Re: [libvirt] [PATCH v2 2/7] internal: introduce macro helpers to check flag requirements

On Fri, Mar 27, 2015 at 11:01:23AM +0100, Pavel Hrdina wrote: > Similar to VIR_EXLUSIVE_FLAGS, it will error out if flag requirement is > not met. > > Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com&gt; > --- > src/internal.h | 43 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 43 insertions(+) > > diff --git a/src/internal.h b/src/internal.h > index eb8d231..6363e58 100644 > --- a/src/internal.h > +++ b/src/internal.h > @@ -371,6 +371,49 @@ > goto LABEL; \ > } > > +/* Macros to help dealing with flag requirements. */ > + > +/** > + * VIR_REQUIRE_FLAG_RET: > + * > + * @FLAG1: First flag to be checked. > + * @FLAG2: Second flag that is required by first flag. > + * @RET: Return value. > + * > + * Check whether required flag is set. The checked flags are compared > + * with flags variable. > + * > + * This helper does an early return and therefore it has to be called > + * before anything that would require cleanup. > + */ > +# define VIR_REQUIRE_FLAG_RET(FLAG1, FLAG2, RET) \ > + if ((flags & FLAG1) && !(flags & FLAG2)) { \ > + virReportInvalidArg(ctl, \ > + _("Flag '%s' is required by flag '%s'"), \ > + #FLAG2, #FLAG1); \ > + return RET; \ > + } > + I recommend encapsulating this within a "do { ... } while (1)"

statement. The problem is that the macro hides/exposes an -if- statement to which an -else- keyword can be bound: if (something) VIR_REQUIRE_FLAG_RET(f1, f2, foo) else // matches with -if- inside VIR_REQUIRE_FLAG_RET // doesn't execute when you think it does Note that other macros (see definition of virCheckNonNullArgReturn below) follow this practice. > +/** > + * VIR_REQUIRE_FLAG_GOTO: > + * > + * @FLAG1: First flag to be checked. > + * @FLAG2: Second flag that is required by first flag. > + * @LABEL: Label to jump to. > + * > + * Check whether required flag is set. The checked flags are compared > + * with flags variable. > + * > + * Returns nothing. Jumps to a label if required flag is not set. > + */ > +# define VIR_REQUIRE_FLAG_GOTO(FLAG1, FLAG2, LABEL) \ > + if ((flags & FLAG1) && !(flags & FLAG2)) { \ > + virReportInvalidArg(ctl, \ > + _("Flag '%s' is required by flag '%s'"), \ > + #FLAG2, #FLAG1); \ > + goto LABEL; \ > + } > + Same feedback as above. -Jeff > # define virCheckNonNullArgReturn(argname, retval) \ > do { \ > if (argname == NULL) { \ > -- > 2.0.5 > > -- > libvir-list mailing list > libvir-list(a)redhat.com > https://www.redhat.com/mailman/listinfo/libvir-list -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list