windows的磁碟操作之二——初始化磁碟

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上一節中我們介紹了一些基本概念和主要的API,本節開始我們將列舉並分析一些執行個體。本文中的所有代碼我都在vs2008下測試過,讀者只需要替換少量的宏定義即可編譯執行。

 面對一塊新的磁碟,我們首先要做的就是對其初始化。在系統中通過windows的磁碟管理完成這一點非常容易,但在程式中實現略微複雜。本節的範例程式碼對一塊新硬碟初始化,並在上面建立分區。代碼如下: /******************************************************************************* Function: initialize the disk and create partitions* input: disk, disk name*        parNum, partition number* output: N/A* return: Succeed, 0*         Fail, -1******************************************************************************/DWORD CreateDisk(DWORD disk, WORD partNum){    HANDLE hDevice;               // handle to the drive to be examined    BOOL result;                  // results flag    DWORD readed;                 // discard results    DWORD ret;    WORD i;    CHAR diskPath[DISK_PATH_LEN];    DISK_GEOMETRY pdg;    DWORD sectorSize;    DWORD signature;    LARGE_INTEGER diskSize;    LARGE_INTEGER partSize;    BYTE actualPartNum;        DWORD layoutStructSize;    DRIVE_LAYOUT_INFORMATION_EX *dl;    CREATE_DISK newDisk;     sprintf(diskPath, "\\\\.\\PhysicalDrive%d", disk);     actualPartNum = 4;    if (partNum > actualPartNum)    {        return (WORD)-1;    }        hDevice = CreateFile(                diskPath,                GENERIC_READ|GENERIC_WRITE,
                FILE_SHARE_READ|FILE_SHARE_WRITE,                NULL,           //default security attributes  
                OPEN_EXISTING, // disposition  
                0,              // file attributes  
                NULL                );    if (hDevice == INVALID_HANDLE_VALUE) // cannot open the drive    {        fprintf(stderr, "CreateFile() Error: %ld\n", GetLastError());        return DWORD(-1);    }        // Create primary partition MBR    newDisk.PartitionStyle = PARTITION_STYLE_MBR;    signature = (DWORD)time(NULL);     //get signature from current time    newDisk.Mbr.Signature = signature;        result = DeviceIoControl(                hDevice,                IOCTL_DISK_CREATE_DISK,                &newDisk,                sizeof(CREATE_DISK),                NULL,                0,                &readed,                NULL                );    if (!result)    {        fprintf(stderr, "IOCTL_DISK_CREATE_DISK Error: %ld\n", GetLastError());        (void)CloseHandle(hDevice);        return DWORD(-1);    }     //fresh the partition table    result = DeviceIoControl(                hDevice,                IOCTL_DISK_UPDATE_PROPERTIES,
                NULL,                0,                NULL,                0,                &readed,                NULL                );    if (!result)    {        fprintf(stderr, "IOCTL_DISK_UPDATE_PROPERTIES Error: %ld\n", GetLastError());        (void)CloseHandle(hDevice);        return DWORD(-1);    }     //Now create the partitions    ret = GetDriveGeometry(diskPath, &pdg);    if ((DWORD)-1 == ret)    {        return ret;    }    sectorSize = pdg.BytesPerSector;    diskSize.QuadPart = pdg.Cylinders.QuadPart * pdg.TracksPerCylinder *                        pdg.SectorsPerTrack * pdg.BytesPerSector;       //calculate the disk size;    partSize.QuadPart = diskSize.QuadPart / partNum;     layoutStructSize = sizeof(DRIVE_LAYOUT_INFORMATION_EX) + (actualPartNum - 1) * sizeof(PARTITION_INFORMATION_EX);    dl = (DRIVE_LAYOUT_INFORMATION_EX*)malloc(layoutStructSize);    if (NULL == dl)    {        (void)CloseHandle(hDevice);        return (WORD)-1;    }     dl->PartitionStyle = (DWORD)PARTITION_STYLE_MBR;    dl->PartitionCount = actualPartNum;    dl->Mbr.Signature = signature;     //clear the unused partitions    for (i = 0; i < actualPartNum; i++){        dl->PartitionEntry[i].RewritePartition = 1;        dl->PartitionEntry[i].Mbr.PartitionType = PARTITION_ENTRY_UNUSED;    }    //set the profile of the partitions    for (i = 0; i < partNum; i++){        dl->PartitionEntry[i].PartitionStyle = PARTITION_STYLE_MBR;        dl->PartitionEntry[i].StartingOffset.QuadPart =
            (partSize.QuadPart * i) + ((LONGLONG)(pdg.SectorsPerTrack) * (LONGLONG)(pdg.BytesPerSector));   //32256        dl->PartitionEntry[i].PartitionLength.QuadPart = partSize.QuadPart;        dl->PartitionEntry[i].PartitionNumber = i + 1;        dl->PartitionEntry[i].RewritePartition = TRUE;        dl->PartitionEntry[i].Mbr.PartitionType = PARTITION_IFS;        dl->PartitionEntry[i].Mbr.BootIndicator = FALSE;        dl->PartitionEntry[i].Mbr.RecognizedPartition = TRUE;        dl->PartitionEntry[i].Mbr.HiddenSectors =
            pdg.SectorsPerTrack + (DWORD)((partSize.QuadPart / sectorSize) * i);    }    //execute the layout       result = DeviceIoControl(                hDevice,                 IOCTL_DISK_SET_DRIVE_LAYOUT_EX,
                dl,                 layoutStructSize,                 NULL,                 0,                &readed,                 NULL                );    if (!result)    {        fprintf(stderr, "IOCTL_DISK_SET_DRIVE_LAYOUT_EX Error: %ld\n", GetLastError());        free(dl);        (void)CloseHandle(hDevice);        return DWORD(-1);    }     //fresh the partition table    result = DeviceIoControl(                hDevice,                IOCTL_DISK_UPDATE_PROPERTIES,
                NULL,                0,                NULL,                0,                &readed,                NULL                );    if (!result)    {        fprintf(stderr, "IOCTL_DISK_UPDATE_PROPERTIES Error: %ld\n", GetLastError());        free(dl);        (void)CloseHandle(hDevice);        return DWORD(-1);    }     free(dl);    (void)CloseHandle(hDevice);    Sleep(3000);            //wait the operations take effect    return 0;} 函數CreateDisk包含兩個參數,DWORD disk 填入物理磁碟機代號,參見第一節。WORD partNum 表示需要建立的分區數,partNum <= 4。 函數的執行流程解釋如下:/***************初始化磁碟*****************/1. 根據disk建立裝置名稱,\\\\.\\PhysicalDriveX,這裡由於要轉義,所以”\”都寫為”\\”。2. 調用CreateFile開啟裝置檔案,並獲得控制代碼。3. 用作業碼IOCTL_DISK_CREATE_DISK調用DeviceIoControl函數,初始化磁碟並建立分區表。使用IOCTL_DISK_CREATE_DISK作業碼時,lpInBuffer要填入一個CREATE_DISK結構參數,其中包括分區表類型和磁碟簽名等參數,詳見MSDN。本例中建立MBR分區表,簽名由目前時間產生。4. 重新整理分區表。注意,程式中任何時候對磁碟的分區資訊進行了修改都需要叫用作業碼為IOCTL_DISK_UPDATE_PROPERTIES的DeviceIoControl函數來重新整理分區表,是操作切實生效。/****************建立分區*******************/5. 調用GetDriveGeometry擷取磁碟資訊(GetDriveGeometry參見上一節http://cutebunny.blog.51cto.com/301216/624027)。由於建立分區時要填入分區大小資訊,我們此處先計算磁碟總大小,然後除以partNum將位元組數平均分配到各個分區。6. 分配DRIVE_LAYOUT_INFORMATION_EX結構體空間。我們通過在這個結構體中填入資料來指定如何對硬碟進行分區。結構體定義如下typedef struct _DRIVE_LAYOUT_INFORMATION_EX {DWORD PartitionStyle;DWORD PartitionCount;union {    DRIVE_LAYOUT_INFORMATION_MBR Mbr;    DRIVE_LAYOUT_INFORMATION_GPT Gpt;};PARTITION_INFORMATION_EX
PartitionEntry[1];} DRIVE_LAYOUT_INFORMATION_EX, *PDRIVE_LAYOUT_INFORMATION_EX;       其中PartitionCount為4的倍數,為簡化處理,我們這裡定死為4。       另外還要注意PARTITION_INFORMATION_EX型的數組PartitionEntry[1]。雖然結構體中只定義了一個元素,但事實上必須在其後補足PartitionCount
– 1個元素。所以代碼中為DRIVE_LAYOUT_INFORMATION_EX *dl分配空間的時候加上了(actualPartNum - 1) * sizeof(PARTITION_INFORMATION_EX)。7. 在DRIVE_LAYOUT_INFORMATION_EX結構體空間dl中填入資料。先將所有分區都設為PARTITION_ENTRY_UNUSED,後面具體分配多少個分區再設定回來。然後再迴圈體內對每個分區的PartitionEntry賦值,其中StartingOffset除了跳過前面的分區已佔據的空間外,還要加上63個扇區空間(32256位元組)。PartitionNumber從1開始。Mbr.PartitionType = PARTITION_IFS表示NTFS格式。Mbr.HiddenSectors MSDN上說The number of hidden sectors to be allocated when the partition table is created.
我理解得不是很深刻,歡迎補充。8. 叫用作業碼為IOCTL_DISK_SET_DRIVE_LAYOUT_EX的DeviceIoControl函數執行分區,參數需要填入剛才準備好的DRIVE_LAYOUT_INFORMATION_EX結構體和大小。9. 重新整理分區表,原理同4。另外,我在函數末尾加上了Sleep(3000)。這是因為我發現建立分區操作需要一定的執行時間,如果後續緊跟著其它相關操作(例如格式化該分區)可能會產生分區不存在的錯誤,所以此處等待3秒確保其執行完畢。本節涉及的類型較多,但各類型具有很強的關聯性,讀者可隨時查閱MSDN獲得更詳細的說明。

 

本文出自 “bunny技術坊” 部落格,請務必保留此出處http://cutebunny.blog.51cto.com/301216/624052

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