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12a7e0f88e
This incorporates: 2016-09-07 flexmember: new macro FLEXALIGNOF 2016-09-07 flexmember: port better to GCC + valgrind 2016-08-18 Port modules to use getprogname explicitly 2016-09-02 manywarnings: add -fno-common * admin/merge-gnulib (GNULIB_TOOL_FLAGS): Don’t avoid flexmember, since time_rz now uses part of it. Instead, remove m4/flexmember.m4. * configure.ac (AC_C_FLEXIBLE_ARRAY_MEMBER): Define away, since Emacs assumes C99 and therefore removes m4/flexmember.m4. * lib/euidaccess.c, lib/group-member.c, lib/time_rz.c: * m4/manywarnings.m4: Copy from gnulib. * lib/flexmember.h: New file, from gnulib. * lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
43 lines
1.7 KiB
C
43 lines
1.7 KiB
C
/* Sizes of structs with flexible array members.
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Copyright 2016 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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Written by Paul Eggert. */
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#include <stddef.h>
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/* Nonzero multiple of alignment of TYPE, suitable for FLEXSIZEOF below.
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On older platforms without _Alignof, use a pessimistic bound that is
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safe in practice even if FLEXIBLE_ARRAY_MEMBER is 1.
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On newer platforms, use _Alignof to get a tighter bound. */
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#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112
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# define FLEXALIGNOF(type) (sizeof (type) & ~ (sizeof (type) - 1))
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#else
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# define FLEXALIGNOF(type) _Alignof (type)
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#endif
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/* Upper bound on the size of a struct of type TYPE with a flexible
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array member named MEMBER that is followed by N bytes of other data.
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This is not simply sizeof (TYPE) + N, since it may require
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alignment on unusually picky C11 platforms, and
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FLEXIBLE_ARRAY_MEMBER may be 1 on pre-C11 platforms.
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Yield a value less than N if and only if arithmetic overflow occurs. */
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#define FLEXSIZEOF(type, member, n) \
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((offsetof (type, member) + FLEXALIGNOF (type) - 1 + (n)) \
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& ~ (FLEXALIGNOF (type) - 1))
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