[LTP] [PATCH v2] lib: tst_test: Add reproducible output.

[Avinesh Kumar]

Hi,

Reviewed-by: Avinesh Kumar <akumar@suse.de>


On Friday, May 9, 2025 11:28:13 AM CEST Cyril Hrubis wrote:
> This commit adds an environment variable LTP_REPRODUCIBLE_OUTPUT that
> when set skips printing parts of the test messages that may contain data
> that differ on subsequent runs (e.g. pids).
> 
> With this you can run a test twice under a different conditions and
> check if the test codeflow was identical by simply doing diff of the
> outputs from the two runs.
> 
> Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
> Suggested-by: Martin Doucha <mdoucha@suse.cz>
> CC: valgrind-developers@lists.sourceforge.net
> ---
>  lib/tst_test.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/lib/tst_test.c b/lib/tst_test.c
> index 2bb4519dd..f14627544 100644
> --- a/lib/tst_test.c
> +++ b/lib/tst_test.c
> @@ -64,6 +64,7 @@ static int mntpoint_mounted;
>  static int ovl_mounted;
>  static struct timespec tst_start_time; /* valid only for test pid */
>  static int tdebug;
> +static int reproducible_output;
>  
>  struct results {
>  	int passed;
> @@ -312,6 +313,9 @@ static void print_result(const char *file, const int lineno, int ttype,
>  	str += ret;
>  	size -= ret;
>  
> +	if (reproducible_output)
> +		goto print;
> +
>  	ssize = size - 2;
>  	ret = vsnprintf(str, size, fmt, va);
>  	str += MIN(ret, ssize);
> @@ -329,6 +333,7 @@ static void print_result(const char *file, const int lineno, int ttype,
>  				"Next message is too long and truncated:");
>  	}
>  
> +print:
>  	snprintf(str, size, "\n");
>  
>  	/* we might be called from signal handler, so use write() */
> @@ -1312,6 +1317,8 @@ static void do_setup(int argc, char *argv[])
>  	if (tst_test->supported_archs && !tst_is_on_arch(tst_test->supported_archs))
>  		tst_brk(TCONF, "This arch '%s' is not supported for test!", tst_arch.name);
>  
> +	reproducible_output = !!getenv("LTP_REPRODUCIBLE_OUTPUT");
> +
>  	assert_test_fn();
>  
>  	TCID = tid = get_tid(argv);
> 

Regards,
Avinesh