Mercurial > gnulib
view tests/null-ptr.h @ 40212:8da9577294da
unistr/*, uniconv/*: Fix undefined behaviour.
Reported by Jeffrey Walton <noloader@gmail.com>.
* lib/unistr/u-cpy.h (FUNC): Don't invoke memcpy with a zero size.
* lib/unistr/u-cpy-alloc.h (FUNC): Likewise.
* lib/uniconv/u8-conv-from-enc.c (u8_conv_from_encoding): Likewise.
* lib/uniconv/u8-conv-to-enc.c (u8_conv_to_encoding): Likewise.
author | Bruno Haible <bruno@clisp.org> |
---|---|
date | Sat, 09 Mar 2019 00:01:47 +0100 |
parents | b06060465f09 |
children |
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/* Return a NULL pointer, without letting the compiler know it. Copyright (C) 2017-2019 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 . */