emacs/lib/xalloc-oversized.h
Paul Eggert 39c2fa3f4e Merge from gnulib and try to repair bad merge
This attempts to repair problems introduced by the bad merge
5491fd1098.  The easiest way for me
to fix the badly-merged gnulib files was to run
'admin/merge-gnulib', so I did that, which also imported the
following changes:
* build-aux/update-copyright, m4/gnulib.m4:
Update from gnulib, incorporating:
2015-01-15 time: port to MinGW32 3.21
2015-01-15 update-copyright: apply to self
2015-01-11 update-copyright: recognize groff's \(co marker
2015-01-27 22:24:47 -08:00

38 lines
1.6 KiB
C

/* xalloc-oversized.h -- memory allocation size checking
Copyright (C) 1990-2000, 2003-2004, 2006-2015 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef XALLOC_OVERSIZED_H_
# define XALLOC_OVERSIZED_H_
# include <stddef.h>
/* Return 1 if an array of N objects, each of size S, cannot exist due
to size arithmetic overflow. S must be positive and N must be
nonnegative. This is a macro, not a function, so that it
works correctly even when SIZE_MAX < N.
By gnulib convention, SIZE_MAX represents overflow in size
calculations, so the conservative dividend to use here is
SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
However, malloc (SIZE_MAX) fails on all known hosts where
sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
exactly-SIZE_MAX allocations on such hosts; this avoids a test and
branch when S is known to be 1. */
# define xalloc_oversized(n, s) \
((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
#endif /* !XALLOC_OVERSIZED_H_ */