lib/xmalloca.h

   1 /* Safe automatic memory allocation with out of memory checking.
   2    Copyright (C) 2003, 2005, 2007, 2009-2024 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 /* This file uses _GL_ATTRIBUTE_ALLOC_SIZE, _GL_ATTRIBUTE_DEALLOC,
  22    _GL_ATTRIBUTE_MALLOC, _GL_ATTRIBUTE_RETURNS_NONNULL, HAVE_ALLOCA.  */
  23 #if !_GL_CONFIG_H_INCLUDED
  24  #error "Please include config.h first."
  25 #endif
  26
  27 #include "malloca.h"
  28 #include "xalloc.h"
  29 #include "xalloc-oversized.h"
  30
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36
  37 /* xmalloca(N) is a checking safe variant of alloca(N).  It allocates N bytes
  38    of memory allocated on the stack, that must be freed using freea() before
  39    the function returns.  N should not have side effects.
  40    Upon failure, it exits with an error message.  */
  41 #if HAVE_ALLOCA
  42 # define xmalloca(N) \
  43   ((N) < 4032 - (2 * sa_alignment_max - 1)                                   \
  44    ? (void *) (((uintptr_t) (char *) alloca ((N) + 2 * sa_alignment_max - 1) \
  45                 + (2 * sa_alignment_max - 1))                                \
  46                & ~(uintptr_t)(2 * sa_alignment_max - 1))                     \
  47    : xmmalloca (N))
  48 extern void * xmmalloca (size_t n)
  49   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC (freea, 1)
  50   _GL_ATTRIBUTE_ALLOC_SIZE ((1)) _GL_ATTRIBUTE_RETURNS_NONNULL;
  51 #else
  52 # define xmalloca(N) \
  53   xmalloc (N)
  54 #endif
  55
  56 /* xnmalloca(N,S) is an overflow-safe variant of xmalloca (N * S).
  57    It allocates an array of N objects, each with S bytes of memory,
  58    on the stack.  S must be positive and N must be nonnegative,
  59    and S and N should not have side effects.
  60    The array must be freed using freea() before the function returns.
  61    Upon failure, it exits with an error message.  */
  62 #if HAVE_ALLOCA
  63 /* Rely on xmalloca (SIZE_MAX) calling xalloc_die ().  */
  64 # define xnmalloca(n, s) \
  65     xmalloca (xalloc_oversized (n, s) ? (size_t) (-1) : (n) * (size_t) (s))
  66 #else
  67 # define xnmalloca(n, s) \
  68     xnmalloc (n, s)
  69 #endif
  70
  71
  72 #ifdef __cplusplus
  73 }
  74 #endif
  75
  76
  77 #endif /* _XMALLOCA_H */