src/safe_memclear.c

   1 #include "first.h"
   2
   3 #include "settings.h"
   4
   5 #include "safe_memclear.h"
   6
   7 #include <string.h>
   8
   9 #if !defined(HAVE_MEMSET_S) && !defined(HAVE_EXPLICIT_BZERO)
  10
  11 #  if defined(HAVE_WEAK_SYMBOLS)
  12 /* it seems weak functions are never inlined, even for static builds */
  13 __attribute__((weak)) void __li_safe_memset_hook(void *buf, size_t len);
  14
  15 void __li_safe_memset_hook(void *buf, size_t len)
  16 {
  17         UNUSED(buf);
  18         UNUSED(len);
  19 }
  20 #  endif /* HAVE_WEAK_SYMBOLS */
  21
  22 static void* safe_memset(void *s, int c, size_t n)
  23 {
  24         if (n > 0) {
  25                 volatile unsigned volatile_zero = 0;
  26                 volatile unsigned char *vs = (volatile unsigned char*)s;
  27
  28                 do {
  29                         memset(s, c, n);
  30                 } while (vs[volatile_zero] != (unsigned char)c);
  31 #  if defined(HAVE_WEAK_SYMBOLS)
  32                 __li_safe_memset_hook(s, n);
  33 #  endif /* HAVE_WEAK_SYMBOLS */
  34         }
  35
  36         return s;
  37 }
  38 #endif /* !defined(HAVE_MEMSET_S) && !defined(HAVE_EXPLICIT_BZERO) */
  39
  40
  41 void safe_memclear(void *s, size_t n) {
  42 #if defined(HAVE_MEMSET_S)
  43         memset_s(s, n, 0, n);
  44 #elif defined(HAVE_EXPLICIT_BZERO)
  45         explicit_bzero(s, n);
  46 #else
  47         safe_memset(s, 0, n);
  48 #endif
  49 }