Re: [libvirt] [PATCHv2] Ignore bridge template names with multiple printf conversions

On 05/05/2015 12:39 PM, Eric Blake wrote: > On 05/05/2015 10:26 AM, Ján Tomko wrote: >> On Tue, May 05, 2015 at 10:14:18AM -0600, Eric Blake wrote: >>> On 05/05/2015 10:05 AM, Ján Tomko wrote: >>>> For some reason, we allow a bridge name with %d in it, which we replace >>>> with an unsigned integer to form a bridge name that does not yet exist >>>> on the host. >>>> > >>>> + if (def->bridge && >>>> + (p = strchr(def->bridge, '%')) == strrchr(def->bridge, '%') && >>>> + strstr(def->bridge, "%d")) >>> >>> Simpler as: >>> >>> if (def->bridge && >>> strstr(def->bridge, "%d") == strrchr(def->bridge, '%')) >> >> I still don't see it. >> >> [A] strchr(def->bridge, '%') >> [B] strrchr(def->bridge, '%') >> [C] strstr(def->bridge, "%d")) >> >> When def->bridge is '%s%s%s%d', [A] points to the first %s, [B] points >> to the %d and so does [C] >> >> This string would pass the simplified condition (B == C), but not the >> full one (A != C) > > Okay, I see your counterargument. Still, strstr() is pretty expensive > compared to just: > > if (def->bridge && > (p = strchr(def->bridge, '%')) == strrchr(def->bridge, '%') && > p[1] == 'd') > Coverity complains : Event returned_null: "strchr" returns null (checked 273 out of 288 times).

Event var_assigned: Assigning: "p" = null return value from "strchr". Event cond_true: Condition "(p = strchr(def->bridge, 37)) == strrchr(def->bridge, 37)", taking true branch Event dereference: Dereferencing a null pointer "p". John