lib/alloca_.h

   1 /* Memory allocation on the stack.
   2    Copyright (C) 1995, 1999, 2001-2003 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify it
   5    under the terms of the GNU General Public License as published
   6    by the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public
  15    License along with this program; if not, write to the Free Software
  16    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  17    USA.  */
  18
  19 /* When this file is included, it may be preceded only by preprocessor
  20    declarations.  Thanks to AIX.  Therefore we include it right after
  21    "config.h", not later.  */
  22
  23 #ifndef _ALLOCA_H
  24 # define _ALLOCA_H
  25
  26 /* alloca(N) returns a pointer (void* or char*) to N bytes of memory
  27    allocated on the stack, and which will last until the function returns.
  28    Use of alloca should be avoided:
  29      - inside arguments of function calls - undefined behaviour,
  30      - in inline functions - the allocation may actually last until the
  31        calling function returns,
  32      - for huge N (say, N >= 65536) - you never know how large (or small)
  33        the stack is, and when the stack cannot fulfill the memory allocation
  34        request, the program just crashes.
  35  */
  36
  37 # ifdef __GNUC__
  38 #  ifndef alloca
  39 #   define alloca __builtin_alloca
  40 #  endif
  41 # else
  42 #  ifdef _MSC_VER
  43 #   include <malloc.h>
  44 #   define alloca _alloca
  45 #  else
  46 #   if HAVE_ALLOCA_H
  47 #    include <alloca.h>
  48 #   else
  49 #    ifdef _AIX
  50  #    pragma alloca
  51 #    else
  52 #     ifdef __hpux /* This section must match that of bison generated files. */
  53 #      ifdef __cplusplus
  54 extern "C" void *alloca (unsigned int);
  55 #      else /* not __cplusplus */
  56 extern void *alloca ();
  57 #      endif /* not __cplusplus */
  58 #     else /* not __hpux */
  59 #      ifndef alloca
  60 extern char *alloca ();
  61 #      endif
  62 #     endif /* __hpux */
  63 #    endif
  64 #   endif
  65 #  endif
  66 # endif
  67
  68 #endif /* _ALLOCA_H */