| /* Sizes of structs with flexible array members. |
| |
| Copyright 2016-2018 Free Software Foundation, Inc. |
| |
| This file is part of the GNU C Library. |
| |
| The GNU C Library 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. |
| |
| The GNU C Library 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 the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. |
| |
| Written by Paul Eggert. */ |
| |
| #include <stddef.h> |
| |
| /* Nonzero multiple of alignment of TYPE, suitable for FLEXSIZEOF below. |
| On older platforms without _Alignof, use a pessimistic bound that is |
| safe in practice even if FLEXIBLE_ARRAY_MEMBER is 1. |
| On newer platforms, use _Alignof to get a tighter bound. */ |
| |
| #if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 |
| # define FLEXALIGNOF(type) (sizeof (type) & ~ (sizeof (type) - 1)) |
| #else |
| # define FLEXALIGNOF(type) _Alignof (type) |
| #endif |
| |
| /* Upper bound on the size of a struct of type TYPE with a flexible |
| array member named MEMBER that is followed by N bytes of other data. |
| This is not simply sizeof (TYPE) + N, since it may require |
| alignment on unusually picky C11 platforms, and |
| FLEXIBLE_ARRAY_MEMBER may be 1 on pre-C11 platforms. |
| Yield a value less than N if and only if arithmetic overflow occurs. */ |
| |
| #define FLEXSIZEOF(type, member, n) \ |
| ((offsetof (type, member) + FLEXALIGNOF (type) - 1 + (n)) \ |
| & ~ (FLEXALIGNOF (type) - 1)) |