src/safe_memclear.c

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