mirror of
https://git.savannah.gnu.org/git/guile.git
synced 2025-04-30 03:40:34 +02:00
60 lines
2.4 KiB
C
60 lines
2.4 KiB
C
/* xalloc-oversized.h -- memory allocation size checking
|
|
|
|
Copyright (C) 1990-2000, 2003-2004, 2006-2021 Free Software Foundation, Inc.
|
|
|
|
This program is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser 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 does not fit into both ptrdiff_t and size_t.
|
|
S must be positive and N must be nonnegative.
|
|
This expands to a constant expression if N and S are both constants.
|
|
By gnulib convention, SIZE_MAX represents overflow in size_t
|
|
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_t;
|
|
#else
|
|
typedef size_t xalloc_count_t;
|
|
#endif
|
|
|
|
/* Return 1 if an array of N objects, each of size S, cannot exist reliably
|
|
because its total size in bytes exceeds MIN (PTRDIFF_MAX, SIZE_MAX).
|
|
N must be nonnegative, S must be positive, and either N or S should be
|
|
of type ptrdiff_t or size_t or wider. This is a macro, not a function,
|
|
so that it works even if an argument exceeds MAX (PTRDIFF_MAX, SIZE_MAX). */
|
|
#if 7 <= __GNUC__ && !defined __clang__
|
|
# define xalloc_oversized(n, s) \
|
|
__builtin_mul_overflow_p (n, s, (xalloc_count_t) 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_t __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_ */
|