On Fri, Aug 02, 2024 at 05:48:13PM +0200, Thomas Weißschuh wrote:
> > With all these libc functionality added, it isn't nolibc looks like :)
>
> Well :-)
>
> The main motivation is to provide kselftests compatibility.
> Maybe Willy disagrees.
No no I'm perfectly fine with adding the functions that developers use
or need to write their test or init tools. I don't have any strong
opinion on scanf(). Just like strtok(), I stopped using it 25 years ago
when I noticed that it never survives code evolutions, lacks a lot of
flexibility and is often strongly tied to your types (more than printf
where you can cast). But I perfectly understand that others are used to
it and would appreciate to have it, for example if it helps with command
line arguments.
> > > +static int test_scanf(void)
> > > +{
> > > + unsigned long long ull;
> > > + unsigned long ul;
> > > + unsigned int u;
> > > + long long ll;
> > > + long l;
> > > + void *p;
> > > + int i;
> > > +
> > > + if (sscanf("", "foo") != EOF)
> > > + return 1;
> > > +
> > > + if (sscanf("foo", "foo") != 0)
> > > + return 2;
> > > +
> > > + if (sscanf("123", "%d", &i) != 1)
> > > + return 3;
> > > +
> > > + if (i != 123)
> > > + return 4;
> > > +
> > > + if (sscanf("a123b456c0x90", "a%db%uc%p", &i, &u, &p) != 3)
> > > + return 5;
> > > +
> > > + if (i != 123)
> > > + return 6;
> > > +
> > > + if (u != 456)
> > > + return 7;
> > > +
> > > + if (p != (void *)0x90)
> > > + return 8;
> > > +
> > > + if (sscanf("a b1", "a b%d", &i) != 1)
> > > + return 9;
> > > +
> > > + if (i != 1)
> > > + return 10;
> > > +
> > > + if (sscanf("a%1", "a%%%d", &i) != 1)
> > > + return 11;
> > > +
> > > + if (i != 1)
> > > + return 12;
> > > +
> > > + if (sscanf("1|2|3|4|5|6",
> > > + "%d|%ld|%lld|%u|%lu|%llu",
> > > + &i, &l, &ll, &u, &ul, &ull) != 6)
> > > + return 13;
> > > +
> > > + if (i != 1 || l != 2 || ll != 3 ||
> > > + u != 4 || ul != 5 || ull != 6)
> > > + return 14;
> > > +
> > > + return 0;
> >
> > Can we simplify this code? It is hard to read code with too
> > many conditions. Maybe defining an array test conditions
> > instead of a series ifs.
>
> I tried that and didn't find a way.
> Any pointers are welcome.
I think it would be difficult by nature of varargs.
However, since you grouped some expressions, maybe a one-liner comment
between each scanf() to explain the intent of the test would make it
easier to follow. E.g:
/* test multiple naked numbers */
...
/* test numbers delimited with a character */
...
/* test multiple integer types at once */
etc. This allows the reviewer to more easly re-focus on the test they
were reading.
Willy
