| 1 | /* xalloc-oversized.h -- memory allocation size checking
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| 2 |
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| 3 | Copyright (C) 1990-2000, 2003-2004, 2006-2012 Free Software Foundation, Inc.
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| 4 |
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| 5 | This program is free software: you can redistribute it and/or modify
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| 6 | it under the terms of the GNU General Public License as published by
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| 7 | the Free Software Foundation; either version 3 of the License, or
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| 8 | (at your option) any later version.
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| 9 |
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| 10 | This program is distributed in the hope that it will be useful,
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | GNU General Public License for more details.
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| 14 |
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| 15 | You should have received a copy of the GNU General Public License
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| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */
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| 17 |
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| 18 | #ifndef XALLOC_OVERSIZED_H_
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| 19 | # define XALLOC_OVERSIZED_H_
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| 20 |
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| 21 | # include <stddef.h>
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| 22 |
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| 23 | /* Return 1 if an array of N objects, each of size S, cannot exist due
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| 24 | to size arithmetic overflow. S must be positive and N must be
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| 25 | nonnegative. This is a macro, not an inline function, so that it
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| 26 | works correctly even when SIZE_MAX < N.
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| 27 |
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| 28 | By gnulib convention, SIZE_MAX represents overflow in size
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| 29 | calculations, so the conservative dividend to use here is
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| 30 | SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
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| 31 | However, malloc (SIZE_MAX) fails on all known hosts where
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| 32 | sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
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| 33 | exactly-SIZE_MAX allocations on such hosts; this avoids a test and
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| 34 | branch when S is known to be 1. */
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| 35 | # define xalloc_oversized(n, s) \
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| 36 | ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
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| 37 |
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| 38 | #endif /* !XALLOC_OVERSIZED_H_ */
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