Physical/Logical partition info - how to get?

Posted on 1998-01-24
Last Modified: 2013-12-03
I have a computer with one hard disk. the disk is splited into two logical drives (C:, D:). I need to write a procedure that retrive this data (one hard disk with two logical drives).
The real task is to know how many hard disks the computer have( IDE or SCSI ) and which logical drive reside in which hard disk.
I know how to do this by reading from the registry in win95, but the NT registry is different from the win95 one, so I can't use this.
I also tried use the DeviceIOCtrl, but failed to make it work right.
There is also an int 21 service that deals with the subject but I couldn't make it work properly.
I already post this question in the delphi section but they helped none. Please answer this only if you REALLY know the answer.
Question by:TheSwine
LVL 32

Expert Comment

ID: 1410297
Use the DevIoControl IOCTL_DISK_GET_DRIVE_LAYOUT operation.  This gets you a DRIVE_LAYOUT_INFORMATION structure which points to a series of PARTITION_INFORMATION structutes for each partition.

Author Comment

ID: 1410298
As I wrote before, I failed make this work using DeviceIOControl. I am familiar with everything you wrote, please add some full sample code, Thanks.

Author Comment

ID: 1410299
Adjusted points to 305

Expert Comment

ID: 1410300
You might recognize me, cause I already tried to answer your question
in the delphi section.
You see, I am also interessed in solving that problem.
I'm writing here now to keep the question alive ;)
Would you agree to help me solve your problem ?
May you send me the code you already tryed out ?
I will only have time to answer that question next week,
cause for now I still have exams at school :(
Unfortunately I had done a part of the answer yesterday,
but since I'm very new to using NT, I made some changes that
crashed the NT partition, so I lost the code source I wrote in temp ;).
I wrote C++ in parallel with pascal, and I did not get the same
result in pascal. this might be because I had to write the
structures by myself. How do you translate following in pascal ?

partLayout test[1];

partLayout is the type. The msdn says this is a variable array.
How do you make such a thing in pascal?

I'm waiting your suggestions ?

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Expert Comment

ID: 1410301
Dear Jeurk,

The partLayout test[1]; code is a generic code that indicates the test variable may contain several partLayout structures attached end to end in the memory: The direct translation is

  test : array[0..0] of partLayout;

but I should see the actual API help fragment to correcly interpret. If need help please give the keyword for WIN32 help


Expert Comment

ID: 1410302
Hi Igor,
Your help is welcome, i'm at school for now.
I'll come back tomorrow and post the structures I need
to be translated.

CU, Jeurk
LVL 15

Accepted Solution

Tommy Hui earned 300 total points
ID: 1410303
Here's some sample code:

void CDrvLayView::AddLine(const CString& msg)
      CRichEditCtrl& ctrl = GetRichEditCtrl();

      long l = ctrl.GetTextLength();
      ctrl.SetSel(l, l);

struct _PTMAP
      int   m_PT;
      char* m_Info;
} g_PTMap[] =
      { PARTITION_ENTRY_UNUSED, "Entry unused" },
      { PARTITION_FAT_12, "Specifies a partition with 12-bit FAT entries" },
      { PARTITION_XENIX_1, "Specifies a Xenix type 1 partition" },
      { PARTITION_XENIX_2, "Specifies a Xenix type 2 partition" },
      { PARTITION_FAT_16, "Specifies a partition with 16-bit FAT entries" },
      { PARTITION_EXTENDED, "Specifies an extended partition entry" },
      { PARTITION_HUGE, "Specifies an MS-DOS V4 huge partition" },
      { PARTITION_IFS, "Specifies an IFS partition" },
      { PARTITION_PREP, "Specifies a PowerPC Reference Platform partition" },
      { PARTITION_UNIX, "Specifies a UNIX partition" },
      { VALID_NTFT, "Specifies an NTFT partition" },
      { PARTITION_XINT13, "Specifies a Windows 95 partition that uses extended int13 services" },
      { PARTITION_XINT13_EXTENDED, "Same as PARTITION_EXTENDED, but uses extended int13 services" },

CString ConvertBool(BOOL b)
      return b ? "True" : "False";

void CDrvLayView::OnDrivesSelChange()
      CString driveLetter =  g_DriveTB->GetCurrentDrive();

      CString msg;
      msg.Format("Changing to %s.\r\n", driveLetter);

      CString drive = "\\\\.\\" + driveLetter;

            OPEN_EXISTING, 0, NULL);

      if (h == INVALID_HANDLE_VALUE)
            msg.Format("Failed to open %s. GetLastError() returned %d\r\n",
                  driveLetter, GetLastError());
            DWORD bytesReturned = 0;

            if (!DeviceIoControl(h, IOCTL_DISK_GET_PARTITION_INFO, NULL, 0,
                  &pi, sizeof(pi), &bytesReturned, NULL))
                  msg.Format("Failed to obtain partition info for %s. GetLastError() returned %d\r\n",
                        driveLetter, GetLastError());
                  msg.Format("Offset at 0x%08X:0x%08X\r\n", pi.StartingOffset.HighPart,

                  msg.Format("Length at 0x%08X:0x%08X\r\n", pi.PartitionLength.HighPart,

                  msg.Format("Number of hidden sectors: %d\r\n", pi.HiddenSectors);

                  msg.Format("Number of partitions: %d\r\n", pi.PartitionNumber);

                  CString partitionType = "Unknown";

                  for (int i = 0; i < sizeof(g_PTMap) / sizeof(g_PTMap[0]); i++)
                        if (pi.PartitionType == g_PTMap[i].m_PT)
                              partitionType = g_PTMap[i].m_Info;

                  msg.Format("Type of partitions: %s\r\n", partitionType);

                  msg.Format("Bootable? %s\r\n", ConvertBool(pi.BootIndicator));

                  msg.Format("Recognized? %s\r\n", ConvertBool(pi.RecognizedPartition));

//                  msg.Format("Rewritable? %s\r\n", ConvertBool(pi.RewritePartition));
//                  AddLine(msg);



Author Comment

ID: 1410304
Thanks tui.
It will take me about a week to check it up cause I'm very busy right now. I'll get back to you in few day's

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