[LTP] [PATCH v2] misc: rewrite crash02 test

[Martin Doucha]

On 01. 07. 25 13:39, Andrea Cervesato wrote:
> 
> On 6/30/25 3:51 PM, Martin Doucha wrote:
>> This algorithm has two problems:
>> 1. Undefined behavior if i == 3 && (rand() & 0xFF) > 0x7f
>> 2. Except as a result of the above undefined behavior, the algorithm 
>> will never generate a negative value nor a value larger than INT_MAX.
> I see that using multiple rand() create an issue on the numeric 
> dimension. By calling rand() multiple times and move the bytes results 
> around, usually generates big numbers values.
> Probably we should just get back to the old algorithm. WDYT?

No, this is how to fix the algorithm:

static long rand_number(void)
{
	unsigned long ret = 0;

	for (int i = 0; i < sizeof(unsigned long); i++)
		num |= ((rand() & 0xffUL) << (i * 8));

	return ret;
}

This will generate random numbers in the full range from LONG_MIN to 
LONG_MAX and without any undefined behavior.

-- 
Martin Doucha   mdoucha@suse.cz
SW Quality Engineer
SUSE LINUX, s.r.o.
CORSO IIa
Krizikova 148/34
186 00 Prague 8
Czech Republic