/* xalloc-oversized.h -- memory allocation size checking Copyright (C) 1990-2000, 2003-2004, 2006-2015 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 . */ #ifndef XALLOC_OVERSIZED_H_ #define XALLOC_OVERSIZED_H_ #include #ifndef __has_builtin # define __has_builtin(x) 0 #endif /* Return 1 if an array of N objects, each of size S, cannot exist due to size 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. By gnulib convention, SIZE_MAX represents overflow in size calculations, so the conservative dividend to use here is SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value. However, malloc (SIZE_MAX) fails on all known hosts where sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for exactly-SIZE_MAX allocations on such hosts; this avoids a test and branch when S is known to be 1. */ #if 5 <= __GNUC__ || __has_builtin (__builtin_mul_overflow) # define xalloc_oversized(n, s) \ ({ size_t __xalloc_size; __builtin_mul_overflow (n, s, &__xalloc_size); }) #else # define xalloc_oversized(n, s) \ ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n)) #endif #endif /* !XALLOC_OVERSIZED_H_ */