Re: [PATCH v3 2/5] selftests/resctrl: Add helpers for the non-contiguous test

[Reinette Chatre <reinette.chatre@intel.com>]

On 1/25/2024 4:14 AM, Ilpo Järvinen wrote:
> On Thu, 25 Jan 2024, Maciej Wieczor-Retman wrote:


>> +	fp = fopen(file_path, "r");
>> +	if (!fp) {
>> +		snprintf(reason, sizeof(reason), "Error in opening %s file\n", filename);
>> +		ksft_perror(reason);
> 
> Was this the conclusion of the kstf_perror() discussion with Reinette? I 
> expected a bit different outcome when I stopped following it...
> 
> In any case, it would be nice though if ksft_perror() (or some kselftest.h 
> function yet to be added with a different name) would accept full printf 
> interface and just add the errno string into the end of the string so one 
> would not need to build constructs like this at all.
> 
> It will require a bit of macro trickery into kselftest.h. I don't know how 
> it should handle the case where somebody just passes a char pointer to it, 
> not a string literal, but I guess it would just throw an error while 
> compiling if somebody tries to do that as the macro string literal 
> concatenation could not build useful/compilable token.
> 
> It would make these prints informative enough to become actually useful 
> without needed to resort to preparing the string in advance which seems
> to be required almost every single case with the current interface.

I think this can be accomplished with a new:
	void  ksft_vprint_msg(const char *msg, va_list args)

... but ksft_perror() does conform to perror() and I expect that having one
support variable number of arguments while the other does to cause confusion.

To support variable number of arguments with errno I'd propose just to use
ksft_print_msg() with strerror(errno), errno as the arguments (or even %m
that that errno handling within ksft_print_msg() aims to support). This does
indeed seem to be the custom in other tests.

Reinette