debug/explicit_bzero_chk.c

   1 /* Generic implementation of __explicit_bzero_chk.
   2    Copyright (C) 1991-2023 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 /* This is the generic definition of __explicit_bzero_chk.  The
  20    __explicit_bzero_chk symbol is used as the implementation of
  21    explicit_bzero throughout glibc.  If this file is overriden by an
  22    architecture, both __explicit_bzero_chk and
  23    __explicit_bzero_chk_internal have to be defined (the latter not as
  24    an IFUNC).  */
  25
  26 #include <string.h>
  27
  28 void
  29 __explicit_bzero_chk (void *dst, size_t len, size_t dstlen)
  30 {
  31   /* Inline __memset_chk to avoid a PLT reference to __memset_chk.  */
  32   if (__glibc_unlikely (dstlen < len))
  33     __chk_fail ();
  34   memset (dst, '\0', len);
  35   /* Compiler barrier.  */
  36   asm volatile ("" ::: "memory");
  37 }
  38
  39 /* libc-internal references use the hidden
  40    __explicit_bzero_chk_internal symbol.  This is necessary if
  41    __explicit_bzero_chk is implemented as an IFUNC because some
  42    targets do not support hidden references to IFUNC symbols.  */
  43 strong_alias (__explicit_bzero_chk, __explicit_bzero_chk_internal)