上一節中介紹瞭如何初始化一塊空白的磁盤，並創建分區。那麼對於一塊已存在分區的磁盤，我們如何獲得其分區信息，如何刪除其分區信息呢？本節對這兩類操作進行討論。
獲得磁盤分區信息的代碼如下。
/******************************************************************************
* Function: get the disk's drive layout infomation
* input: disk, disk name
* output: drive layout info
* return: Succeed, 0
* Fail, -1
******************************************************************************/
DWORD GetDiskDriveLayout(const CHAR *disk, DRIVE_LAYOUT_INFORMATION_EX *driveLayout)
{
HANDLE hDevice; // handle to the drive to be examined
BOOL result; // results flag
DWORD readed; // discard results
hDevice = CreateFile(
disk, // drive to open
GENERIC_READ | GENERIC_WRITE, // access to the drive
FILE_SHARE_READ | FILE_SHARE_WRITE, //share mode
NULL, // default security attributes
OPEN_EXISTING, // disposition
0, // file attributes
NULL // do not copy file attribute
);
if (hDevice == INVALID_HANDLE_VALUE) // cannot open the drive
{
fprintf(stderr, "CreateFile() Error: %ld\n", GetLastError());
return DWORD(-1);
}
result = DeviceIoControl(
hDevice, // handle to device
IOCTL_DISK_GET_DRIVE_LAYOUT_EX, // dwIoControlCode
NULL, // lpInBuffer
0, // nInBufferSize
driveLayout, // output buffer
sizeof(*driveLayout), // size of output buffer
&readed, // number of bytes returned
NULL // OVERLAPPED structure
);
if (!result)
{
fprintf(stderr, "IOCTL_DISK_GET_DRIVE_LAYOUT_EX Error: %ld\n", GetLastError());
(void)CloseHandle(hDevice);
return DWORD(-1);
}
(void)CloseHandle(hDevice);
return 0;
}
如果你已對上一節中創建分區的代碼http://cutebunny.blog.51cto.com/301216/624052 有了比較深刻的瞭解，那麼這段代碼就非常簡單了。程序執行流程爲：
1． 根據disk名稱調用CreateFile打開設備句柄。
2． 調用操作碼爲IOCTL_DISK_GET_DRIVE_LAYOUT_EX的DeviceIoControl函數獲取分區信息。返回的信息存儲在DRIVE_LAYOUT_INFORMATION_EX *driveLayout中。本例中我們只考慮了一個分區的情況，如果有多個分區，適當調整DeviceIoControl函數中的nOutBufferSize參數即可。
3． 解析*driveLayout即可獲得分區信息。
刪除磁盤分區信息的代碼如下，
/******************************************************************************
* Function: delete the partition layout of the disk
* input: disk, disk name
* output: N/A
* return: Succeed, 0
* Fail, -1
******************************************************************************/
DWORD DestroyDisk(DWORD disk)
{
HANDLE hDevice; // handle to the drive to be examined
BOOL result; // results flag
DWORD readed; // discard results
CHAR diskPath[DISK_PATH_LEN];
sprintf(diskPath, "\\\\.\\PhysicalDrive%d", disk);
hDevice = CreateFile(
diskPath, // drive to open
GENERIC_READ | GENERIC_WRITE, // access to the drive
FILE_SHARE_READ | FILE_SHARE_WRITE, //share mode
NULL, // default security attributes
OPEN_EXISTING, // disposition
0, // file attributes
NULL // do not copy file attribute
);
if (hDevice == INVALID_HANDLE_VALUE) // cannot open the drive
{
fprintf(stderr, "CreateFile() Error: %ld\n", GetLastError());
return DWORD(-1);
}
result = DeviceIoControl(
hDevice, // handle to device
IOCTL_DISK_DELETE_DRIVE_LAYOUT, // dwIoControlCode
NULL, // lpInBuffer
0, // nInBufferSize
NULL, // lpOutBuffer
0, // nOutBufferSize
&readed, // number of bytes returned
NULL // OVERLAPPED structure
);
if (!result)
{
//fprintf(stderr, "IOCTL_DISK_DELETE_DRIVE_LAYOUT 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);
}
(void)CloseHandle(hDevice);
return 0;
}
參數DWORD disk爲物理驅動器號。函數執行流程爲：
1． 根據驅動器號生成設備名稱。
2． 調用CreateFile打開設備並獲得設備句柄。
3． 調用操作碼爲IOCTL_DISK_DELETE_DRIVE_LAYOUT的DeviceIoControl函數刪除分區表。
4． 刷新分區表。
調用DestroyDisk後的磁盤在windows磁盤管理中的狀態爲
