RE: [GD-Windows] retrieving the cluster size on xp

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Your assumption about every FS using clusters is just plain wrong.
I never had real problems with GetDiskFreeSpaceEx(). It may prove
to be imprecise on 9x, but I've never seen it fail. If you're
dealing with those values, be prepared to handle 1-sector clusters.
Because there's such stuff as virtual filesystems.
I think you're confusing clusters and sectors. And even sectors
do not have to be bigger than 1 byte. There are plenty of schemes
that handle allocations on 1-byte boundaries pretty well. And most
filesystems do _not_ use linked lists of sectors.
If you dig through some of the very fine literature on filesystem
design, you'll see that the whole concept of clusters is arbitrary
and a clear sign of a design that doesn't fit the amount of data
it is trying to handle.

Best regards,

Carsten Orthbandt
Founder + Development Director
SEK SpieleEntwicklungsKombinat GmbH
http://www.sek-ost.de

Wenn ich Visionen habe, gehe ich zum Arzt. - Helmut Schmidt
=20

> -----Original Message-----
> From: gam...@li...=20
> [mailto:gam...@li...] On=20
> Behalf Of tweety
> Sent: Monday, March 15, 2004 4:28 AM
> To: gam...@li...
> Subject: RE: [GD-Windows] retrieving the cluster size on xp
>=20
>=20
> EVERY filesystem is divided in clusters, even CDFS/UDF and linux'
> filesystems (reiserfs and... Whatever the normal one is=20
> called, I forgot :)
> ), even if they're as small as 1 byte (I personally never=20
> heard of one).
> That's because, when adding new parts to a file surrounded by=20
> 2 other files,
> you need a way to tell the os where to look for the next part, and you
> really can't add a LONGLONG (int64) after every byte... Even=20
> a rle-based
> approach would be slow when updating. So they just stuff a=20
> "next pointer"
> for each cluster (since most fss store the next pointer at=20
> the beginning,
> the macimum number of files/folders/objects etc is limited).
> I know deviceiocontrol works differently on w200x/xp, but I=20
> haven't been
> able to find out anything but bytes/sector, and I still need=20
> sectors/cluster
> or something.
> So, now tell me why is it so wrong to expect a function that=20
> receives a path
> within the system (on windows it could be an itemidlist) (the path is
> required because of the mounting points in wnt+ and linux=20
> etc) and retrieve
> the cluster size of that folder (or return false when it=20
> cannot)? I'm not
> talking about an os-independent function, I'm talking about a=20
> wrapper of the
> different methods to get the cluster size (that's now; if=20
> they would have
> thaught of that sooner, they could have written a propper=20
> getclusersize from
> the beginning).
>=20
> About the null pointer: the first write of a function as=20
> esoteric as my
> w9x-compatible getclustersize that uses vxds and=20
> deviceiocontrol really
> isn't that centered at handling internally errors, I just=20
> step through it
> with the debugger. And I just used the disk in "readonly"=20
> mode, I love my
> hard disk too :))
>=20
> ----------------------------------
> Peace and love,
> Tweety
> mi...@sy... - twe...@us...
> YahooID: tweety_04_01
>=20
>=20
>=20
> -----Original Message-----
> From: gam...@li...
> [mailto:gam...@li...] On Behalf Of
> Carsten Orthbandt
> Sent: March 14, 2004 6:43 PM
> To: gam...@li...
> Subject: RE: [GD-Windows] retrieving the cluster size on xp
>=20
> Erm... Show me _one_ *.vxd on a NT based OS. There ain't none.
> DeviceIoControl is _documented_ to be different on NT and 9x.
> If you rely on specific behaviour for portable code, you're=20
> doomed. OTOH,
> given the wide variety of filesystems on Win32 systems, why=20
> do you expect to
> find something like a cluster size at all? Why should it matter?
> You either write portable application code and shouldn't have=20
> to resort to
> native OS constants. Or you write OS specific code and then=20
> you'll have to
> face the differences. And you better know about them.
> 9x and NT/2K/XP _are_ different platforms. System information=20
> easily tells
> you that. Having nearly the same API on both of them is a=20
> mere convenience,
> not a guarantee.
>=20
> And: Your code crashes because CreateFile() returned NULL???
> You'd better learn proper error handling before messing with=20
> my hard disk...
>=20
> Carsten Orthbandt
> Founder + Development Director
> SEK SpieleEntwicklungsKombinat GmbH
> http://www.sek-ost.de
>=20
> Wenn ich Visionen habe, gehe ich zum Arzt. - Helmut Schmidt
>=20
>=20
> > -----Original Message-----
> > From: gam...@li...
> > [mailto:gam...@li...]=20
> On Behalf Of=20
> > tweety
> > Sent: Sunday, March 14, 2004 10:37 PM
> > To: gam...@li...
> > Subject: RE: [GD-Windows] retrieving the cluster size on xp
> >=20
> >=20
> > I didn't explain myself properly... I wrote some=20
> deviceiocontrol code=20
> > for wme/w98 and it craches because createfile on vmm32.vxd (or=20
> > whatever) returns null.
> > Getdiskfreespace works properly on my machine (then again,=20
> I have 32k=20
> > and 4k clusters...). Still, there should be a function that=20
> works on=20
> > ALL windowses and that returns the cluster size.
> >=20
> > ----------------------------------
> > Peace and love,
> > Tweety
> > mi...@sy... - twe...@us...
> > YahooID: tweety_04_01
> >=20
> >=20
> >=20
> > -----Original Message-----
> > From: gam...@li...
> > [mailto:gam...@li...]=20
> On Behalf Of=20
> > Carsten Orthbandt
> > Sent: March 14, 2004 3:58 AM
> > To: gam...@li...
> > Subject: RE: [GD-Windows] retrieving the cluster size on xp
> >=20
> > I'd bet some money on your source being the reason for=20
> crashing. The=20
> > GetDiskFreeSpace API works fine for me on all flavours of Win32. I=20
> > don't think you'll crash XP calling this function, it's your app.=20
> > Generally, Win9x is much more forgiving when it comes to invalid=20
> > memory accesses than the WinNT siblings. Wich is actually a good=20
> > thing.
> >=20
> > Carsten Orthbandt
> > Founder + Development Director
> > SEK SpieleEntwicklungsKombinat GmbH
> > http://www.sek-ost.de
> >=20
> > Wenn ich Visionen habe, gehe ich zum Arzt. - Helmut Schmidt
> >=20
> >=20
> > > -----Original Message-----
> > > From: gam...@li...
> > > [mailto:gam...@li...]
> > On Behalf Of
> > > tweety
> > > Sent: Sunday, March 14, 2004 5:02 AM
> > > To: gam...@li...
> > > Subject: RE: [GD-Windows] retrieving the cluster size on xp
> > >=20
> > >=20
> > > Ok, I'll try it. Thanks. By the way, I did it in w98/me a=20
> long time=20
> > > ago, it just crashes on xp... :) You know, I find really sad that=20
> > > there's a function in *foxpro* to find the cluster size of
> > a drive and
> > > there's not ONE thing in the whole windows 32 api to return the=20
> > > cluster size reliably in all operating systems... Maybe=20
> longhorn?...
> > >=20
> > > ----------------------------------
> > > Peace and love,
> > > Tweety
> > > mi...@sy... - twe...@us...
> > > YahooID: tweety_04_01
> > >=20
> > > =20
> > >=20
> > > -----Original Message-----
> > > From: gam...@li...
> > > [mailto:gam...@li...]
> > On Behalf Of
> > > Simon O'Connor
> > > Sent: March 13, 2004 5:06 PM
> > > To: gam...@li...
> > > Subject: RE: [GD-Windows] retrieving the cluster size on xp
> > >=20
> > >=20
> > > Hi Tweety,
> > >=20
> > >=20
> > > GetDiskFreeSpace() is supported on Windows XP, Windows=20
> 2000, Windows=20
> > > NT, Windows Me, Windows 98, Windows 95, and Windows Server 2003...
> > >=20
> > > My comments about 9x were just addressing your preference for a=20
> > > portable method.
> > >=20
> > >=20
> > > Cheers,
> > >=20
> > > Simon O'Connor
> > > Programmer @ Acclaim
> > > & Microsoft DirectX MVP
> > >=20
> > > > -----Original Message-----
> > > > From: gam...@li...
> > > > [mailto:gam...@li...]
> > > On Behalf Of
> > > > tweety
> > > > Sent: 13 March 2004 21:55
> > > > To: gam...@li...
> > > > Subject: RE: [GD-Windows] retrieving the cluster size on xp
> > > >=20
> > > > I specified in the subject that I'm interested in=20
> finding out the=20
> > > > cluster size (it's not a hint, but not partitionmagic, I'm
> > > just trying
> > > > to find out the waste of space on my drive) on *xp*, not
> > 9x/me. And
> > > > I'd really, REALLY, REEEALY preffer not to go to the ddk...
> > > >=20
> > > > ----------------------------------
> > > > Peace and love,
> > > > Tweety
> > > > mi...@sy... - twe...@us...
> > > > YahooID: tweety_04_01
> > > >=20
> > > > =20
> > > >=20
> > > > -----Original Message-----
> > > > From: gam...@li...
> > > > [mailto:gam...@li...]
> > > On Behalf Of
> > > > Simon O'Connor
> > > > Sent: March 13, 2004 4:42 PM
> > > > To: gam...@li...
> > > > Subject: RE: [GD-Windows] retrieving the cluster size on xp
> > > >=20
> > > >=20
> > > > Hi Tweety,
> > > >=20
> > > >=20
> > > > You can use GetDiskFreeSpace() to find the number of=20
> sectors per=20
> > > > cluster and the number of bytes per sector so simply
> > > multiply them to
> > > > find the size of a cluster.
> > > >=20
> > > >=20
> > > > The docs for GetDiskFreeSpace() do mention that the
> > returned sectors
> > > > per cluster value can be inaccurate under Windows 9x/ME
> > for drives
> > > > with more than 64 sectors per cluster (the 80Gb drive in
> > > this machine
> > > > only has 8 per cluster so it might be a fairly unusual case).
> > > >=20
> > > > This is probably only an issue for you if your
> > application needs to
> > > > use this for something more than a "hint" (e.g. if=20
> you're writing=20
> > > > something like PartitionMagic etc). If you do need the totally=20
> > > > accurate value, you could obtain the DDK and take a look at the=20
> > > > Win9x/Me specific FS_GetDiskInfo() function.
> > > >=20
> > > > =20
> > > > Cheers,
> > > > =20
> > > > Simon O'Connor
> > > > Programmer @ Acclaim
> > > > & Microsoft DirectX MVP
> > > >=20
> > > >=20
> > > > ________________________________
> > > >=20
> > > > 	From: gam...@li...
> > > > [mailto:gam...@li...]
> > > On Behalf Of
> > > > tweety
> > > > 	Sent: 11 March 2004 23:39
> > > > 	To: gam...@li...
> > > > 	Subject: [GD-Windows] retrieving the cluster size on xp
> > > > =09
> > > > =09
> > > > 	Can someone please tell me how to get the cluster
> > > allocation size in
> > >=20
> > > > windowsxp? of course, a portable way is the best, but just
> > > 2000/xp is
> > > > fine.
> > > > i searched the internet far and wide and all i could find
> > is how to
> > > > find it on fat16/12 partitions and on w95/98/xp. i looked at=20
> > > > deviceiocontrol's functions, but none seems to return the
> > > cluster size
> > > > or something that i could use... can you tell me?
> > > > 	=20
> > > > 		----------------------------------
> > > > 	Peace and love,
> > > > 	Tweety
> > > > 	mi...@sy... - twe...@us...
> > > > 	YahooID: tweety_04_01
> > > > =09
> > > > =09
> > > >=20
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