--tool=addrcheck
on the Valgrind command line.
src
and dst
pointers in
memcpy()
and related functions
Rather than duplicate much of the Memcheck docs here (a.k.a. since I am a lazy b'stard), users of Addrcheck are advised to read the section on Memcheck. Some important points:
The result is that Addrcheck's leak checker may "discover" pointers to blocks that Memcheck would not. So it is possible that Memcheck could (correctly) conclude that a block is leaked, yet Addrcheck would not conclude that.
Whether or not this has any effect in practice is unknown. I suspect not, but that is mere speculation at this stage.
Addrcheck is, therefore, a fine-grained address checker. All it really does is check each memory reference to say whether or not that location may validly be addressed. Addrcheck has a memory overhead of one bit per byte of used address space. In contrast, Memcheck has an overhead of nine bits per byte.
Due to lazyness on the part of the implementor (Julian), error messages from Addrcheck do not distinguish reads from writes. So it will say, for example, "Invalid memory access of size 4", whereas Memcheck would have said whether the access is a read or a write. This could easily be remedied, if anyone is particularly bothered.
Addrcheck is quite pleasant to use. It's faster than Memcheck, and the lack of valid-value checks has another side effect: the errors it does report are relatively easy to track down, compared to the tedious and often confusing search sometimes needed to find the cause of uninitialised-value errors reported by Memcheck.
Because it is faster and lighter than Memcheck, our hope is that
Addrcheck is more suitable for less-intrusive, larger scale testing
than is viable with Memcheck. As of mid-November 2002, we have
experimented with running the KDE-3.1 desktop on Addrcheck (the entire
process tree, starting from startkde
). Running on a
512MB, 1.7 GHz P4, the result is nearly usable. The ultimate aim is
that is fast and unintrusive enough that (eg) KDE sessions may be
unintrusively monitored for addressing errors whilst people do real
work with their KDE desktop.
Addrcheck is a new experiment in the Valgrind world. We'd be interested to hear your feedback on it.