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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 16:58:41 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 16:58:41 +0000 |
commit | e1908ae95dd4c9d19ee4dfabfc8bf8a7f85943fe (patch) | |
tree | f5cc731bedcac0fb7fe14d952e4581e749f8bb87 /lib/xalloc-oversized.h | |
parent | Initial commit. (diff) | |
download | coreutils-upstream.tar.xz coreutils-upstream.zip |
Adding upstream version 9.4.upstream/9.4upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'lib/xalloc-oversized.h')
-rw-r--r-- | lib/xalloc-oversized.h | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/lib/xalloc-oversized.h b/lib/xalloc-oversized.h new file mode 100644 index 0000000..5dbdfb5 --- /dev/null +++ b/lib/xalloc-oversized.h @@ -0,0 +1,65 @@ +/* xalloc-oversized.h -- memory allocation size checking + + Copyright (C) 1990-2000, 2003-2004, 2006-2023 Free Software Foundation, Inc. + + This file 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 2.1 of the + License, or (at your option) any later version. + + This file 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. + N and S should be nonnegative and free of side effects. + 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) \ + ((s) != 0 \ + && ((size_t) (PTRDIFF_MAX < SIZE_MAX ? PTRDIFF_MAX : SIZE_MAX - 1) / (s) \ + < (n))) + +/* Return 1 if and only if an array of N objects, each of size S, + cannot exist reliably because its total size in bytes would exceed + MIN (PTRDIFF_MAX, SIZE_MAX - 1). + + N and S should be nonnegative and free of side effects. + + Warning: (xalloc_oversized (N, S) ? NULL : malloc (N * S)) can + misbehave if N and S are both narrower than ptrdiff_t and size_t, + and can be rewritten as (xalloc_oversized (N, S) ? NULL + : malloc (N * (size_t) S)). + + 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__ && PTRDIFF_MAX < SIZE_MAX +# define xalloc_oversized(n, s) \ + __builtin_mul_overflow_p (n, s, (ptrdiff_t) 1) +#elif (5 <= __GNUC__ && !defined __ICC && !__STRICT_ANSI__ \ + && PTRDIFF_MAX < SIZE_MAX) +# define xalloc_oversized(n, s) \ + (__builtin_constant_p (n) && __builtin_constant_p (s) \ + ? __xalloc_oversized (n, s) \ + : ({ ptrdiff_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_ */ |