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/* xalloc-oversized.h -- memory allocation size checking
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Copyright (C) 1990-2000, 2003-2004, 2006-2012 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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#ifndef XALLOC_OVERSIZED_H_
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# define XALLOC_OVERSIZED_H_
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/* Return 1 if an array of N objects, each of size S, cannot exist due
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to size arithmetic overflow. S must be positive and N must be
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nonnegative. This is a macro, not an inline function, so that it
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works correctly even when SIZE_MAX < N.
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By gnulib convention, SIZE_MAX represents overflow in size
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calculations, so the conservative dividend to use here is
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SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
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However, malloc (SIZE_MAX) fails on all known hosts where
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sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
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exactly-SIZE_MAX allocations on such hosts; this avoids a test and
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branch when S is known to be 1. */
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# define xalloc_oversized(n, s) \
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((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
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#endif /* !XALLOC_OVERSIZED_H_ */
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lib/xalloc-oversized.h
