_PERFORMANCE    啟用並獲取磁碟效能統計

IOCTL_DISK_PERFORMANCE_OFF    關閉磁碟效能統計

IOCTL_DISK_REASSIGN_BLOCKS    使磁碟裝置影射一塊區域做為它的備用儲存塊公用池（spare block pool）。

IOCTL_DISK_SET_CACHE_INFORMATION    設定磁碟的配置資訊

IOCTL_DISK_SET_DRIVE_LAYOUT_EX    根據給定的磁碟資訊對磁碟進行分割槽。

IOCTL_DISK_SET_PARTITION_INFO_EX    設定指定分割槽的分割槽資訊。包括AT和EFI (Extensible Firmware Interface)分割槽的佈局資訊。

IOCTL_DISK_UPDATE_PROPERTIES    使緩衝的分割槽表無效並重新獲取一份。

IOCTL_DISK_VERIFY    對指定磁碟進行邏輯格式化  

另一個引數hDevice指向要操作的裝置控制代碼，呼叫函式CreateFile獲得。CreateFile函式原型為

HANDLE WINAPI CreateFile(

 __in          LPCTSTR lpFileName,

 __in          DWORD dwDesiredAccess,

 __in          DWORD dwShareMode,

 __in          LPSECURITY_ATTRIBUTES lpSecurityAttributes,

 __in          DWORD dwCreationDisposition,

 __in          DWORD dwFlagsAndAttributes,

 __in          HANDLE hTemplateFile

);

lpFileName為需要開啟裝置的名稱，對於磁碟來說，可能為以下幾種形式：

對於物理驅動器x，形式為 \\.\PhysicalDriveX ，編號從0開始，例如

名稱	含義
\\.\PhysicalDrive0	開啟第一個物理驅動器
\\.\PhysicalDrive2	開啟第三個物理驅動器

對於邏輯分割槽（卷），形式為 \\.\X: ，例如

名稱	含義
\\.\A:	開啟A盤（軟碟機）
\\.\C:	開啟C盤（磁碟邏輯分割槽）

最後複製一段MSDN上的示例程式碼作為本節的結束，該示例獲取磁碟的詳細資訊（包括柱面、磁軌、扇區等統計資訊）並打印出來。

/* The code of interest is in the subroutine GetDriveGeometry. The

   code in main shows how to interpret the results of the call. */

#include <windows.h>

#include <winioctl.h>

#include <stdio.h>

BOOL GetDriveGeometry(DISK_GEOMETRY *pdg)

{

 HANDLE hDevice;               // handle to the drive to be examined

 BOOL bResult;                  // results flag

 DWORD junk;                   // discard results

 hDevice = CreateFile(TEXT("\\\\.\\PhysicalDrive0"), // drive

                    0,                // no access to the drive

                    FILE_SHARE_READ | // share mode

                    FILE_SHARE_WRITE,

                    NULL,             // default security attributes

                    OPEN_EXISTING,   // disposition

                    0,                // file attributes

                    NULL);            // do not copy file attributes

 if (hDevice == INVALID_HANDLE_VALUE) // cannot open the drive

 {

    return (FALSE);

 }

 bResult = DeviceIoControl(hDevice, // device to be queried

      IOCTL_DISK_GET_DRIVE_GEOMETRY, // operation to perform

                             NULL, 0, // no input buffer

                            pdg, sizeof(*pdg),     // output buffer

                            &junk,                 // # bytes returned

                            (LPOVERLAPPED) NULL); // synchronous I/O

 CloseHandle(hDevice);

 return (bResult);

}

int main(int argc, char *argv[])

{

 DISK_GEOMETRY pdg;            // disk drive geometry structure

 BOOL bResult;                 // generic results flag

 ULONGLONG DiskSize;           // size of the drive, in bytes

 bResult = GetDriveGeometry (&pdg);

 if (bResult)

 {

    printf("Cylinders = %I64d\n", pdg.Cylinders);

    printf("Tracks/cylinder = %ld\n", (ULONG) pdg.TracksPerCylinder);

    printf("Sectors/track = %ld\n", (ULONG) pdg.SectorsPerTrack);

    printf("Bytes/sector = %ld\n", (ULONG) pdg.BytesPerSector);

    DiskSize = pdg.Cylinders.QuadPart * (ULONG)pdg.TracksPerCylinder *

      (ULONG)pdg.SectorsPerTrack * (ULONG)pdg.BytesPerSector;

    printf("Disk size = %I64d (Bytes) = %I64d (Gb)\n", DiskSize,

           DiskSize / (1024 * 1024 * 1024));

 }

 else

 {

    printf ("GetDriveGeometry failed. Error %ld.\n", GetLastError ());

 }

 return ((int)bResult);

}