On Tue, Mar 17, 2026 at 01:02:34AM +0100, Stefano Brivio wrote:
> On Mon, 16 Mar 2026 16:46:28 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > +++ b/util.h
> > @@ -73,10 +73,14 @@ void abort_with_msg(const char *fmt, ...)
> >   * Therefore, avoid using the usual do while wrapper we use to force the macro
> >   * to act like a single statement requiring a ';'.
> >   */
> > -#define ASSERT_WITH_MSG(expr, ...)					\
> > +#define assert_with_msg(expr, ...)					\
> >  	((expr) ? (void)0 : abort_with_msg(__VA_ARGS__))
> > -#define ASSERT(expr)							\
> > -	ASSERT_WITH_MSG((expr), "ASSERTION FAILED in %s (%s:%d): %s",	\
> > +/* The standard library assert() hits our seccomp filter and dies before it can
> > + * actually print a message.  So, replace it with our own version.
> > + */
> > +#undef assert
> > +#define assert(expr)							\
> > +	assert_with_msg((expr), "ASSERTION FAILED in %s (%s:%d): %s",	\
> >  			__func__, __FILE__, __LINE__, STRINGIFY(expr))
> 
> While looking this up to make sure it's specified as a macro (it is,
> and this builds against musl as well), I realised that POSIX.1-2024
> says:
> 
>   https://pubs.opengroup.org/onlinepubs/9799919799/functions/assert.html
> 
>   Forcing a definition of the name NDEBUG, either from the compiler
>   command line or with the preprocessor control statement #define NDEBUG
>   ahead of the #include <assert.h> statement, shall stop assertions from
>   being compiled into the program.
> 
> ...so, I wonder, now that it's called assert(), should we define it as
> "do { } while(0)" #ifdef NDEBUG, for correctness (and maybe somebody
> has obscure usages for NDEBUG which we shouldn't sabotage)?

I like the idea in principle.  Actually implementing it turns out to
be kind of a pain in the arse, because if we actually try to compile
with -DNDEBUG then we get a much of warnings due to reaching the end
of functions (assert(0) stopped us otherwise) or unused variables
(they're only used in the assert expression or message).

A project for some other time, I think.

> This will conflict with "[PATCH v2 3/3] vu_common: Move iovec management
> into vu_collect()" by the way, but I'll take care of it, if it still
> conflicts by the time I merge it.
> 
> -- 
> Stefano
> 

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson