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Phil Gardner's Wrapper.sys & MS-DOS7 bug (Miscellaneous)

posted by cm(R) Homepage E-mail, Düsseldorf, Germany, 12.12.2009, 11:48

> Why would it care about the DOS version for this? To make a DOS drive from
> the block device's units it needs to make a DPB, yes, but the kernel has a
> function for this.

No, the kernel function only fills the DPB with data. For this, the DPB must be allocated. DEVLOAD needs to know the DPB's size to allocate it. (Sorry, me stating it needs to "create" DPBs was too vague.)

> If by explicit you want it in letters ten feet high "test for whether DOS
> has FAT32 support", then no, but that was never very much Microsoft's way
> in the days of DOS or VxDs.

My previous example Int21.71A0 is called "LFN Get volume information" and one of the returned flags is "Supports DOS long filename functions". I'd count that as explicit, though you're right: many other interfaces don't have explicit checks.

> If you want to test that support exists, you
> try to use the desired support in a way that won't change anything
> important, but whose success you can assess.

Exactly. Unfortunately not all programmers had this good idea, especially regarding checks for DOS FAT32 and LFN support.

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l

 

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