From e0023883c6d2e6745a19e4b48e186ed156c1fca8 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 17:19:27 +0200 Subject: Adding upstream version 2.11.2. Signed-off-by: Daniel Baumann --- gl/lib/flexmember.h | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 gl/lib/flexmember.h (limited to 'gl/lib/flexmember.h') diff --git a/gl/lib/flexmember.h b/gl/lib/flexmember.h new file mode 100644 index 0000000..1545639 --- /dev/null +++ b/gl/lib/flexmember.h @@ -0,0 +1,60 @@ +/* Sizes of structs with flexible array members. + + Copyright 2016-2022 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 + . + + Written by Paul Eggert. */ + +#include + +/* 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 + +/* Yield a properly aligned 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. The result is suitable as an + argument to malloc. For example: + + struct s { int n; char d[FLEXIBLE_ARRAY_MEMBER]; }; + struct s *p = malloc (FLEXSIZEOF (struct s, d, n * sizeof (char))); + + FLEXSIZEOF (TYPE, MEMBER, N) is not simply (sizeof (TYPE) + N), + since FLEXIBLE_ARRAY_MEMBER may be 1 on pre-C11 platforms. Nor is + it simply (offsetof (TYPE, MEMBER) + N), as that might yield a size + that causes malloc to yield a pointer that is not properly aligned + for TYPE; for example, if sizeof (int) == alignof (int) == 4, + malloc (offsetof (struct s, d) + 3 * sizeof (char)) is equivalent + to malloc (7) and might yield a pointer that is not a multiple of 4 + (which means the pointer is not properly aligned for struct s), + whereas malloc (FLEXSIZEOF (struct s, d, 3 * sizeof (char))) is + equivalent to malloc (8) and must yield a pointer that is a + multiple of 4. + + 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)) -- cgit v1.2.3