blob: b978418a188e293617d5de1f9ee1a50bd4cf6dd2 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
|
/* Return a NULL pointer, without letting the compiler know it.
Copyright (C) 2017-2020 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <stdlib.h>
/* Return NULL.
Usual compilers are not able to infer something about the return value. */
static void *
null_ptr (void)
{
unsigned int x = rand ();
unsigned int y = x * x;
if (y & 2)
return (void *) -1;
else
return (void *) 0;
}
/* If you want to know why this always returns NULL, read
https://en.wikipedia.org/wiki/Quadratic_residue#Prime_power_modulus . */
|
