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Getting the Volume Serial Number using Borland C++ 4.5 (16-Bit)

ehilder asked
Last Modified: 2008-03-03
I am trying to write a dll in C++ that will return the Volume Serial Number of any drive (or at least Drive C:).  I am not sure exactly how to do this.  I'm sure there is a pretty easy way, but I am new at C and have very little time to learn it.  Could someone send me source for a simple 16-bit DLL that will return the Volume Serial Number?
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Could you tell us some information concerning your environment? (Win 3.1x, Win95/NT). Do you absolutly need a 16-bit dll?


The application that will use the DLL is designed in Visual D-Base.  The application will be run on all platforms of Windows. (3.1x, Win95 and WinNt)  Since it is possible that the application will be run on Windows 3.1 without Win32s, I would prefer a 16-bit DLL.  If this is absolutely impossible, I could recommend that the application be run only in 32-bit mode.

The following function will return you the volume name and serial number of any drive.

static      void      Get_Volume_Info(int Disk, char *Vol, char *SSN)
  unsigned      char buf[1024];
  int           i;

  strcpy(Vol, "");
  strcpy(SSN, "");

  i = biosdisk(2, Disk, Disk >= 0x80 ? 1 : 0, 0, 1, 1, &buf);
  if(i == 0)
#pragma warn -ucp
    strncpy(Vol, buf+0x2B, 11);
    Vol[11] = '\0';
    sprintf(SSN, "%02X%02X-%02X%02X", buf[0x2a], buf[0x29],       buf[0x28], buf[0x27]);
#pragma warn +ucp


I know that I am new to C, but I was just wondering...  How exactly do you use a DOS ONLY function in a Windows DLL?
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The 16-Bit example works great, but I do need a little more information.  I am increasing the points to 150.

I am new to C++ and I was wondering if you could post an example using the GetVolumeInformation() function in Win32.  Also, is there a way to tell if Windows is running 16-bit or 32-bit.  
The reasoning is that this DLL needs to run in 16-bit and 32-bit and on Windows NT.

If I can tell that Windows is running in 32-bit, I can branch from the 16-bit routine to the 32-bit routine.  Even if they are in two DLL's.  Can you test for 32-bit mode in a 16-bit DLL???  If so, this is how I would like to work it.

Does this make sense?

The following is the example using GetVolumeInformation.

CHAR szVolumeName[MAX_PATH], szFSName[MAX_PATH];
      DWORD dwVolSerialNum,
      ::GetVolumeInformation("c:\\",  // "d:\\" for d:, NULL for current directory

CHAR szBuf[256];
                   "szVolumeName = %s\n"
                   "dwVolSerialNum = %lX\n"
                   "dwMaxCompLen = %lu\n"
                     "dwFSFlags = %lu\n"
                     "szFSName = %s\n",
      ::MessageBox(NULL, szBuf, "GetVolumeInformation", MB_OK);

If your program is 32-bit, it must be running on a 32-bit platform (including Win32s on Windows 3.1, you can check it with GetVersionEx function). A 16-bit platform cannot run a 32-bit program.

If your program is 16-bit, it may be running on a 16-bit platform or a 32-bit platform. You can check the version with GetVersion function in a 16-bit program. For Windows 3.1, it returns version 3.1. For Windows 95, it returns version 3.95. I have not tried it on Windows NT. However, you cannot call a 32-bit DLL from a 16-bit program or DLL although you can run a 32-bit EXE from a 16-bit program or DLL.

So, in your case, you might need to provide two version: one is 16-bit, another is 32-bit.

Sorry, I think I made a mistake. I said "you cannot call a 32-bit DLL from a 16-bit program or DLL". In fact, there is a way to do so. Generic Thunks allow a 16-bit Windows-based application to load and call a Win32-based DLL on Windows NT and Windows 95. See the following Win32 SDK documentation:
Win32 SDK/Programming Guides and Tools/Programming Techniques/Generic Thunks.

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