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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.
45 lines
1.8 KiB
C
45 lines
1.8 KiB
C
/* Generic implementation of __memset_explicit_chk.
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Copyright (C) 1991-2025 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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/* This is the generic definition of __memset_explicit_chk. The
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__memset_explicit_chk symbol is used as the implementation of
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memset_explicit throughout glibc. If this file is overridden by an
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architecture, both __memset_explicit_chk and
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__memset_explicit_chk_internal have to be defined (the latter not as
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an IFUNC). */
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#include <string.h>
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void *
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__memset_explicit_chk (void *dst, int c, size_t len, size_t dstlen)
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{
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/* Inline __memset_chk to avoid a PLT reference to __memset_chk. */
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if (__glibc_unlikely (dstlen < len))
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__chk_fail ();
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memset (dst, c, len);
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/* Compiler barrier. */
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asm volatile ("" ::: "memory");
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return dst;
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}
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/* libc-internal references use the hidden
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__memset_explicit_chk_internal symbol. This is necessary if
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__memset_explicit_chk is implemented as an IFUNC because some
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targets do not support hidden references to IFUNC symbols. */
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strong_alias (__memset_explicit_chk, __memset_explicit_chk_internal)
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