RE: retrieving the cluster size on xp

"Carsten Orthbandt" <[email protected]> Mon, 15 Mar 2004 10:04:48 +0100
Newsgroups	gmane.games.devel.windows
Message-ID	<[email protected]>
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
 

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