On Fri, Dec 28, 2012 at 09:08:39AM -0800, Paul Eggert wrote: > On 12/28/2012 05:29 AM, Ondřej Bílka wrote: > >Initialy I examined gnulib one but it uses hash tables and is hard to > >inline so I wrote faster variant. > > Where is the faster variant?
Below. I fixed few details since first submission to libc-alpha. > Should/could it be merged into gnulib? Should. I am not expert on portability issues so improving portability would be appreciated. /* Safe automatic memory allocation. Copyright (C) 2012 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, see <http://www.gnu.org/licenses/>. */ #ifndef _MALLOCA_H #define _MALLOCA_H #include <alloca.h> #include <stddef.h> #include <stdlib.h> #include <stdio.h> #include <stdint.h> #ifdef __cplusplus extern "C" { #endif #define _ALLOCA_MC 0x2439a2431bca4812L #define _MALLOC_MC 0x1bca48122439a243L /* AIX requires this to be the first thing in the file. */ #ifndef __GNUC__ # if HAVE_ALLOCA_H || defined _LIBC # include <alloca.h> # else # ifdef _AIX #pragma alloca # else # ifndef alloca /* predefined by HP cc +Olibcalls */ char *alloca (); # endif # endif # endif #endif /* malloca(N) is a safe variant of alloca(N). It allocates N bytes of memory allocated on the stack or heap for large requests. It must be freed using freea() before the function returns. Upon failure, it returns NULL. */ #if 1 #define malloca(n) ({\ void *__r__ = NULL;\ if (n < 4096 - 8)\ {\ __r__ = alloca (n + sizeof (uint64_t));\ if (__r__)\ {\ *((uint64_t *)__r__) = _ALLOCA_MC;\ __r__ += sizeof (uint64_t);\ }\ }\ if (!__r__)\ {\ __r__ = malloc (n + sizeof (uint64_t));\ if (__r__)\ {\ *((uint64_t *)__r__) = _MALLOC_MC;\ __r__ += sizeof (uint64_t);\ }\ }\ __r__;\ }) /* If desired we could detect more corruption by adding constant to end of alloca'd array.*/ #define freea(r) {\ void *__r__ = r;\ if (__r__)\ {\ __r__ -= sizeof (uint64_t);\ if ( *((uint64_t *)__r__) == _MALLOC_MC)\ free (__r__);\ else if (*((uint64_t *)__r__) != _ALLOCA_MC)\ __abort_freea();\ }\ } static void __abort_freea() { fprintf(stderr, "double freea or corruption\n"); abort(); } #else #define malloca malloc #define freea free #endif #ifdef __cplusplus } #endif #endif /* _MALLOCA_H */
