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libiconv 1.16

    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_ */