Re: [libvirt] [PATCH] tests: dynamically replace dnsmasq path

On 01/31/2012 07:58 AM, Philipp Hahn wrote: memcpy() is safe when the code is provably visiting non-overlapping strings, as is the case with your second use of memmove(). memcpy() is a mistake where the code is provably visiting overlapping strings, as is the case with your first memmove(). On some libc, memmove and memcpy are the same function; but since the standards allow memcpy to be more efficient than memmove by exploiting the non-overlap guarantee, you might as well use the more efficient method in the cases where things really are non-overlapping. Libvirt isn't so strict as to pessimize correct uses of memcpy() just because it can sometime be misused. It also helps that static analyzers like Coverity are getting pretty good at pointing out mis-uses of memcpy(). You do have a valid counterpoint here - this is a test, and not a hot path, so the savings of memcpy() vs. memmove() are in the noise compared to any extra realloc(); thankfully, neither overhead is worth worrying about too much. At any rate, I'll review your v2 now. -- Eric Blake eblake(a)redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org