kc3-lang/gnulib/lib/xalloc-oversized.h

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• Hash : 32a72f45
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  Date : 2023-01-01T01:14:21
  

  maint: run 'make update-copyright'
  

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• lib/xalloc-oversized.h

• /* xalloc-oversized.h -- memory allocation size checking
  
     Copyright (C) 1990-2000, 2003-2004, 2006-2023 Free Software Foundation, Inc.
  
     This file is free software: you can redistribute it and/or modify
     it under the terms of the GNU Lesser General Public License as
     published by the Free Software Foundation; either version 2.1 of the
     License, or (at your option) any later version.
  
     This file 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 Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  
  #ifndef XALLOC_OVERSIZED_H_
  #define XALLOC_OVERSIZED_H_
  
  #include <stddef.h>
  #include <stdint.h>
  
  /* True if N * S does not fit into both ptrdiff_t and size_t.
     N and S should be nonnegative and free of side effects.
     This expands to a constant expression if N and S are both constants.
     By gnulib convention, SIZE_MAX represents overflow in size_t
     calculations, so the conservative size_t-based dividend to use here
     is SIZE_MAX - 1.  */
  #define __xalloc_oversized(n, s) \
    ((s) != 0 \
     && ((size_t) (PTRDIFF_MAX < SIZE_MAX ? PTRDIFF_MAX : SIZE_MAX - 1) / (s) \
         < (n)))
  
  /* Return 1 if and only if an array of N objects, each of size S,
     cannot exist reliably because its total size in bytes would exceed
     MIN (PTRDIFF_MAX, SIZE_MAX - 1).
  
     N and S should be nonnegative and free of side effects.
  
     Warning: (xalloc_oversized (N, S) ? NULL : malloc (N * S)) can
     misbehave if N and S are both narrower than ptrdiff_t and size_t,
     and can be rewritten as (xalloc_oversized (N, S) ?  NULL
     : malloc (N * (size_t) S)).
  
     This is a macro, not a function, so that it works even if an
     argument exceeds MAX (PTRDIFF_MAX, SIZE_MAX).  */
  #if 7 <= __GNUC__ && !defined __clang__ && PTRDIFF_MAX < SIZE_MAX
  # define xalloc_oversized(n, s) \
     __builtin_mul_overflow_p (n, s, (ptrdiff_t) 1)
  #elif (5 <= __GNUC__ && !defined __ICC && !__STRICT_ANSI__ \
         && PTRDIFF_MAX < SIZE_MAX)
  # define xalloc_oversized(n, s) \
     (__builtin_constant_p (n) && __builtin_constant_p (s) \
      ? __xalloc_oversized (n, s) \
      : ({ ptrdiff_t __xalloc_count; \
           __builtin_mul_overflow (n, s, &__xalloc_count); }))
  
  /* Other compilers use integer division; this may be slower but is
     more portable.  */
  #else
  # define xalloc_oversized(n, s) __xalloc_oversized (n, s)
  #endif
  
  #endif /* !XALLOC_OVERSIZED_H_ */
  

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