Re: [PATCH] util: In ASSERT(), use "fprintf(stderr, ...)" rather than err(...)

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Aug 05, 2024 at 04:10:27PM +0200, Laurent Vivier wrote:
> We use our own implementation of assert() because the glic implementation
> uses syscalls that aren't in our seccomp filter, see 7a8ed9459dfe
> ("Make assertions actually useful"). And we replaced it by an err(),
> followed by an abort() (that is also catched by seccomp).

I think Stefano's said everything I would on the change itself, but..

> We don't have a coredump or a backtrace but we have at least the
> error message... only if logging is enabled.

Whether we get a coredump shouldn't be affected by our weird ASSERT()
here.  If coredumps are enabled (which they're not by default on
current distros, AFAICT), we should still get a coredump with the
SIGSYS here, just as we would for a SIGABRT.

> As this kind of information is needed in any case, replace the "err()"
> function by an "fprintf(stderr, ...)".
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  util.h | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/util.h b/util.h
> index b7541ce24e5a..b44b4bfdccd7 100644
> --- a/util.h
> +++ b/util.h
> @@ -13,6 +13,7 @@
>  #include <stdint.h>
>  #include <string.h>
>  #include <signal.h>
> +#include <stdio.h>
>  #include <arpa/inet.h>
>  
>  #include "log.h"
> @@ -67,8 +68,10 @@
>  #define ASSERT(expr)							\
>  	do {								\
>  		if (!(expr)) {						\
> -			err("ASSERTION FAILED in %s (%s:%d): %s",	\
> -			    __func__, __FILE__, __LINE__, STRINGIFY(expr)); \
> +			fprintf(stderr,					\
> +				"ASSERTION FAILED in %s (%s:%d): %s\n",	\
> +				__func__, __FILE__, __LINE__,		\
> +				STRINGIFY(expr));			\
>  			/* This may actually SIGSYS, due to seccomp,	\
>  			 * but that will still get the job done		\
>  			 */						\

-- 
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

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