yenganti pradeep wrote:
Hi,
Hi,
I've created a new entry under /proc, to make tests.
I've defined an static int var=0;
Then I link my proc entry read function to a function
that only performs this:
int length;
length=sprintf(page,"Value %d",var++);
return length;
But when I cat/vi the file continuosly I get:
Value 0
Value 3
Value 6
etc...
Why is this three numbers increment?
'cat' will issue a read for more bytes than your function provides. As
this read isn't fully satisfied it will issue another read for the rest
at a different offset, etc. So your function gets called several times.
Just do a 'strace' on 'cat' to see what 'cat' really does. For more
details search for the thread 'procfs uglyness caused by "cat"'.
Your read function really shouldn't have side effects...
--
Paulo Marques - www.grupopie.com
Pointy-Haired Boss: I don't see anything that could stand in our way.
Dilbert: Sanity? Reality? The laws of physics?
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