compat/posix_memalign.c

   1 /*****************************************************************************
   2  * posix_memalign.c: POSIX posix_memalign() replacement
   3  *****************************************************************************
   4  * Copyright © 2012, 2019 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include <errno.h>
  26 #include <stdlib.h>
  27 #include <limits.h>
  28
  29 #ifdef HAVE_MEMALIGN
  30 # include <malloc.h>
  31 #else
  32
  33 static void *memalign(size_t align, size_t size)
  34 {
  35     void *p = malloc(size);
  36
  37     if ((uintptr_t)p & (align - 1)) {
  38         free(p);
  39         p = NULL;
  40     }
  41
  42     return p;
  43 }
  44
  45 #endif
  46
  47 static int check_align(size_t align)
  48 {
  49     if (align & (align - 1)) /* must be a power of two */
  50         return EINVAL;
  51     if (align < sizeof (void *)) /* must be a multiple of sizeof (void *) */
  52         return EINVAL;
  53     return 0;
  54 }
  55
  56 int posix_memalign(void **ptr, size_t align, size_t size)
  57 {
  58     int val = check_align(align);
  59     if (val)
  60         return val;
  61
  62     /* Unlike posix_memalign(), legacy memalign() requires that size be a
  63      * multiple of align.
  64      */
  65     if (size > (SIZE_MAX / 2))
  66         return ENOMEM;
  67
  68     size += (-size) & (align - 1);
  69
  70     int saved_errno = errno;
  71     void *p = memalign(align, size);
  72     if (p == NULL) {
  73         val = errno;
  74         errno = saved_errno;
  75         return val;
  76     }
  77
  78     *ptr = p;
  79     return 0;
  80 }