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Annotation of embedaddon/libiconv/srclib/xalloc-oversized.h, revision 1.1

1.1     ! misho       1: /* xalloc-oversized.h -- memory allocation size checking
        !             2: 
        !             3:    Copyright (C) 1990-2000, 2003-2004, 2006-2019 Free Software Foundation, Inc.
        !             4: 
        !             5:    This program is free software: you can redistribute it and/or modify
        !             6:    it under the terms of the GNU General Public License as published by
        !             7:    the Free Software Foundation; either version 3 of the License, or
        !             8:    (at your option) any later version.
        !             9: 
        !            10:    This program is distributed in the hope that it will be useful,
        !            11:    but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            12:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            13:    GNU General Public License for more details.
        !            14: 
        !            15:    You should have received a copy of the GNU General Public License
        !            16:    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
        !            17: 
        !            18: #ifndef XALLOC_OVERSIZED_H_
        !            19: #define XALLOC_OVERSIZED_H_
        !            20: 
        !            21: #include <stddef.h>
        !            22: #include <stdint.h>
        !            23: 
        !            24: /* True if N * S would overflow in a size_t calculation,
        !            25:    or would generate a value larger than PTRDIFF_MAX.
        !            26:    This expands to a constant expression if N and S are both constants.
        !            27:    By gnulib convention, SIZE_MAX represents overflow in size
        !            28:    calculations, so the conservative size_t-based dividend to use here
        !            29:    is SIZE_MAX - 1.  */
        !            30: #define __xalloc_oversized(n, s) \
        !            31:   ((size_t) (PTRDIFF_MAX < SIZE_MAX ? PTRDIFF_MAX : SIZE_MAX - 1) / (s) < (n))
        !            32: 
        !            33: #if PTRDIFF_MAX < SIZE_MAX
        !            34: typedef ptrdiff_t __xalloc_count_type;
        !            35: #else
        !            36: typedef size_t __xalloc_count_type;
        !            37: #endif
        !            38: 
        !            39: /* Return 1 if an array of N objects, each of size S, cannot exist
        !            40:    reliably due to size or ptrdiff_t arithmetic overflow.  S must be
        !            41:    positive and N must be nonnegative.  This is a macro, not a
        !            42:    function, so that it works correctly even when SIZE_MAX < N.  */
        !            43: 
        !            44: #if 7 <= __GNUC__
        !            45: # define xalloc_oversized(n, s) \
        !            46:    __builtin_mul_overflow_p (n, s, (__xalloc_count_type) 1)
        !            47: #elif 5 <= __GNUC__ && !defined __ICC && !__STRICT_ANSI__
        !            48: # define xalloc_oversized(n, s) \
        !            49:    (__builtin_constant_p (n) && __builtin_constant_p (s) \
        !            50:     ? __xalloc_oversized (n, s) \
        !            51:     : ({ __xalloc_count_type __xalloc_count; \
        !            52:          __builtin_mul_overflow (n, s, &__xalloc_count); }))
        !            53: 
        !            54: /* Other compilers use integer division; this may be slower but is
        !            55:    more portable.  */
        !            56: #else
        !            57: # define xalloc_oversized(n, s) __xalloc_oversized (n, s)
        !            58: #endif
        !            59: 
        !            60: #endif /* !XALLOC_OVERSIZED_H_ */