| /* xalloc-oversized.h -- memory allocation size checking |
| |
| Copyright (C) 1990-2000, 2003-2004, 2006-2019 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/>. */ |
| |
| #ifndef XALLOC_OVERSIZED_H_ |
| #define XALLOC_OVERSIZED_H_ |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| /* True if N * S would overflow in a size_t calculation, |
| or would generate a value larger than PTRDIFF_MAX. |
| This expands to a constant expression if N and S are both constants. |
| By gnulib convention, SIZE_MAX represents overflow in size |
| calculations, so the conservative size_t-based dividend to use here |
| is SIZE_MAX - 1. */ |
| #define __xalloc_oversized(n, s) \ |
| ((size_t) (PTRDIFF_MAX < SIZE_MAX ? PTRDIFF_MAX : SIZE_MAX - 1) / (s) < (n)) |
| |
| #if PTRDIFF_MAX < SIZE_MAX |
| typedef ptrdiff_t __xalloc_count_type; |
| #else |
| typedef size_t __xalloc_count_type; |
| #endif |
| |
| /* Return 1 if an array of N objects, each of size S, cannot exist |
| reliably due to size or ptrdiff_t arithmetic overflow. S must be |
| positive and N must be nonnegative. This is a macro, not a |
| function, so that it works correctly even when SIZE_MAX < N. */ |
| |
| #if 7 <= __GNUC__ |
| # define xalloc_oversized(n, s) \ |
| __builtin_mul_overflow_p (n, s, (__xalloc_count_type) 1) |
| #elif 5 <= __GNUC__ && !defined __ICC && !__STRICT_ANSI__ |
| # define xalloc_oversized(n, s) \ |
| (__builtin_constant_p (n) && __builtin_constant_p (s) \ |
| ? __xalloc_oversized (n, s) \ |
| : ({ __xalloc_count_type __xalloc_count; \ |
| __builtin_mul_overflow (n, s, &__xalloc_count); })) |
| |
| /* Other compilers use integer division; this may be slower but is |
| more portable. */ |
| #else |
| # define xalloc_oversized(n, s) __xalloc_oversized (n, s) |
| #endif |
| |
| #endif /* !XALLOC_OVERSIZED_H_ */ |