1  /* Erasure of sensitive data, generic implementation.
       2     Copyright (C) 2016-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C 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 the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  /* An assembler implementation of explicit_bzero can be created as an
      20     assembler alias of an optimized bzero implementation.
      21     Architecture-specific implementations also need to define
      22     __explicit_bzero_chk.  */
      23  
      24  #include <string.h>
      25  
      26  /* glibc-internal users use __explicit_bzero_chk, and explicit_bzero
      27     redirects to that.  */
      28  #undef explicit_bzero
      29  
      30  /* Set LEN bytes of S to 0.  The compiler will not delete a call to
      31     this function, even if S is dead after the call.  */
      32  void
      33  explicit_bzero (void *s, size_t len)
      34  {
      35    memset (s, '\0', len);
      36    /* Compiler barrier.  */
      37    asm volatile ("" ::: "memory");
      38  }