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0f201f4a81
Add the C23 memset_explicit function to glibc. Everything here is closely based on the approach taken for explicit_bzero. This includes the bits that relate to internal uses of explicit_bzero within glibc (although we don't currently have any such internal uses of memset_explicit), and also includes the nonnull attribute (when we move to nonnull_if_nonzero for various functions following C2y, this function should be included in that change). The function is declared both for __USE_MISC and for __GLIBC_USE (ISOC23) (so by default not just for compilers defaulting to C23 mode). Tested for x86_64 and x86.
40 lines
1.4 KiB
C
40 lines
1.4 KiB
C
/* Erasure of sensitive data, generic implementation.
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Copyright (C) 2016-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* An assembler implementation of memset_explicit can be created as an
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assembler alias of an optimized memset implementation.
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Architecture-specific implementations also need to define
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__memset_explicit_chk. */
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#include <string.h>
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/* glibc-internal users use __memset_explicit_chk, and memset_explicit
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redirects to that. */
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#undef memset_explicit
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/* Set LEN bytes of S to C. The compiler will not delete a call to
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this function, even if S is dead after the call. */
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void *
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memset_explicit (void *s, int c, size_t len)
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{
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memset (s, c, len);
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/* Compiler barrier. */
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asm volatile ("" ::: "memory");
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return s;
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}
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