src/mem.c

   1 /*
   2     Copyright (C) 2017-2023 Ben Kibbey <bjk@luxsci.net>
   3
   4     This file is part of libpwmd.
   5
   6     This library is free software; you can redistribute it and/or
   7     modify it under the terms of the GNU Lesser General Public
   8     License version 2.1 as published by the Free Software Foundation.
   9
  10     This library 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 GNU
  13     Lesser General Public License for more details.
  14
  15     You should have received a copy of the GNU Lesser General Public
  16     License along with this library; if not, write to the Free Software
  17     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
  18     USA
  19 */
  20 #ifdef HAVE_CONFIG_H
  21 #include <config.h>
  22 #endif
  23
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <stddef.h>
  28 #ifdef HAVE_UNISTD_H
  29 #include <unistd.h>
  30 #endif
  31
  32 #include "mem.h"
  33
  34 void *
  35 _xrealloc_gpgrt (void *p, size_t n)
  36 {
  37   if (n)
  38     return p ? _xrealloc (p, n) : _xmalloc (n);
  39
  40   _xfree (p);
  41   return NULL;
  42 }
  43
  44 /* Borrowed from g10code:
  45  * https://lists.gnupg.org/pipermail/gnupg-devel/2018-November/034060.html
  46  */
  47 void
  48 wipememory (void *ptr, int c, size_t len)
  49 {
  50 #if defined(HAVE_W32_SYSTEM) && defined(SecureZeroMemory)
  51   (void)c;
  52   SecureZeroMemory (ptr, len);
  53 #elif defined(HAVE_EXPLICIT_BZERO)
  54   (void)c;
  55   explicit_bzero (ptr, len);
  56 #elif defined(HAVE_MEMSET_S)
  57   memset_s (ptr, len, c, len);
  58 #else
  59   /* Prevent compiler from optimizing away the call to memset by accessing
  60      memset through volatile pointer. */
  61   static void *(*volatile memset_ptr)(void *, int, size_t) = (void *)memset;
  62   memset_ptr (ptr, c, len);
  63 #endif
  64 }
  65
  66 #ifndef MEM_DEBUG
  67 struct memchunk_s
  68 {
  69   size_t size;
  70   char data[1];
  71 };
  72
  73 void
  74 _xfree (void *ptr)
  75 {
  76   struct memchunk_s *m;
  77   void *p;
  78
  79   if (!ptr)
  80     return;
  81
  82   m = (struct memchunk_s *)((char *)ptr-(offsetof (struct memchunk_s, data)));
  83   p = (void *)((char *)m+(offsetof (struct memchunk_s, data)));
  84   wipememory (p, 0, m->size);
  85   free (m);
  86 }
  87
  88 void *
  89 _xmalloc (size_t size)
  90 {
  91   struct memchunk_s *m;
  92
  93   if (!size)
  94     return NULL;
  95
  96   m = malloc (sizeof (struct memchunk_s)+size);
  97   if (!m)
  98     return NULL;
  99
 100   m->size = size;
 101   return (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 102 }
 103
 104 void *
 105 _xcalloc (size_t nmemb, size_t size)
 106 {
 107   void *p;
 108   struct memchunk_s *m;
 109
 110   m = malloc (sizeof (struct memchunk_s)+(nmemb*size));
 111   if (!m)
 112     return NULL;
 113
 114   m->size = nmemb*size;
 115   p = (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 116   memset (p, 0, m->size);
 117   return p;
 118 }
 119
 120 void *
 121 _xrealloc (void *ptr, size_t size)
 122 {
 123   void *p, *np;
 124   struct memchunk_s *m, *mp;
 125   size_t n;
 126
 127   if (!size && ptr)
 128     {
 129       m = (struct memchunk_s *)((char *)ptr-(offsetof (struct memchunk_s, data)));
 130       p = (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 131       wipememory (p, 0, m->size);
 132       free (m);
 133       return NULL;
 134     }
 135   else if (!ptr)
 136     return _xmalloc (size);
 137
 138   m = malloc (sizeof (struct memchunk_s)+size);
 139   if (!m)
 140     return NULL;
 141
 142   m->size = size;
 143   np = (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 144
 145   mp = (struct memchunk_s *)((char *)ptr-(offsetof (struct memchunk_s, data)));
 146   p = (void *)((char *)mp+(offsetof (struct memchunk_s, data)));
 147
 148   n = size > mp->size ? mp->size : size;
 149   memcpy (np, p, n);
 150   wipememory (p, 0, mp->size);
 151
 152   free (mp);
 153   return (void *)((char *)m+(offsetof (struct memchunk_s, data)));
 154 }
 155 #endif