[libvirt] [PATCH] virnetdevopenvswitch: Don't call strlen() twice on the same string
Andrea Bolognani
abologna at redhat.com
Wed Jan 27 10:00:53 UTC 2016
n Wed, 2016-01-27 at 10:49 +0100, Jiri Denemark wrote:
> On Wed, Jan 27, 2016 at 10:41:15 +0100, Andrea Bolognani wrote:
> > Commit 871e10f fixed a memory corruption error, but called strlen()
> > twice on the same string to do so. Even though the compiler is
> > probably smart enough to optimize the second call away, having a
> > single invocation makes the code slightly cleaner.
> >
> > Suggested-by: Michal Privoznik <mprivozn at redhat.com>
> > ---
> >
> > How about this? :)
> >
> > src/util/virnetdevopenvswitch.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/src/util/virnetdevopenvswitch.c b/src/util/virnetdevopenvswitch.c
> > index db01dcf..9283bbb 100644
> > --- a/src/util/virnetdevopenvswitch.c
> > +++ b/src/util/virnetdevopenvswitch.c
> > @@ -207,6 +207,7 @@ int virNetDevOpenvswitchRemovePort(const char *brname ATTRIBUTE_UNUSED, const ch
> > int virNetDevOpenvswitchGetMigrateData(char **migrate, const char *ifname)
> > {
> > virCommandPtr cmd = NULL;
> > + size_t len;
> > int ret = -1;
> >
> > cmd = virCommandNewArgList(OVSVSCTL, "--timeout=5", "--if-exists", "get", "Interface",
> > @@ -223,8 +224,9 @@ int virNetDevOpenvswitchGetMigrateData(char **migrate, const char *ifname)
> > }
> >
> > /* Wipeout the newline, if it exists */
> > - if (strlen(*migrate) > 0)
> > - (*migrate)[strlen(*migrate) - 1] = '\0';
>
> Or just
>
> if (**migrate)
> (*migrate)[strlen(*migrate) - 1] = '\0';
>
> (or similar check for the first character in *migrate) since we only
> need to check if it's empty or not :-)
Yeah, that would work just as nicely, and would even save us the
call to strlen() altogether when the string is empty.
However, I'd argue that it makes the code a tiny bit more opaque
rather than a tiny bit cleaner, so I'd still go with the version
I posted if that's okay with you :)
Cheers.
--
Andrea Bolognani
Software Engineer - Virtualization Team
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