lib/xmalloca.h

   1 /* Safe automatic memory allocation with out of memory checking.
   2    Copyright (C) 2003, 2005, 2007, 2009-2020 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2003.
   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 _XMALLOCA_H
  19 #define _XMALLOCA_H
  20
  21 #include "malloca.h"
  22 #include "xalloc.h"
  23
  24
  25 #ifdef __cplusplus
  26 extern "C" {
  27 #endif
  28
  29
  30 /* xmalloca(N) is a checking safe variant of alloca(N).  It allocates N bytes
  31    of memory allocated on the stack, that must be freed using freea() before
  32    the function returns.  Upon failure, it exits with an error message.  */
  33 #if HAVE_ALLOCA
  34 # define xmalloca(N) \
  35   ((N) < 4032 - (2 * sa_alignment_max - 1)                                   \
  36    ? (void *) (((uintptr_t) (char *) alloca ((N) + 2 * sa_alignment_max - 1) \
  37                 + (2 * sa_alignment_max - 1))                                \
  38                & ~(uintptr_t)(2 * sa_alignment_max - 1))                     \
  39    : xmmalloca (N))
  40 extern void * xmmalloca (size_t n);
  41 #else
  42 # define xmalloca(N) \
  43   xmalloc (N)
  44 #endif
  45
  46 /* xnmalloca(N,S) is an overflow-safe variant of xmalloca (N * S).
  47    It allocates an array of N objects, each with S bytes of memory,
  48    on the stack.  S must be positive and N must be nonnegative.
  49    The array must be freed using freea() before the function returns.
  50    Upon failure, it exits with an error message.  */
  51 #if HAVE_ALLOCA
  52 /* Rely on xmalloca (SIZE_MAX) calling xalloc_die ().  */
  53 # define xnmalloca(n, s) \
  54     xmalloca (xalloc_oversized ((n), (s)) ? (size_t) (-1) : (n) * (s))
  55 #else
  56 # define xnmalloca(n, s) \
  57     xnmalloc ((n), (s))
  58 #endif
  59
  60
  61 #ifdef __cplusplus
  62 }
  63 #endif
  64
  65
  66 #endif /* _XMALLOCA_H */