[Valgrind-users] ptrcheck

[Yoni <ilo...@gm...>]

Hi All,
I was trying to run valgrind using exp-ptrcheck, and i keep getting 
errors on a perfectly good code.
I am not a valgrind expert, but I looked a bit on ptrcheck code, and I 
could not understand how it can work.
As I understand, every instruction is classified in the first use, and 
in the second time ptrcheck will compare the current status to the 
previews one (in helperc__mem_access).
This approach could generate false alarms when you change a pointer 
legitimately (for example, by passing a pointer to pointer as an 
argument to a functions).
that is what generating the error in my case: the following line 
generated an error
char **p;
....
(*p)[len] = 0;

and when i changed it to:
char **p, *tmp;
...
tmp = (*p);
tmp[len] = 0;

It was OK.

I would love if someone could explain to me this approach.
Thanks,
Yoni.