How do I use SetFilePointerEx to go to the end of a physical disk?

I have been able to use SetFilePointerEx just fine, when setting the position only.

SetFilePointerEx(PD, 512, @PositionVar, FILE_BEGIN);
SetFilePointerEx(PD, 0, @PositionVar, FILE_CURRENT);

Both work; I can set positions and even check m开发者_JS百科y current one. But when I set FILE_END as per the documentation no matter what the second parameter is and whether or not I provide a pointer for the third parameter, it fails, even on a valid handle that many other operations are able to use without fail.

For example:

SetFailed := SetFilePointerEx(PD, 0, @PositionVar, FILE_END);
SetFailed := SetFilePointerEx(PD, 0, nil, FILE_END);

Whatever I put, it fails. I am working with a handle to a physical disk and it most definitely has an end. SetFilePointer works just fine, but it's just a little more trouble than I would like.

It's not the end of the world, but whats happening.

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You can't do this as you have found out. You have to seek from the beginning or current. Use DeviceIoControl to find out the size of the device.