src/mem.c

   1 /*
   2     Copyright (C) 2006-2021 Ben Kibbey <bjk@luxsci.net>
   3
   4     This file is part of pwmd.
   5
   6     Pwmd is free software: you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License version 2 as
   8     published by the Free Software Foundation.
   9
  10     Pwmd 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 Pwmd.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18 #ifdef HAVE_CONFIG_H
  19 #include <config.h>
  20 #endif
  21
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <unistd.h>
  25 #include <string.h>
  26 #include <stddef.h>
  27
  28 #include "mem.h"
  29
  30 void *
  31 xrealloc_gpgrt (void *p, size_t n)
  32 {
  33   if (n)
  34     {
  35       if (p)
  36         return xrealloc (p, n);
  37
  38       return xmalloc (n);
  39     }
  40
  41   xfree (p);
  42   return NULL;
  43 }
  44
  45 /* Borrowed from g10code:
  46  * https://lists.gnupg.org/pipermail/gnupg-devel/2018-November/034060.html
  47  */
  48 void
  49 wipememory (void *ptr, int c, size_t len)
  50 {
  51 #if defined(HAVE_W32_SYSTEM) && defined(SecureZeroMemory)
  52   (void)c;
  53   SecureZeroMemory (ptr, len);
  54 #elif defined(HAVE_EXPLICIT_BZERO)
  55   (void)c;
  56   explicit_bzero (ptr, len);
  57 #elif defined(HAVE_MEMSET_S)
  58   memset_s (ptr, len, c, len);
  59 #else
  60   /* Prevent compiler from optimizing away the call to memset by accessing
  61      memset through volatile pointer. */
  62   static void *(*volatile memset_ptr)(void *, int, size_t) = (void *)memset;
  63   memset_ptr (ptr, c, len);
  64 #endif
  65 }
  66
  67 #ifndef MEM_DEBUG
  68 struct memchunk_s
  69 {
  70   size_t size;
  71   char data[1];
  72 } __attribute ((packed));
  73
  74 void
  75 xfree (void *ptr)
  76 {
  77   struct memchunk_s *m;
  78   void *p;
  79
  80   if (!ptr)
  81     return;
  82
  83   m = (struct memchunk_s *)((char *)ptr-(offsetof (struct memchunk_s, data)));
  84   p = (void *)((char *)m+(offsetof (struct memchunk_s, data)));
  85   wipememory (p, 0, m->size);
  86   free (m);
  87 }
  88
  89 void *
  90 xmalloc (size_t size)
  91 {
  92   struct memchunk_s *m;
  93
  94   if (!size)
  95     return NULL;
  96
  97   m = malloc (sizeof (struct memchunk_s)+size);
  98   if (!m)
  99     return NULL;
 100
 101   m->size = size;
 102   return (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 103 }
 104
 105 void *
 106 xcalloc (size_t nmemb, size_t size)
 107 {
 108   void *p;
 109   struct memchunk_s *m;
 110
 111   m = malloc (sizeof (struct memchunk_s)+(nmemb*size));
 112   if (!m)
 113     return NULL;
 114
 115   m->size = nmemb*size;
 116   p = (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 117   memset (p, 0, m->size);
 118   return p;
 119 }
 120
 121 void *
 122 xrealloc (void *ptr, size_t size)
 123 {
 124   void *p, *np;
 125   struct memchunk_s *m, *mp;
 126   size_t n;
 127
 128   if (!size && ptr)
 129     {
 130       m = (struct memchunk_s *)((char *)ptr-(offsetof (struct memchunk_s, data)));
 131       p = (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 132       wipememory (p, 0, m->size);
 133       free (m);
 134       return NULL;
 135     }
 136   else if (!ptr)
 137     return xmalloc (size);
 138
 139   m = malloc (sizeof (struct memchunk_s)+size);
 140   if (!m)
 141     return NULL;
 142
 143   m->size = size;
 144   np = (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 145
 146   mp = (struct memchunk_s *)((char *)ptr-(offsetof (struct memchunk_s, data)));
 147   p = (void *)((char *)mp+(offsetof (struct memchunk_s, data)));
 148
 149   n = size > mp->size ? mp->size : size;
 150   memcpy (np, p, n);
 151   wipememory (p, 0, mp->size);
 152
 153   free (mp);
 154   return (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 155 }
 156
 157 #endif