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2008.08.23 15:54 "Re: creating sparse files......", by Bob Friesenhahn
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.
> 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.
Bob
======================================
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/