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2008.08.23 15:58 "Re: creating sparse files......", by Rogier Wolff
On Sat, Aug 23, 2008 at 10:54:54AM -0500, Bob Friesenhahn wrote:
> On Sat, 23 Aug 2008, Rogier Wolff wrote:
> >
> >>For example,
> >>Apple OS-X's HFS+ does not support holes.
> >
> >Weird. So, will my suggested code fail? No.
>
> OS-X's HFS+ will simply consume the space with zeros.
>
> >>Windows FAT type
> >>filesystems (still very much in use in millions of systems/devices) do
> >>not support holes.
> >
> >Correct. But will my code fail? No. It does skip the copying of
> >"zeroes" from userspace into the kernel. Wether this will in fact
> >increase or decrease perfomance when all things are added up, I don't
> >know.
>
> The code may very well fail.
Nope.
> >It is likely that you don't know that the posix specifications are
> >pretty clear about this.
> >
> >If I program
> >
> > main (int argc, char **argv)
> > {
> > int a;
> > int b;
> > a = 3;
> > b = 5;
> > printf ("%d\n", a+b);
> > }
> >
> >the output should be "8". This is because I used standard features of
> >a standard programming language. Opening and writing files goes a bit
>
> You are communicating with someone who has used and programmed "unix"
> for twenty years now. The above was not called for.
Same here. So?
You say: "The code may very well fail". How can I provide arguments
against that? There are standards that imply the answer "8" from the
short program above, and correct results from the code I suggested.
Roger.
--
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