How to tell if Windows partition is active?

[dc_2000]

My goal is to know if Windows is installed on an active disk partition. Any ideas?

[2kaud]

From within Windows?

[OReubens]

From within windows: may not even be possible depending on what sort of raw access you get to the partition information. On a typical windows, you can't access this other than writing a kernel disk driver.

if outside of windows. "It depends". Do you only care about MBR based partitioning or do you also need to support other partitioning schemes like EFI, GPT, MIX ?

Do you care about bootmenu's that boot the PC into a menu, then allow you to launch your OS even from non-active partitions or even logical partitions insife an extended partition (on MBR).
The concept of "active partition" kinda means you 're asking about MBR because other schemes have other terminilogy or maybe even no such concept as "active partition" at all.

[dc_2000]

Hmm. Good points guys. And yes, I do need it from within Windows. In other words, my app needs to know if the Windows it runs under is installed on an active partition. (And to OReubens's point, I'll be honest with you, I'm not very well versed in the subject of disk partitions, but from what I understand after reading about the subject, I do need it for the Master boot record.)

Let me explain. The reason I need to know this, is to diagnose an issue with workstations not being able to enter sleep mode if Windows is not installed on an active partition. (The real issue in this case probably lies within the chipset driver, but since I do not have direct access to the driver(s) that may be installed on those workstations, a quick workaround of making a partition active seems to solve the issue. In my case I need to know this from a user-mode service to flag it for the admins.)

[Arjay]

Check out using the WMI classes such as Win32_LogicalDisk or Win32_DiskPartition

[Igor Vartanov]

IOCTL_DISK_GET_PARTITION_INFO_EX looks like what you need.

[dc_2000]

Arjay, thanks. I tried playing with those two WMI classes and although Win32_DiskPartition seems to have the 'BootPartition' property that looks like what I need, I couldn't find a way to connect to that class by a partition path. None of its properties come close to it.

Igor, thanks for the info. I need to look into that ioctl function.

[Arjay]

Arjay, thanks. I tried playing with those two WMI classes and although Win32_DiskPartition seems to have the 'BootPartition' property that looks like what I need, I couldn't find a way to connect to that class by a partition path. None of its properties come close to it.

Igor, thanks for the info. I need to look into that ioctl function.

Use the WMI tools to view what you have on your system. One of the properties on it may identify the partition but not allow you to search by the property. If that is the case, then you can enumerate the disk partitions and select the match (based on the read-only property). Do a search on this forum for some WMI helper classes that I've written - it makes dealing with WMI fairly straightforward.

[OReubens]

what about..
booting in windows (from an active partition)
then from windows change the active partition so next reboot will be another OS
yes, this can be done.

Does that mean your diagnostic needs to fail because the currently active partition is not a windows one ?
or do you need to know if the running windows was actually started from a partition that was active at the time of boot.
How about if it was booted through a bootmenu that never made the Windows partition active ?
How about a VM that just emulates a real disk where functions like asking about partitions may fail entirely because partitions don't exist.
How about WINE on Linux ?