Re: [libvirt] [PATCH 2/4] Update modified mac address in place in virGetInterface
On 07/22/2009 11:36 AM, Daniel P. Berrange wrote:
On Wed, Jul 22, 2009 at 11:25:38AM -0400, Laine Stump wrote:
> On 07/22/2009 10:20 AM, Daniel Veillard wrote:
>
>> Agreed, patch applied, I only had to add _() to get the message localized,
>>
> I've idly wondered about that macro, as it causes scores of compile
> warnings, like this:
>
> datatypes.c:291: warning: format not a string literal and no format
> arguments
>
> What's it for? And what's the best way to change things to eliminate the
> warnings?
>
It is a potential security hole, if the user finds a way to send a string
with an embeded format specifier. Thus if you're not doing any subsitutions,
and the string isn't constant, then you should always at least do
char *therealstring = ...from somewhere untrusted...
printf("%s", therealstring)
Yeah, I understand the perils of using a non-literal string as the
format to *printf(). I'm wondering what the purpose of _() is, and why
it causes the compiler to believe the string isn't a literal. (I
received this warning when others don't because I use "-Wformat
-Wformat-security" in my CFLAGS, at Jim's suggestion).
NB, anyone sending patches should always set
--enable-compile-warnings=error
when running 'autogen.sh' and make sure all warnings & errors are fixed
before submitting a patch.
It's actually because I like doing this that I'd like to know the
preferred method of eliminating the warnings I mentioned. There are a
bunch of them pre-existing in the code that I want to get rid of so I
can turn on warnings=error (without turning off these warnings in
CFLAGS), and I want to do it the "accepted" way. For example, from
domain_conf.c:2137:
virDomainReportError(conn, VIR_ERR_XML_ERROR,
_("invalid security type"));
spits out the warning. We all know that it really *is* literal, but the
macro is changing the class so the compile thinks it isn't. It would be
simple to just change it to:
virDomainReportError(conn, VIR_ERR_XML_ERROR,
"%s", _("invalid security type"));
(and there are plenty of those too), but that's inefficient, and doesn't
do the _() around the "%s" (is that correct or not?).
If someone wants to tell me the preferred way of doing these, I'll
handle the grunt work of making the changes.