/* Sizes of structs with flexible array members. Copyright 2016-2017 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))